With advancements in minimally invasive surgery for colorectal cancer, rapid postoperative recovery and reintegration into daily life have become essential considerations. Although existing Enhanced Recovery After Surgery (ERAS) guidelines are available [1,2], there is a growing need to develop those that are appropriate for Korean healthcare. Consequently, the Korean Society of Surgical Metabolism and Nutrition has established an ERAS committee to formulate evidence-based practice guidelines. The primary objective is to assist frontline physicians treating colorectal cancer by providing evidence-based recommendations with clear levels of evidence and benefits for the application of ERAS protocols in postoperative recovery. This aims to facilitate safer and more effective clinical decision-making. Furthermore, it seeks to enhance the understanding of policymakers and patients desiring treatment.

The guidelines were developed using a de novo approach. The systematic review conducted for the development followed the methodology proposed by the Cochrane Collaboration [3]. The assessment of the quality of evidence and the determination of the strength of recommendations were based on the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology [4]. To enhance applicability within the Korean context, supplementary local studies were identified and incorporated.

Formulating key questions

The committee examined existing ERAS guidelines [1,2] to identify pivotal yet debatable issues needing evidence. After thorough discussions, they prioritized and finalized 13 key questions (KQs) (Table 1).

Table 1

Summary of recommendations

Recommendation	Strength	Level of evidence
KQ 1. Is prehabilitation effective for patients scheduled for elective surgery for colorectal cancer? - Prehabilitation is recommended for patients scheduled to undergo surgery for colorectal cancer.	Conditional for	Moderate
KQ 2. Is preoperative oral nutritional supplement effective for patients scheduled for elective surgery for colorectal cancer? - Preoperative nutritional support using oral nutritional supplements is recommended for patients scheduled for colorectal cancer surgery.	Conditional for	Moderate
KQ 3. What are the appropriate methods to prevent postoperative nausea and vomiting in patients scheduled for elective surgery for colorectal cancer? - The use of dexamethasone in combination with a serotonin receptor antagonist rather than monotherapy is recommended for the prevention of postoperative nausea and vomiting in patients scheduled for colorectal cancer surgery.	Strong for	High
KQ 4. Is the use of oral antibiotics in combination with mechanical bowel preparation effective for patients scheduled for elective colorectal cancer surgery? - The use of oral antibiotics in conjunction with mechanical bowel preparation is recommended for patients scheduled for colorectal cancer surgery.	Conditional for	High
KQ 5. Is preoperative oral carbohydrate loading effective for patients scheduled for elective colorectal cancer surgery? - Oral carbohydrate loading up to 2 hours before colorectal cancer surgery is recommended.	Conditional for	Moderate
KQ 6. Is goal-directed fluid therapy beneficial during elective surgery for colorectal cancer? - Goal-directed fluid therapy during surgery may be considered for high-risk patients undergoing colorectal cancer surgery.	Conditional for	Moderate
KQ 7. Is the insertion of an intra-abdominal drain necessary during elective surgery for colorectal cancer? - It is suggested that an intra-abdominal drain is not inserted during surgery for colorectal cancer.	Conditional against	Moderate
KQ 8. During elective surgery for colorectal cancer, does the insertion of a nasogastric tube aid in the patient’s recovery? - It is suggested that a nasogastric tube is not inserted during surgery for colorectal cancer.	Conditional against	Low
KQ 9. Is transversus abdominis plane (TAP) block effective for postoperative pain control following elective surgery for colorectal cancer? - TAP block may be considered for pain control during surgery for colorectal cancer.	Conditional for	Moderate
KQ 10. Is thromboprophylaxis necessary for patients scheduled for elective surgery for colorectal cancer? - Preoperative pharmacologic thromboprophylaxis is recommended for patients scheduled for colorectal cancer surgery.	Conditional for	Moderate
KQ 11. How long should urinary catheters be maintained after elective surgery for colorectal cancer? - It is recommended that urinary catheters are removed the day after colorectal cancer surgery.	Conditional for	Moderate
KQ 12. Is early feeding effective following elective surgery for colorectal cancer? - Early feeding is recommended to start the day after surgery for colorectal cancer.	Conditional for	Moderate
KQ 13. Is early ambulation effective following elective surgery for colorectal cancer? - Early ambulation is recommended to commence on the day after surgery for colorectal cancer.	Conditional for	Moderate

Literature search

A literature search was conducted by deriving primary search terms through discussions between the methodology expert and the development committee members responsible for each KQ. Search strategies were then established using MEDLINE (PubMed). The MEDLINE, Embase, Cochrane, and KoreaMed databases were used. Studies were collected without restrictions on publication year or language to ensure comprehensiveness, reproducibility, and homogeneity through a consistent approach for all KQs. The search was performed on August 15, 2023. At least three individuals, including the methodology expert, the committee member responsible for each KQ, and the committee chair, participated in all stages of the search process to eliminate subjective judgment. The finalized search strategies are included in Supplement Material 1.

Selection of literature

The selection of evidence was conducted by assigning at least two reviewers to each KQ, ensuring no overlap, and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Flow Diagram (Supplement Fig. 1) [5]. Inclusion and exclusion criteria for each KQ were formulated and applied using the Population, Intervention, Comparison, Outcomes, Study Design framework. All KQs targeted randomized controlled trials (RCTs) exclusively. If fewer than two RCTs were available, studies using propensity score matching were also included.

Risk of bias assessment

The quality assessment of the literature was conducted separately according to individual study designs (RCTs: Cochrane RoB [Risk-of-Bias Tool for Randomized Trials] 2.0 [6], non-randomized studies: ROBINS-I (Risk of Bias in Nonrandomized Studies of Intervention) [7]). The quality assessment of literature was conducted independently by the designated committee member for each KQ. Any discrepancies in assessment results were resolved through consensus among the committee members (Supplement Fig. 2).

Summation of estimates (meta-analysis)

Meta-analysis was conducted if there was no unexplained heterogeneity and multiple outcomes were available. Duplicate study results were managed by selecting the most recent or largest sample size. A fixed-effect model was used, and both statistical (I² statistic) and clinical heterogeneity were evaluated. The analysis covered all relevant outcomes of the intervention.

Level of evidence

The assessment of the level of evidence followed the grading criteria provided by the GRADE working group (Table 2). The assignment of each level of evidence was based on outcome measures. When both randomized and non-randomized studies provided evidence for the same outcome measure, the level of evidence from randomized studies was used as the reference value. The assigned level of evidence for recommendations was based on the level of evidence for the most critical primary outcome associated with each recommendation.

