A rare case of peritonitis complicating acute appendicitis in a Patient on peritoneal dialysis

Abstract

Peritonitis is the most common complication in patients undergoing peritoneal dialysis (PD). However, its persistence despite appropriate antibiotic therapy should prompt consideration of alternative diagnoses, particularly acute appendicitis. We report the case of a 39-year-old PD patient who presented with culture-negative peritonitis unresponsive to treatment, ultimately resulting in a diagnosis of latero-cecal acute appendicitis. Diagnosis was confirmed by abdominal CT scan and exploratory laparoscopy, leading to surgical management with appendectomy and peritoneal lavage, while the catheter was preserved. Clinical improvement was achieved with targeted antibiotic therapy, and PD was resumed with low-volume exchanges without switching to hemodialysis. This case highlights the diagnostic challenge of acute appendicitis in PD patients, where clinical signs can be masked by frequent peritoneal lavage and intraperitoneal antibiotics. Prompt imaging and early surgical intervention are crucial to prevent complications.

INTRODUCTION

Abdominal pain is a concerning clinical sign in peritoneal dialysis (PD) and often raises suspicion for peritonitis as the primary diagnosis. Peritonitis, typically presenting with abdominal symptoms and cloudy dialysis effluent[1], is the most common infectious complication in PD patients. It generally responds well to antibiotic therapy without requiring surgery. However, other abdominal conditions can mimic or coexist with peritonitis and should be considered, especially when peritonitis is refractory to antibiotics. These include surgical peritonitis due to organ perforation, pancreatitis, cholecystitis, and acute appendicitis[2]. Abdominal computed tomography (CT) and laparoscopy are particularly useful in the diagnosis and the management of such cases[3].

In this context, we report a rare case of a PD patient who developed acute appendicitis associated with peritonitis.

CASE REPORT

We present the case of a 39-year-old male with end-stage renal disease of unknown origin who had been undergoing CAPD since 2021.

Four months after initiating dialysis, he developed his first episode of peritonitis due to methicillin-sensitive Staphylococcus aureus, which was successfully treated with intraperitoneal (IP) cefazolin for 21 days based on the results of antibiotic susceptibility testing. The treatment resulted in full recovery without recurrence.

Two years later, the patient presented with abdominal pain and cloudy dialysis effluent, without fibrin or drainage abnormalities.

Clinical examination revealed a blood pressure of 160/100 mmHg and tachycardia at 118 beats per minute. There were no signs of fluid overload, and the patient was afebrile.

Investigations

Laboratory findings revealed an inflammatory syndrome with neutrophilic leukocytosis (13.6 G/L) and a CRP level of 190 mg/L. Lipase was negative at 20 IU/L. Liver function tests and transaminases were within normal limits: AST 28 IU/L, ALT 22 IU/L, GGT 28 IU/L, and ALP 61 IU/L. The patient had inflammatory anemia with a hemoglobin level of 9.9 g/dL.

Electrolyte results were as follows: potassium 4.4 mmol/L, bicarbonate 27 mmol/L, sodium 134 mmol/L, chloride 95 mmol/L, glucose 1.08 g/L, blood urea 30.4 mmol/L, and serum creatinine 1,034 µmol/L.

Bacteriological analysis of the dialysis effluent confirmed a diagnosis of culture-negative peritonitis, with a leukocyte count, predominantly neutrophils, of 6,300/mm³ in the dialysate. No organism was isolated from the exit site.

In accordance with our protocol, antibiotic therapy was initiated with intraperitoneal cefazolin and ceftazidime, along with a single dose of an aminoglycoside.

After 48 hours, the patient showed clinical and biological deterioration: ongoing abdominal pain, persistent cloudy effluent, and development of bowel obstruction symptoms (absence of stool and gas). An abdominal X-ray showed diffuse colonic gas without air-fluid levels. An abdominal CT scan revealed acute latero-cecal appendicitis, characterized by cecal fluid distension extending to the ascending colon (measuring 56 mm), with the PD catheter still in place in the pelvis (Figure 1:).

A diagnosis of peritonitis associated with latero-cecal acute appendicitis in a PD patient was thus established.

Figure 1:CT scan image confirming the diagnosis of acute appendicitis (red arrow)

Therapeutic Management

Given the diagnosis of acute appendicitis, an exploratory laparoscopy was performed and revealed a thickened appendix with adjacent inflammatory signs and several adhesions. The catheter was in place and remained patent. A peritoneal lavage, appendectomy, and adhesiolysis were performed, while the catheter was preserved (Figure 2:)

Figure 2:Surgical specimen from the appendectomy

Histologically, the anatomopathological examination revealed an enlarged latero-cecal appendix, with an 11-mm-thick stercolith and adjacent fat infiltration. The cytobacteriological analysis revealed a positive culture for Escherichia coli and Group B Streptococcus. Given the lack of clinical improvement and persistent febrile syndrome, the antibiotic therapy was changed to ertapenem. Peritoneal dialysis was resumed with small volumes 72 hours later, without reliance on hemodialysis. Antibiotic therapy was maintained for a total duration of three weeks. The patient’s condition showed clinical and biological improvement, and no recurrence of peritonitis was noted after one year of follow-up.

DISCUSSION

Peritonitis in PD patients is a common complication but is generally well treated with IP antibiotics. However, in this context, acute appendicitis represents a significant diagnostic challenge due to the attenuation of clinical symptoms specific to peritonitis. PD patients often present with atypical symptoms in cases of acute appendicitis due to the effect of peritoneal lavage: Frequent dialysate exchanges reduce bacterial load and delay abscess formation, thus masking typical signs such as localized pain or rebound tenderness[4][5]. Additionally, the use of IP antibiotics alters the inflammatory response and delays the diagnosis[5][6]. Persistent abdominal pain despite 48 hours of appropriate antibiotic treatment may indicate a secondary cause, such as appendicitis[1][2], while polymicrobial peritonitis involving enteric or anaerobic organisms serves as another warning sign[8]. In these cases, complementary exams play a crucial role: Abdominal CT, although often inconclusive, is essential for revealing the possibility of appendicitis or for ruling out other causes[9], while laparoscopy, recommended in cases of doubt, allows direct visualization and surgical management[10].

Appendicitis in PD patients can lead to peritoneal adhesions and catheter obstruction, as observed in our patient and supported by other cases in the literature where pelvic organs or inflamed appendices trap the catheter [9,11]. Delaying laparoscopy in these situations may increase morbidity and mortality[7][12]. Early surgical intervention, via laparoscopy or laparotomy, is essential to treat the appendicitis and reposition or replace the catheter if necessary. Resumption of PD at low volume is often possible after the procedure, although conversion to hemodialysis may sometimes

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