Estimation of ascitic fluid volume using Tc-99(m) labelled macroaggregatedalbumin

We have assessed the usefulness of a radionuclide dilution method for estim ation of ascitic fluid volume. Tc-99(m) macroaggregated albumin (10 MBq) wa s injected into the peritoneal fluid. Multiple samples were taken using a t rocath peritoneal dialysis catheter over a 4-h period. Blood samples were t aken at the same time and a 4-h urine collection was made during the study. At 4 h a controlled drainage of ascitic fluid, followed by suction drainag e, was used and a total drained volume measured. For comparison, peritoneal volumes were measured from the radioactivity of peritoneal fluid activity samples using dilution techniques. The estimated peritoneal fluid volume us ing the radionuclide method was consistently higher than the drained volume . This was attributed to tither a lack of uniform distribution of the activ ity in the peritoneal cavity by 4 h or early breakdown and absorption of ac tivity from the peritoneal cavity. In two patients it was not possible to m easure a volume due to poor distribution of the radionuclide in the periton eal fluid. We found that in our group of patients the radionuclide dilution is of little value in estimating the peritoneal fluid volume. ((C) 2000 Li ppincott Williams & Wilkins).