Table 2

Level of evidence

Level	Definition
High	Evidence from a well-conducted RCT/meta-analysis with low risk of bias in study design and conduct, or from an observational study with no bias in study design or conduct and an effect size rated as very large
Moderate	Evidence derived from RCT or meta-analysis with bias in study design and conduct, or from an observational study without bias in study design or conduct and a large effect size
Low	Evidence resulting from RCT or meta-analysis with biases reported in two or more aspects of study design and conduct, or from an observational study without biases in study design and conduct
Very low	Evidence from observational studies, case reports, or inadequately conducted observational studies with biases in study design and conduct

RCT = randomized controlled trial.

Strength of recommendation

The members developed a preliminary recommendation and recommendation grade for each KQ based on the level of evidence. The considerations included the strengths and limitations of the evidence, the balance between benefits and harms, the size of the benefits and harms, patient values and preferences, barriers to implementation by healthcare providers, financial considerations, and applicability within the specific healthcare institution. The strength of recommendation was defined by evaluating the balance of benefits and harms for each intervention based on evidence, through a blind voting process by the committee (Table 3).

Table 3

The definition of the strength of recommendation

Strength of recommendation	Strength	Direction	Definition
Strong recommendation	Strong	For	When the benefits of treatment or testing clearly outweigh the associated risks, burdens, and costs
Conditional recommendation	Conditional		When the benefits of treatment or testing potentially exceed the associated risks, burdens, and costs but remain uncertain
Conditional against	Conditional	Against	When the risks, burdens, and costs of treatment or testing potentially exceed the benefits but remain uncertain
Strong against	Strong		When the risks, burdens, and costs of treatment or testing clearly outweigh the benefits

Recommendation consensus

The draft recommendations underwent evaluation through a blind vote if participation from at least 70% of all internal committee members was achieved. Eleven members of the internal committee within the development committee participated in the recommendation grading process. If individual items received over 70% approval in the vote, with over 70% in favor, the committee considered it a consensus decision. If fewer than 70% of the votes were in favor, the development committee members considered amendments and a second vote was conducted.

External expert review

Relevant experts were selected to evaluate the content of the guidelines to enhance their quality. The Korean Society of Coloproctology recommended 18 individuals from among colorectal surgeons specializing in primary to tertiary hospitals, who had experience in conducting systematic reviews or had experience in developing other clinical guidelines. These individuals were surveyed for their opinions on the pros and cons of the recommendations and the validity of outcome indicators related to benefits and harms.

Guideline update plan

The guidelines are planned to be revised on a three-year cycle, with the addition of new recommendations or modifications and enhancements to existing recommendations when high-quality evidence regarding new diagnostic methods, medications, or treatments is reported. The revision process for the guidelines follows the principles of new development, applying the same methods as those used in the original guideline development. However, for recommendations that are developed subsequently, evidence searching will be conducted only for evidence added after August 15, 2023.

KQ 1. Is prehabilitation effective for patients scheduled for elective surgery for colorectal cancer?

Recommendation 1.

Prehabilitation is recommended for patients scheduled to undergo surgery for colorectal cancer.

Strength of the recommendation: conditional for

Level of evidence: moderate

Prehabilitation primarily consists of increasing physical activity, improving nutritional status, and stabilizing mental well-being. Prehabilitation through exercise consists of aerobic/anaerobic exercise sessions, lasting approximately one hour, three to four times per week over a period of 3 to 6 weeks. Prehabilitation has been shown to improve postoperative outcomes by enhancing baseline physical condition and mental functional capacity before surgery. The incidence rate of postoperative complications (Clavien Dindo Classification I, II) was assessable after analyzing a total of 9 studies [8-16]. Among the studies analyzed, several demonstrated significant differences between the two groups, indicating that patients who underwent preoperative prehabilitation had a statistically significant reduction in postoperative complication rates (Clavien Dindo Classification I, II) compared to those who did not undergo prehabilitation (odds ratio [OR], 0.70; 95% confidence interval [CI], 0.51–0.97) (Supplement Fig. 3A). However, no significant differences were observed between the two groups in terms of postoperative complications (Clavien Dindo Classification≥III), length of hospital stay, readmission rate, and mortality (Supplement Fig. 3B-F).

However, reflecting the situation in Korea, although there may be variations between institutions, it is generally assumed that if surgery for colorectal cancer is typically performed within three weeks of diagnosis, preoperative rehabilitation may not be feasible. Additionally, if patients prefer to undergo surgery shortly after diagnosis, the implementation of prehabilitation may be challenging. Furthermore, as described above, the introduction of comprehensive prehabilitation requires resources from various fields, including exercise, but it should be considered that it may not be feasible for all medical institutions to provide these resources within limited means.

Recommendation consensus meeting results

Ninety percent of the attending members (9 out of 10) endorsed the proposal. However, there were discussions on whether it is appropriate to allocate limited resources to prehabilitation, the practical feasibility of implementing several weeks of prehabilitation within the context of South Korea, and which patient groups should be conditionally recommended for prehabilitation.

External expert review results

The external experts’ opinions on the recommendation strength of the guideline revealed a relatively lower agreement rate (7–9 points) of 72% (13 out of 18). However, there was a high level of concordance (94%, 17 out of 18) for the response of “conditional for”regarding the appropriate recommendation level. Consequently, the committee confirmed the recommendation level as ‘conditional for’ without dissent.

KQ 2. Is preoperative oral nutritional supplement effective for patients scheduled for elective surgery for colorectal cancer?

Recommendation 2.

Preoperative nutritional support using oral nutritional supplements (ONS) is recommended for patients scheduled for colorectal cancer surgery.

Strength of the recommendation: conditional for

Level of evidence: moderate

It is well established that patients at nutritional risk have a higher incidence of postoperative complications and prolonged hospital stays [17,18]. Specifically, in colorectal cancer, symptoms such as loss of appetite, diarrhea, and bowel obstruction can increase the vulnerability of patients to malnutrition [18]. Consequently, perioperative nutritional supplementation is essential for appropriate recovery in these patients. In cases where adequate nutritional intake through oral consumption is challenging, the use of ONS prior to surgery is recommended. Immunonutrition, which includes arginine, ω-3 fatty acids, nucleotides, and high concentrations of protein, is preferred [19].The meta-analysis of postoperative complications encompassed a total of 8 studies [20-27]. While 6 studies did not demonstrate significant differences between the intervention and control groups, some reported that preoperative oral nutritional supplementation reduced postoperative complications [20,23]. Furthermore, the results revealed a significant association between preoperative oral nutritional supplementation and decreased postoperative complications (OR, 0.74; 95% CI, 0.55–0.98) (Supplement Fig. 4A). The analysis of hospital stay length included 5 studies reporting results on this outcome [21,24-27]. While Xu et al. [27] demonstrated a significant association between the intervention and control groups in terms of hospital stay, a meta-analysis of the 5 studies did not confirm this significance (mean difference [MD], –0.30; 95% CI, –0.95 to 0.36) (Supplement Fig. 4B). Regarding mortality, no patients were reported to have died within 30 days of surgery in any of the 8 studies included.

