Anatomy

Abdominal anatomy must be considered when performing paracentesis. Large volumes of ascitic fluid tend to float the air-filled bowel anteriorly and toward the midline when the patient is in the supine position. Other pelvic organs that must be considered include an overly distended bladder and a gravid uterus. In addition, the cecum is relatively fixed and less mobile than the sigmoid colon; thus, bowel perforation is more likely to occur in the right lower quadrant than in the left. Traditionally, the procedure has been performed through the linea alba using a midline insertion 2 cm below the umbilicus with the patient in a semiupright position (Fig. 201-1). Increasingly, a lateral approach has been advocated, with access 3 to 5 cm medial and cranial to the anterior superior iliac spine (Fig. 201-2). Using this approach, one must remain lateral to the rectus sheath to avoid the inferior epigastric artery. Paracentesis can be performed with the patient in the supine position or in the lateral decubitus position (or slight variants of these), which helps “float” the bowel away from the insertion site and can provide access to a deeper ascitic pool.

Figure 201-1 View of the midline approach with anatomic landmarks.

Figure 201-2 View of the lateral approach with anatomic landmarks.

Indications

Contraindications

Equipment and Supplies

Commercially prepared kit or the following equipment:

• 25- or 27-gauge, -inch needle for local anesthesia

• 18-gauge, – to 3-inch needle

Alternative devices: 18- or 20-gauge spinal needle, 18- or 20-gauge, – to 3-inch angiocatheter needle, -inch Caldwell needle (needle/cannula system designed for therapeutic large-volume paracentesis; studies have suggested this is the most expedient technique), or catheter-over-wire system (Seldinger technique)

Precautions

Careful attention to site selection as discussed in the section on Anatomy will minimize the risk of bleeding and injury to the bowel. In addition, entry near prior surgical scars should be avoided because there is a risk of adherent bowel loops near surgical scars. The slow introduction of the needle through the abdominal wall minimizes the risk of bowel injury because the needle can push mobile bowel away rather than injuring it. The application of intermittent negative pressure (aspiration) with the syringe while introducing the needle is generally preferred to constant negative pressure because the latter can quickly attract bowel or omentum on entry to the peritoneal cavity and occlude the needle. Needle occlusion can mask your entry into the peritoneal cavity and increase the risk of bowel injury as well as lead to a false sense of a “dry tap.” Patients taking warfarin or who have any coagulopathy other than DIC or fibrinolysis should have the process reversed before paracentesis. If possible, antiplatelet medications should be held for 5 to 7 days. Warfarin can be held for 5 to 7 days (until the international normalized ratio [INR] normalizes) and the patient converted to low–molecular-weight heparin during this time, with the dose being held the day of the procedure. Alternatively, the INR can be reversed the day of the procedure with fresh-frozen plasma. Some experts suggest that patients with thrombocytopenia or an abnormal INR (for reasons other than taking warfarin) can be given platelets or the INR reversed with factor replacement; however, this process is considered controversial and there are no data to support it.

Preprocedure Patient Education

Explain the procedure to the patient outlining the indications relevant to his or her medical situation and the anticipated benefits (diagnosis, ruling out infection, or decreased symptoms from therapeutic paracentesis). Risks of the procedure, as noted in the Complications section, should also be explained and informed consent obtained. Discuss anticipated patient positioning and ensure the patient is able to maintain the desired position. The patient should be aware that the local anesthetic may cause some discomfort, as well as the needle (or catheter) used to perform paracentesis.

Technique

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