Situation: A 62-year-old woman with chronic kidney disease (CKD) stage G5 performs continuous ambulatory peritoneal dialysis (CAPD) at home with four exchanges a day. Her husband helps her with the exchanges. She attends the hospital's peritoneal dialysis clinic for follow-up. Two weeks later, her husband calls because this morning's drained fluid is cloudy and she has mild abdominal pain. At the unit, her temperature is 37.9 °C, and the physician prescribes an intraperitoneal antibiotic, paracetamol, and laboratory tests. Which action should the nurse take FIRST?

Cloudy effluent with abdominal pain is peritonitis until proven otherwise. The effluent sample for cell count, Gram stain, and culture is sent first, because antibiotics given beforehand can make the culture negative and hide the organism; the prescribed intraperitoneal antibiotic is then started without delay. Fever relief and exit-site care are appropriate but do not take priority.

Clinical situation
A CAPD patient presents with cloudy effluent and mild abdominal pain, with a temperature of 37.9 °C. This combination is peritonitis until proven otherwise, and the diagnostic sample must be obtained before any antibiotic is instilled.

Why the effluent sample comes first
The priority action is to send an effluent sample for cell count, Gram stain, and culture. Peritoneal dialysis–related peritonitis is diagnosed primarily by an elevated dialysate white blood cell count and a positive effluent culture. If an intraperitoneal antibiotic is added to the dialysate bag before the sample is collected, the antibiotic can suppress bacterial growth in the culture and produce a false-negative result, masking the causative organism and delaying targeted therapy. The sample must therefore be obtained before the prescribed antibiotic is administered, but the antibiotic itself should then be started without unnecessary delay.

How the evidence supports this sequence
Case reports consistently describe the diagnostic value of effluent analysis. In one report, an 88-year-old man presented with cloudy effluent and a dialysate WBC count of 800/μL, which confirmed peritonitis and guided initial intraperitoneal cefazolin and ceftazidime therapy ^[2]. Another patient had an effluent WBC count of 1500/μL at presentation, and the culture subsequently identified Moraxella osloensis, allowing de-escalation to ceftazidime monotherapy ^[4]. These examples illustrate that the cell count establishes the diagnosis rapidly, while the culture identifies the pathogen for definitive treatment. Key point! A negative culture after early antibiotic exposure does not rule out infection; it simply removes the ability to identify the organism.

Why the other options are not first
Paracetamol addresses fever and discomfort but does not treat the underlying infection or secure the diagnosis. Adding the antibiotic to the next dialysate bag is essential, but doing so before collecting the effluent sample risks losing the microbiologic diagnosis. Exit-site care and antibiotic cream target the catheter exit site, which is a separate concern from intraperitoneal infection; cloudy effluent reflects inflammation inside the peritoneal cavity, not the exit site.

Clinical reasoning for the licensure exam
The sequence to remember is: sample first, then antibiotic. The diagnostic triad for PD peritonitis is cloudy effluent, abdominal pain, and an elevated effluent WBC count. Watch out! Cloudy effluent can occasionally have noninfectious causes, such as malignancy, as reported in a case of high-grade B-cell lymphoma presenting with persistent cloudy effluent despite antibiotics . However, the initial clinical approach remains the same: treat as infectious peritonitis until proven otherwise, and obtain cultures before starting antimicrobials. In this scenario, the nurse should first send the effluent sample for cell count, Gram stain, and culture, then proceed with the prescribed intraperitoneal antibiotic.