Paracentesis

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Paracentesis is a procedure in which fluid is removed from the peritoneum for diagnostic and/or therapeutic purposes. Diagnostic paracentesis is the removal of a small volume of intraperitoneal fluid for the evaluation of newly diagnosed ascites or to assess for spontaneous bacterial peritonitis in patients with chronic ascites. Therapeutic paracentesis is the removal of large volumes of intraperitoneal fluid to relieve associated abdominal pain and/or respiratory symptoms. Relative contraindications include pregnancy, visceral distention, severe coagulopathy, and infection over the procedure site. The procedure is always performed using sterile technique and is usually guided by ultrasound. Complications include a persistent fluid leak, postparacentesis circulatory dysfunction, and hepatic encephalopathy.

• Diagnostic paracentesis: aspiration of a small volume of fluid from the peritoneum to aid in the diagnosis and management of ascites and other intraabdominal conditions
• Therapeutic paracentesis: removal of a large volume of fluid from the peritoneum to relieve symptoms caused by ascites
• Large volume paracentesis: removal of > 5 L of fluid from the peritoneum during one procedure ^[2]

Diagnostic paracentesis ^[2][3][4]

• New-onset ascites
• Suspected spontaneous bacterial peritonitis (SBP): See “Indications for diagnostic paracentesis in SBP” for details.

Occult SBP is common in patients with ascites and cirrhosis, and delays in diagnosis result in increased mortality. ^[5]

Therapeutic paracentesis ^[2][3][6][7]

• Tense or large ascites (first-line treatment)
• Respiratory distress or abdominal discomfort associated with ascites
• Refractory ascites (can be repeated approximately every 2 weeks) ^[7]
• Malignancy-related ascites
• If diuretics are contraindicated

• Absolute: none ^[8]
• Relative ^[3][4][8]
  • Pregnancy
  • Skin infection over the procedure site
  • Severe coagulopathy ^[3]
  • Bowel distention or obstruction
  • Uncooperative patient

Transfusion of clotting factors and/or platelets prior to paracentesis in patients with coagulopathy is not routinely recommended unless there is active DIC. ^[3]

We list the most important contraindications. The selection is not exhaustive.

Landmarks ^[3][8]

Choose a needle entry site that avoids abdominal scars, underlying blood vessels, and inflamed or infected skin. Preferred sites include:

• Midline
  • Needle entry site: 2 cm below the umbilicus
  • Trajectory angle: determined by ultrasound examination
• Lower quadrant: RLQ or LLQ
  • Needle entry site: ∼ 4–5 cm cephalad and ∼ 4–5 cm medial to the anterior superior iliac spine
  • Trajectory angle: determined by ultrasound examination

Positioning ^[3][8]

• Large volume ascites: The patient is supine with the head of the bed elevated.
• Small volume ascites
  • Patient is in the lateral decubitus position
  • Patient is facedown, in a hands-and-knees position (rare)

Ultrasound guidance ^[3][9]

Recommended because it can locate fluid collections, inform patient positioning, and identify conditions that increase procedural risk

• Use color flow Doppler to identify avoidable blood vessels in the abdominal wall.
• Static guidance (most common): Optimal needle entry site is identified and marked prior to skin prep.
• Dynamic guidance: real-time ultrasound guidance of needle movements, e.g., for small volumes of fluid and/or enlarged viscera
• See “FAST” and “Bowel POCUS” for the basic principles of abdominal ultrasound.

Consider performing paracentesis under ultrasound guidance to reduce the risk of serious complications and improve success rates. ^[9]

All patients ^[3][8][10]

• Ultrasound machine
• Sterile ultrasound probe cover
• Sterile gown and gloves
• Sterile gauze
• Sterile drapes
• Surgical mask
• Antiseptic solution
• Occlusive dressing
• Local anesthesia
  • Local anesthetic
  • 5 mL syringe
  • 18-gauge needle for drawing up
  • 25-gauge needle for administration

Diagnostic paracentesis ^[3][8][10]