Recommendation consensus meeting results

Ninety percent of the attending members (9 out of 10) supported the proposal. The final recommendation was subsequently decided without dissent through consensus.

External expert review results

Seventy-two percent of the external experts (17 out of 18) endorsed the recommendation strength and direction of the guideline, with scores ranging from 7 to 9. Additionally, 94% (17 out of 18) responded with “conditional for” to the question regarding the appropriate recommendation strength. Consequently, the committee confirmed the recommendation strength as ‘conditional for’ without dissent.

KQ 3. What are the appropriate methods to prevent postoperative nausea and vomiting in patients scheduled for elective surgery for colorectal cancer?

Recommendation 3.

The use of dexamethasone in combination with a serotonin receptor antagonist rather than monotherapy is recommended for the prevention of postoperative nausea and vomiting (PONV) in patients scheduled for colorectal cancer surgery.

Strength of the recommendation: strong for

Level of evidence: high

PONV is one of the most common postoperative complications, causing patient dissatisfaction and discomfort. These symptoms can also lead to increased healthcare costs, prolonged hospital stays, or unexpected readmissions [28-31]. A systematic review was conducted on the efficacy of combined therapy using serotonin receptor antagonists (5-HT3 antagonists) and steroids, which is well-documented for the prevention of PONV.

A meta-analysis of 7 studies investigating PONV within 6 hours of surgery revealed that the combination of a serotonin receptor antagonist and dexamethasone significantly lowered the incidence compared to other treatments (OR, 0.48; 95% CI, 0.31–0.76) (Supplement Fig. 5A) [32-38]. Additionally, a meta-analysis of 14 studies examining PONV within 24 hours of surgery showed that combination therapy had a significantly lower incidence rate compared to serotonin receptor antagonist monotherapy (OR, 0.43; 95% CI, 0.33–0.56) (Supplement Fig. 5B) [33,35,36,38-48].

Common side effects of serotonin receptor antagonists and dexamethasone include headache, dizziness, fatigue, diarrhea, and pruritus. However, the most frequently reported side effects in the majority of studies were headache and dizziness. A meta-analysis of 4 studies reporting overall side effects found no significant difference between combination therapy and monotherapy (OR, 0.93; 95% CI, 0.60–1.44) [33,35,41,46] (Supplement Fig. 5C). Additionally, meta-analyses of 6 studies specifically analyzing headache (OR, 1.00; 95% CI, 0.55–1.82) and dizziness (OR, 0.77; 95% CI, 0.38–1.57) also showed no significant differences between combination therapy and monotherapy (Supplement Fig. 5D, E) [33,35,41,43,46,47].

The committee conducted a review of commonly used pharmacological agents and their clinical outcomes, in addition to those specified in the KQs. A summary of the types and doses of various agents used for the prevention of PONV is presented in Supplement Table 1. Among NK1 receptor antagonists, aprepitant, which is available domestically, shows comparable efficacy in preventing postoperative vomiting with an oral dose of 40 mg to an intravenous palonosetron of 0.075 mg [49]. Dexamethasone monotherapy has also been used for several years and is well-known for its effectiveness in PONV prevention. It is generally recommended in doses ranging from 4 to 10 mg, although recent reports have highlighted the efficacy of 8 mg or higher [50-52]. Among anti-dopaminergic agents, droperidol and haloperidol have shown efficacy in preventing PONV; however, there is a concern about the prolongation of QT interval [28]. Metoclopramide at doses of 25 and 50 mg is also effective in the prevention of PONV but extrapyramidal symptoms can occur as a side effect. Additionally, there are reports on the antiemetic efficacy of anticholinergic agents [53], and various combination therapies, as addressed in this study.

Recommendation consensus meeting results

Ninety-one percent of the attending members (10 out of 11) supported the recommendation strength and direction for the use of a combination of serotonin receptor antagonists and dexamethasone to prevent nausea and vomiting after elective colorectal surgery. Although there were concerns about a strong recommendation level, the committee reached consensus that the high level of evidence and the clear benefits of nausea and vomiting prevention provided by the combination therapy outweighed any minor side effects, thus justifying a strong recommendation.

External expert review results

The proportion of external experts who supported the recommendation strength for this key question was 61% (11 out of 18), which is relatively low. When asked about the appropriate recommendation strength, 50% (9 out of 18) favored a strong recommendation, while a significant number of experts chose “conditional for” (28%, 5 out of 18) or “conditional against” (22%, 4 out of 18). As mentioned, there are various methods for preventing nausea and vomiting. This guideline does not mandate the use of a combination of serotonin receptor antagonists and dexamethasone but rather strongly recommends the combination therapy over serotonin receptor antagonists alone. The choice of method for preventing nausea and vomiting should be at the discretion of the clinician, and various alternatives are detailed. After the discussion, the committee reached a consensus that a ‘strong recommendation’ is appropriate and confirmed it as the final recommendation.

KQ 4. Is the use of oral antibiotics in combination with mechanical bowel preparation effective for patients scheduled for elective colorectal cancer surgery?

Recommendation 4.

The use of oral antibiotics in conjunction with MBP is recommended for patients scheduled for colorectal cancer surgery.

Strength of the recommendation: conditional for

Level of evidence: high

When referring to bowel preparation methods to reduce surgical site infections (SSIs), previous guidelines have suggested that MBP provides no clinical benefit and is not recommended for colorectal cancer surgeries [54]. However, recent studies have demonstrated that the combination of MBP and oral antibiotic prophylaxis leads to a reduction in complications compared to using either method alone [55,56]. The incidence of SSIs was analyzed across 8 studies [57-64]. Several studies demonstrated significant differences between the groups, showing that the combination of preoperative MBP and oral antibiotic administration significantly reduced the incidence of SSIs compared to MBP alone (OR, 0.51; 95% CI, 0.39–0.66) (Supplement Fig. 6A). However, there were no significant differences between the groups concerning organ-space SSIs [57-63], including anastomotic leaks (Supplement Fig. 6B), or the readmission rate within 30 days (Supplement Fig. 6C) [57-60].

