MBBS OSCE · Gastroenterology
OSCE — Ascites and Spontaneous Bacterial Peritonitis
Eight-minute OSCE station on Ascites and Spontaneous Bacterial Peritonitis: focused history, examination priorities, investigations, emergency and definitive management.
On this page
Study tools
Exam tags
Brief (to candidate)
You will assess a patient with a presentation consistent with Ascites and Spontaneous Bacterial Peritonitis.
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.[1]
Clinical context
Ascites is the pathological accumulation of fluid in the peritoneal cavity. Cirrhosis causes over 80 percent of cases through portal hypertension, hypoalbuminaemia, splanchnic vasodilation (nitric oxide) and renal sodium and water retention (RAAS and sympathetic activation). The serum-ascites albumin gradient (SAAG) of 1.1 g/dL or more separates portal-hypertensive from non-portal causes. Spontaneous bacterial peritonitis (SBP) is a monomicrobial infection of ascitic fluid without an obvious intra-abdominal source, defined by an ascitic polymorphonuclear neutrophil count of 250 cells/mm3 or more, treated with a third-generation cephalosporin (cefotaxime 2 g IV every 8 hours) for 5 days plus intravenous albumin (1.5 g/kg on day 1 and 1 g/kg on day 3), with norfloxacin 400 mg daily for secondary prophylaxis.[3]
Candidate tasks
- Clarify onset, severity, associated features, and red-flag symptoms.[1]
- State focused examination priorities.
- List first-line investigations and any named score/criteria.
- Give immediate resuscitation steps.
- Outline definitive management with doses/routes where standard.
- Name complications and disposition (ward / HDU / theatre / discharge safety-net).
- Mention one special-population modifier (pregnancy, child, elderly, CKD).[2]
Examiner checklist
| Domain | Pass behaviours |
|---|---|
| Definition | Correct working diagnosis language |
| Assessment | Focused, prioritised, red flags sought |
| Investigations | Appropriate first-line + interpretation |
| Emergency care | ABC / time-critical actions first |
| Definitive care | Specific drugs/procedures, not generic phrases |
| Safety | Cirrhotic with ascites and fever, pain or unexplained deterioration — SBP until proven otherwise; immediate diagnostic tap; treat if PMN 250 cells/mm3 or more.[2] |
| Safety | Tense ascites with respiratory compromise — large-volume paracentesis with albumin 6 to 8 g per litre when 5 L or more is removed |
| Safety | Rising creatinine in a decompensated cirrhotic — hepatorenal syndrome; stop diuretics and nephrotoxins, albumin, terlipressin |
| Communication | Clear plan and safety-netting |
Model outline
Lead with the working diagnosis and life threats. Resuscitate before definitive tests when unstable. Use guideline-standard therapy with named agents and doses. Document escalation criteria and follow-up. A safe candidate is specific, structured, and never delays critical care for non-urgent imaging.[3]
References4ShowHide
- [1]Runyon BA, Montano AA, Akriviadis EA, et al. The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites Ann Intern Med, 1992.PMID 1616215
- [2]Koulaouzidis A Diagnosis of spontaneous bacterial peritonitis: an update on leucocyte esterase reagent strips World J Gastroenterol, 2011.PMID 21448413
- [3]Sort P, Navasa M, Arroyo V, et al. Effect of intravenous albumin on renal impairment and mortality in patients with cirrhosis and spontaneous bacterial peritonitis N Engl J Med, 1999.PMID 10432325
- [4]Runyon BA, McHutchison JG, Antillon MR, et al. Short-course versus long-course antibiotic treatment of spontaneous bacterial peritonitis Gastroenterology, 1991.PMID 2019378