Differential Diagnosis for SBP (Spontaneous Bacterial Peritonitis)
Single Most Likely Diagnosis
- Spontaneous Bacterial Peritonitis (SBP): This is the most likely diagnosis given the context of the question. SBP is an infection of the ascitic fluid in the absence of any intra-abdominal source of infection, commonly seen in patients with cirrhosis and ascites. The diagnosis is typically made by analyzing the ascitic fluid for a high neutrophil count (>250 cells/mm^3) and the presence of bacteria.
Other Likely Diagnoses
- Secondary Peritonitis: This condition occurs when there is an identifiable source of infection within the abdomen, such as a perforated viscus or an intra-abdominal abscess. The clinical presentation can be similar to SBP, but the presence of an intra-abdominal source distinguishes it.
- Tuberculous Peritonitis: This is a form of peritonitis caused by Mycobacterium tuberculosis. It can present similarly to SBP but is more chronic and often associated with other systemic symptoms of tuberculosis.
- Malignant Ascites: Ascites due to peritoneal carcinomatosis can mimic the symptoms of SBP, including abdominal pain and fever, but the ascitic fluid analysis would show malignant cells rather than a high neutrophil count.
Do Not Miss Diagnoses
- Intra-abdominal Abscess: Missing an intra-abdominal abscess could be catastrophic as it requires prompt drainage. Symptoms can overlap with SBP, and imaging studies are crucial for diagnosis.
- Perforated Viscus: A perforation of the gastrointestinal tract is a surgical emergency. While the presentation can be dramatic, in some cases, it may be subtle, especially in patients with cirrhosis and ascites, making it a "do not miss" diagnosis.
- Pancreatitis: Acute pancreatitis can cause severe abdominal pain and can lead to secondary infection or abscess formation. It's crucial to consider this diagnosis, especially if there are elevated pancreatic enzymes.
Rare Diagnoses
- Eosinophilic Peritonitis: A rare condition characterized by an elevated eosinophil count in the ascitic fluid, often associated with parasitic infections or eosinophilic gastroenteritis.
- Fungal Peritonitis: This is a rare but serious infection that can occur, especially in immunocompromised patients or those with a history of antibiotic use. It requires a high index of suspicion for diagnosis.
- Chylous Ascites: Although not an infection, chylous ascites (the accumulation of lymphatic fluid in the peritoneal cavity) can present with abdominal distension and discomfort, mimicking infectious causes of ascites.