• 20–22-gauge 1.5 inch needle
• 18–22-gauge 3.5 inch spinal needle for obese patients
• 60 mL syringe for sample collection
• Blood culture bottles

Therapeutic paracentesis ^[3][8][10]

• Prepackaged set, e.g., 18-gauge needle with preloaded 8 Fr catheter
• Or 14–18-gauge peripheral IV catheter ^[10]

Drainage set-up (if indicated)

• Three-way stopcock
• High-pressure tubing
• Drainage bag or evacuated container

• Obtain informed consent.
• Ensure the patient has voided.
• Ready the ultrasound machine.
• Perform abdominal ultrasound.
  • Determine optimal patient position and entry site.
  • Measure the depth between soft tissue and fluid.
• Mark the proposed entry site and ensure the patient remains in this position.
• Perform skin preparation and maintain a sterile field.
• Assemble the appropriate needle, stopcock, and syringe.
• Single-point local anesthesia infiltration to include the peritoneum
• Consider cardiac monitoring.

1. Pull the skin ∼ 2 cm caudad prior to needle insertion (Z-track technique).
2. Insert the needle perpendicular to the skin at the marked location.
3. Apply negative pressure on the syringe plunger and advance slowly until fluid returns.
4. Advance another few millimeters, then fix the needle in this location or slide the catheter off the needle.
5. Diagnostic paracentesis: Aspirate 60 mL of fluid into large syringes.
6. Therapeutic paracentesis: Connect high-pressure tubing from the needle to the drainage system.
7. Large volume paracentesis: Infuse albumin during or immediately after the procedure. ^[2][12][13]
8. Once fluid collection is complete, remove the needle or catheter.
9. Apply an occlusive dressing.

The following can be prevented by using real-time ultrasound guidance and needle-catheter systems with side ports (e.g., Caldwell needle) to improve flow.

Interruption of fluid flow ^[3][8]

• Cause: obstruction likely, e.g. kinked catheter, orifice obstructed by omentum or other intraabdominal structure
• Management: inject a small amount of intraperitoneal fluid back through the needle or catheter, then reattempt aspiration.

No fluid flow ^[3][8]

• Causes
  • Obstruction
  • Small volume of fluid or loculated fluid, or obstruction
• Management
  • Retract the needle to skin level and redirect.
  • Consider real-time ultrasound guidance.

Do not reposition the needle while the tip is within the peritoneum, as it may injure the bowel, omentum, and/or blood vessels. ^[8]

• Samples sent for ascitic fluid analysis (if indicated)
• Serum albumin level obtained (if indicated)
• Albumin administered (for large volume paracentesis)
• Patient evaluated for postprocedural fluid leak and bleeding
• Procedure documented

• Ascites: See “Ascitic fluid analysis.”
• SBP: See “Peritoneal fluid analysis in SBP.”

Postprocedural fluid leak ^[3][8]

• Prevention: Z-track technique
  • Pull the skin ∼ 2 cm caudad prior to needle insertion and do not release until the needle has passed into the peritoneum.
  • Once the needle has been removed, the skin will return to its original position and seal the peritoneal insertion site.
• Management ^[6][8][10]
  • Position the patient so that the needle site is nondependent.
  • Consider a skin suture or tissue adhesive.

Postparacentesis circulatory dysfunction (PPCD) ^[2][14][15]

• Clinical presentation: AKI, hyponatremia, hepatic encephalopathy, and/or clinical deterioration occurring hours to days after paracentesis
• Prevention: administration of albumin at the time of large volume paracentesis ^[2][4]
  • Recommended for paracentesis volumes > 5 L
  • Consider for paracentesis volumes ≤ 5 L if the patient has hypotension, hyponatremia, and/or AKI. ^[2]

Other complications

• Systemic: hepatic encephalopathy, hyponatremia
• Local: abdominal wall hematoma
• Intraperitoneal (rare): visceral injury, intraperitoneal hemorrhage

PPCD rarely manifests during the procedure. Albumin should be administered even if the patient is asymptomatic and normotensive. ^[2][12][13]

We list the most important complications. The selection is not exhaustive.