Postoperative Infections After Appendectomy for Acute Appendicitis: The Surgeon’s Checklist

Leandri, M., Vallicelli, C., Santandrea, G., Perrina, D., Bravi, F., Sartelli, M., Coccolini, F., Ansaloni, L., Agnoletti, V., & Catena, F. (2025). Postoperative Infections After Appendectomy for Acute Appendicitis: The Surgeon's Checklist. Antibiotics (Basel, Switzerland), 14(9), 954. https://doi.org/10.3390/antibiotics14090954

Acute appendicitis is one of the most common surgical emergencies, and while appendectomy is a standard and effective treatment, postoperative infections remain a significant clinical challenge. The overall probability of such infections ranges from 5% to 15%, with rates approaching 15.4% in cases of complicated appendicitis (defined by gangrene, perforation, or abscess). A comprehensive analysis of recent literature reveals a multifactorial landscape of risk, encompassing patient-specific attributes, disease severity, and surgical technique.

Key evidence-based takeaways indicate that the laparoscopic approach is markedly superior to open surgery, associated with a significant reduction in incisional surgical site infections (SSIs) and half the risk of sepsis. The choice of appendiceal stump closure also impacts outcomes, with polymeric clips (e.g., Hem-o-lok) emerging as a cost-effective and efficient alternative to endoloops or staplers, potentially reducing rates of intra-abdominal abscesses (IAA).

Furthermore, recent high-quality evidence challenges several traditional intraoperative practices. Routine abdominal drainage is now understood to provide no benefit in preventing abscesses and may increase morbidity and hospital stay. Similarly, the routine collection of intraoperative cultures is of questionable value in most adult patients. While the efficacy of standard peritoneal lavage is debated—with suction alone often proving equivalent—emerging data supports the use of antiseptic solutions to reduce SSI rates.

The management of postoperative IAA follows a stepwise, evidence-based protocol. Small abscesses (<4 cm) are typically managed with broad-spectrum antibiotics, while larger abscesses (≥4 cm) warrant image-guided percutaneous drainage. For cases refractory to these measures, laparoscopic re-intervention has proven to be a safe and effective option in hemodynamically stable patients. Finally, the implementation of Enhanced Recovery After Surgery (ERAS) protocols demonstrates clear benefits in reducing hospital stays and improving patient recovery without increasing complication rates.

1. The Scope and Incidence of Post-Appendectomy Infections

Acute appendicitis has a lifetime incidence of approximately 7–8% in the United States and Europe, making appendectomy a frequent emergency procedure. Despite advances in surgical care, postoperative infections—including superficial and deep SSIs, intra-abdominal abscesses (IAA), and sepsis—continue to challenge clinicians.

The incidence of these infections varies, but several large-scale studies provide a clear picture:

• Overall Infection Rate: The average reported incidence of post-appendectomy infection is between 5% and 15%.
• Complicated Appendicitis: A 2023 meta-analysis of over 5,000 patients found that the infection rate in complicated cases (gangrenous, perforated, or with abscess) was substantially higher, at 15.4%.
• Large Cohort Data: An extensive retrospective study in China involving over 9,000 patients identified a cumulative SSI rate of 6.2% (3.7% incisional, 3.0% organ/space). A European multicenter analysis reported a similar overall rate of 6.6%, with organ/space infections accounting for 4.6%.

The transition from open to laparoscopic appendectomy has been a critical factor in reducing infection rates, with the Chinese study noting a drop in incisional SSIs from 6.7% to 2.2% over the study period.

2. Key Risk Factors for Postoperative Infection

The risk of developing an infection after an appendectomy is determined by a complex interplay of patient, disease, and surgical factors.

2.1 Patient-Related Factors

• Advanced Age: Patients over 60 are at a greater risk for sepsis and wound infections.
• Visceral Obesity: Recent studies highlight that Visceral Adipose Tissue (VAT), assessed via CT scan, is a more significant predictor of incisional infections than Body Mass Index (BMI). A 2023 multicenter study found that visceral obesity was associated with a nearly threefold increase in risk (OR 2.68).

