Risk factors for intra-abdominal abscess formation after appendectomy: a multicenter retrospective cohort study from Africa

Abstract

Background

Postoperative intra-abdominal abscess (IAA) remains a significant cause of morbidity after appendectomy, particularly in low-resource settings where delayed presentation and advanced disease are common. This study aimed to identify factors associated with postoperative IAA formation after appendectomy in an African setting and to evaluate management strategies and outcomes.

Methods

A multicenter retrospective cohort study was conducted across three tertiary hospitals in Mogadishu, Somalia. All patients who underwent appendectomy between January 2024 and July 2025 were screened for eligibility. Demographic, clinical, intraoperative, and postoperative variables were collected from medical records. The primary outcome was the development of an intra-abdominal abscess within 30 days after appendectomy. Patients with and without postoperative IAA were compared.

Results

Ninety-two patients were included, of whom 19 patients (20.7%) developed postoperative IAA. Delayed presentation beyond 48 h was significantly more frequent in the abscess group than in the non-abscess group (94.7% vs. 30.1%, p < 0.001). Perforated appendicitis and the presence of an appendicolith were strongly associated with IAA formation. Operative duration longer than 60 min and drain placement were also more common among patients with IAA. These patients experienced longer hospital stays and higher rates of wound infection and sepsis. Most postoperative IAA were managed successfully with antibiotics alone in selected cases (13/19, 68.4%).

Conclusion

Postoperative IAA formation after appendectomy in this low-resource setting was strongly associated with delayed presentation and advanced disease severity. Improving early access to surgical care and optimizing perioperative management may reduce postoperative morbidity.

Introduction

Postoperative intra-abdominal abscess (IAA) remains a clinically relevant postoperative complication associated with increased morbidity, prolonged hospitalization, and higher healthcare utilization [1–3]. Despite improvements in surgical technique and perioperative care, IAA continues to occur, particularly in patients with complicated appendicitis.

Disease severity is consistently reported as the strongest predictor of postoperative IAA formation, with perforated and gangrenous appendicitis carrying a substantially higher risk than uncomplicated disease [1, 4, 5]. Additional patient- and surgery-related factors, including obesity, inflammatory markers, hyperbilirubinemia, prolonged operative time, and the presence of an appendicolith, have also been implicated [2, 6, 7]. Although operative strategies such as peritoneal irrigation and abdominal drainage have been investigated, evidence regarding routine drain use remains inconsistent, and no clear consensus has been established [1, 8].

Most published literature on post-appendectomy IAA comes from high-income countries with well-established healthcare systems. In contrast, in low-resource settings—typical of many African regions—complications of appendicitis are more common as a result of delayed presentation and limited access to timely surgical services [9]. Structural barriers to timely surgical access may increase the burden of complicated appendicitis and postoperative infectious complications, including IAA [10]. However, region-specific risk factor data remain scarce.

Management of postoperative IAA includes antibiotic therapy alone, image-guided percutaneous drainage, or surgical re-intervention, depending on abscess characteristics and available resources [3, 11, 12]. Understanding how these factors interact in resource-constrained environments is essential for optimizing patient outcomes.

The primary aim of this study was to identify factors associated with postoperative IAA formation following appendectomy in a low-resource African setting. The secondary aim was to evaluate management strategies and clinical outcomes in this context.

Materials and methods

Study design

This study was designed as a multicenter retrospective cohort study evaluating factors associated with postoperative IAA formation following appendectomy.

Study setting

The study was conducted in Mogadishu, Somalia, across three tertiary hospitals providing general surgical services. Royal Hospital is a private tertiary-care referral center. Alami Specialist Hospital is a private high-volume tertiary hospital managing both elective and emergency surgical cases. Samadeeq Hospital is a tertiary multidisciplinary hospital serving predominantly public-sector and emergency patients. All three institutions function as training centers for surgical residents and medical trainees under consultant supervision.

Study population and study period

All consecutive patients who underwent appendectomy between January 1, 2024, and July 31, 2025, were screened for eligibility. Case identification was performed retrospectively using surgical logs and institutional medical record systems. The patient selection process, including screening, exclusions, and final inclusion, is presented in Fig. 1.

