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)
- Sterile pack
- Cleansing snap-sponge x2 (iodine or alcohol/chlorhexidine)
- OPTIONAL: Sterile drape with hole in centre (or 2-3 drapes without holes in)
- 10ml syringe and 3 needles (1 blunt fill 18G drawing-up needle, 1 orange 25G, 1 green 21G) for local anaesthetic
- 20ml syringe and green 21G needle for aspirating ascitic fluid
- Cotton gauze swabs (used whenever needed throughout procedure to dry/clean sterile area)
- Sterile dressing
- Equipment to be kept outside of the sterile field
- 10ml 1% lidocaine (maximum 3mg/kg – note 1ml 1% lidocaine = 10mg)
- Bottles: 1-3 white-topped sample collection bottles, purple EDTA haematology tube, yellow SST biochemistry tube, blood culture bottles
- 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
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
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
Learn how to interpret the results too…
Ascitic fluid result interpretation is covered here!