Ascites is the abnormal accumulation of fluid within the peritoneal cavity, the space inside the abdomen containing the organs. This fluid buildup causes discomfort and complications. The procedure used to remove this excess fluid is called paracentesis, often called an abdominal tap. It involves inserting a needle or catheter into the abdominal space to drain the liquid.
Reasons for Draining Ascites
The decision to perform paracentesis falls into two main categories: diagnostic and therapeutic. Diagnostic paracentesis involves removing a small fluid sample (25 to 30 milliliters) for laboratory analysis. Testing the fluid helps determine the underlying cause or check for infection, such as spontaneous bacterial peritonitis.
Therapeutic paracentesis removes a large volume of fluid to relieve pressure and symptoms. A large accumulation, known as tense ascites, causes abdominal pain, pressure, and difficulty breathing due to upward pressure on the diaphragm. Removing several liters of fluid, often five liters or more, significantly improves patient comfort and respiratory function.
What to Expect Before the Procedure
Before the procedure, the medical team ensures patient preparedness. The patient provides informed consent after the purpose, risks, and benefits have been explained. The patient is typically positioned lying on their back with the head slightly elevated, allowing fluid to pool in the lower abdomen.
Blood tests, such as clotting factors, are checked, though abnormal results often do not prevent the procedure. Bedside ultrasound guidance is routinely used to identify the safest insertion site. This imaging technique locates the deepest fluid pocket while avoiding blood vessels, the bladder, and bowel loops. The chosen site is commonly in the lower abdominal quadrant, lateral to the main abdominal muscle.
The Paracentesis Steps
The procedure begins after the insertion site is determined by ultrasound and marked on the skin. The area is cleaned with an antiseptic solution, such as chlorhexidine, to minimize infection risk. A local anesthetic, typically lidocaine, is injected into the skin and deeper tissues along the planned path to numb the area. The clinician advances the needle intermittently while infiltrating the anesthetic, confirming the absence of blood return.
Once numb, a specialized needle or catheter is introduced through the abdominal wall into the peritoneal cavity. Clinicians often use the Z-track method, displacing the skin before insertion. This creates a non-linear path from the skin surface to the peritoneum. When the needle is removed, the skin returns to its original position, sealing the track and reducing post-procedure fluid leakage.
Upon entering the fluid-filled space, which may be felt as a slight pop or loss of resistance, the needle is secured, and a catheter is advanced. For therapeutic drainage, the catheter connects to drainage tubing and a collection container. The fluid drains, and the procedure typically takes between 30 and 90 minutes, depending on the volume removed.
Post-Procedure Monitoring and Care
After the fluid is drained, the needle or catheter is carefully withdrawn. Pressure is applied to the insertion site to stop bleeding, and a sterile dressing is placed over the puncture wound. For diagnostic procedures, the fluid is immediately sent to the laboratory for analysis of cell count, protein, and other markers.
The patient is closely monitored for one to four hours following the procedure, especially after large-volume drainage. Nurses check vital signs like heart rate and blood pressure to watch for a rapid drop, a potential complication known as hypovolemia or circulatory dysfunction. Small amounts of clear fluid leakage from the site are common. Patients are instructed to contact their healthcare provider if the leakage increases, or if they experience fever, worsening abdominal pain, or bleeding. Activity is usually limited for the remainder of the day, with a return to normal activities permitted the following day.