Triploidy: Pregnancy complications and clinical findings in seven cases

Abstract

Seven cases of triploidy were encountered by the Prenatal Diagnosis Program at Dartmouth-Hitchcock Medical Center over an 8-year period through associated pregnancy complications. We describe the characteristic findings that facilitate prenatal diagnosis and management. Our experience includes fetuses with major central nervous system abnormalities (spina bifida aperta, holoprosencephaly) and anterior abdominal wall defects, which are detectable with routine prenatal diagnostic screening examinations (ultrasound and AFP). In addition, we stress the importance of recognizing obstetric complications and associated cystic placental changes, which are quite common among triploid conceptuses. Molar changes associated with triploidy have a more benign prognosis than that associated with diploid moles. Such molar changes may relate to the presence of a diploid paternal chromosome complement. The usefulness of cytofluorometric DNA determinations in helping to confirm a clinical suspicion of triploidy is emphasized. These cases are presented in an effort to facilitate prenatal recognition and management of this common cytogenetic condition and prevent unnecessary Caesarean section deliveries.

Triploidy: antenatal sonographic features with post-mortem correlation

“…Although some of these may be difficult to identify on US scan, they occurred with sufficient frequency to suggest the diagnosis of triploidy (Al Saadi et al, 1976;Doshi et al, 1983;Rubenstein et al, 1986;Graham et al, 1989). They include facial dysmorphic features, limb defects, and major cardiovascular and urogenital anomalies.…”

“…Since then case reports of antenatal diagnosis of triploidy by ultrasound scan have been sporadic, few authors being able to muster more than few cases of their own (Crane et al, 1985;Rubenstein et al, 1986;Lockwood et al, 1987;Pircon et al, 1989;Graham et al, 1989). Jauniaux et al (1996) have recently published the largest series of triploidy describing the antenatal US scan features in great detail.…”

Importance of accurate diagnosis in counseling for neural tube defects diagnosed prenatally

“…The association of fetal neural tube defects, omphalocele and trisomy 18, as seen in Case 2, has been documented previously, with neural tube defects occurring in 6-7% and omphaloceles in 6% of cases of trisomy 18 (Moore et al 1988, Flannery & Kahler 1986. Neural tube defects and/or omphaloceles can also occur in association with other chromosomal anomalies, such as trisomy 13 (Holmes et al 1976) or triploidy (Graham et al 1989). The importance of knowing that a NTD is due to a chromosomal anomaly is that the recurrence risk may change significantly from the 3% likelihood quoted for an isolated WTD: the appropriate recurrence rate may be much lower (e.g., in cases where there is a de noYo chromosomal rearrangement), similar or slightly lower (e.g., in cases where there is an autosomal trisomy), or higher (in cases where certain familial chromosomal rearrangements are found).…”

A normal 46,XX infant with a 46,XX/ 69.XXY placenta: A major contribution to the placenta is from a resorbed twin

“…The macroscopic and histological appearance of the placenta was clharacteristic of that seen in partial hydatidiform mole (Szulman and Surti, 1982). Triploidy is cornmonly associated with severe pre-eclampsia (Graham et al, 1989), which occurred in this pregnancy. These data are consistent with a major portion of the placenta being a functioning triploid placenta which was apparently compatible with the development of a normal diploid fetus.…”