Drainage at the Edge of Pressure

A paracentesis is a medical procedure used to remove abnormal fluid that has collected inside the abdomen. That fluid buildup is called ascites. A needle or small catheter is passed through the abdominal wall into the fluid-filled peritoneal cavity. The procedure can be done either to find out why the fluid is there or to remove a larger amount to make the patient feel and breathe better.

What exactly is ascites?

Normally there is only a tiny amount of lubricating fluid between the layers of the peritoneum, the membrane surrounding the abdominal organs. With ascites, much larger amounts accumulate there.

A person can eventually develop:

Abdominal swelling • tightness • pressure • pain • bloating • indigestion • constipation • reduced appetite • rapid weight gain • difficulty bending or walking • shortness of breath

The breathing difficulty happens partly because a large volume of abdominal fluid can push upward against the diaphragm.

Modern paracentesis is frequently performed with ultrasound guidance, which allows the clinician to locate a good pocket of fluid while avoiding organs and blood vessels.

The basic sequence is:

1. The abdomen is examined and the fluid located.

Ultrasound may be used to confirm the safest drainage location.

2. The bladder is emptied.

This helps keep it away from the puncture site.

3. The skin is cleaned and sterilized.

4. Local anesthetic is injected.

Usually, lidocaine is used to numb the skin and deeper tissues.

5. A needle is carefully advanced through the abdominal wall.

6. A small flexible catheter may then be advanced into the fluid.

The needle can be removed while the catheter stays in position.

7. The fluid drains into a syringe, collection bag or vacuum bottle.

8. When enough has been removed, the catheter is taken out, and a dressing is placed over the site.

Diagnostic ascitic fluid can provide an enormous amount of information. Depending on the situation, doctors may examine:

White blood cells and neutrophils — infection

Bacterial cultures — identifies organisms

Albumin — helps determine why the ascites developed

Total protein — provides additional diagnostic clues

Cytology — looks for malignant cells

Glucose

LDH

Amylase and other tests when particular diseases are suspected.

One particularly useful calculation is the serum-ascites albumin gradient (SAAG). Doctors compare albumin in the patient's blood with albumin in the abdominal fluid. It can help determine whether portal hypertension is driving the fluid accumulation.

What are the dangers?

Paracentesis is generally considered a low-risk procedure, particularly when performed by an experienced clinician with ultrasound guidance, but complications are possible.

The important ones are:

Bleeding: A blood vessel can be injured. Serious internal hemorrhage is uncommon but can be dangerous.

Low blood pressure: Removing a very large amount of fluid can produce major circulatory shifts.

Fluid leakage: Ascitic fluid may continue leaking from the puncture site afterward.

Infection: Bacteria can enter through the puncture site.

Hematoma: Blood can collect beneath the skin.

Bowel perforation: The needle can rarely puncture the intestine.

Bladder or blood-vessel injury: Also uncommon, particularly when ultrasound guidance and proper positioning are used.

Kidney/circulatory dysfunction after large-volume drainage: One reason albumin may be given when substantial quantities are removed.