[Clinico-pathological study of the partial hydatidiform mole].

We studied 302 spontaneous abortuses with no molar swelling of villi (S.Ab.) and 156 partial moles (P.M.), clinico-pathologically. The results were as follow: The estimated "in utero retention time" of the conceptus of S.Ab. and P.M. was 24.8 +/- 13.1 days (n = 63) and 45.9 +/- 10.7 days (n = 37), respectively (p less than 0.01). Among the cases with "in utero retention time" of 4 or more weeks, 9 of 35 S.Ab. and 32 of 37 P.M. showed no degenerative change of trophoblasts. IgG was localized on the cell membrane of the syncytiotrophoblasts in 19 of 63 S.Ab. and 27 of 37 P.M. (p less than 0.01). IgM was also localized on the cell membrane of syncytiotrophoblasts in 29 of 63 S.Ab and 6 of 37 P.M. (p less than 0.01). Six patients (3.85%, 6/156) with P.M. received operative procedure and/or chemotherapy after evacuation of the mole. Four had invasive mole, on had metastatic lesion in the lung and one had persistent trophoblastic disease. Four of these six patients with subsequent disease were 40 years of age or older. All patients with partial mole needed hCG assay monitoring because of the risk of abnormal sequelae.