Ascitic tap and paracentesis
Tap every cirrhotic admitted with ascites. Neutrophils over 250 means SBP. For large drains, give albumin 8 g per litre removed when more than 5 litres come off.
A 55-year-old man with hepatitis C cirrhosis has tense ascites, mild confusion and a temperature of 37.9 °C. You need a diagnostic tap and he will then need large-volume drainage for breathlessness. INR 1.9, platelets 62,000/µL. The nurse asks whether to give FFP first.
Do you correct the clotting, where do you put the needle, and what do you send?
- Consent and ultrasound if availableMark a deep pocket of fluid away from bowel and vessels.
- SiteLeft lower quadrant, 2 finger-breadths medial and above the anterior superior iliac spine. Avoid scars, veins and the rectus sheath edge.
- ClottingRoutine FFP or platelets are not needed for a tap.
- Diagnostic tap20–30 mL, inoculate blood culture bottles at the bedside.
- SendCell count with differential, albumin, total protein, Gram stain and culture. Add cytology, amylase, ADA or AFB if indicated.
- Large-volume drainageAlbumin 8 g per litre removed if over 5 L, per protocol. Remove the drain within about 6 hours.
- AfterwardsBP, pulse, leak, bleeding, pain.
- Bleeding from the site or falling Hb
- Low BP during or after drainage
- Fluid that looks like blood or bowel content
- Neutrophils above 250
- Confusion worsening
- SBP (may have no pain or fever)
- Bowel perforation (feculent fluid)
- Inferior epigastric artery injury
- Post-paracentesis circulatory dysfunction
- Persistent leak
| SBP | Ascitic neutrophils above 250/mm³ |
| SAAG | Serum albumin minus ascitic albumin, 1.1 g/dL (11 g/L) or more = portal hypertension |
| Albumin with drainage | 8 g per litre removed (about 100 mL of 20% per 2.5 L) if over 5 L drained |
| Diagnostic sample | 20–30 mL, with 10 mL into each blood culture bottle |
| Drain | Remove within about 6 hours |
| Needle | Green (21G) for diagnostic tap, drainage catheter for therapeutic |
Check every dose against a current drug reference and your hospital protocol.
On this page
Indications
- Diagnostic: every admission with ascites, new ascites, and any deterioration (fever, confusion, kidney injury, GI bleed) to look for SBP.
- Therapeutic: tense or symptomatic ascites (breathlessness, discomfort).
Contraindications and cautions
- Not routinely needed: correcting INR or platelets. Serious bleeding is rare.
- Caution: DIC, very low platelets with bleeding, distended bowel, pregnancy, scars at the site, infected skin.
Where to go in
Mark the deepest pocket away from bowel and vessels
Left lower quadrant, 2 finger-breadths medial and above the anterior superior iliac spine
Scars (adherent bowel), visible veins, rectus sheath edge (inferior epigastric artery), infected skin
The inferior epigastric artery runs along the lateral edge of the rectus sheath. Paramedian taps risk a serious bleed. Stay lateral.
Diagnostic tap
- PrepareConsent, sterile field, chlorhexidine, lidocaine 1%, green needle, 50 mL syringe, blood culture bottles, sample tubes.
- PositionLying flat or slightly tilted to the side of the tap.
- AnaestheticInfiltrate down to the peritoneum.
- Z-trackPull the skin down 2 cm before inserting; reduces leak afterwards.
- AspirateAdvance slowly with gentle suction until fluid flows. Take 20–30 mL.
- Bottles at the bedside10 mL into each blood culture bottle (higher yield), the rest in sterile tubes.
Large-volume paracentesis
- Drainage catheter in the same site, connected to a bag.
- Drain freely; remove the drain within about 6 hours to reduce infection risk.
- Albumin 20%: 8 g per litre removed (about 100 mL per 2.5 L) if more than 5 litres are drained, given during or soon after, per local protocol.
- Watch BP; stop if hypotensive.
- Leak afterwards: a stoma bag over the site, or a purse-string suture.
Interpreting the fluid
| Test | Result | Meaning |
|---|---|---|
| Neutrophils | Above 250/mm³ | SBP: antibiotics and albumin |
| SAAG | 1.1 g/dL or more | Portal hypertension (cirrhosis, heart failure, Budd-Chiari) |
| SAAG | Below 1.1 g/dL | TB, cancer, pancreatitis, nephrotic syndrome |
| Total protein | Low (below 1.5 g/dL) | Higher SBP risk; consider prophylaxis |
| Total protein | High (above 2.5 g/dL) with high SAAG | Heart failure |
| Cytology | Malignant cells | Peritoneal cancer |
| ADA | High | TB peritonitis |
| Amylase | High | Pancreatic ascites |
| Several organisms, very high protein, low glucose | Secondary peritonitis (perforation) | CT, surgeons |
Treatment
See decompensated cirrhosis for SBP management.