2.2 Disease-Related Factors

• Complicated Appendicitis: This is the single most significant disease-related risk factor. Large cohort studies consistently show that complicated appendicitis increases the odds of SSI approximately fourfold compared to uncomplicated cases.
• Intra-abdominal Contamination: The presence of purulent or feculent peritoneal fluid during surgery is a direct indicator of organ/space infection risk. The 2020 WSES Jerusalem Guidelines strongly recommend aspirating this fluid.
• Timing of Intervention: While early appendectomy has been the traditional approach, recent evidence suggests a more nuanced strategy. Total disease duration appears more critical than in-hospital delay.
  • Uncomplicated Appendicitis: An in-hospital delay of up to 24 hours in stable patients does not significantly increase SSI risk.
  • Complicated Appendicitis: For patients with suspected complications, urgent surgery within 8 to 12 hours is recommended to minimize disease progression.
  • Meta-Analyses Findings: Two major 2024 meta-analyses support this view, demonstrating that while delays beyond 24 hours increase overall morbidity, they are not independently associated with higher postoperative infection rates.

Study	Population	Main Findings	Effect on Post-Operative SSI
Tang et al. (2024) [8]	> 500,000 adults	Delays >24 h increased complicated appendicitis and general morbidity.	No association with SSI.
Calpin et al. (2024) [9]	232,678 adults	Surgery within 24 h was associated with lower rates of complicated appendicitis, shorter hospital stays, and reduced mortality.	No significant reduction in SSI compared to later surgery.

2.3 Surgical Factors

• Surgical Approach: Laparoscopic appendectomy (LA) is consistently associated with lower rates of SSI compared to open procedures. One multicenter study documented that open surgery carries twice the risk of sepsis. Furthermore, the use of CO2 pneumoperitoneum during laparoscopy has been shown to reduce the systemic inflammatory response (lower IL-6, CRP, and TNF-α levels).
• Appendix Stump Closure: The technique used to close the appendix stump is a critical modifiable risk factor. Evidence increasingly favors non-absorbable polymeric Hem-o-lok (H-O-L) clips over traditional endoloops and more expensive endostaplers.

Study	Study Design	Technique Compared	Main Findings	Conclusions
Soll et al. (2016) [12]	Retrospective	Hem-o-lok vs. Endoloop	Lower rate of IAAs with H-O-L.	First large-scale evidence favoring polymeric clips.
Vuille et al. (2020) [13]	Retrospective	Hem-o-lok vs. Endoloop vs. Stapler	Similar overall IAA rates, but data consistently favored H-O-L. No significant difference clip vs. stapler.	H-O-L performs at least as well as staplers.
Ihnát et al. (2021) [15]	RCT	Hem-o-lok vs. Endoloop vs. Stapler	H-O-L shortest operative time (~38 min); no increase in infection rate.	Efficiency benefit with H-O-L.
WSES (2020) [7]	Guidelines [1B]	Endoloop vs. Stapler vs. Clips	No proven advantage of stapler over endoloop; clips viable and economical in selected cases.	Clips suitable for appendix base ≤10 mm.

The material cost analysis shows substantial savings, with a kit of H-O-L clips costing approximately €25 compared to €360 for an endostapler.

3. Intraoperative Prevention Strategies and Evolving Evidence

Several long-standing intraoperative practices aimed at preventing infection are now being re-evaluated based on high-quality evidence.

3.1 Abdominal Drainage

The routine prophylactic placement of abdominal drains in complicated appendicitis is not supported by recent evidence. A pivotal 2025 Cochrane review concluded that drainage:

• Does not meaningfully reduce intra-abdominal abscesses or wound infections.
• May increase mortality and lengthen hospital stays.
• Is linked to a higher incidence of superficial wound infections, fistula, bowel obstruction, and ileus.

International guidelines, including the WSES, have moved away from endorsing routine drainage, recommending selective and individualized use instead (Weak recommendation, 2C).

3.2 Intraoperative Culture Swabs (ICS)

The utility of routinely collecting peritoneal cultures is highly contested.

• Evidence Against Routine Use: Studies by Akingboye et al. (2019) and Peña et al. (2020) concluded that ICS are of "little clinical value" for most adults, as results rarely lead to changes in antibiotic therapy and do not appear to reduce postoperative morbidity.
• Evidence for Selective Use: A 2023 Colombian study found that in patients with complicated appendicitis, antibiotic regimens were adjusted based on culture results in over 56% of cases, leading to a subsequent reduction in SSIs.
• Guideline Recommendation: The WSES guidelines advise against routine ICS use, recommending it only for high-risk patients (e.g., immunocompromised, nosocomial infections, or known exposure to resistant organisms).