Recommendation consensus meeting results

Ninety percent of the attending members (9 out of 10) supported the recommendation strength and direction for this key question. There were concerns about whether recommending MBP and oral antibiotics for both colon and rectal cancer might be excessive, considering the resources required and patient discomfort. However, after reviewing the current evidence, it was determined that the benefits clearly outweigh the risks. Therefore, it was agreed to recommend the approach with a ‘conditional for’ recommendation strength.

External expert review results

Sixty-one percent of the external experts (11 out of 18) supported the recommendation strength (scoring 7–9), with 6 experts providing a score of 6. Most experts (94%, 17 out of 18) provided scores of 6 or higher. When asked about the appropriate recommendation strength, 72% (13 out of 18) selected ‘conditional for.’ Consequently, the committee integrated the results from the consensus meeting with the external experts’ opinions and confirmed ‘conditional for’ as the final recommendation strength.

KQ 5. Is preoperative oral carbohydrate loading effective for patients scheduled for elective colorectal cancer surgery?

Recommendation 5.

Oral carbohydrate loading up to 2 hours before colorectal cancer surgery is recommended.

Strength of the recommendation: conditional for

Level of evidence: moderate

The stress associated with surgery can induce peripheral insulin resistance, leading to hyperglycemia, which may increase the risk of postoperative complications and delay recovery [65]. Therefore, it can be hypothesized that preoperative oral carbohydrate loading may reduce insulin resistance and thereby decrease postoperative complications. The incidence of postoperative complications was assessed in 7 studies [66-72]. Most studies reported no significant differences between the groups, and meta-analysis also failed to demonstrate a significant correlation between preoperative oral carbohydrate supplementation and the incidence of postoperative complications (OR, 0.77; 95% CI, 0.49–1.19) (Supplement Fig. 7A). Similarly, there were no significant differences between the groups in terms of individual complications such as SSI [66-69,71,72] and prolonged postoperative ileus [66-72]. However, in the oral carbohydrate group, the time to first flatus was significantly shorter (MD, –0.52; 95% CI, –0.76 to –0.28) [66,69-71,73] and the length of hospital stay was also shorter (MD, –1.03; 95% CI, –1.39 to –0.68) [67-71,74,75] (Supplement Fig. 7B-E).

Preoperative fasting induces psychological stress in patients, and reducing the duration of fasting as much as possible has been shown to be effective for patients’ psychological well-being in several studies [76]. Rizvanović et al. [74] reported that the intake of oral carbohydrate solutions before colorectal surgery positively affects patients’ subjective feelings.

Recommendation consensus meeting results

Ninety-one percent of the attending members (10 out of 11) supported the recommendation strength and direction for prescribing oral carbohydrate supplements in elective colorectal surgery. While there were concerns that intake might be restricted in patients with bowel obstruction, it was agreed by the majority that since the guideline is limited to elective surgery, there would likely be few patients unable to take oral carbohydrate supplements due to bowel obstruction.

External expert review results

Eighty-nine percent of the external experts (16 out of 18) provided a support score of 7 or higher for a ‘conditional for’ recommendation. Additionally, 67% of the external experts (12 out of 18) endorsed the recommendation strength as ‘conditional for.’ Although 4 external experts (22%) suggested that a ‘strong recommendation’ might be more appropriate, the consensus was that a strong recommendation would be unsuitable due to potential difficulties in taking oral carbohydrate supplements for patients with diabetes or bowel obstruction. Consequently, the development committee confirmed ‘conditional for’ as the final recommendation strength.

KQ 6. Is goal-directed fluid therapy beneficial during elective surgery for colorectal cancer?

Recommendation 6.

GDFT during surgery may be considered for high-risk patients undergoing colorectal cancer surgery.

Strength of the recommendation: conditional for

Level of evidence: moderate

In relation to the ERAS protocol, restrictive fluid therapy or zero-balance fluid management has been introduced and widely studied to prevent weight gain due to postoperative fluid retention [1]. This approach can accelerate the recovery of gastrointestinal motility post-surgery and potentially reduce the length of hospital stay. However, excessive restriction of fluids requires caution as it may lead to acute kidney dysfunction [1,77]. GDFT refers to the adjustment of fluid administration based on the monitoring of various hemodynamic parameters [78]. There is no standardized criterion for targets in GDFT. However, it typically involves the monitoring of cardiac output and stroke volume using transesophageal echocardiography, central venous pressure via a central venous catheter, and stroke volume variation through arterial waveform analysis. Additionally, various bioimpedance analyses are used. The group receiving GDFT demonstrated a trend toward a lower incidence of overall postoperative complications compared to the control group, though this did not reach statistical significance (OR, 0.78; 95% CI, 0.60–1.01) (Supplement Fig. 8A) [79-88]. However, the incidence of SSIs was significantly reduced in the GDFT group (OR, 0.54; 95% CI. 0.30–0.97) (Supplement Fig. 8B) [79,85,86,88-90]. There were no significant differences between the groups concerning the frequency of anastomotic leaks (Supplement Fig. 8C) [79,82,85-91], prolonged postoperative ileus (Supplement Fig. 8D) [79,82,84-86,88,90], or mortality within 30 days post-surgery (Supplement Fig. 8E) [79-82,84,85,87,88,90-92]. Importantly, the length of hospital stay was significantly shorter in the GDFT group (MD, –0.30; 95% CI, –0.45 to –0.14) (Supplement Fig. 8F) [79-91,93].

According to previous studies, GDFT has been reported to be effective in high-risk patients [1,78]. A previous meta-analysis of patients undergoing abdominal surgery reported no benefit from the implementation of GDFT for all patients [94]. Specifically, with the application of the ERAS protocol, preoperative fasting and MBP are minimized, thereby reducing preoperative fluid deficit to a minimum, suggesting that zero-balance fluid management may be sufficient. Therefore, it is essential to select and apply GDFT to high-risk patients. While the definition of high-risk varies, it generally includes patients with severe cardiopulmonary disease, patients over 70 years old with poor general health, and surgeries expected to last longer than eight hours [1]. By applying GDFT to high-risk patients in medical institutions equipped with monitoring devices, a faster recovery can be achieved.

As stated above, this recommendation is limited to high-risk patients. In actual clinical practice, performing medical procedures such as transesophageal echocardiography for GDFT in non-high-risk patients would lead to a waste of medical resources and should be avoided. For non-high-risk patients, zero-balance fluid therapy (administration of 1–4 mL/kg/h of crystalloid solution excluding blood loss) as described in other guidelines is considered sufficient [1,2].

Recommendation consensus meeting results

The recommendation strength and direction for the use of GDFT during colorectal surgery were unanimously supported by all attending members (11 out of 11). However, it was emphasized that GDFT should be selectively applied only to high-risk patients, as its benefits do not extend to all patients. Consequently, the guideline specifies that GDFT should be considered only for high-risk patients.

