Pocket Medicine

GASTROENTEROLOGY

ASCITES

Pathophysiology

•  Portal hypertension → systemic vasodilatation (? due to release of NO) → ↓ effective arterial volume → renal Na retention

•  ↓ serum oncotic pressure from hypoalbuminemia; ↑ hepatic lymph production

Symptoms

•  ↑ abd girth, wt gain, new abd hernia, abd pain, dyspnea, nausea, early satiety

Evaluation (JAMA 2008;299:1166; Hepatology 2009;29:2087)

•  Physical exam: flank dullness (NPV ~90%; >1500 mL needed), shifting dullness (Se ~83%)

•  Radiologic: U/S detects >100 mL; MRI/CT (also help with Ddx)

•  Paracentesis (NEJM 2006;355:e21; Dig Dis Sci 2007;52:3307): perform in all Pts w/ new ascites and consider in all hospitalized cirrhotics w/ ascites; complic. <1% (bleeding, but risk not related to PT or plt count; Hepatology 2004;40:484); U/S ↑ success but does not ↓ complic.

•  Serum-ascites albumin gradient (SAAG): ~95% acc. for portal HTN (Annals 1992;117:215)

≥1.1 g/dL → portal hypertension related; <1.1 g/dL → non–portal hypertension related

if portal HTN + another cause (seen in ~5% of cases) SAAG still ≥1.1

if known cirrhosis and SAAG <1.1 but no other readily identifiable cause, likely just cirrhosis (Am J Gastro 2009;104:1401)

•  Ascites fluid total protein (AFTP): useful when SAAG ≥1.1 to distinguish cirrhosis (AFTP <2.5 g/dL) from cardiac ascites (AFTP ≥ 2.5 g/dL)

•  Rule out infection: cell count w/ diff + Gram stain/cx define bacterial peritonitis (see later); bedside inoculation of cx bottles ↑ yield to 90% (Gastro 1988;95:1351) fungal cx if prolonged hosp, abx use; AFB cx + adenosine deaminase to r/o TB

•  Other tests: amylase (pancreatitis, gut perforation); triglycerides (chylous ascites); cytology (peritoneal carcinomatosis, ~95% Se w/ 3 samples); LDH, glc, CEA, AΦ (perforation)

Treatment

•  If 2° to portal HTN (see “Cirrhosis” for details): ↓ Na intake + diuretics (spironolactone + furosemide); if refractory → large-volume paracentesis or TIPS

•  If non–portal HTN related: depends on underlying cause (TB, malignancy, etc.)

•  Vaptans ↑ Na, mobilize ascites, but no morb/mort benefit (Al Pharm & Ther 2012;36:619)

Bacterial peritonitis (Gut 2012;61:297)

•  SBP/CNNA: seen in cirrhosis (qv) b/c ascites have ↓ opsonins; rare in other causes

•  NNBA: often resolves w/o Rx; follow closely → Rx only if sx or persistently culture 

•  Secondary intra-abdominal abscess or perforation so often polymicrobial ascitic fluid TP >1 g/dL, glc <50 mg/dL, LDH >225 U, CEA >5, AΦ >240 Rx: 3rd-gen. ceph + metronidazole; urgent abdominal imaging ± ex lap

•  Peritoneal dialysis-associated: cloudy fluid, abd pain, fever, nausea pathogens: 70% GPC, 30% GNR; Rx: vanc + gent (IV load, then administer in PD)