3.3 Peritoneal Irrigation and Appendix Extraction

The practice of peritoneal lavage to reduce bacterial load is another area of controversy.

Study	Study Design	Intervention	Key Finding	Conclusions
Gemici et al. (2020) [21]	RCT	Saline lavage (500 mL) vs. aspiration alone	No significant difference in IAA, wound infection, or hospital stay.	Lavage provides no added benefit over aspiration alone.
Burini et al. (2021) [22]	Meta-analysis	Suction alone vs. lavage (any type)	Suction alone equivalent for IAA prevention; better operative time, fewer reoperations.	Lavage not superior; suction-only may be preferable.
Wang et al. (2021) [23]	Retrospective	Lavage/suction before vs. after appendix extraction	Lower SSI in group with lavage before extraction.	Timing of lavage may affect infection risk.
Sellappan et al. (2024) [24]	PLaSSo trial (RCT)	Super-oxidized solution vs. saline	Significant reduction in deep and superficial SSIs with antiseptic solution.	Antiseptic lavage is safe and superior to saline in open surgery.
Singal et al. (2016) [25]	RCT	Super-oxidized solution vs. saline	Reduced bacterial load and shorter hospital stay with antiseptic solution.	Antiseptics may benefit broader peritonitis management.

Regarding appendix extraction, the routine use of a specimen retrieval bag (endobag) may be unnecessary. A large 2019 study of 4,646 patients found no significant difference in SSI rates whether a bag was used or not. A selective approach is recommended, reserving endobag use for cases with gross contamination or removal through an enlarged port site.

4. Management of Post-Appendectomy Intra-Abdominal Abscesses

The development of an IAA is a significant complication, with an overall incidence of 2-3%. Management follows a well-defined, stepwise approach based on clinical stability and abscess characteristics.

Stepwise Management Flowchart

The following protocol outlines the management of postoperative abscesses:

1. Initial Confirmation: An IAA is confirmed radiologically.
2. Size-Based Stratification:
   • Abscess < 4 cm:
     • Action: Initiate broad-spectrum antibiotic therapy (e.g., piperacillin-tazobactam or ceftriaxone with metronidazole).
     • Follow-up: Monitor for clinical improvement. If the patient fails to respond, proceed to consider source control measures like percutaneous drainage or re-intervention.
   • Abscess > 4 cm:
     • Action: Perform image-guided (US or CT) percutaneous drainage combined with antibiotic therapy. This approach has a reported success rate of 78% in postoperative abscesses.
     • Follow-up: If drainage fails or sepsis persists, re-intervention is necessary.
3. Re-Intervention (Laparoscopy):
   • Indication: Failure of conservative or percutaneous management, presence of multiloculated abscesses, or persistent sepsis.
   • Approach: Laparoscopic washout is a safe and effective alternative to open surgery in hemodynamically stable patients. Studies show it is feasible in over 80% of cases, maintaining the benefits of a minimally invasive approach.
   • Contraindications: Hemodynamic instability, diffuse peritonitis, or extensive intra-abdominal adhesions.

Routine postoperative antibiotic use does not prevent abscess development; rather, treatment decisions should be individualized based on clinical presentation and imaging findings. A 4-day antibiotic course post-source control has been shown to be non-inferior to longer courses.

5. The Role of Enhanced Recovery After Surgery (ERAS) Protocols

ERAS protocols are increasingly being applied to emergency appendectomy with promising results. Key components include patient education, avoiding drains, early mobilization, and prompt resumption of diet.

• Proven Benefits: Randomized controlled trials have shown that ERAS protocols significantly reduce length of hospital stay (median 1.25 vs. 2.0 days in one study), lower pain scores, accelerate bowel function recovery, and decrease hospitalization costs.
• Impact on Infection Rates:
  • While appendectomy-specific trials have not demonstrated a statistically significant reduction in SSI rates, the outcomes are not worse.
  • A comprehensive 2024 meta-analysis of ERAS across all gastrointestinal surgeries revealed a favorable trend toward lower SSI rates (OR 0.80) and a notable reduction in pulmonary infections (OR 0.44).

These findings confirm that ERAS protocols can be safely and effectively implemented for both uncomplicated and complicated appendicitis, improving patient recovery without increasing infectious complications.