A COMMON SURGICAL DIAGNOSIS MASQUERADING AS A COMMON MEDICAL DIAGNOSIS: MULTIPLE CAUSES OF SPONTANEITY IN SPONTANEOUS BACTERIAL PERITONITIS

Learning objectives: This vignette demonstrates diagnostic challenges in a patient with symptoms that could be explained by both common medical and surgical diagnoses.  1) Participants will learn to be cautious about premature diagnostic closure when therapy is not producing expected results.  2) Participants will learn to be cautious about premature closure when a specialist makes a very early diagnostic error.  3) Participants will appreciate the role of an independent diagnostic investigation, despite multiple consultants focusing on a single diagnosis.

Case information: A 61 year-old man with renal failure on peritoneal dialysis (PD) presented to his PD clinic with severe abdominal pain, fever, nausea, and cloudy diasylate.   Abdominal CT showed pericecal and appendiceal inflammation that was most likely reactive to ascitic fluid from an infected PD catheter.  The patient was cared for by a primary medical team, transplant surgery, and nephrology. The patient’s symptoms persisted after eight days of antibiotic therapy for presumed spontaneous bacterial peritonitis (SBP) without improvement.  The peritoneal catheter was then removed, and exploratory laparoscopy revealed a perforated appendix with multiple loculations and abscesses.   The patient required acute, inpatient rehabilitation prior to discharge.

Discussion: The primary service, nephrology, and transplant surgery all failed to diligently confirm that competing diagnoses were ruled out, enabling premature closure—a common diagnostic error.^1-3  Even when treatment effectiveness was questioned, diagnostic momentum interfered with meaningful reevaluation.  As a result, the patient suffered increased length of stay, unnecessary pain, and prolonged rehabilitation. While SBP is the most common cause of peritonitis in PD patients, primary gastrointestinal disorders cannot be overlooked.  Atypical clinical presentations of acute appendicitis have been well documented.^4-8  The surgical literature recommends early diagnostic laparoscopy in patients whose symptoms fail to improve after twenty-four hours of antibiotic therapy, even when CT findings are negative.⁴