Fig. 1.

Patient flow diagram

All patients received preoperative antibiotic therapy according to institutional protocols. Broad-spectrum antibiotics were administered before surgery. The choice of antimicrobial agent—including meropenem, gentamicin, piperacillin, piperacillin–tazobactam, or ciprofloxacin—was determined on the basis of clinical severity, the presence of sepsis, allergy status, and the availability of microbiological data, when applicable.

Inclusion and exclusion criteria

Patients were eligible for inclusion if they underwent appendectomy during the defined study period and had complete documentation of perioperative and postoperative data. Patients referred after appendectomy performed at another institution were excluded to avoid misclassification of intraoperative and postoperative variables. Cases with incomplete records, particularly those with missing operative findings or postoperative follow-up data, were also excluded.

A census sampling strategy was applied. All patients meeting the inclusion criteria during the study period were included. No formal a priori sample size calculation was performed because of the retrospective design; the final sample size was determined by the total number of eligible patients identified during the predefined study interval.

Endpoint assessment

The primary endpoint was postoperative IAA formation within 30 days after appendectomy. Patients were evaluated during in-hospital follow-up and at outpatient visits within this 30-day postoperative period. Any documented clinical suspicion of intra-abdominal infection prompted imaging evaluation.

Secondary endpoints included management strategies such as antibiotics alone, percutaneous drainage, or reoperation, as well as microbiological findings, hospital length of stay, and readmission within 30 days.

Definition of intra-abdominal abscess and nutritional status

IAA was defined as a postoperative intra-abdominal fluid collection that occurred within 30 days after appendectomy and met at least one of the following criteria:

1. Imaging confirmation by ultrasonography or computed tomography showing a localized intra-abdominal collection consistent with abscess formation, in conjunction with clinical signs of infection, such as fever, leukocytosis, and abdominal pain; or

2. Intraoperative identification of a purulent intra-abdominal collection during re-intervention.

Radiological confirmation was required in all non-operative cases.

Nutritional status was assessed using body mass index (BMI), and patients were categorized as underweight, normal weight, or overweight/obese according to BMI classification.

Data collection

Data were collected using a standardized extraction form from admission notes, operative reports, anesthesia records, laboratory results, imaging findings, and discharge summaries.

Statistical analysis

All data were analyzed using Stata version 18 (StataCorp LLC, College Station, TX, USA). Continuous variables were expressed as means with standard deviations or medians with interquartile ranges, as appropriate. Categorical variables were reported as frequencies and percentages.

Bivariate analyses were performed using the chi-square test or Fisher’s exact test for categorical variables and independent-samples t-tests or Mann–Whitney U tests for continuous variables, as appropriate. A p-value < 0.05 was considered statistically significant.

Results

During the study period, 128 patients underwent appendectomy across the three participating hospitals. After the exclusion of 36 patients, including 12 who did not meet the inclusion criteria, 19 with missing data, and 5 for other reasons, 92 patients were included in the final analysis (Fig. 1). Of these, 73 patients did not develop postoperative IAA, whereas 19 patients were diagnosed with postoperative IAA within 30 days after appendectomy. Among patients who developed postoperative IAA, 17 of 19 patients had perforated appendicitis at the time of surgery, often associated with localized contamination rather than a well-formed intra-abdominal abscess.

The cohort was predominantly male, and patients presented with varying durations of symptoms. Postoperative IAA occurred in 16.0% of female patients (4/25) and 22.4% of male patients (15/67), with no statistically significant difference between the sexes (p = 0.50). Perforated appendicitis was observed in 42.4% of the cohort, and 43.6% of patients with perforation developed postoperative IAA (Table 1). Most procedures were performed using an open approach, and drain placement was documented in more than half of the cohort. Detailed baseline demographic and perioperative characteristics are summarized in Table 1.

Table 1.

