Paracentesis is a procedure that removes ascitic fluid from the abdominal cavity with a needle or a catheter. A diagnostic paracentesis may determine the cause of ascites and rule out spontaneous bacterial peritonitis. A therapeutic paracentesis will remove excess fluid.
The mechanism for the development of ascites (excess fluid accumulation in the peritoneal space) is not well understood. Cirrhosis is the leading cause of ascites due to portal hypertension. Capillary pressure increases with obstruction of venous blood flow through the damaged liver. Reduced hepatic metabolism of aldosterone increases renal sodium and water retention. Reduced hepatic synthesis of albumin contributes to fluid moving from the vascular space into the peritoneal space. In addition to cirrhosis, other causes of portal hypertension include right heart failure, portal vein thrombosis, Budd-Chiari syndrome, and liver metastases. Pancreatitis, chylous fluid accumulation, nephritic syndrome, serositis, colitis, peritoneal carcinomatosis, tuberculous peritonitis, and peritonitis may cause ascites through a different mechanism.
Any amount of peritoneal fluid withdrawn during paracentesis is abnormal. A diagnostic test (60 cc of fluid) includes:
Cell count and differential (few mL)
Gram stain and culture (ideally, 5 mL in an anaerobic and aerobic blood culture bottle)
Simultaneous serum albumin to calculate a serum albumin ascites gradient (few mL)
Cytology (the more fluid, the greater yield)
Other studies such as amylase, triglycerides, and AFB are performed only if clinically indicated.
Practice algorithm: preprocedure preparation.
Table 126-1Basic Considerations ||Download (.pdf) Table 126-1 Basic Considerations
|Indications ||Diagnostic Paracentesis ||Comments |
| || |
New onset ascites of unclear etiology
Any change in the clinical status of the patient with known ascites, including hospital admission
Suspected peritonitis relating to peritoneal dialysis
To relieve abdominal discomfort and dyspnea
Portal hypertension: liver disease, heart failure
Nonportal hypertensive causes: malignancy, pancreatitis, malnutrition, protein wasting
To rule out spontaneous bacterial peritonitis, even in the absence of signs of infection
Infected abdominal wall at entry site
Distended bowel or bladder
Caput medusa or superficial veins
Hernia at chosen site
Scar tissue (vascularity)
There is no recommendation of INR or platelet cutoffs for patients with liver disease; it is generally accepted to reverse INR to <1.5 for patients on warfarin. There are inadequate data relating to antiplatelet agents
Choose another site
|Procedural preparation || |
Confirm location, amount of fluid, nearby vessels
Visualize structures (history of adhesions, presence of scars)
Visualize suspectedwidespread malignancy
US best modality
Consider abdominal CT
Have patient urinate prior to tap
|Complications during procedure || |
Sheared-off catheter fragments hemoperitoneum, hematoma
Risk factors: hypovolemia
Risk factors: blind tap, inexperience
Risk factors: coagulopathy
|Complications after procedure || |
Persistent leak of ascitic fluid
Place a temporary ostomy bag, repeat therapeutic thoracentesis, or ...