paracentesis
Meaning of paracentesis: Two jobs in one puncture: draining the fluid eases the pressure of a swollen abdomen, while a sample of it explains why the fluid gathered.
Definition of paracentesis
Paracentesis is a procedure in which a needle or thin tube is passed through the abdominal wall to draw off fluid that has collected in the peritoneal cavity, the space around the abdominal organs. That collection is called ascites. Fluid may be removed to relieve pressure, sent for laboratory testing, or both in the same sitting.
How paracentesis is built
- para- Prefix · Greek beside, near, alongside, abnormal
- -centesis Suffix · Greek surgical puncture to withdraw fluid
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
Why does fluid collect in the abdomen?
Several unrelated problems end in the same finding, and the point of sampling the fluid is to tell them apart. Scarring of the liver raises pressure in the portal vein and forces fluid out of the circulation, which accounts for most cases of ascites. Heart failure raises venous pressure throughout the body with a similar result. Cancer spreading across the lining of the abdomen leaks protein rich fluid directly. Very low blood albumin, from kidney disease or severe malnutrition, lets fluid escape because there is too little protein to hold it in the vessels. Infection and pancreatic inflammation are less common causes.
What is the fluid tested for?
| Test | What it distinguishes |
|---|---|
| Albumin, compared with blood albumin | Whether raised portal pressure is the driver, or something else entirely |
| White cell count and differential | Infection of the fluid itself, which can develop without obvious symptoms |
| Culture | Which organism is present, if any |
| Cytology | Whether cancer cells are present in the peritoneal fluid |
| Total protein, amylase, triglycerides | Pancreatic and lymphatic causes |
A small volume is enough for all of this, so a diagnostic tap is quick even when no fluid needs removing for comfort.
How is the procedure carried out?
Ultrasound is generally used first to find a deep pocket of fluid and to check that no bowel or blood vessel lies in the path. The lower abdomen away from the midline is the usual entry point. Local anesthetic numbs the skin and the layers beneath it, then a needle is advanced until fluid returns. A diagnostic tap collects a modest sample and is over in minutes. A therapeutic drain uses a soft catheter and removes a large volume slowly, which relieves the pressure that makes breathing and eating difficult. Removing a large volume shifts fluid balance across the whole circulation, so blood pressure is watched and albumin is sometimes given alongside. Recognized risks include bleeding, puncture of the bowel or bladder, persistent leakage at the site, and infection introduced through the skin. The laboratory test results usually return within hours.
Also known as
Used in a sentence
Paracentesis was performed to relieve abdominal distension and to analyze the fluid for signs of infection.
Good to know
Paracentesis can serve a symptom relieving purpose, a diagnostic purpose, or both at once, since the withdrawn fluid is commonly sent for laboratory analysis regardless of the reason the procedure was performed.
Word origin
Where “paracentesis” comes from
Formed from Greek para-, meaning beside, and kentesis, meaning puncture, describing a puncture made to reach fluid alongside the organs.