Gastrointestinal & Hepatic · Topic 6 of 26

Ascites & Spontaneous Bacterial Peritonitis

Hepatic · complication of cirrhosis

Ascites & Spontaneous Bacterial Peritonitis

Tap every new or admitted ascites: SAAG ≥ 1.1 means portal hypertension, PMN > 250 means SBP — treat with a cephalosporin plus albumin.

Key numbers

SAAG ≥ 1.1 g/dL means portal hypertensionSAAG ≥ 1.1 g/dL

Ascitic PMN > 250/mm³ diagnoses SBPPMN > 250/mm³

Albumin 1.5 g/kg, then 1 g/kg1.5 g/kg → 1 g/kg (day 3)

Large-volume paracentesis for tense ascites6–8 g albumin/L if > 5 L

01 · Defined bySAAG ≥ 1.1 g/dL means portal hypertension

Serum-ascites albumin gradient (serum minus ascitic albumin) ≥ 1.1 g/dL reflects portal hypertension (cirrhosis, heart failure, Budd-Chiari); < 1.1 g/dL excludes it (carcinomatosis, tuberculosis, pancreatitis, nephrotic syndrome).

02 · Defined byAscitic PMN > 250/mm³ diagnoses SBP

Spontaneous bacterial peritonitis is diagnosed by an ascitic neutrophil (PMN) count above 250/mm³; start empirical IV antibiotics at that count without waiting for the culture.

03 · GiveAlbumin 1.5 g/kg, then 1 g/kg

Give IV albumin with antibiotics in SBP — 1.5 g/kg on day 1, 1 g/kg on day 3 — to prevent hepatorenal syndrome and improve survival, especially with AKI or jaundice.

Causes & risk factors

Why it happens

Primary prophylaxis: protein < 1.5 plus organ dysfunctionConsider primary prophylaxis for ascitic protein < 1.5 g/dL plus renal dysfunction (creatinine > 1.2 mg/dL, BUN > 25 mg/dL or sodium < 130) or liver failure (Child-Pugh > 9, bilirubin > 3 mg/dL).

Presentation

What you'll see

SBP may present only as encephalopathy or AKISBP can cause fever, diffuse abdominal pain and tenderness, but up to one-third of patients have no abdominal findings and present only with encephalopathy, AKI or worsening liver function.

Diagnosis & monitoring

Work-up

Refractory ascites: refer for TIPS or transplantRefractory ascites persists or recurs despite maximal diuretics (spironolactone 400 mg plus furosemide 160 mg daily) or because diuretics cause AKI, hyponatremia or hypotension; refer for TIPS or liver transplant evaluation.

Do right now

In this order

First moves

Diagnostic paracentesis for new or admitted ascites

→

Inoculate blood culture bottles before antibiotics

→

IV third-generation cephalosporin for community SBP

→

Albumin 1.5 g/kg, then 1 g/kg1.5 g/kg → 1 g/kg (day 3)

Why each step

Diagnostic paracentesis for new or admitted ascitesDo a diagnostic paracentesis for new-onset ascites, for every patient with cirrhotic ascites admitted emergently (even without signs of infection), and whenever infection, encephalopathy, AKI or unexplained deterioration appears.

Inoculate blood culture bottles before antibioticsInoculate ascitic fluid into aerobic and anaerobic blood culture bottles at the bedside before the first antibiotic dose — this raises culture yield — and draw blood cultures too.

IV third-generation cephalosporin for community SBPCommunity-acquired SBP: IV third-generation cephalosporin (cefotaxime 2 g every 12 h or ceftriaxone) for 5–7 days. Nosocomial SBP, recent broad-spectrum antibiotics or septic shock: piperacillin-tazobactam or meropenem, tailored to resistance risk.

Albumin 1.5 g/kg, then 1 g/kgGive IV albumin with antibiotics in SBP — 1.5 g/kg on day 1, 1 g/kg on day 3 — to prevent hepatorenal syndrome and improve survival, especially with AKI or jaundice.

