Healthcare and Medicine Reference
In-Depth Information
Table 8.2 Causes of ascites classifi ed as transudate and exudate.
Persistent leakage from site of tap —If necessary apply a stoma bag to
the site until leakage stops.
Transudate
(protein <30 g/L; SAAG >11 g/L)
Exudate
(protein >30g/L; SAAG <11 g/L)
Abdominal wall haematoma —The risk is higher with deranged
clotting, but most resolve spontaneously.
Cirrhosis
Malignancy
Chronic liver disease
Pancreatitis
Signifi cant haemorrhage and perforation —These are extremely rare
complications of diagnostic ascitic tap if it performed correctly.
They may result if bowel is adherent to the abdominal wall or if
there is signifi cant collateral vessel within abdominal wall. Seek
senior help.
Congestive cardiac failure
Peritoneal tuberculosis
Constrictive pericarditis
Nephrotic syndrome
Chylous ascites
and normal peritoneal fluid has a protein concentration of
40 g/L.
Calculation of the serum ascites albumin gradient (SAAG) is a
more reliable method of determining whether the fl uid is a tran-
sudate or exudate:
SAAG = [serum albumin] - [ascitic fl uid albumin]; transudate
Handy hints/troubleshooting
Take time to position your patient correctly and identify your
landmarks.
Occasionally, you may only be able to aspirate a few mL of fl uid -
in this case, ask the lab how much fl uid is needed for each test
and prioritise tests according to clinical suspicion.
Consider using an ultrasound-guided technique if the blind
>11 g/L; exudate <11 g/L.
Table 8.2 describes causes of exudative and transudative ascites.
technique is unsuccessful or if there are particular concerns.
Microbiology
A cell count can be performed rapidly and is the single best test for
the detection of spontaneous bacterial peritonitis (SBP):
neutrophil count > 250 cells/microlitre = SBP.
Further reading
SBP is often associated with low concentrations of bacteria. The
rate of detection can be increased by the direct inoculation of blood
culture bottles with ascitic fl uid at the bedside.
Hoefs JC. (1990) Diagnostic paracentesis: a potent clinical tool. Gastroenterology
98: 230-6.
Jeffery J, Murphy M. (2008) Ascitic fl uid analysis. Hosp Med 62(5): 282-6.
Mallory A, Schaefer J. (1978) Complications of diagnostic paracentesis in
patients with liver disease. JAMA 239(7): 628-30.
Moore K, Aithal G. (2006) British Society of Gastroenterology Guidelines on
the management of ascites in cirrhosis. Gut 55: 1-12.
Runyon B, Canawati H, Akriviadis E. (1988) Optimisation of ascitic fl uid
culture technique. Gastroenterology 95: 1351-5.
Runyon B, Montano A, Akriviadis E et al . (1992) The serum ascites albumin
gradient is superior to the exudates-transudate concept in the diagnosis of
ascites. Ann Intern Med 117: 215-20.
Williams J, Simel D. (1992) Does this patient have ascites? JAMA 267(19):
2645-8.
Wong C, Holroyd-Leduc J, Thorpe K et al . (2008) Does this patient have
bacterial peritonitis or portal hypertension? JAMA 299(10): 1166-78.
Cytology
The presence of malignant cells in ascitic fl uid confi rms the
diagnosis of malignancy, but it is important to remember that
the absence of malignant cells does not exclude malignancy. Liver
metastases and primary hepatocellular carcinoma are unlikely to
provide positive fi ndings.
Potential complications
Failure to obtain sample —If it is not possible to obtain a sample,
repeating at a different site or changing sides may help. If it is still
not possible, then an ultrasound scan should be performed and
either a site marked for aspiration or a sample obtained under
direct ultrasound guidance.
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