Paracentesis: The Procedure
The time it takes to perform a paracentesis is minimal, just about three minutes. Evacuating peritoneal fluid into vacuum-sealed containers will take extra time, but this can easily be monitored by a nurse while you send your samples to the lab and document your procedure. (See our previous blog, "Using Ultrasound for Paracentesis," discussing which laboratory samples to send: http://bit.ly/EMN-ProceduralPause.)
The key to a successful paracentesis starts with identifying your landmarks, using ultrasound to determine your evacuation site, and having all your equipment prepped and ready to go. All paracentesis kits are different, and some do not include lidocaine, so you may need to obtain lidocaine before beginning the procedure. We also recommend having two sets of sterile gloves.
Photo by Martha Roberts.
Ultrasound-guided paracentesis in the left lateral rectus site of the lower quadrant of the abdomen approximately 4-5 cm cephalad and medial to the anterior superior iliac spine.
Have the patient empty his bladder before starting the procedure. The patient should be on cardiac and pulse oximetry monitors and positioned comfortably because he may feel dyspneic from the fluid overload. If a supine position is not possible, try a lateral decubitus position instead. A partner for this procedure is a must.
- If the patient had a paracentesis recently, ask where the last site of entry was and use the same site. Evacuations can be completed daily if needed.
- If this is the patient's first paracentesis, choose the lateral rectus left or right lower abdominal quadrant (area 2 in photo) or the infraumbilical region (area 1) in the midline through the linea alba. Confirm the absence of bowel at the puncture site with ultrasound.
- Mark your entry site with a pen.
- Look for and avoid entry over any engorged abdominal wall vessels.
The best sites for drainage include the infraumbilical approach in the midline through the linea alba. An alternate site is either side of the lateral rectus in either lower quadrant 4-5 cm cephalad and medial to the anterior superior iliac spine. Courtesy of Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care, 7th edition, Philadelphia: Saunders/Elsevier, 2018.
- Clean the site with two chlorhexidine prep pads and apply a sterile drape.
- Anesthetize the site, first by creating a superficial wheel and then go deeper using the Z-track method. (More about this below.)
- The paracentesis catheter and needle come as a single unit that are separated once the needle tip is introduced into the peritoneal space. A blunt-tipped obturator within the needle retracts with pressure to expose a sharp tip. Once the peritoneal cavity is entered, the needle and obturator are removed to leave behind a plastic catheter, which drains the fluid.
The needle apparatus separated, left, and a close-up of the tips. Once the needle is retracted, it cannot be reloaded because it is protected by a ball-spring mechanism. Photos by Martha Roberts.
- Attach a syringe to the back of the paracentesis needle unit.
- Insert the paracentesis unit into the anesthetized track perpendicular to the skin in a Z-track maneuver and slowly advance in 5 mm increments until fluid returns in the syringe (20-60 mL). Pull back on the syringe continuously to aspirate fluid. Then remove the needle to leave only the plastic catheter in the peritoneal cavity.
- Set your filled syringe aside for diagnostic sampling and testing.
- Ensure that the stopcock is closed and the roller ball is down on the tubing you plan to connect for further removal of fluid.
- Securely attach the high-pressure tubing to the catheter hub.
- Place the other end directly into a vacuum-sealed container.
- Open the stopcock to allow fluid to pass, and release the roller ball on the tubing.
- Once the procedure is completed, remove the catheter and place an adhesive bandage or pressure dressing to avoid fluid leakage. You can secure this with gauze pads, benzoin, and paper tape.
- Yellow or clear fluid usually indicates cirrhosis, congestive heart failure, or nephrosis. Bloody fluid typically indicates neoplasm, although it could also be tuberculous peritonitis or pancreatic ascites.
Discussion: The Z-track method minimizes fluid leakage from the puncture site. Injecting medication into the skin using this method is important to preventing post-procedure leaking. Once a needle has entered subcutaneous tissue and muscle, it opens a track that may not reseal immediately. There are also studies suggesting that Z tracks may reduce pain during injection. We suggest using the method during your paracentesis procedure.
Z tracks are used for all kinds of intramuscular injections and can be applied to other sites on the body. Pull and press the skin and tissue 2 cm caudad to the deep abdominal wall and insert the needle (A). Fluid returning in the syringe means you are in the peritoneum, and you can release traction (B). Z tracks help seal the track and prevent persistent fluid leaks (C, D). Courtesy of Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care, 7th edition, Philadelphia: Saunders/Elsevier, 2018.