The abdominal cavity normally contains a small amount of fluid, but certain medical conditions can cause an abnormal accumulation known as ascites. This fluid collects within the peritoneal space, often as a complication of severe liver disease, such as cirrhosis. Changes in blood flow and pressure cause fluid to leak out of vessels. When this accumulation causes significant problems, the procedure to remove the fluid is called paracentesis.
Indications for Fluid Removal
Paracentesis is performed for two primary reasons: to relieve uncomfortable symptoms and for diagnostic analysis. Substantial fluid accumulation creates tension and pressure, leading to symptoms like pain, bloating, and difficulty breathing. Removing a large volume of fluid, known as therapeutic paracentesis, provides immediate relief by reducing internal pressure.
The procedure is also performed for diagnostic reasons, even if the fluid volume is not yet causing severe symptoms. Analyzing a small sample of the ascitic fluid is necessary to determine the underlying cause of the accumulation. This diagnostic tap is particularly important when an infection, such as Spontaneous Bacterial Peritonitis (SBP), is suspected. Prompt analysis helps guide immediate treatment decisions, making the diagnostic tap a time-sensitive procedure.
Pre-Procedure Steps and Site Selection
Before the procedure, the patient is asked to empty their bladder to minimize the risk of accidental puncture. Informed consent is obtained, during which the medical team explains the process, risks, and expected outcomes. Blood work, including tests for coagulation, is often reviewed to assess the patient’s bleeding risk.
The patient is typically positioned lying on their back with the head slightly elevated (semi-Fowler’s), or sometimes slightly tilted to one side. This positioning allows gravity to help the fluid collect in the lower abdomen, making it easier to access. The exact insertion point is determined using bedside ultrasound guidance, which is now considered a standard of care.
Ultrasound allows the clinician to visualize the abdominal wall layers and identify the safest pocket of fluid, avoiding blood vessels and bowel loops. The preferred site is usually in the lower quadrant of the abdomen, lateral to the rectus muscle. This location minimizes the risk of injuring the inferior epigastric artery. Once marked, the skin is thoroughly cleaned with an antiseptic solution to create a sterile field.
Performing the Drainage
The first step involves applying a local anesthetic, such as lidocaine, injected into the skin and deeper tissues along the planned needle path. This numbing agent ensures the patient remains comfortable during the insertion of the needle and catheter. The procedure is performed under strictly sterile conditions to prevent the introduction of bacteria into the peritoneal cavity.
A specialized paracentesis needle or catheter is inserted through the anesthetized site and into the fluid pocket. To reduce fluid leakage after removal, the clinician may use the Z-track method. This involves pulling the skin taut before insertion so the needle tract is offset once the skin is released. For a diagnostic tap, a small needle collects 10 to 60 milliliters of fluid for laboratory analysis.
When the goal is therapeutic relief, a larger catheter is inserted and connected to a vacuum bottle or drainage system. This is termed large-volume paracentesis (LVP) and involves the removal of several liters of fluid, often five liters or more. Drainage continues until the flow significantly slows or the patient reports reduced abdominal pressure.
Monitoring and Immediate Recovery
Once the desired volume of fluid has been drained, the catheter is swiftly removed, and firm pressure is immediately applied to the insertion site. A sterile dressing is placed over the small puncture wound, and the patient is advised to remain resting briefly. The medical team closely monitors the patient’s vital signs, paying particular attention to blood pressure.
A rapid drop in blood pressure (hypotension) is a potential complication following large-volume paracentesis, due to a sudden shift in fluid balance. To mitigate this risk, patients who have more than five liters of fluid removed are typically given an intravenous infusion of albumin. Albumin acts as a volume expander, helping to stabilize circulatory function and prevent post-paracentesis circulatory dysfunction. The recommended dose is eight grams of albumin for every liter of fluid drained beyond the five-liter mark.