Factors associated with postoperative intra-abdominal abscess following appendectomy

Variables		Intra-abdominal abscess		Total	p
		No (n = 73)	Yes (n = 19)
Sex					0.501
Female	n (%)	21 (84.00)	4 (16.00)	25 (100.00)
Male	n (%)	52 (77.61)	15 (22.39)	67 (100.00)
Age					0.741
<14	n (%)	14 (70.00)	6 (30.00)	20 (100.00)
15–24	n (%)	18 (78.26)	5 (21.74)	23 (100.00)
25–34	n (%)	25 (86.21)	4 (13.79)	29 (100.00)
35–44	n (%)	7 (77.78)	2 (22.22)	9 (100.00)
45 above	n (%)	9 (81.82)	2 (18.18)	11 (100.00)
Nutritional Status					0.094
Normal	n (%)	57 (81.43)	13 (18.57)	70 (100.00)
Overweight/Obese	n (%)	12 (85.71)	2 (14.29)	14 (100.00)
Underweight	n (%)	4 (50.00)	4 (50.00)	8 (100.00)
Comorbidities					0.425
Yes	n (%)	18 (72.00)	7 (28.00)	25 (100.00)
No	n (%)	55 (82.09)	12 (17.91)	67 (100.00)
Time from Symptom Onset					< 0.001
0–12 hours	n (%)	6 (100.00)	0 (0.00)	6 (100.00)
12–24 hours	n (%)	20 (100.00)	0 (0.00)	20 (100.00)
24–48 hours	n (%)	25 (96.15)	1 (3.85)	26 (100.00)
>48 hours	n (%)	22 (55.00)	18 (45.00)	40 (100.00)
Appendicolith					< 0.001
Yes	n (%)	15 (55.56)	12 (44.44)	27 (100.00)
No	n (%)	58 (89.23)	7 (10.77)	65 (100.00)
Types of Appendicitis					< 0.001
Simple/Uncomplicated	n (%)	44 (97.78)	1 (2.22)	45 (100.00)
Gangrenous	n (%)	7 (87.50)	1 (12.50)	8 (100.00)
Perforated	n (%)	22 (56.41)	17 (43.59)	39 (100.00)
Surgical Approach					0.313
Laparoscopic	n (%)	10 (90.91)	1 (9.09)	11 (100.00)
Open	n (%)	63 (77.78)	18 (22.22)	81 (100.00)
Operative Time					0.032
30–60 minutes	n (%)	20 (80.00)	5 (20.00)	25 (100.00)
60–120 minutes	n (%)	39 (75.00)	13 (25.00)	52 (100.00)
>120 minutes	n (%)	14 (93.33)	1 (6.67)	15 (100.00)
Surgeon Level					0.466
Resident	n (%)	2 (100.00)	0 (0.00)	2 (100.00)
Consultant	n (%)	71 (78.89)	19 (21.11)	90 (100.00)
Drain placement					< 0.001
Yes	n (%)	34 (66.67)	17 (33.33)	51 (100.00)
No	n (%)	39 (95.12)	2 (4.88)	41 (100.00)
Timing of drain removal					0.494
Within 24 hours post-surgery	n (%)	3 (100.00)	0 (0.00)	3 (100.00)
1 to 3 days post-surgery	n (%)	11 (73.33)	4 (26.67)	15 (100.00)
3 to 5 days post-surgery	n (%)	18 (60.00)	12 (40.00)	30 (100.00)
More than 5 days post-surgery	n (%)	6 (66.67)	3 (33.33)	9 (100.00)
Duration of Antibiotic Therapy					0.123
<4 days	n (%)	25 (92.59)	2 (7.41)	27 (100.00)
5–10 days	n (%)	41 (74.55)	14 (25.45)	55 (100.00)
>10 days	n (%)	7 (70.00)	3 (30.00)	10 (100.00)
Length of Hospital Stay					< 0.001
<4 days	n (%)	35 (97.22)	1 (2.78)	36 (100.00)
5–7 days	n (%)	35 (70.00)	15 (30.00)	50 (100.00)
>7 days	n (%)	3 (50.00)	3 (50.00)	6 (100.00)
Postoperative Complications					< 0.001
Wound infection	n (%)	3 (33.33)	6 (66.67)	9 (100.00)
Sepsis	n (%)	0 (0.00)	2 (100.00)	2 (100.00)
Ileus	n (%)	1 (100.00)	0 (0.00)	1 (100.00)
None	n (%)	69 (86.25)	11 (13.75)	80 (100.00)