External expert review results

In the external review conducted by the 18 external experts, 89% of the reviewers (16 out of 18) provided a support score of 7 or higher for a ‘conditional for’ recommendation. Additionally, 89% of the reviewers (16 out of 18) endorsed the same recommendation strength as ‘conditional for,’ indicating overall support for the recommendation. The final review by the development committee also confirmed this decision without dissent.

KQ 7. Is the insertion of an intra-abdominal drain necessary during elective surgery for colorectal cancer?

Recommendation 7.

It is suggested that an intra-abdominal drain is not inserted during surgery for colorectal cancer.

Strength of the recommendation: conditional against

Level of evidence: moderate

Prophylactic drainage is believed to have several benefits [95]: (1) it can reduce the incidence of anastomotic leakage by removing blood and serous fluids, which, if infected, may cause abscess formation and potentially lead to the abscess rupturing into the anastomosis [96]; (2) it helps in mitigating the severity of such complications by allowing for earlier detection [97]; and (3) it aids in identifying intraperitoneal bleeding [96]. However, surgeons who argue against the use of drainage suggest that it (1) might actually promote the production of serous fluid [98]; (2) could introduce infections from external sources [99,100]; (3) might increase the risk of leakage by hindering the movement of the omentum and nearby organs, which otherwise help seal the anastomotic site [99,101], or by causing leaks through mechanical erosion of the anastomosis [102]; and (4) is typically enclosed quickly by the body [103].

The meta-analysis revealed that drain placement did not significantly impact the overall complication rates across the studies analyzed (OR, 0.86; 95% CI, 0.62–1.19) (Supplement Fig. 9A) [95,104-107]. There was no significant difference in the incidence of anastomotic leakage associated with drain placement (OR, 0.93; 95% CI, 0.69–1.24) (Supplement Fig. 9B) [95,104-108]. Additionally, no significant differences were observed between the groups regarding the incidence of pelvic fluid collection and sepsis (OR, 0.96; 95% CI, 0.70–1.33) [95,104,106-108], intestinal obstruction (OR, 0.66; 95% CI, 0.42–1.05) [95,104,106,108], or the reoperation rate (OR, 1.00; 95% CI, 0.67–1.50) (Supplement Fig. 9C-E) [95,106,108]. While not statistically significant, the tendency was toward a lower incidence of each complication, except for the reoperation rate, in the group without drain placement (Supplement Fig. 9E).

Recommendation consensus meeting results

Seventy percent of the attending members (7 out of 10) supported the recommendation strength and direction for not using a drainage catheter during colorectal surgery. There were concerns that there might be insufficient evidence to deviate from traditional practices, as some felt that not using a drainage catheter did not provide clear benefits or avoid risks. However, the consensus was that given the absence of clear benefits and considering patient discomfort and the potential for earlier discharge, recommending not using a drainage catheter was justified.

External expert review results

In the external review conducted by the 18 external experts, only 39% of the reviewers (7 out of 18) provided a support score of 7 or higher for ‘conditional against.’ Additionally, only 44% of the reviewers (8 out of 18) endorsed the same recommendation strength as ‘conditional against,’ while 33% of the reviewers (6 out of 18) suggested ‘conditional for’ as the appropriate recommendation strength. A significant number of clinicians use drainage catheters during colorectal surgeries, especially rectal surgeries, primarily due to concerns about anastomotic leakage. The review results from the external experts reflect this reality. Although there may be some discrepancy with actual clinical practice, the guideline is evidence-based and, considering the essence of the ERAS guidelines, the development committee agreed that a recommendation against using drainage catheters was appropriate. Consequently, the final recommendation strength was confirmed as ‘conditional against.’

KQ 8. During elective surgery for colorectal cancer, does the insertion of a nasogastric tube aid in the patient’s recovery?

Recommendation 8.

It is suggested that a nasogastric tube is not inserted during surgery for colorectal cancer.

Strength of the recommendation: conditional against

Level of evidence: low

The necessity of nasogastric tube insertion during surgery has been widely researched in abdominal surgeries over the years. A Cochrane review published in 2007 concluded that routine insertion of nasogastric tubes for decompression purposes in all patients undergoing abdominal surgery is unnecessary [109]. Our meta-analysis also revealed results consistent with those of similar studies. No statistically significant differences were observed in anastomotic leakage (Supplement Fig. 10A), time to bowel movement (Supplement Fig. 10B) and gas passage (Supplement Fig. 10C), SSIs (Supplement Fig. 10D), or length of hospital stay (Supplement Fig. 10F) between two groups [110,111]. However, Venara et al. [111] reported a significantly higher incidence of respiratory infections in patients with a nasogastric tube insertion compared to those without (3.0% vs. 0.4%, P<0.001), which was corroborated by the meta-analysis (OR, 7.12; 95% CI. 2.48–20.47) (Supplement Fig. 10E) [110,111].

Recommendation consensus meeting results

Ninety percent of the attending members (9 out of 10) supported the recommendation strength and direction regarding the use of nasogastric tubes during elective colorectal surgery. Although it has long been known that there are no benefits to nasogastric tube insertion, some suggested that the recommendation strength should be ‘strongly against.’ However, it was agreed that the evidence level is insufficient to justify a strong recommendation. Therefore, the consensus was to recommend against the use of nasogastric tubes, but not at a strong level.

External expert review results

In the external review conducted by the 18 external experts, 67% (12 out of 18) provided a support score of 7 or higher for ‘conditional against.’ However, only 39% of the reviewers (7 out of 18) deemed ‘conditional against’ as the appropriate recommendation strength, which was a relatively low proportion. A significant number of reviewers (44%, 8 out of 18) suggested ‘strongly against’ as the appropriate recommendation strength. This aligns with the opinions expressed during the development committee’s consensus meetings. Considering the level of evidence, the final decision was to confirm the recommendation strength as ‘conditional against’ through the final meeting.

KQ 9. Is transversus abdominis plane block effective for postoperative pain control following elective surgery for colorectal cancer?

Recommendation 9.

Transversus abdominis plane (TAP) block may be considered for pain control during surgery for colorectal cancer.

Strength of the recommendation: conditional for

Level of evidence: moderate

Effective pain management following colorectal cancer surgery is a key component of ERAS protocols, as it can aid in facilitating rapid patient recovery and early discharge from the hospital. Opioid-based patient-controlled analgesia (PCA) has been widely used due to its ease of use, simplicity, and effectiveness in pain management [112]. However, opioids can cause side effects such as nausea and vomiting, and reduce gastrointestinal motility, which can slow recovery [1,112]. Therefore, the most crucial aspect emphasized in other ERAS guidelines for postoperative pain management is to avoid opioids and apply multimodal analgesia, which combines two or more pain control methods [1,2].

