Does acute pancreatitis classically present with acute peritonitis?

Acute Pancreatitis Does Not Classically Present with Acute Peritonitis

Acute pancreatitis does not classically present with acute peritonitis, although patients may exhibit signs of abdominal tenderness that can mimic peritonitis in severe cases. 1, 2

Clinical Presentation of Acute Pancreatitis

• Acute pancreatitis typically presents with upper abdominal pain and vomiting, with features of epigastric or diffuse abdominal tenderness 2, 3
• The inflammatory process is primarily localized to the pancreas and peripancreatic tissues, not causing a true peritonitis in most cases 1, 2
• In severe cases, body wall ecchymoses such as Cullen's sign (periumbilical bruising) or Grey-Turner's sign (flank bruising) may be evident, indicating retroperitoneal hemorrhage rather than peritonitis 2, 3
• Peritoneal signs may be present but are not part of the classic presentation and should prompt consideration of alternative or additional diagnoses 1

Diagnostic Considerations

• When peritoneal signs are prominent in a patient with suspected pancreatitis, other intra-abdominal catastrophes should be considered, including perforated viscus 1
• Ultrasound examination can detect free peritoneal fluid in the abdomen, which may be present in pancreatitis but does not necessarily indicate peritonitis 1, 2
• The color of peritoneal fluid in acute pancreatitis ranges from clear to "prune juice," which has prognostic significance but is not routinely assessed 1, 2
• CT scan is indicated when clinical and biochemical findings are inconclusive or when assessment of severity is needed 1, 3

When to Consider Peritonitis in Pancreatitis

• Rarely, when the clinical suspicion of peritonitis is high and all other tests, including CT scan, are inconclusive, laparotomy may be warranted 1
• Occasionally, acute pancreatitis and another intra-abdominal catastrophe may coexist, leading to true peritonitis 1
• Spontaneous intraperitoneal rupture of an acute necrotic fluid collection is a rare complication that can lead to peritonitis, requiring emergency surgical management 4
• Acute chylous peritonitis is an extremely rare complication of acute pancreatitis with fewer than 100 cases reported in the literature 5

Diagnostic Approach When Peritonitis is Suspected

• If peritoneal fluid is detected by imaging techniques in the absence of other biochemical or radiological signs of pancreatitis, the fluid should be sampled, preferably under radiological guidance 1
• Microscopical examination of the fluid may reveal bacterial contamination suggestive of perforation rather than uncomplicated pancreatitis 1
• A high fluid amylase content may suggest pancreatitis, although this can occur in other acute abdominal conditions 1
• Peritoneal fluid sampling is not recommended as a routine procedure in acute pancreatitis 1, 2

Common Pitfalls

• Misdiagnosing peritonitis in non-perforated pancreatitis as perforated viscus can lead to unnecessary surgical intervention 2
• Relying solely on clinical assessment for diagnosis is unreliable and may misclassify around 50% of patients 1, 2
• In patients on peritoneal dialysis, acute pancreatitis can present with cloudy dialysate and symptoms mimicking infectious peritonitis 6
• Early CT scan (within 72 hours of symptom onset) may not show necrotic areas and may underestimate the severity of pancreatitis 2