gastrointestinal disorders
How To Do Paracentesis
Step by Step Description of Paracentesis
Explain the procedure to the patient and obtain written informed consent. Ask the patient to empty the bladder by voiding, or catheterize the patient. Place the patient in bed with the head elevated 45 to 90°. In patients with obvious and a large amount of ascites, locate an insertion site at the midline between the umbilicus and the pubic bone, about 2 cm below the umbilicus. Locate an alternative site in the left lower quadrant, eg, about 3 to 5 cm superior and medial to the anterior superior iliac spine. If choosing the left lower quadrant site, roll the patient partially onto the left side to allow the fluid to pool in the area. The insertion site should be lateral enough to avoid the rectus sheath, which contains the inferior epigastric artery. Alternatively, place the patient in a lateral decubitus position. In this position, the air-filled bowel loops float up, migrating away from the point of entry, which should be down in the fluid-filled region. The left lateral decubitus position with needle insertion in the left lower quadrant is preferred by some physicians because the cecum may be distended with gas in the right lower quadrant. The right lateral decubitus position can be used if needed. To choose a needle insertion site, carefully percuss, because dullness to percussion confirms the presence of fluid. If needed, use ultrasound to identify a site, confirming the presence of ascitic fluid and the absence of overlying bowel. In selecting an insertion site, avoid surgical scars and visible veins. If available, mark the insertion site with a skin marking pen. Prepare the area with a skin cleansing agent, such aschlorhexidineor povidone iodine, and apply a sterile drape while wearing sterile gloves. Using a 25-gauge needle, place a wheal of local anesthetic over the insertion point. Switch to a larger (20- or 22-gauge) needle and inject anesthetic progressively deeper until reaching the peritoneum, which should also be infiltrated because it is sensitive. When the needle is advanced, maintain constant negative pressure to ensurelidocaineis not injected into a blood vessel. For diagnostic paracentesis, select an 18- to 22-gauge (1.5-inch or 3.5-inch as needed) needle. For therapeutic paracentesis, select an 18- to 14-gauge (1.5-inch or 3.5-inch as needed) needle or a Caldwell needle (15-gauge, 3.25-inch). Smaller-gauge needles lessen the risk of complications, such as ascitic fluid leakage, but take longer to complete therapeutic paracentesis. Insert the needle perpendicular to the skin at the marked site. Alternatively, insert the needle using the Z-track method, which can be done in several ways. One option: Pull the skin, insert the needle perpendicularly, and maintain this skin traction until the needle enters the peritoneal cavity. Another option: Puncture just the skin, and pull it down, then advance into the peritoneal cavity. A third option: Insert the needle at an angle (usually 45°) to the skin and advance it. The Z-track method is preferred because it allows the intra-abdominal pressure to help seal the tract after removing the needle and decreases the risk of peritoneal fluid leak. Insert the needle slowly to help avoid puncturing the bowel and use intermittent suction to avoid entering into a blood vessel. Avoid continuous suction because this can cause tissue (eg, bowel, omentum) to occlude the needle tip. Insert the needle through the peritoneum (generally accompanied by a popping sensation) and gently aspirate fluid. For diagnostic paracentesis, withdraw enough fluid (eg, 30 to 50 mL) into the syringe and place the fluid in appropriate tubes and bottles for testing, including blood culture bottles. For therapeutic paracentesis, if a Caldwell needle is used, advance the outer metal catheter over the needle, then remove the needle from inside the catheter. Attach the catheter to a collection bag or vacuum bottle using tubing. For therapeutic paracentesis, a large volume of fluid is removed. Removal of 5 to 6 L of fluid is generally well tolerated. In some patients, up to 8 L can be removed. Colloid replacement, such as concurrent infusion of IValbumin, is often recommended during large-volume paracentesis (eg, removal of > 5 L) to help avoid significant intravascular volume shift and post-procedure hypotension. A 3-way stopcock can be used to control the flow of fluid when changing collection bottles or if a diagnostic sample is needed. Remove the needle and apply pressure to the site. Apply a sterile adhesive bandage to the insertion site. Video created by Hospital Procedures Consultants at www.hospitalprocedures.org. 