Diagnostic abdominal paracentesis (ascitic tap) [advanced]

Before you start

Indications: diagnosis of cause of new ascites; diagnose spontaneous bacterial peritonitis or other infections (e.g. abdominal TB); diagnose blood in peritoneal space in trauma

Relative contraindications: severe coagulopathy (disseminated intravascular coagulation or accelerated fibrinolysis); pregnancy; distended bowel (obstruction/ileus); organomegaly; distended bladder

Introduction

• Wash hands, Introduce self, Patients name & DOB & wrist band, Explain procedure and get written consent
  • Risks: pain; bleeding; infection; damage to local structures (including bowel perforation); paracentesis leak
  • Ask patient to empty their bladder prior to procedure
• **Check patients clotting screen, platelet count and if they have been on an therapeutic anticoagulant/clopidogrel**
• Ensure assistant is available
• Examine patient and tap out ascites
• Use ultrasound to confirm the presence/location of ascites, check the depth of the abdominal wall and mark the spot pre-procedure (although, if there is tense ascites with fluid thrill, it is usually safe to proceed without ultrasound)

Preparation part

• Wash hands and apply apron
• Clean a trolley
• Gather equipment onto bottom of trolley (think through what you need in order)

• Walk to patient
• Wash hands
• Open sterile pack to form a sterile field on the top of the trolley
• Open packets (without touching the instruments themselves) and drop sterile instruments neatly into the sterile field
• Pick up waste bag from sterile pack without touching anything else and stick to side of trolley

Patient part

Positioning and exposure

• Position patient lying supine in bed with head of bed elevated (aids fluid accumulation in lower abdomen)
• Expose patient’s abdomen

If the insertion point has not already been marked using ultrasound…

• Locate insertion point:
  • Traditionally in the right iliac fossa (approximately 5cm above and up to 5cm medial to the right ASIS)
  • Tap out ascites and confirm flank dullness at intended insertion point
• Use different site if there is overlying infection
• Mark insertion point with a skin pen/indentation

Preparation

• Wash hands
• Apply sterile gloves using sterile technique (open pack on a side surface)
• Sterilize area
  • Work from middle outwards in one spiral motion (using cleansing snap-sponge)
  • Repeat with second cleansing snap-sponge
  • Discard used snap-sponges as they are no longer sterile, but note all equipment used after this (including all needles) can be returned to the sterile field after use
  • OPTIONAL: Apply the sterile drape over the patient’s body so that the hole is in the correct place to allow access to the insertion site (or apply 2-3 drapes centred around exposed insertion site if no holes)
• Anaesthetise tract
  • Ask assistant to snap open lidocaine bottle and hold open upside-down
  • Draw up lidocaine using drawing-up needle on 10 ml syringe and expel any air
  • Change to the orange needle and insert at an acute angle to form a single subcutaneous bleb around insertion site in order to anaesthetise the skin
  • Change to the green needle and insert perpendicular to the skin to anaesthetise the insertion tract
    • This is done by instilling lidocaine in small increments of increasing depth
    • Always aspirate when advancing the needle (so you know when you get to the peritoneal cavity) and aspirate before injecting lidocaine (to check you are not in a vessel)
    • When fluid is aspirated, remove needle and do not advance further
  • Wait 1 minute to work

Paracentesis

• Attach new green needle to the 20ml syringe
• Insert perpendicular to the skin into the same tract, aspirating during infiltration
• When fluid is aspirated, stop advancing and remove 20ml of ascitic fluid
• Remove needle

Finally

• Dress wound

To complete

• Thank patient and cover them
• Bin waste and gloves, dispose of sharps safely, clean trolley and wash hands
• Decant ascitic fluid into sample tubes, label them and send to lab
  • MC&S (blood culture bottles or white-top) → microbiology
  • Albumin (white-top or yellow SST tube) → biochemistry
  • Cytology if first ascitic sample (white-top) → histopathology
  • Cell count (purple EDTA top) → haematology
  • Other tests to consider: protein, glucose (paired)
• Perform venepuncture to determine concurrent albumin level
• Fully document procedure in patients notes