There are many options available for multimodal analgesia. Among non-opioids, the most easily prescribed medications are acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs). These are the easiest alternatives to opioids as they do not require special equipment or procedures. However, caution is needed with non-selective NSAIDs like diclofenac due to reports of increased anastomotic leaks. Ketorolac or COX-2 selective NSAIDs are recommended instead [1,113]. Other medications such as gabapentinoids (e.g., gabapentin, pregabalin) and ketamine can also be used, but their analgesic effects are disputed and side effects must be considered [1].

Thoracic epidural analgesia has been proven effective for open surgery but is not recommended for minimally invasive colorectal cancer surgery due to a lack of evidence of its superiority over other analgesic methods and potential side effects [1]. The use of continuous wound infiltration with local anesthetics via a catheter is becoming more widespread, and new local pain control methods, such as the use of thermosensitive hydrogels for local anesthetic delivery, are being developed [1,114]. Additionally, nerve blocks such as TAP block and rectus sheath block have been reported to reduce opioid use and the duration of hospital stay, making them viable options for multimodal analgesia. The selection of methods to be combined for multimodal analgesia should be determined based on the available resources and the preferences of the medical staff at each hospital. This guideline establishes KQs and conducts a systematic review on the TAP block, which has been widely studied in colorectal surgery.

This meta-analysis compared the effectiveness and side effects of TAP block with other pain management methods (placebo using saline solution, local anesthetic-based pain control, or traditional opioid analgesia) during colorectal surgery. The analysis of postoperative pain using the visual analogue scale indicated significantly lower pain scores in the TAP block group compared to the control group at both 2 hours (MD, –1.31; 95% CI, –1.41 to –1.21) (Supplement Fig. 11A) [115-126] and 24 hours (MD, –1.04; 95% CI, –1.14 to –0.94) post-surgery (Supplement Fig. 11B) [115,117-126]. Additionally, the TAP block group had a significantly shorter hospital stay compared to the control group (MD, –0.38 days; 95% CI, –0.53 to –0.22) (Supplement Fig. 11C) [115-118,120,122,123,125-128]. While variability in reporting standards and units posed challenges for aggregating opioid consumption data, several studies demonstrated consistently reduced opioid requirements in the TAP block group relative to the control group [116,117,122,123,127-129]. A meta-analysis by Liu et al. [130], using the standardized mean difference (SMD), further confirmed the reduction in postoperative opioid use in the TAP block group compared to the control group (SMD, –0.26; 95% CI, –0.47 to –0.05).

The incidence of PONV was significantly lower in the TAP block group compared to the control group (OR, 0.51; 95% CI, 0.36–0.72) (Supplement Fig. 11D) [115-118,120-122,125,126,128,129,131]. However, there was no statistically significant difference between the two groups concerning the incidence of postoperative ileus (Supplement Fig. 11E) [115-118,120,123,126,128,129,131].

As described above, there are many methods for postoperative pain management. Instead of relying on a single method, combining multiple techniques in a multimodal analgesia approach is more effective for pain control. TAP block should also be used as part of this multimodal analgesia. The ultimate goal is to minimize the use of opioids.

Recommendation consensus meeting results

The recommendation strength and direction for the use of TAP block during colorectal surgery were unanimously supported by all attending members (11 out of 11), with no dissenting opinions regarding the recommendation.

External expert review results

The external review of this key question by the external experts showed that the proportion of those who supported the recommendation strength (7–9 points) was 50% (9 out of 18), which was not high. However, 89% of the reviewers (16 out of 18) indicated ‘conditional for’ when asked about the appropriate recommendation strength. It is believed that this survey result reflects the fact that various pain control methods can be included in multimodal analgesia. As mentioned earlier, TAP block, as an element of multimodal analgesia, was ultimately agreed to be ‘conditional for,’ and the recommendation strength was confirmed.

KQ 10. Is thromboprophylaxis necessary for patients scheduled for elective surgery for colorectal cancer?

Recommendation 10.

Preoperative pharmacologic thromboprophylaxis is recommended for patients scheduled for colorectal cancer surgery.

Strength of the recommendation: conditional for

Level of evidence: moderate

For preoperative thromboprophylaxis, clinical methods include mechanical prophylaxis (such as compression stockings or intermittent pneumatic compression) and pharmacologic prophylaxis. Mechanical prophylaxis has been proven effective and is used in clinical practice [132,133]. However, the use of pharmacologic prophylaxis remains less established. Therefore, this analysis evaluated RCTs comparing preoperative pharmacologic thromboprophylaxis with placebo or intermittent pneumatic compression.

The incidence of postoperative deep vein thrombosis (DVT) or pulmonary embolism (PE) was analyzed in two studies included in the analysis [134,135]. Both studies reported a significantly lower incidence in the group that received preoperative thromboprophylaxis. Consequently, the meta-analysis results also demonstrated a significant association between preoperative thromboprophylaxis and reduced rates of postoperative DVT or PE (OR, 0.45; 95% CI, 0.20–0.99) (Supplement Fig. 12A).

Preoperative thromboprophylaxis carries a potential risk of postoperative bleeding. Both studies included major bleeding requiring transfusion and minor bleeding not requiring transfusion in their analysis [134,135]. When combined, the studies confirmed that preoperative thromboprophylaxis was not associated with major bleeding (OR, 4.04; 95% CI, 0.45–36.29) or minor bleeding (OR, 2.48; 95% CI, 0.92–6.68) (Supplement Fig. 12B, C).

However, the limited number of RCTs supporting preoperative pharmacologic thromboprophylaxis in colorectal surgery specifically targeting Korean populations, presents a significant barrier. A prospective study conducted on a Korean cohort found no significant difference in the incidence of thrombotic complications between patients who received preoperative pharmacologic thromboprophylaxis and those who did not [136], which could hinder the implementation of such measures.

As an alternative, it may be practical to selectively administer preoperative pharmacologic thromboprophylaxis to patients at high risk for thromboembolic events. For example, patients with obesity or multiple underlying conditions, who are at a higher risk for thrombotic complications [137-140], might benefit more from targeted prophylactic interventions. If nomograms for identifying patients at high risk for thrombosis are developed, they could serve as valuable tools for deciding whether to implement preoperative pharmacologic thromboprophylaxis.

