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Abdominal Paracentesis
Paracentesis uses a needle or tube to remove fluid that has built up in the abdomen, to relieve discomfort and to test the fluid.
Quick answer
Abdominal Paracentesis: what it is and what the results mean
Abdominal paracentesis (ascitic tap or drain) involves passing a needle or thin tube through the abdominal wall, often with ultrasound guidance, to remove fluid that has collected in the abdominal cavity (ascites).
- Why it is done: It is used to relieve a swollen, uncomfortable abdomen caused by fluid build-up, and to test the fluid to find the cause, such as liver disease, infection, heart failure or cancer.
- Understanding results: Draining fluid relieves pressure and discomfort.
What it is
Abdominal paracentesis (ascitic tap or drain) involves passing a needle or thin tube through the abdominal wall, often with ultrasound guidance, to remove fluid that has collected in the abdominal cavity (ascites).
Why it is done
It is used to relieve a swollen, uncomfortable abdomen caused by fluid build-up, and to test the fluid to find the cause, such as liver disease, infection, heart failure or cancer.
What to expect
You lie back and, after local anaesthetic, a needle or tube is inserted into the abdomen; a small sample may be taken (a tap) or a larger amount drained over hours. Ultrasound is often used for safety.
Understanding the results
Draining fluid relieves pressure and discomfort. The fluid is analysed for infection, protein and sometimes cancer cells, helping to identify the cause and guide treatment, including of the underlying condition.
Good to know
Risks and limitations
Risks are small but include bleeding, infection, fluid leakage and, with large drains, changes in blood pressure or salts, so you are monitored. Ultrasound guidance improves safety.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Abdominal Paracentesis: frequently asked questions
What is the difference between a tap and a drain?
A “tap” takes a small sample of fluid mainly for testing, while a “drain” removes a larger amount over several hours to relieve a swollen, uncomfortable abdomen. Both use a similar technique.
Why does the fluid keep coming back?
Fluid re-accumulates because the underlying condition — often liver disease, heart failure or cancer — continues to produce it. Treatment focuses on the cause, alongside repeat drainage when needed.
Related tests
Other other investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Relevant royal college / professional body
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