Ultrasound-guided paracentesis is a common hospital procedure that medical professionals perform to drain ascites in patients with advanced cirrhosis. It has a low bleeding risk and is used for diagnostic or therapeutic purposes.
Although paracentesis is generally a safe procedure, sometimes severe bleeding may occur, especially in patients with coagulopathy (a bleeding disorder) and chronic kidney disease. Other serious complications include infection, persistent ascitic fluid leak, or organ puncture.
To avoid risks and ensure patient safety, healthcare professionals must be thoroughly familiar with the procedure. Using ultrasound guidance for paracentesis markedly decreases medical risks while enhancing patient outcomes.
Here, we delve into the procedure, its contraindications, equipment, patient preparation, and other aspects that you must know about.
Contraindications of Paracentesis
Paracentesis has a few contraindications, including thrombocytopenia and coagulopathy, which are common in patients with cirrhosis. Paracentesis should also not be performed among patients with the following medical conditions:
- Disseminated intravascular coagulation (DIC)
- An acute abdomen (severe, sudden abdominal pain)
Healthcare professionals should also perform paracentesis with extra care when treating patients with certain conditions:
- Patients who are pregnant
- People suffering from ileus, organomegaly, distended bladders, or bowel obstructions
Additionally, medical professionals must carefully avoid not to pass the catheter or needle through surgical scars, skin infections, abdominal wall hematomas, or engorged abdominal wall vessels.
Medical professionals can get prepackaged kits for ultrasound-guided paracentesis procedures. These kits have plastic cannulas that are joined to syringes and stopcocks.
Medical professionals can also use conventional large-bore intravenous catheters or standard spinal 18-gauge to 20-gauge needles. They can attach these catheters or needles to syringes for medical aspiration or an IV tube for draining fluid.
In the absence of a prepackaged paracentesis kit, clinicians require the following tools and equipment:
- Sterile disposable towels or drapes
- Sterile gloves
- Betadine or chlorhexidine as an antibacterial cleaning solution
- 1% lidocaine (local anesthetic)
- A needle for injecting the anesthetic (a 22-gauge needle for diagnostic paracentesis, a 25-gauge needle for injection sites on the skin, or a needle with a smaller gauge for soft tissues)
- A needle (14-gauge or 16-gauge) or intravenous (IV) catheter for aspiration (a spinal needle in cases that involve obese patients)
- A syringe (20-cc or 60-cc) to collect a fluid sample
- IV tubing
- Plastic canisters or vacuum bottles (for large-volume procedures)
- A 4×4 bandage or gauze
- Chemistry, microbiology, and hematology sample tubes
- Two blood culture bottles for ascites cultures and another vial for cytology, biochemistry, and microscopy
Large-volume paracentesis also calls for paracentesis drains with a 15cm plastic drainage catheter with many drainage holes near the tip of an 18-gauge needle. Upon removing the central needle, fluid drains rapidly through the catheter that is secured to the patient.
It is not advisable to use an intravenous cannula for large-volume paracentesis as they are usually too short and may kink or become dislodged.
Patient Preparation for Paracentesis
Informed patient consent is necessary for ultrasound-guided paracentesis, including intravenous albumin replacement for large-volume paracentesis.
It is not required to use antibiotic prophylaxis before the procedure. Patients also do not need to discontinue their antiplatelet or anticoagulant medications.
If significant bleeding occurs, the healthcare professional will need to take a drug history of the patient to aid in anticoagulant reversal.
Liver and renal function blood tests and a baseline full blood count are also recommended to study the patient’s baseline organ function and determine the serum albumin ascites gradient.
If cardiac failure is the potential reason for ascites, a serum (blood) brain natriuretic peptide in an ethylenediaminetetraacetic acid (EDTA) tube is necessary.
Patients should also empty their bladder before the procedure.
The lower quadrant of the abdomen lateral to the rectus sheath is the preferred site for a bedside ultrasound-guided paracentesis. Ultrasound also helps determine the presence of fluid and the right site for the procedure. Making patients with lower fluid volumes tilt to their side can help clinicians easily identify fluid pockets.
Ultrasound-guided paracentesis requires proper skin antisepsis by preparing and draping the patient and cleansing their skin with a cleaning solution. This aseptic procedure is performed under local anesthesia to minimize patient discomfort.
The needle or catheter attached to a syringe at 90 degrees to the skin is inserted. Alternatively, it’s possible to use the z-track injection method to decrease the risk of persistent ascitic fluid leakage. In this method, the skin will be punctured and pulled caudally before the needle is inserted into the soft tissue and peritoneum.
With guidance from ultrasound imaging, the clinician can target the areas with the most fluid while avoiding major vessels in mild-to-moderate ascites. They should also identify the inferior epigastric artery to minimize the risk of bleeding.
The syringe must be held with negative pressure. The needle or catheter is then inserted until no resistance is detected. This will begin the flow of ascites. The needle of the catheter will then be guided through the peritoneal space (the space inside the abdomen containing the stomach, the intestines, and the liver).
After collecting enough fluid for analysis, the needle is removed (for diagnostic taps) or the tubing or catheter’s stopcock is connected to it. The excess fluid is then drained into plastic canisters, vacuum containers, or drainage bags. It’s best to limit the total drained volume to 8 liters or less.
Upon draining the excess fluid and removing the needle or catheter, pressure must be applied to the insertion site to stop any bleeding. After the procedure, administer 8 gm of albumin per liter of drained ascitic fluid for large-volume paracentesis procedures of over 5 liters to prevent post-paracentesis circulatory dysfunction.
Ultrasound-guided paracentesis is a safe and effective procedure for cirrhotic patients. Follow the right steps and take the necessary precautions before, during, and after the procedure to minimize risks and complications.
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