Management

Orders

Restrict sodium to 2 g/day; fluid rarelyPrescribe moderate dietary sodium restriction (2 g or 90 mmol/day); restrict fluid only for hyponatremia with serum sodium ≤ 125 mmol/L.

Spironolactone 100 mg ± furosemide 40 mgStart spironolactone 100 mg/day (up to 400 mg), adding furosemide 40 mg/day (up to 160 mg) as needed; target weight loss ≤ 0.5 kg/day without edema, up to 1 kg/day with edema.

Large-volume paracentesis for tense ascitesLarge-volume paracentesis is first-line for grade 3 (tense) and refractory ascites; when more than 5 L is removed, give albumin 6–8 g per liter removed to prevent post-paracentesis circulatory dysfunction.

Long-term prophylaxis after an SBP episodeAfter SBP give long-term daily secondary prophylaxis — norfloxacin, or oral ciprofloxacin 500 mg daily in the US, where norfloxacin was withdrawn — because SBP recurs in about 70% within a year without it.

Ceftriaxone prophylaxis in cirrhotic GI bleedingEvery patient with cirrhosis and upper GI hemorrhage gets SBP prophylaxis: IV ceftriaxone 1 g every 24 hours for a maximum of 7 days.

Hold beta-blockers if MAP < 65 or AKITemporarily hold nonselective beta-blockers in SBP when the patient becomes hypotensive (MAP < 65 mmHg) or develops AKI; restart after the infection clears.

Red flags & don'ts

Avoid harm

Avoid NSAIDs, ACE inhibitors, ARBs, aminoglycosides avoidIn cirrhotic ascites avoid NSAIDs, ACE inhibitors and ARBs — they precipitate AKI, hyponatremia and diuretic resistance — and avoid aminoglycosides whenever possible.

The rules

Know these

No FFP or platelets before paracentesisCoagulopathy and thrombocytopenia (even INR > 1.5, platelets < 50,000) do not contraindicate paracentesis, and routine plasma or platelet transfusion beforehand is not recommended; DIC is the possible exception.

Spontaneous or secondary bacterial peritonitis?

Commonly confused

Source	No intra-abdominal source
Ascitic culture	Usually a single organism
PMN after 48 h of antibiotics	Falls by 25% or more
Management	IV cephalosporin plus albumin

More detail

Reference

Show 6 reference facts

Repeat paracentesis 48 hours into treatment can assess response: a PMN fall of less than 25% from baseline means treatment failure — broaden antibiotics and look for secondary bacterial peritonitis.

Bacterascites — positive culture with PMN < 250/mm³ and no signs of infection — is not treated; repeat the paracentesis to check for progression to SBP.

Post-paracentesis circulatory dysfunction (AKI or HRS, dilutional hyponatremia, encephalopathy) risk rises when more than 8 L is removed in one session, even with albumin.

For TIPS in refractory ascites, a covered stent under 10 mm lowers post-TIPS encephalopathy; MELD ≥ 18, older age and cardiopulmonary disease predict poor outcomes, and ascites clears gradually over weeks to months.

Hepatic hydrothorax is a transudative, usually right-sided effusion from ascites crossing diaphragmatic defects; treat with sodium restriction, diuretics and thoracentesis, avoid chest tubes, and consider TIPS or transplant.

A spot urine sodium/potassium ratio above 1 correlates with natriuresis; persistent ascites despite adequate urinary sodium excretion means dietary sodium indiscretion, not diuretic failure.

Pearl

Tap first, treat at 250: a PMN count above 250/mm³ starts antibiotics and albumin before the culture is back.

Sources · Biggins SW et al. Diagnosis, Evaluation, and Management of Ascites, Spontaneous Bacterial Peritonitis and Hepatorenal Syndrome: 2021 Practice Guidance by the AASLD. Hepatology 2021;74:1014–1048 · Merck Manual Professional — Ascites · Merck Manual Professional — Spontaneous Bacterial Peritonitis (SBP) · Kaplan DE et al. AASLD Practice Guidance on risk stratification and management of portal hypertension and varices in cirrhosis. Hepatology 2024;79:1180–1211 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).