Paracentesis

Make the Diagnosis: Paracentesis

Why Do a Paracentesis?

Once ascites is identified, diagnostic paracentesis yields a sample of fluid that can be analyzed to assess the likelihood of infected ascites, portal hypertension, or malignancy. Spontaneous bacterial peritonitis is present in almost a third of cirrhosis patients admitted to the hospital for evaluation and management of symptoms associated with ascites.^1-3 Paracentesis can also be done as a therapeutic procedure when large volumes of fluid are removed to provide the patient relief from symptoms.

Adverse Events

1. Bleeding complications are the most common adverse event, but studies show rates of only 0%-2.7%. Bowel performation is infrequent (0.83%, 95% confidence interval [CI] 0.10%-3.0%) as is residual catheter tip fragmentation (0.41%, 95% CI 0.01%-2.3%). The death rate is < 1.2%.

2. Therapeutic paracentesis can result in hyponatremia (0%-20%), renal insufficiency (0%-8.8%), encepathalopathy (1.7%-8.6%), or ascitic fluid leak (0%-24%). Plasma expanders do not decrease these events (Odds ratio CIs for plasma expanders vs no plasma expanders include 1 for each outcome). Patients needing therapeutic paracentesis are sick, so over the ensuing weeks after paracentesis 0%-13% may die, though it is unknown if these deaths are attributable to the procedure.

Contraindications

The relative contraindications are an uncooperative patient, skin infection at the proposed puncture site, pregnancy, or severe bowel distension.

Preprocedure Planning

1. Review the rationale and adverse events with the patient so that informed consent is obtained.

2. Though 1 expert suggests avoiding the procedure when the patient has active fibrinolysis or disseminated intravascular coagulation, routine preprocedure coagulopathy studies are probably unnecessary.⁴

3. Ultrasound guidance improves the success rate of diagnostic paracentesis by about 10% (61% without ultrasound vs 71% with ultrasound), though the difference is not significant (P = 0.39), and the number of needle passes is identical (P = 1.0). Ultrasound could be reserved for patients with small amounts of ascites undetected by physical examination or when conventional paracentesis does not yield ascitic fluid.

Evidence-Based Technique

The items below represent those that have been studied. Other factors such as needle insertion site, patient position, and course of the needle depend on physician preferences and patient factors (eg, the presence of scars or superficial varicosities, the ability of the patient to position themselves in the bed).

1. Diagnostic paracentesis. Use a 1.5-inch, 22-gauge metal needle, and if unsuccessful, try with a 3.5-inch, 22-gauge replacement. Successful aspiration can be achieved in at least 94% of patients.

2. Therapeutic paracentesis. A 15-gauge, 3.25-inch needle-cannula results in less multiple peritoneal punctures [P = .05] and termination due to poor fluid return [P = .02] vs a 14-gauge needle.

Evidence-Based Diagnostic Tests Following Paracentesis

Immediately inoculate the fluid into culture bottles, ...