Ascitic Tap

Last Updated on by frcemuser



  • Determine the cause of new onset ascites, ascites of unknown origin, or suspected malignant ascites
  • Suspicion of bacterial peritonitis in a patient with known ascites with associated pyrexia, hypotension, tachycardia or encephalopathy.


  • Remove excess intraperitoneal fluid to assist respiration and provide symptomatic relief.


A diagnostic ascitic tap should not be attempted in the presence of the following conditions:

  • Uncooperative patient
  • acute abdomen requiring surgical intervention
  • urinary retention/distended bladder
  • pregnancy
  • abdominal wall infection
  • extensive adhesions
  • dilated loops of bowel (e.g. volvulus).

If required, it may be possible to perform a tap under direct vision using ultrasound guidance.


  • Depending on patient size this is typically 5 cm superior and medial to the anterior superior iliac spine.
  • It is important to remember that the inferior epigastric vessels run adjacent to the rectus abdominis muscles and therefore the site should be as far lateral as possible to avoid vascular damage


Transudate (protein <30 g/L; SAAG >11 g/L)

  • Cirrhosis
  • Chronic liver disease
  • Congestive cardiac failure
  • Constrictive pericarditis

Exudate (protein >30g/L; SAAG <11 g/L)

  • Malignancy
  • Pancreatitis
  • Peritoneal tuberculosis
  • Nephrotic syndrome
  • Chylous ascites



Things to put on the Lab Form:

  • albumin
  • LDH
  • glucose
  • amylase
  • pH
  • triglycerides
  • WCC
  • gram stain and culture (put some fluid into blood culture bottles)
  • cell count and differential
  • cytology

Calculation of the serum-ascites albumin gradient (SAAG) is a more reliable method of determining whether the fluid is a transudate or exudate:

SAAG = [serum albumin] – [ascitic fluid albumin]; transudate >11 g/L; exudate <11 g/L. Microbiology(neutrophil count > 250 cells/microlitre = SBP), Cytology,Biochemistry


  • Failure to obtain sample -sample can be obtained under direct ultrasound guidance.
  • Abdominal wall hematoma – correct coagulopathies before insertion
  • Persistent leakage from the site of tap
  • Significant hemorrhage and perforation – under direct ultrasound guidance

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