ObjectiveTo analyze the results of prenatal findings and the outcome of triploidy and to organize an efficient approach to prenatal diagnosis during the second trimester.MethodsWe reviewed 70 cases of triploidy presenting between 13 and 29 weeks' gestation over a 10-year period.ResultsEach fetus had at least one measurement below the normal range, and 50 cases (71.4%) presented with asymmetrical growth restriction and normal placental appearance. All cases of triploidy associated with partial mole were diagnosed before 25 weeks. Structural fetal defects were observed antenatally in 65 (92.9%) cases. The most common defects were abnormalities of the hands (52.3%), bilateral cerebral ventriculomegaly (36.9%), heart anomalies (33.8%), and micrognathia (26.2%). The most frequent combination of abnormalities was malformation of the hands and ventriculomegaly. Decreased red blood cell counts and high mean cell volume were found in the 50 cases tested. Vaginal bleeding in the first or second trimester was the most common maternal symptom reported.ConclusionsThe major features that should alert the sonographer to the possible diagnosis of triploidy are partial molar changes or severe asymmetrical fetal growth restriction in the presence of an apparently normal placenta.