Paracentesis and diagnostic peritoneal lavage

Paracentesis: Before the procedure

Indications

Paracentesis is the insertion of a needle or catheter into the peritoneal cavity for the purpose of aspirating peritoneal fluid. It is most often indicated for diagnostic or therapeutic evacuation of ascites.
Diagnostic indications
- New-onset ascites: fluid evaluation to help determine etiology, differentiate transudate versus exudate, detect the presence of cancerous cells, or address other considerations
- Differentiate between suspected spontaneous or secondary bacterial peritonitis
Therapeutic indications
- Respiratory compromise secondary to ascites
- Abdominal pain or pressure secondary to ascites (including abdominal compartment syndrome)

Contraindications

Absolute contraindication
- Acute abdomen that requires surgery
Relative contraindications
- Inadequate volume of ascites on imaging (e.g., ultrasound)
- Uncorrected hypovolemia
- Severe uncorrected thrombocytopenia (platelet count <20,000/μL) or coagulopathy (international normalized ratio [INR] >2.0)
- Pregnancy
- Distended urinary bladder
- Abdominal wall cellulitis
- Distended bowel
- Intraabdominal adhesions

Equipment

Ultrasound machine
Local anesthetic
Chlorhexidine prep
Sterile towels, gloves
18- or 20-gauge, 2- to 3-inch needle
20- to 50-mL syringe
14- to 16-gauge cannula-over-needle
8.5F 40-cm polyurethane pigtail catheter with guide wire
2-0 polypropylene suture

Anatomy

The site for paracentesis is in the abdomen, lateral to the rectus muscle in the lower quadrant midway between the umbilicus and the anterior superior iliac spine, avoiding prior surgical incisions. Ultrasound guidance is recommended to identify the site of the largest volume of ascites and reduce the chance of injury to the intestines.

Procedure

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The patient should be supine. Bedside ultrasonography can be a valuable aid for localizing the largest collection of ascites and avoiding injury to the bowel and should be employed routinely. The patient should void or have a urinary bladder drainage tube inserted before the procedure. The area is cleansed, draped, and anesthetized.
When a small volume of ascitic fluid is needed for diagnostic studies, an 18- or 20-gauge, 2- to 3-inch needle attached to a 20- to 50-mL syringe is inserted into the abdomen lateral to the rectus muscle in the lower quadrant, midway between the umbilicus and the anterior superior iliac spine, avoiding prior surgical incisions. The skin is retracted caudad while inserting the needle. When fluid is aspirated, the needle is stabilized, and the fluid sample is obtained by syringe. After removal of the needle, the skin is released, causing the entrance and exit needle sites to form a “Z-track” that reduces the chance of ascitic fluid leakage.
For large-volume paracentesis, a 14- to 16-gauge cannula-over-needle is employed. Once the fluid is aspirated into the syringe, the needle is removed, leaving the plastic catheter in place, which is attached to plastic tubing and a vacuum canister. Usually, 4–6 L of ascites can be safely removed, although larger volumes have also been obtained.
If it is necessary to place a catheter into the peritoneal cavity, a guide wire should be inserted into the peritoneal cavity through the needle; an 8.5F 40-cm polyurethane pigtail catheter should be guided into the peritoneal cavity over the wire and sutured in place.
The aspirated fluid should be submitted for a cell count, absolute polymorphonuclear neutrophil count, albumin, total protein concentration, Gram stain, and cultures. Optional studies, based on clinical suspicion, may include glucose concentration, amylase concentration, lactate dehydrogenase concentration, bilirubin concentration, and cytology.

After the procedure

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