Value of carcinoembryonic antigen (CEA) and cholesterol assays of ascitic fluid in cases of inconclusive cytology

Aim-To determine whether assays of carcinoembryonic antigen (CEA) and chole sterol in ascites add diagnostic value to cytology. Methods-The additional diagnostic efficacy of the biochemical assays was st udied in the ascitic fluid from 130 patients, of whom 57 had peritoneal car cinomatosis. All diagnoses were verified by subsequent necropsy and/or hist ology. Results-CEA concentrations over 5 ng/ml indicated carcinomas, occasionally without peritoneal involvement of the tumour. However, increased values wer e significantly more common in cancer with peritoneal involvement (p < 0.01 ), giving a sensitivity of 51% and specificity of 97% for carcinomatosis. A cholesterol value exceeding 1.21 mmol/litre was found in 93% of cancers wi th peritoneal involvement, but it was not entirely specific (96%) for carci nomatosis. Simultaneous increases in CEA and cholesterol concentrations wer e specific for carcinomatosis and this combination increased the sensitivit y for diagnosing carcinomatosis from 77% with cytology alone to 88%. The co rrect diagnosis could thus be made in five of 12 cases with inconclusive cy tology. Conclusions-The measurements of both CEA and cholesterol concentrations in ascites give additional specific information about peritoneal carcinomatosi s and can therefore be a useful adjunct to cytology-in particular, in incon clusive cases.