Accuracy of fine needle aspiration cytology of abdominal masses without radiological guidance.

This study was undertaken to evaluate the accuracy of FNAC of abdominal masses without the help of radiological guidance and to determine factors which affect the outcome of the procedure. Five hundred consecutive patients were studied. FNAC was reported by a single cytopathologist without knowledge of subsequent histology. In calculating indices of accuracy of FNAC only those patients in whom both FNAC and histology reports were available (N = 383) were considered. The overall incidence of unsatisfactory specimens was 5.6%. Consistency of the mass did not affect accuracy of FNAC. However, age (below 12 years) plane of the swelling, mobility of mass and size of the swelling, all significantly affected the adequacy of cytological yield. The overall true positive rate was 100.0% and there were no false positives. The true negative rate was 40.2% and false negative rate was 70.9%. The high false negative rates in hepatic and pancreatic lesions can be reduced by imaging techniques. Luminal organs had poor accuracy rates. The overall accuracy rate was 73.5%, comparable to that reported in literature. A positive diagnosis of malignancy had a 100% predictive value. Overall, it appears that nonguided FNAC is as accurate as guided FNAC except for very small lesions or discrete lesions such as hepatic secondaries where guidance may be useful.