Malignant ascites of unknown origin.

To determine the clinical characteristics of patients presenting with malignant ascites, as well as means of evaluating the outcome of patients with the disease, a retrospective review was conducted of all cases of malignant peritoneal effusions diagnosed from 1978 to 1987 at a University Hospital and a Veterans Administration Hospital. Of 65 patients with malignant ascites (40 women; 25 men), the primary site was known in 51 cases (80%). Common sites in women were the ovaries, endometrium, and cervix; in men, common sites were the colon, rectum, and stomach. For five women and nine men the primary site was unknown. Median survival from diagnosis was 7.5 days (mean, 43 days; range 1-256 days). Chest radiograph and abdominal computed tomography (CT) scan did not disclose the occult primary. An occult primary was detected while the patient was alive in only two cases and at autopsy in two other patients. Due to the poor prognosis for this disease, we do not recommend an aggressive approach to malignant ascites of unknown origin, except perhaps in women, in whom ovarian cancer should be suspected.