General

Paracentesis[1] is a simple procedure, which can be performed as a day case (usually only removing 2-4 litres maximum), or as an in-patient. In tense, symptomatic ascites there may be up to 12 litres ascites present. Removal of 4-6 litres is usually enough to give symptomatic relief; more than 4-6 litres increases the risk of hypovolaemia and adverse effects, but may allow longer until ascites re-accumulates. For an ill patient, small volume paracentesis repeated as needed may be preferable.

Indications

For indications see Ascites

• pain, discomfort, or tightness due to stretching of the abdominal wall
• dyspnoea, usually exacerbated by exertion, due to raising of the diaphragm
• vomiting due to the 'squashed stomach' syndrome

Patients are usually symptomatic only when the abdominal wall is tensely distended. Patients who are also bothered by ankle (or generalized) oedema, may fare better with diuretic therapy.

Complications

After a large volume paracentesis, the large fluid shifts from circulating volume into extracellular fluid can decompensate the patient's cardiovascular system leading to hypovolaemia, and in severe cases, collapse and renal failure. A low albumen or sodium level will exacerbate this effect.

The cannula site may continue to leak ascites after removal. If a limited, partial paracentesis has been performed, this may rarely become a continuing leak over days to weeks.

Bowel perforation is a risk, especially if intestinal obstruction is present.

Infection is a rare complication, providing aseptic technique is used.

Investigations

An ultrasound scan will confirm the presence of ascites, and may determine if it is 'pocketed' by tumour adhesions. A scan should be performed if:

• ascites is not easily clinically identified
• vomiting - or any indication of bowel obstruction/distension

A serum albumen and U&E should be taken if:

• more than 4-6 litres is to be removed, and the patient has oedema, or
• the patient is clinically dehydrated, or
• the patient has reacted badly to a previous paracentesis

Platelet count and clotting screen if the patient has any symptoms of bleeding or unexplained bruising.

Contraindications

• local or systemic infection
• coagulopathy - platelets < 40 or INR > 1.4

Limit paracentesis to 4-6 litres maximum if:

• hepatic or renal failure (creatinine > 250)
• albumen < 30 or sodium < 125

The procedure

• Patient should be asked to pass urine before the procedure.
• Blood pressure should be measured and recorded.
• Patient should lie in a semi-recumbent position.
• It may be helpful for them to tilt 30 degrees towards the side of the paracentesis.
• Use left iliac fossa unless local disease is present, and avoid inferior epigastric artery (see below).
• Confirm that site is dull to percussion.
• Using aseptic technique, give local anaesthetic to skin.
• A large bore IV cannula or Bonanno catheter can be used
• Do not clamp to control rate of drainage - malignant ascites can be very proteinaceous and is likely to block the catheter if clamped off.

Usual sites for paracentesis, avoiding the inferior epigastric arteries.

Large volume paracentesis (> 6 litres)

If it is intended to drain to dryness, or > 6 litres:

• Stop diuretics (if used solely for ascites) 48h before procedure.
• Check blood pressure and pulse every 30 minutes during paracentesis, then hourly for 6h.
• IV dextran 70 or gelatine infusion (Haemaccel or Gelofusine) 150mL for every litre of ascites drained, given during the paracentesis or shortly afterwards will reduce hypovolaemia.[2]

Management of complications

Hypovolaemia:

• Volume expanders (as above) should be given.

Leak from paracentesis site:

• Usually dry gauze dressings are sufficient and the leak will stop after a few hours to days.
• Enbucrilate tissue adhesive (Histoacryl) has been used to seal the skin on withdrawal of the cannula after paracentesis.[3]
• Colostomy bags can be used to collect ascites if large volumes leak.
• A purse-string suture around the site may be used.

Follow-up care

Ascites will usually re-form after a paracentesis; this can vary between one and many weeks. Diuretics may reduce the rate of re-accumulation, or prevent it becoming so tense again. Repeated paracentesis on as as-needed basis is appropriate management for patients with advanced cancer.