The peritoneum is the lining of the abdominal cavity. This lining supports all of the abdominal organs and provides protection from infection. The very surface of the inside of the peritoneum normally produces a very small amount of fluid known as peritoneal fluid. It is this small amount of fluid that allows the organs in the abdomen to move against one another without discomfort or friction. Certain conditions within the abdomen can cause excessive buildup of the peritoneal fluid, creating discomfort for the patient. At times samples of this fluid are used to obtain a diagnosis of certain conditions.
A procedure called Paracentesis is performed to obtain a sample or drain fluid from the abdomen. Normally, a patient’s abdomen has little or no fluid at all. A large collection of fluid can be a symptom of a problem, including possible mesothelioma. Excess peritoneal fluid can create significant discomfort for the patient. Paracentesis reveals infection, tumors (cancerous or non-cancerous), appendicitis, cirrhosis of the liver, pancreatic disease, kidney disease, heart disease, or a damaged bowel. Paracentesis allows the physician to identify the cause of fluid accumulation, identify infected abdominal fluid, or to drain large amounts of fluid that is creating discomfort.
The procedure is done by inserting a needle or catheter into the peritoneal cavity, whereby fluid is removed for therapeutic or diagnostic purposes. The procedure is generally safe and is usually completed in the doctor’s office, as an out-patient at the hospital or clinic.
There are two types of Paracentesis or abdominal taps: diagnostic (where a syringe of fluid is withdrawn to be sent to the lab and tested) and large volume (drainage of fluid buildup in order to relieve abdominal discomfort).
What to Expect
An ultrasound scan is usually done before starting the procedure in order to mark the spot for the paracentesis and to measure the distance past the skin to the fluid. The risks, benefits, and alternatives will be thoroughly explained to the patient so that an informed consent can be obtained. The patient will then need to empty the bladder. Patients lie on their backs and expose the abdomen in order for the procedure site to be cleansed, shaved and an antiseptic solution, such as Betadine, will be applied along with sterile drapes. The physician will numb the site by injecting a local anesthetic to a small area of skin.
A tap needle or a bore needle (needle with a plastic sheath), is then be inserted approximately 1 to 2 inches (2 to 5 cm) in order to reach the peritoneal fluid. At times a small incision is made to assist with the insertion of the needle. The needle is then removed leaving behind the plastic sheath or tube for drainage of the abdominal fluids. Fluid can be drained by flow of gravity or a vacuum bottle may be used. It is not unusual for 5 to 10 liters to withdrawn.
If a fluid sample is needed, than a syringe is used to simply withdraw the needed fluid for mesothelioma diagnosis. Next the needle or sheath is removed and the puncture site is bandaged. In the case that an incision was needed, a couple of stitches may be used for closure of the wound.
The patient’s blood pressure will be monitored with the drainage of excess fluid, since low blood pressure can result from extensive drainage. In the case of hypotension or low blood pressure, an albumin IV may be used. An albumin IV is given to avoid intra vascular fluid shift and renal failure when such a large amounts of abdominal fluid are removed.
The patient may feel some slight stinging sensations from the local anesthetic or numbing medication. There will also be some pressure as the needle is inserted and if large amounts of fluid are withdrawn, patients can feel dizzy or lightheaded upon sitting up. All in all, paracentesis is a fairly complication free procedure, although there is a slight chance of a possible needle puncture to a blood vessel. And, of course, as with any surgical procedure there is always a slight chance of infection.