Categorical variables were compared using Chi-square or Fisher’s exact test, as appropriate

Postoperative IAA developed in 19 patients (20.7%). Delayed presentation beyond 48 h was strongly associated with IAA formation (p < 0.001). IAA developed in 43.6% of patients with perforated appendicitis, compared with 2.2% among patients with uncomplicated appendicitis (p < 0.001). Similarly, 44.4% of patients with an appendicolith developed IAA, compared with 10.8% of those without an appendicolith (p < 0.001).

Operative duration longer than 60 min was associated with an increased risk of abscess formation (p = 0.032). Drain placement was more common in patients who subsequently developed IAA (p < 0.001), likely reflecting greater intraoperative contamination in these cases.

The length of hospital stay was significantly prolonged in the IAA group (p < 0.001). Additionally, postoperative wound infection and sepsis occurred more frequently among patients with IAA (p < 0.001). No significant differences were observed with respect to sex, age distribution, nutritional status, comorbidities, level of surgeon experience, or surgical approach.

Among patients who developed postoperative IAA, ultrasonography was the most frequently used imaging modality. Conservative management with antibiotics alone was the most commonly used treatment strategy, followed by percutaneous drainage and reoperation. Escherichia coli was the most frequently isolated organism. Overall outcomes were favorable, with the majority of patients discharged in improved condition. Detailed management characteristics are presented in Table 2.

Table 2.

Clinical management and outcomes of postoperative intra-abdominal abscess

Variables	n (%)*
Method of abscess diagnosis
CT scan	5 (26.32)
Ultrasound	14 (73.68)
Time to onset of symptoms post-appendectomy
<10 days	7 (36.84)
>10 days	12 (63.16)
Abscess management
Antibiotics only	13 (68.42)
Percutaneous drainage	4 (21.05)
Reoperation	2 (10.53)
Microbial culture obtained
No	6 (31.58)
Yes	13 (68.42)
Organism isolated (among cultures obtained)
No growth	3 (23.08)
Growth detected	10 (76.92)
Type of organism isolated†
Escherichia coli	7 (70.00)
Bacteroides species	2 (20.00)
Pseudomonas aeruginosa	1 (10.00)
Antibiotic susceptibility patterns
Meropenem + Gentamicin + Piperacillin	3 (25.00)
Meropenem + Piperacillin + Tazobactam	3 (25.00)
Ciprofloxacin + Meropenem + Gentamicin	4 (33.33)
Other combinations	2 (16.67)
Outcome
Discharged improved	17 (89.47)
Readmission required	2 (10.53)

*All variables are reported among patients who developed postoperative intra-abdominal abscess (n = 19)

†Percentages for organism type are calculated among patients with positive cultures (n = 10)

Discussion

This multicenter retrospective study highlights several clinically and health-system-related factors associated with the development and management of IAA following appendectomy in a low-resource African setting. The findings underscore the critical interplay between delayed presentation, disease severity, operative factors, and postoperative management in shaping outcomes after appendectomy.

Delayed diagnosis and late surgical intervention are well-established determinants of complicated appendicitis and postoperative IAA formation in low- and middle-income countries (LMICs). Recent African multicenter studies report that 60–80% of patients with complicated appendicitis present more than 48 h after symptom onset, with postoperative abscess rates commonly ranging from 15% to 30% among delayed presenters [13, 14]. In our cohort, delayed presentation beyond 48 h was observed in 94.7% of patients who developed IAA, compared with 30.1% of those without abscess formation (p < 0.001), indicating a substantially higher burden of delayed access to care than reported in most contemporary LMIC series.

High-risk pathological features, particularly perforated appendicitis and the presence of an appendicolith, have consistently been associated with increased postoperative abscess risk [15]. Recent evidence suggests that the presence of an appendicolith increases the likelihood of complicated appendicitis by more than threefold (odds ratio 3.52), a condition that is itself associated with higher rates of postoperative IAA formation [16]. In our study, perforated appendicitis was present in 89.5% of patients who developed IAA versus 30.1% of those without abscess formation (p < 0.001), and appendicoliths were identified in 63.2% versus 20.5%, respectively (p < 0.001). These markedly higher proportions suggest that advanced disease at presentation is the dominant driver of postoperative IAA development in this setting.

