Paracentesis

Key Clinical Questions

What are the indications for a paracentesis?
When should you use ultrasound guidance or involve interventional radiology?
When should you correct a coagulopathy?
What is the role of albumin administration?
What is the best site location to enter to reduce the risk of complications?

Introduction

Paracentesis is a procedure that involves removing ascitic fluid from the abdominal cavity with a needle or catheter. Using local anesthesia, hospitalists, other internists, Emergency Medicine physicians, proceduralists, and radiologists perform this procedure in either an outpatient or inpatient setting. A diagnostic paracentesis can determine the cause of ascites and rule out spontaneous bacterial peritonitis. A therapeutic paracentesis will remove excess fluid.

Dating back to the time of Hippocrates, paracentesis using large bore catheters was the only available option to remove ascitic fluid. In the 1950s, oral diuretics and sodium restriction were introduced as a safer alternative, typically requiring an extended hospital stay. In the mid 1980s, large-volume paracentesis was reintroduced without plasma expanders and was once again deemed a safe practice that would not cause a change in plasma volume. Abdominal imaging has replaced the practice of evaluating abdominal trauma by performing a diagnostic paracentesis.

Pathophysiology

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 in the setting of portal hypertension. Capillary pressure increases with obstruction of venous blood flow through the damaged liver. Failure of the liver to metabolize aldosterone increases sodium and water retention through the kidney. Failure of the liver to produce 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.

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Case 116-1

A 55-year-old woman with hypertension and atrial fibrillation presented to the emergency department with an increase in abdominal girth, weight gain, shortness of breath and lower extremity edema over the last several months. She denied alcohol consumption and intravenous drug use. Her medications included metoprolol and warfarin. Her vital signs revealed that she was afebrile with an oxygen saturation of 92% on room air. Her physical examination was notable for tachypnea, significant ascites, and pitting edema. Her laboratory values significant for a normal white blood cell count, an INR of 2.6 and a platelet count of 125,000/mm3. A paracentesis was performed.

Indications: Any new onset ascites of unclear etiology needs to be tapped to determine etiology.
Pre- procedure individual risk assessment of bleeding: Her warfarin was held and fresh frozen plasma was given. No platelets were administered as there is no evidence of a platelet cutoff in the literature.
Procedure: A diagnostic and therapeutic paracentesis was performed under ultrasound guidance at the right lower quadrant. Ultrasound guidance was used as it was readily available and the largest pocket of fluid was in the right lower quadrant. A therapeutic volume of six liters was removed to relieve her symptoms.
Postprocedure: Albumin was given because greater than 4 to 5 liters of ascitic fluid was removed.
Testing: Her fluid was sent for cell count and differential, gram stain and culture, albumin, and cytology.

Indications for the Procedure

Ascitic fluid may be collected for both diagnostic and therapeutic purposes. Diagnostically, emergent examination of the ascitic fluid provides essential information in many clinical situations:

New-onset ascites of unclear etiology. Evaluation of the fluid can help classify the cause into portal hypertensive causes (liver disease and congestive heart failure) or nonportal hypertensive causes (malignancy, pancreatitis, and malnutrition/protein wasting).
Any change in clinical status of a known cirrhotic including a hospital admission. A diagnostic paracentesis should be performed to rule out spontaneous bacterial peritonitis even if no signs of infection are apparent.
Suspected peritonitis relating to peritoneal dialysis.

Therapeutic paracentesis is performed to help relieve abdominal discomfort and dyspnea for symptomatic patients.

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Case 116-2

A 58-year-old man with known alcoholic cirrhosis presented to the emergency department with increased abdominal girth and shortness of breath. His physical examination was notable for tachypnea and tense ascites. His laboratory values were significant for a normal white blood cell count, platelet count of 75,000/mm3, INR of 2.8, and creatinine of 3.0 mg/dL. A paracentesis was performed.

Indications: Patient had deteriorated clinically.
Preprocedure individual risk assessment of bleeding: There was no indication for FFP or platelets.
Procedure: A diagnostic and therapeutic paracentesis was performed without ultrasound guidance in the left lower quadrant. No ultrasound (US) was readily available. The left lower quadrant is recommended when the tap is blind and there is tense ascites. Ten liters of straw colored fluid was removed from the left lower quadrant, the preferred location in this setting.
Postprocedure: Albumin was given due to the possibility of hepatorenal syndrome and greater than 4 to 5 liters of fluid removal.
Testing: His ascitic fluid was sent for cell count and differential, gram stain, culture, and albumin.

Contraindications

Paracentesis is a relatively benign procedure even though contraindications do exist. Absolute contraindications include an acute abdomen, an uncooperative patient, and disseminated intravascular coagulopathy. Relative contraindications include coagulopathy, abdominal adhesions, infected abdominal wall at entry site, distended bowel or bladder, and pregnancy.

The American Association for the Study of Liver Diseases (AASLD) has not recommended reversing the INR or administering platelets in patients who have liver disease–induced coagulopathy or thrombocytopenia. Proceduralists should be cautious of performing paracentesis without reversing the coagulopathy on patients receiving anticoagulants. Although there is no recommended guideline, a generally accepted practice is to reverse the INR to less than 1.5 if the patient is receiving warfarin. There is inadequate data to guide proceduralists at this time relating to antiplatelet agents. Each patient should be evaluated individually to determine the risk of bleeding complications.

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Practice Point

There is no recommendation of INR or platelet cutoffs for patients with liver disease.
It is generally accepted to reverse the coagulopathy to INR < 1.5 for patients receiving warfarin.
Evaluate each patient for risk of bleeding.

Complications

Paracentesis is a relatively safe procedure with complications occuring in less than 1 in 1000 procedures. Complications include hypotension, infection, bowel perforation, sheared-off catheter fragments, persistent leak of ascitic fluid, hemoperitoneum, hematoma, and patient discomfort. The incidence of clinically significant bleeding with paracentesis is very low. In a retrospective study of more than 4700 patients, patients with elevated creatinines had an increased risk of bleeding that was not statistically significant.

Steps to minimize the complication rate include:

Check coagulation status prior to performing the procedure and reverse as appropriate.
Make sure that the patient does indeed have enough ascites that can be tapped. Ultrasound can be very useful to help confirm fluid location and amount.
Make sure the patient is not already hypovolemic.
Follow procedure protocols at your institution.
Ensure competency in performance or seek adequate supervision.
Intervene in a timely manner when a complication develops.