Complications from paracentesis are uncommon but include hemorrhage (0% to 0.93%), abdominal wall hematoma, mesenteric hematoma, bladder or bowel perforation, inferior epigastric artery aneurysm, vessel laceration (aorta, mesenteric artery, iliac artery), hypotension, infection (0.58% to 0.63%), and persistent ascitic fluid leak (5%).⁸

Patient Positioning And Landmarks

Typically, the patient is either supine or in a slight lateral decubitus position with the head raised to maximize drainage. The areas recommended for the traditional technique are midline and 2 cm below the umbilicus or 4-5 cm superior and medial to the anterior superior iliac spine in either lower quadrant. Use these landmarks with ultrasound to find the deepest fluid pocket. The abdominal scan should be done immediately before the procedure with the patient remaining in the same position for the procedure.

Scanning for Ascites

Ultrasound may be used statically to mark the entry site prior to paracentesis or dynamically to observe the needle entering the peritoneal cavity. The latter is helpful for smaller fluid collections.

Use a 2-5 MHz low-frequency curvilinear transducer under the abdominal setting to scan the abdomen. Simple transudative ascites is anechoic and extraperitoneal. Loops of bowel appear hyperechoic and will float and peristalse within the fluid. The bowel may have dirty shadowing, depending on how much intraluminal gas is present, and have a mesenteric stalk. Complex ascitic fluid has varying echogenicities depending on its composition, including protein, fibrin, leukocytes and erythrocytes.

The bladder is located in the midline infraumbilical abdomen with a hyperechoic dome and anechoic urine. Locate where the largest pocket of ascitic fluid and the thinnest abdominal wall are. A fluid pocket that is at least 3-cm deep is adequate for the procedure. Mark this pocket in two orthogonal planes if using ultrasound statically.

Equipment

Most of the equipment required can be found in a peritoneal lavage kit.

• Gloves, gown
• Mask, cap
• Ultrasound probe cover
• Ultrasound machine
• Antiseptic
• Fenestrated drape
• Gauze
• Lidocaine
• Syringes: 10 mL, 60 mL
• Injection needles: 25 ga, 22 ga
• Scalpel, #11 blade
• Catheter 8 F over 18 ga x 7.5” needle
• 3-way stopcock
• Tubing set
• Drainage bag or vacuum container
• Specimen vials (3)

Technique

• Prep and drape the patient aseptically.
• Anesthetize the skin by making a wheal. Anesthetize down to the peritoneum along the catheter tract. Apply negative pressure when advancing the needle.
• Make a small nick in the skin with the scalpel.
• With your nondominant hand, apply traction to the entry site caudad or cephalad, creating a “Z track.” Once the catheter is removed at the end of the procedure and the skin returns to its normal position, the track will be indirect, decreasing persistent leak.
• Insert the catheter over needle.
• If using ultrasound statically, insert the catheter over needle perpendicular to the entry site while applying negative pressure in the syringe.
• If using ultrasound dynamically, have another person center the nick in the middle of the sterile dressed probe. Insert the catheter over needle at 45 degrees to the probe. Visualize the catheter entering the abdominal wall and fluid while applying negative pressure in the syringe.
• Once the syringe fills easily, insert the catheter over needle 3 mm.
• Hold the hub of the needle and advance the catheter.
• Withdraw the needle.
• Attach the 3-way stopcock to the catheter.
• Obtain laboratory samples with the 60 mL syringe for a diagnostic tap.
• Connect the tubing and attach the drainage bag or vacuum bottle for a therapeutic tap.
• Remove the catheter after collecting the desired amount of fluid. Apply firm pressure and a bandage to the entry site.

Laboratory

Depending on the clinical picture, the following may be sent to the laboratory: Routine:

• Cell count and differential
• Bacterial culture
• Albumin
• Protein
• Optional
• Gram stain
• Triglycerides
• Bilirubin
• Glucose
• Amylase
• Lactate dehydrogenase
• Cytology

Disease

The most common cause of ascites is cirrhosis (81%), followed by malignancy (10%), heart failure (3%), tuberculosis (2%), hemodialysis (1%), pancreatic disease (1%) and other (2%).¹⁰ Approximately 5% of patients have mixed ascites, that is, fluid due to more than one cause.¹⁰