Prenatal diagnosis of a digynic triploid fetus in the second trimester: transvaginal two-dimensional ultrasound, color doppler and fetoplacental Doppler velocity waveform findings.

INTRODUCTION: Triploidy in the second trimester is a sporadic, rare lethal chromosomal abnormality characterized by an extra haploid chromosome set (3n = 69). Doppler blood flow study in fetal triploidy syndrome is rarely reported in the literature.

CASE PRESENTATION: A 19-year-old woman at 18 weeks of gestation was referred to our fetal medicine unit. Examination revealed a digynic triploid fetus presenting with asymmetric intrauterine growth restriction, oligohydramnios, relative macrocephaly together with a small thin trunk, low-set ears, micrognathia, bilateral talipes, bilateral syndactyly on the third, fourth and fifth fingers and toes, a large ventricular septal defect, bradycardia, bilateral hyperechogenic kidneys and small placenta. The pattern of abnormalities suggested that the extra set of chromosomes was maternal in origin. Although bilateral maternal uterine artery Doppler measurements were normal, there was increased resistance to blood flow in the umbilical artery and reversed flow in the ductus venosus which were probably due to abnormal placental development and severe intrauterine growth retardation.

CONCLUSION: It can be assumed that among the most frequent indicators of triploidy are the sonographic proof of the existence of early retardation of growth and the presence of oligohydramnios together with other malformations. Triploidy must be in the differential diagnosis and karyotyping is advised in these cases.