Objective: Several studies have noted an increased prevalence of pyelectasis in male fetuses. It is speculated that pyelectasis represents a normal physiologic variant in males, whereas its presence in females indicates an increased risk of chromosomal abnormalities. Thus, we sought to investigate the association between fetal gender and the risk of major trisomies in fetuses with pyelectasis.
Methods: Retrospective analysis of a Genzyme Genetics amniocentesis database (1995 to 2004) was performed. Specimens obtained after an ultrasonographic finding of pyelectasis were eligible for analysis. The prevalence of major trisomies (trisomy 13, 18, or 21) in male and female fetuses with pyelectasis was compared using binomial distribution.
Results: A total of 760,495 amniocentesis specimens were analyzed. Fetal pyelectasis was reported in 671 cases. A male predominance, with a male-to-female ratio of 2.14:1 (457 compared with 214) was statistically significant (P < .001). A major trisomy was detected in 26 male fetuses (5.7%): 18 cases of trisomy 21, 2 cases of trisomy 18, and 6 cases of trisomy 13. Nine female fetuses had a major trisomy (4.2%): 6 cases of trisomy 21 and 3 cases of trisomy 13. There was no significant difference in the overall prevalence of trisomies between male and female fetuses (P = .14).
Conclusion: We concur with previous studies documenting a higher prevalence of pyelectasis in male fetuses. In addition, our results indicate that the prevalence of major trisomies among fetuses with pyelectasis is unlikely to be dependent on fetal gender. Thus, counseling patients with regard to the genetic implications of fetal pyelectasis should be gender independent.
Level of evidence: II-2.