Investigate cause

Common

• Cirrhosis
• Abdominal cancer, especially ovarian and lymphoma
• Heart disease (especially constrictive pericarditis)

Rare

• Tuberculous peritonitis
• Non-cirrhotic portal hypertension
• Hepatic vein occlusion
• Severe hepatitis
• Chronic pancreatic disease
• Myxoedema
• Chronic renal disease
• Polyserositis (e.g. SLE)
• Severe hypoproteinaemia of any cause
• Benign ovarian disease

Examine ascitic fluid

• Bacterial infection

Treat

• Remove fluid to relieve abdominal discomfort or severe dyspnoea
• Introduce chemotherapeutic agents

• If malignant ascites suspected, discuss with relevant on-call specialist to determine risk of potential local seeding

Paracentesis only

Bleeding disorder

• Suggested by unexpected bleeding
• spontaneous or from venepuncture sites

Coagulopathy or thrombocytopenia

• No absolute cut-off, unless clear evidence of spontaneous bleeding disorder
• generally safe to perform paracentesis with or without image guidance with no bleeding risk
• no absolute cut off for INR due to liver disease
• if platelets <50, consider platelet transfusion
• Consider withholding new agent antiplatelets (e.g. clopidogrel, prasugrel, ticagrelor) for 7 days or DOACs 24-48 hr and warfarin 5 days before procedure

Other than bleeding

• Infected ascites <48 hr after starting treatment with antimicrobials
• Previous abdominal surgery, pregnancy, overlying infection and acute abdomen

• Dressing pack and sterile gloves
• Skin antiseptic

Diagnostic sample

• Syringe (20 mL) with green (21 G) needle

Aspiration of ≥50 mL

• Selection of needles: 19-21 G
• Selection of syringes: 5 mL for local anaesthetic; 50-100 mL for aspiration
• Lidocaine 1% plain 5 mL
• If paracentesis planned: peritoneal type catheter and fluid collection system for catheter

Specimen containers

Ascitic WBC

• Either 4 mL EDTA tube to haematology or 10 mL sterile pot to microbiology

Biochemistry

• 10 mL in plain container

Cytology

• 10-20 mL in universal container with citrate anticoagulant
• if unavailable, use clotting studies bottle

Microbiology

• 10 mL in sterile universal container
• Blood culture bottles (aerobic and anaerobic)

• If not competent in procedure, organise supervision by a clinician experienced in the procedure

Patient

• Explain procedure and reassure patient
• Obtain and record written consent
• Complete WHO surgical procedure checklist
• Ensure patient's bladder is empty (if in doubt, catheterise)

Select site

• Lay patient supine
• Re-examine abdomen
• Select site where there is shifting dullness but no solid organs
• preferred sites are iliac fossae (rough guide - lateral to mid-clavicular line at level of umbilicus)
• away from inferior epigastric blood vessels and scars, or suprapubic area

Tapping ascites

• Don mask and sterile gloves
• Cleanse skin and infiltrate 5 mL of lidocaine into anterior abdominal wall down to parietal peritoneum
• lidocaine may not be required for ascitic aspirate
• Attach long, fine needle (19-21 G) to large syringe and introduce needle into abdominal cavity
• keep puncture in abdominal wall as small as possible
• Z technique helps prevent oozing from site
• stretch skin 2 cm caudal to needle insertion and maintain tension until collecting fluid
• remove needle rapidly and allow skin to resume its natural position
• Aspirate gently
• if tip of needle correctly placed, fluid will flow easily into syringe
• if no fluid obtained, reposition either patient or needle
• Remove up to 50 mL of fluid, withdraw needle, and apply simple dressing
• in patients with suspected TB, take much larger quantities of fluid and use centrifuged deposit to isolate causative organism

Paracentesis

• If trained, follow tapping ascites procedure then:

Drainage

• Introduce catheter (recommended catheter is Safe-T-Centesis^® kit)
• Allow free drainage in sterile collecting system
• Drain to dryness or remove catheter after 6-8 hr free drainage
• do not leave drain >8 hr unless specifically instructed

Fluid replacement

• Liver cirrhosis and non-malignant ascites with normal renal function
  
  • immediately infuse intravenously albumin 20% 100 mL, over 1 hr
  • give further doses for every 3 L of fluid drained
• Liver cirrhosis and non-malignant ascites with impaired renal function
  
  • immediately infuse intravenously albumin 20% 100 mL, over 1 hr
  • give further doses for every 2 L of fluid drained
  • discuss with hepatology as possible hepatorenal syndrome management may be required
• Malignant ascites
  
  • albumin is rarely required
  • if >4 L of ascites drained, infuse 250 mL bolus of sodium chloride 0.9% or Hartmann’s solution and
  • repeat to maintain haemodynamic stability

Troubleshooting

No fluid aspirated

• Failure to enter peritoneal cavity, perforation of a viscus, or occlusion of the end of the needle by a piece of Omentum
• Reposition tip of needle and continue to aspirate while withdrawing needle slowly
• it is reasonable to make 2 attempts on each side of the abdomen
• If no fluid obtained after these manoeuvres, request ultrasound scan to confirm presence of ascites
• ask radiologist to aspirate sample under direct scan guidance

Persistent leakage through puncture wounds

• Keep puncture in abdominal wall as small as possible
• Remove sufficient fluid to reduce pressure in abdominal cavity
• A stitch may be needed

Note appearance of fluid

• Cloudy fluid often signifies peritonitis
• Uniform blood staining is most often found in patients who have a cancer or who have suffered abdominal trauma
• Milky fluid indicates chylous ascites: check triglyceride levels of fluid 

Samples

Cytology

• If suspecting malignancy

Microbiology

• Cell count
• If clinical suspicion of infection, bacteriological culture

Biochemistry

• Protein concentration
• If clinical suspicion of infection, enzyme estimations (lactate dehydrogenase)
• If suspect pancreatic damage, amylase

• If several litres of fluid have been removed, record pulse and BP hourly for 4 hr
• Stop diuretics for 24-48 hr