Operative duration has been proposed as a surrogate marker of both disease severity and intraoperative complexity. In a retrospective cohort of 839 appendectomy patients, prolonged operative time was found to correlate with an increased risk of postoperative intra-abdominal infection, with multivariate analysis identifying both appendiceal perforation and extended surgery duration as independent predictors of postoperative abscess formation [17]. In our cohort, procedures lasting longer than 60 min were more frequent among patients who developed IAA (68.4%) compared with those without abscess formation (53.4%) (p = 0.032), supporting the association between prolonged operative duration and infection risk in resource-constrained environments.

The role of postoperative drainage in the prevention of postoperative IAA remains controversial. Recent meta-analyses indicate that routine abdominal drain placement does not significantly reduce the incidence of postoperative IAA after appendectomy [18]. In addition, contemporary systematic reviews and comparative meta-analyses suggest that drain use may be associated with increased postoperative morbidity, including prolonged hospital stay, without a clear protective effect against abscess formation [19]. In our study, drains were placed in 89.5% of patients who developed IAA, compared with 46.6% of those without abscess formation (p < 0.001). This finding likely reflects selective drain use in cases with severe intra-abdominal contamination rather than indicating a protective effect, supporting an indication-based, rather than routine, drainage strategy. This finding should be interpreted with caution because of potential indication bias. Drains were more likely to be placed in patients with perforated appendicitis, localized contamination, or more severe intraoperative findings; therefore, drain placement should not be interpreted as a causative factor for postoperative IAA formation, but rather as a marker of greater disease severity.

Limited access to diagnostic and therapeutic resources is a defining challenge in many African healthcare systems. In sub-Saharan Africa, ultrasonography is widely used as a primary imaging modality for suspected intra-abdominal collections because of limited access to CT and interventional radiology (IR) services, which remain underdeveloped in many tertiary centers. Recent analyses underscore the critical need to expand IR capacity in the region to improve abscess management outcomes [20, 21]. Our findings closely mirror this pattern, with ultrasonography being used in 73.7% of abscess diagnoses and percutaneous drainage performed in only 21.1% of cases, underscoring persistent constraints in advanced imaging and minimally invasive treatment options.

Surgeon experience and trainee involvement in appendectomy have been variably associated with operative performance and postoperative outcomes. Comparisons of laparoscopic appendectomy procedures performed by residents versus senior registrars or consultants have shown no significant differences in postoperative complication rates, including intra-abdominal infections, despite longer operative times among resident-performed procedures, suggesting that resident participation under appropriate supervision does not inherently increase postoperative morbidity [22]. Furthermore, studies evaluating intraoperative performance metrics in emergency appendectomy have demonstrated that surgical experience level may influence technical performance scores and operative duration, indicating that experience can affect procedural efficiency even if complication rates remain similar [23]. Consistent with this evidence, the level of surgeon experience in our cohort did not emerge as a significant predictor of postoperative IAA formation, suggesting that delayed presentation and disease severity were more influential determinants of adverse outcomes in our setting.

Antibiotic stewardship and antimicrobial resistance are increasingly important considerations in postoperative infection management. Recent African studies report empiric broad-spectrum antibiotic use in more than 80% of complicated appendicitis cases, often in the absence of microbiological guidance [24, 25]. In our cohort, cultures were obtained from 68.4% of abscess cases, with Escherichia coli accounting for 70% of isolated organisms, emphasizing the need for local resistance surveillance to guide targeted therapy.

Studies from LMIC settings report wide variability in postoperative IAA rates after appendectomy, with laparoscopic approaches associated with IAA rates of approximately 5–15% and open surgery associated with rates of 10–25%, largely influenced by case mix and disease severity rather than operative modality alone [26]. Consistent with recent comparative data from LMICs showing no statistically significant difference in IAA rates between laparoscopic and open appendectomy after adjustment for perforation and delayed presentation, our findings further support the view that pathological severity and timing of presentation outweigh operative technique in determining postoperative abscess risk in resource-limited settings, as we found no difference in abscess development by surgical approach [27].