Recommendation consensus meeting results

Ninety percent of the attending members (9 out of 10) supported the recommendation strength and direction for implementing preoperative pharmacologic thromboprophylaxis in patients scheduled for elective colorectal cancer surgery. While there was an opinion in the consensus meeting that the recommendation strength should be ‘strongly recommended,’ the view that the level of evidence should be considered and that the decision should be made selectively based on the individual patient’s condition gained traction. Consequently, the consensus was to classify it as ‘conditional for.’

External expert review results

Among the external experts, the proportion of those who provided a support score of 7 or higher for a ‘conditional for’ recommendation was 44% (8 out of 18), which is relatively low. However, 78% of the external experts endorsed ‘conditional for‘ as the appropriate recommendation strength. Conversely, 3 experts (17%) suggested that ‘conditional against’ was more suitable. After reviewing the consensus meeting results, external expert reviews, and meta-analysis outcomes, the final recommendation strength was confirmed as ‘conditional for.’

KQ 11. How long should urinary catheters be maintained after elective surgery for colorectal cancer?

Recommendation 11.

It is recommended that urinary catheters are removed the day after colorectal cancer surgery.

Strength of the recommendation: conditional for

Level of evidence: moderate

Early removal of urinary catheters postoperatively has been reported to reduce the time to first ambulation [141-145] and decrease the length of hospital stay in numerous studies [141,142,144,146,147]. However, the benefits of reducing UTIs through early catheter removal must be weighed against the risks of acute urinary retention that can occur following early removal. The two studies included in the meta-analysis showed a trend toward a reduction in UTIs, but this trend was not statistically significant [148,149]. However, two other studies with relatively larger sample sizes demonstrated a statistically significant reduction in UTIs [150,151]. Therefore, the meta-analysis confirmed that early catheter removal could reduce the incidence of UTIs (OR, 0.36; 95% CI, 0.20–0.67) (Supplement Fig. 13A).

There is a potential for catheter reinsertion due to acute urinary retention following early catheter removal. This is particularly relevant in rectal cancer surgeries, where the risk of damaging the lateral pelvic nerves during pelvic surgery must be considered. In the present analysis, four studies on colorectal surgeries involving the pelvic region were included [148-151]. The meta-analysis revealed that early catheter removal is associated with an increased risk of acute urinary retention following pelvic surgery (OR, 2.16; 95% CI, 1.20–3.89) (Supplement Fig. 13B).

Clean intermittent catheterization (CIC) has been reported not to increase the frequency of UTIs compared to indwelling catheters [152]. Therefore, after removing the catheter on the first day post-surgery, in cases where acute urinary retention occurs, the decision whether to reinsert the catheter for prolonged use based on bladder volume expansion (>600 cm³) or to implement CIC, can be determined [153].

Considering different protocols for colon cancer and rectal cancer surgeries is also warranted. A meta-analysis of colorectal surgeries that included pelvic surgeries conducted in 2019 [154], analyzed three prospective RCTs [148,150,151] and two retrospective cohort studies [155,156]. No significant difference in the frequency of UTIs or acute urinary retention between the first and third days post-surgery was confirmed. Therefore, catheter removal on the second day post-surgery for rectal cancer surgeries is also worth considering.

Additionally, in patients with urinary retention issues due to benign prostatic hyperplasia, there have been reports indicating an increased incidence of acute urinary retention following early catheter removal [157-159]. Therefore, early catheter removal should be approached with caution, and the use of medications such as alpha blockers should be considered prior to removal [160].

Recommendation consensus meeting results

Regarding the recommendation strength and direction for early removal of urinary catheters following elective surgery for colorectal cancer, 90% of the attending members (9 out of 10) supported the recommendation strength. There was a suggestion to create separate guidelines for colon cancer and rectal cancer. However, the meta-analysis included studies that covered both colon and rectal cancers, and there were no prospective randomized studies solely on early catheter removal for colon cancer. This limitation makes it impractical to create separate guidelines based solely on the current evidence.

External expert review results

The external review by 18 experts showed that 78% (14 out of 18) provided a support score of 7 or higher for a ‘conditional for.’ Additionally, all 18 experts unanimously agreed that ‘conditional for’ was the appropriate recommendation strength. Consequently, the final review by the development committee confirmed ‘conditional for’ as the recommendation strength without dissent.

KQ 12. Is early feeding effective following elective surgery for colorectal cancer?

Recommendation 12.

Early feeding is recommended to start the day after surgery for colorectal cancer.

Strength of the recommendation: conditional for

Level of evidence: moderate

Early feeding was defined as the introduction of a liquid diet or more substantial nutrition within 24 hours post-surgery, and a systematic review of the literature was conducted accordingly. The majority of studies included in the meta-analysis did not demonstrate significant differences in complications between the two groups [161-169]. However, Zhou et al.’s study [170], which enrolled the largest number of patients, reported a statistically significant reduction in complications with early dietary advancement, leading to a significant association between early dietary advancement and reduced total postoperative complications in the meta-analysis (OR, 0.50; 95% CI, 0.38–0.65) (Supplement Fig. 14A). Although individual studies did not demonstrate statistical significance in anastomotic leakage [161-163,165-171], when pooled together, a significant association between early dietary advancement and reduced anastomotic leakage was observed (OR, 0.40; 95% CI, 0.19–0.83) (Supplement Fig. 14B). In the early dietary advancement group, time to flatus was significantly shorter (MD, –0.87; 95% CI, –1.00 to –0.74) (Supplement Fig. 14C) [161-164,168,170,171], and hospital stay was also shorter (MD, –0.76; 95% CI, –0.89 to –0.64) (Supplement Fig. 14D) [161-170,172,173]. However, there was no significant difference in mortality rates between the two groups (Supplement Fig. 14E) [161-163,165-168,171].

Early dietary advancement is associated with concerns about inducing ileus or vomiting before complete bowel recovery. A comprehensive analysis of nine papers reporting postoperative vomiting revealed a significantly higher incidence of postoperative vomiting in the early dietary advancement group (OR, 1.58; 95% CI, 1.11–2.26) (Supplement Fig. 14F) [163-165,167-169,171-173]. Postoperative nasogastric tube insertion was more frequently performed in the early dietary advancement group, although statistical significance was not reached (OR, 1.49; 95% CI, 0.96–2.31) (Supplement Fig. 14G) [162-165,167,168,170-172].

Recommendation consensus meeting results

The recommendation strength and direction for early postoperative feeding after elective surgery for colorectal cancer were unanimously supported by all attending members (10 out of 10). There were no dissenting opinions regarding the recommendation.

