Flow cytometric DNA analysis versus cytology in the evaluation of peritoneal fluids

The use of flow cytometric DNA analysis as an adjunct to cytology in peritoneal fluid evaluation was studied. One hundred ninety-five fluids from 193 gynecologic patients were subjected to both DNA analysis and cytologic examination. It was found that 117/195 (60%) had invasive malignancies (50 ovarian, 48 endometrial, 17 cervical, and 2 miscellaneous); 34/117 (28%) patients with malignancies were positive by cytology, and 10/117 (8.5%) were positive (aneuploid) by DNA analysis. Of 34 cytologically positive cases, 7 (21%) were DNA positive, 25 (74%) were DNA negative, and in 2 (6%) insufficient cells were obtained. Only 3 fluids (3%) from malignancies were positive by flow cytometry and negative by cytology (1 stage I ovarian cancer, 1 stage I endometrial cancer, and 1 stage III ovarian cancer). No false-positive cytology and one probable false-positive flow result was obtained. If only those patients with histologically documented peritoneal involvement are considered, 29/43 (65%) had positive cytology and 8/43 (19%) had a positive flow result. We conclude that: (1) the high false-negative rate of flow cytometry (79%) versus cytology in this study may be related to a high percentage of diploid cancers, specimen preparation, or histogram interpretation, and (2) flow cytometry rarely adds to cytologic evaluation and is probably best reserved for use only in selected cases.