The management of post-appendectomy intra-abdominal abscesses is primarily guided by abscess size, anatomical location, patient stability, and institutional resources. Evidence indicates that selected clinically stable patients with small, well-circumscribed abscesses can be successfully managed with antibiotic therapy alone, with reported resolution rates of approximately 60–80%. In contrast, image-guided percutaneous drainage is recommended for larger, multiloculated, or non-resolving collections, achieving clinical success rates exceeding 70% and reducing the need for reoperation [28, 29]. In our cohort, conservative management with antibiotics alone was the most commonly used strategy (68.4%), followed by percutaneous drainage (21.1%), whereas reoperation was required in a minority of cases (10.5%). Despite limited access to interventional radiology, overall outcomes were favorable, with 89.5% of patients discharged in improved condition, suggesting that stepwise, resource-adapted management strategies can yield acceptable outcomes in low-resource settings.

This study has inherent limitations related to its retrospective design, which may introduce selection and information bias because of its reliance on the completeness and accuracy of medical records. The relatively small number of postoperative IAA events limited the feasibility of reliable multivariable modeling, including conventional logistic regression, penalized regression, or Firth logistic regression, without risking model overfitting and unstable estimates. Therefore, only unadjusted bivariate analyses were performed, and the identified factors should be interpreted as associations rather than independent predictors or causal relationships. Additionally, because the study was conducted in tertiary hospitals within a single urban setting, the findings may not be fully generalizable to rural or lower-level healthcare facilities with more limited resources.

Conclusion

In this multicenter retrospective study conducted in a resource-limited African setting, postoperative IAA formation following appendectomy was strongly associated with delayed presentation, greater disease severity, and prolonged operative duration. The findings emphasize that barriers to timely healthcare access remain the primary determinants of postoperative morbidity and underscore the need for early diagnosis, prompt surgical intervention, and targeted management of high-risk patients. Strengthening community awareness of appendicitis symptoms, optimizing perioperative strategies, improving access to diagnostic and therapeutic resources, and reinforcing antibiotic stewardship programs are critical steps toward reducing the burden of post-appendectomy IAA in similar low-resource environments.

Abbreviations

BMI

Body mass index

CT

Computed tomography

IAA

Intra-abdominal abscess

IQR

Interquartile range

IR

Interventional radiology

IRB

Institutional Review Board

LMICs

Low- and middle-income countries

MASAM

Africa Health Training and Research Center

SD

Standard deviation

Authors’ contributions

Ali Mohamed Arif: Project development, protocol development, literature search, data collection and management, data analysis, manuscript writing and editing, critical revision, final approval of the version to be published, and agreement to be accountable for all aspects of the work. Muhammet Ali Aydemir: Project development, literature search, data collection and management, data analysis, manuscript writing, final approval of the version to be published, and agreement to be accountable for all aspects of the work. Tugrul Ozdemir: Protocol development, literature search, data collection and management, data analysis, manuscript writing, final approval of the version to be published, and agreement to be accountable for all aspects of the work. Abdiwahab Dahir Alasow: Literature search, data analysis, manuscript editing, final approval of the version to be published, and agreement to be accountable for all aspects of the work. Feride İrem Simsek: Literature search, data collection and management, data analysis, manuscript editing, critical revision, final approval of the version to be published, and agreement to be accountable for all aspects of the work. Orhan Alimoglu: Project development, protocol development, data collection and management, critical revision, final approval of the version to be published, and agreement to be accountable for all aspects of the work.

Funding

The authors declare that this research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study was derived from a master’s thesis conducted within the School of Postgraduate Studies and Research at Benadir University. Ethical approval was obtained from the Benadir University Institutional Review Board under approval number BU/PSG/53/73.

The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and relevant institutional guidelines and regulations.

The requirement for informed consent to participate was waived by the Benadir University Institutional Review Board because of the retrospective nature of the study and the use of anonymized patient data.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.