External expert review results

In the external review conducted by 18 experts, 78% (14 out of 18) provided a support score of 7 or higher for a ‘conditional for’ recommendation (On a scale of 1 to 9). Additionally, 94% of the experts (17 out of 18) endorsed the recommendation strength as ‘conditional for.’ This overall agreement indicates strong support for the recommendation strength. The development committee also confirmed the ‘conditional for’ recommendation strength without dissent during the final review.

KQ 13. Is early ambulation effective following elective surgery for colorectal cancer?

Recommendation 13.

Early ambulation is recommended to commence on the day after surgery for colorectal cancer.

Strength of the recommendation: conditional for

Level of evidence: moderate

Postoperative early ambulation is believed to prevent intestinal paralysis and pulmonary complications. The two studies included in the analysis both showed no overall difference in complications, and the meta-analysis result also indicated no significant difference in the occurrence rates of complications between the two groups (Supplement Fig. 15) [174,175]. Specific complications could not be analyzed due to a lack of comparable data provided by both studies. However, one study reported a decrease in hospitalization period with early ambulation [175].

Although early ambulation is considered clinically beneficial, meta-analysis results showed insufficient evidence regarding its benefits and harms. Consistent with our findings, other systematic reviews did not report the advantages of early ambulation [176]. The heterogeneity and design of the studies likely influenced these results. Additionally, there are very few RCTs focusing solely on early ambulation, and most studies included early ambulation as part of the ERAS protocol, making it difficult to synthesize the evidence.

Although this meta-analysis did not establish the benefits of early ambulation, its potential advantages as a component of the ERAS protocol cannot be ruled out, and it can be implemented to some extent without a formal program. Based on this, the committee suggests initiating early ambulation from the day after surgery, considering that its potential benefits likely outweigh the risks.

Recommendation consensus meeting results

The recommendation strength and direction for early ambulation after colorectal cancer surgery were unanimously supported by all attending members (10 out of 10), with no dissenting opinions on the recommendation.

External expert review results

The external review by 18 experts showed that 89% of reviewers (16 out of 18) provided a support score of 7 or higher for a ‘conditional for’ on a scale from 1 to 9. Sixty-one percent of the reviewers (11 out of 18) endorsed ‘conditional for’ as the appropriate recommendation strength. The remaining 39% of reviewers (7 out of 18) suggested that a ‘strong recommendation’ might be more appropriate. Despite this, considering the low level of evidence and the fact that some patients may have difficulties with mobility, the consensus was that a strong recommendation would not be suitable. Consequently, the development committee confirmed ‘conditional for’ as the final recommendation strength.

Conceptualization: KL, SYL, MC, SYY, SRH, ECH, DJP, SJP. Data curation: all authors. Formal analysis: MC. Funding acquisition: DJP, SJP. Investigation: all authors. Methodology: SYL, MC. Project administration: SYL, SJP. Resources: SJP. Software: MC. Supervision: SYL, DJP, SJP. Visualization: all authors. Writing – original draft: all authors. Writing – review & editing: all authors.

Do Joong Park is an editorial board member of the journal, but was not involved in the review process of this manuscript. Otherwise, there is no conflict of interest to disclose.

This work was supported by a research fund from the National Cancer Center, Republic of Korea (NCC-2112570-4).

Contact the corresponding author for data availability.

We thank the Korean Cancer Management Guideline Network for the technical support.

Supplementary materials can be found via https://doi.org/10.15747/ACNM.2024.16.2.22

Supplement Material 1. Literature search terms for each key question (KQ).

Supplement Table 1. Multiple pharmacological options for preventing postoperative nausea and vomiting.

Supplement Fig. 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart for each key question (KQ).

Supplement Fig. 2. Risk of bias assessment for each key question (KQ) using Risk of Bias in Non-randomized Studies of Intervention (ROBINS-I), and Cochrane Risk-of-Bias Tool for Randomized Trials 2 (RoB 2).

Supplement Fig. 3. Forest plots of (A) postoperative complication (Clavien Dindo Classification I, II), (B) postoperative complication (Clavien Dindo Classification≥III), (C) hospital stay, (D) readmission within 30 days, (E) readmission within 90 days and (F) postoperative mortality based on prehabilitation.

Supplement Fig. 4. Forest plots comparing oral nutritional supplement for (A) total postoperative complications and (B) length of hospital stay.

Supplement Fig. 5. Forest plots of (A) nausea and vomit (within 6 hours), (B) nausea and vomit (within 24 hours), (C) overall side effects, (D) headache, and (E) dizziness between combination therapy and monotherapy.

Supplement Fig. 6. Forest plots of (A) surgical site infections, (B) organ-space surgical site infections, and (C) readmission rates (within 30 days) in the combination of mechanical bowel preparation and oral antibiotic prophylaxis versus mechanical bowel preparation alone.

Supplement Fig. 7. Forest plots of (A) postoperative complications, (B) surgical site infections, (C) prolonged postoperative ileus, (D) time to flatus, and (E) hospital stay based on preoperative oral carbohydrate loading.

Supplement Fig. 8. Forest plots of (A) postoperative complications, (B) surgical site infections, (C) anastomotic leakage, (D) prolonged postoperative ileus, (E) mortality, and (F) hospital stay based on goal-directed fluid therapy.

Supplement Fig. 9. Forest plots of (A) total postoperative complication, (B) anastomotic leakage, (C) pelvic fluid collection and sepsis, (D) intestinal obstruction, and (E) reoperation based on drain insertion.

Supplement Fig. 10. Forest plots of (A) anastomotic leakage, (B) time to first bowel movement, (C) time to first flatus, (D) surgical site infections, (E) respiratory infections, and (F) hospital stay based on nasogastric tube insertion.

Supplement Fig. 11. Forest plots of (A) postoperative pain using the visual analogue scale (within 2 hours), (B) postoperative pain using the visual analogue scale (within 24 hours), (C) hospital stay, (D) postoperative nausea and vomit, and (E) prolonged postoperative ileus in transversus abdominis plane block versus conventional pain control method.

Supplement Fig. 12. Forest plots of (A) venous thromboembolism, (B) major bleeding, and (C) minor bleeding based on preoperative pharmacologic thromboprophylaxis.

Supplement Fig. 13. Forest plots of (A) urinary infection and (B) acute urinary retention comparing early versus late urinary catheter removal.

Supplement Fig. 14. Forest plots of (A) total postoperative complications, (B) anastomotic leakage, (C) time to flatus, (D) hospital stay, (E) mortality, (F) postoperative vomit, and (G) postoperative nasogastric tube insertion comparing early versus late feeding.

Supplement Fig. 15. Forest plots of total postoperative complication comparing early versus late mobilization.