Common mistakes
- Delaying the tap for FFP or platelets.
- Paramedian taps (inferior epigastric artery).
- Tapping through a scar.
- Putting all the fluid into a plain pot instead of blood culture bottles.
- Draining 8 litres without albumin.
- Leaving a drain in overnight.
Frequently asked questions
Do I need to correct INR and platelets before an ascitic tap?
No. Serious bleeding is rare, and routine FFP or platelet transfusion is not needed.
What is SAAG?
Serum-ascites albumin gradient. A value of 1.1 g/dL or more means the ascites is due to portal hypertension.
Where should an ascitic tap be done?
Left lower quadrant, about 2 finger-breadths medial and above the anterior superior iliac spine, ideally guided by ultrasound, avoiding scars and the rectus sheath edge.
How much albumin is given with large-volume paracentesis?
About 8 g per litre removed when more than 5 litres are drained.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A cirrhotic patient with INR 1.9 needs a diagnostic ascitic tap. What should be done about the INR?
Answer: Proceed without routine FFP. Bleeding after paracentesis is rare; routine correction isn't recommended.
- Give 4 units FFP first: Not needed routinely.
- Cancel the tap: No.
- Give platelets: Not needed.
- Give vitamin K and wait 24 hours: Delays diagnosis.
2. What SAAG indicates ascites from portal hypertension?
Answer: 1.1 g/dL or more. Serum minus ascitic albumin of 1.1 g/dL (11 g/L) or more.
- Exactly zero: No.
- SAAG doesn't help: It does.
- Above 5 g/dL only: No.
- Below 1.1 g/dL: Suggests TB, cancer or pancreatitis.
3. Why is the ascitic tap site lateral, not paramedian?
Answer: To avoid an artery. The inferior epigastric artery runs along the lateral edge of the rectus sheath.
- To avoid the bladder: Partly, but artery is key.
- To avoid the aorta: No.
- To avoid the liver: Different reason.
- For comfort: No.
4. A man with cirrhosis has 8 L of ascitic fluid drained at a large-volume paracentesis. Which fluid replacement is recommended?
Answer: IV albumin (~8 g per litre removed). Large-volume paracentesis (more than about 5 L) can cause post-paracentesis circulatory dysfunction — hypotension, renal impairment and hyponatraemia. Albumin (about 8 g per litre removed, as 20% albumin) prevents this. Saline is less effective and adds to the sodium load.
- 0.9% saline equal to volume drained: Large saline volumes add sodium and are less effective at preventing circulatory dysfunction.
- 5% dextrose 2 L: Worsens hyponatraemia and doesn’t expand plasma volume.
- No replacement needed: After > 5 L removed, post-paracentesis circulatory dysfunction is a real risk.
5. Above the arcuate line, how is the posterior wall of the rectus sheath formed?
Answer: Internal oblique and transversus. Above the arcuate line, the internal oblique aponeurosis splits: its anterior lamina joins the external oblique in front of rectus, and its posterior lamina joins transversus abdominis behind. Below the arcuate line, all three aponeuroses pass in front, so only transversalis fascia lies behind rectus.
- External oblique aponeurosis alone: Forms part of the anterior wall only.
- Transversalis fascia alone: Forms the posterior wall only below the arcuate line.
- Both oblique aponeuroses: The external oblique never contributes to the posterior wall.
- External oblique and transversus: Both contribute to the anterior wall.
6. Which is the most important function of albumin in plasma?
Answer: Plasma oncotic pressure. Albumin is made in the liver (half-life about 20 days) and provides about 80% of plasma oncotic pressure. It also carries bilirubin, fatty acids, calcium, hormones and drugs. Low albumin (liver disease, nephrotic syndrome, malnutrition) causes oedema and lowers total calcium.
- Carrying oxygen: Haemoglobin.
- Clotting blood: Clotting factors.
- Fighting infection: Immunoglobulins.
- Storing iron: Ferritin.
References and dose sources
- Lidocaine (lignocaine) dosing: Drugs.com: Lidocaine dosage (see also our lidocaine (lignocaine) dose page)
- Ceftriaxone dosing: Drugs.com: Ceftriaxone dosage (see also our ceftriaxone dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.