Fetal sexing by ultrasound in the second trimester: maternal preference and professional ability.

The study was planned to determine the proportion of parents that wish to know the sex of their fetus at the 20-week anomaly scan, and to investigate our ability to diagnose correctly the sex of the fetus when undertaken as part of a routine scan. A total of 472 patients gave their informed consent. An attempt was made to identify the genitalia as part of the routine scan. No extra time was allowed to determine the sex of the fetus. Altogether 353 (74.7%) women wanted to know the sex, of which four (0.9%) wanted to know but did not want their partners to know. In 50 (10.6%) cases, it was not possible to determine the fetal sex in the time allowed. When the sex was identified, it was correct in 408 (96.7%) cases, and incorrect in 14 (3.3%) cases. Where the parents wanted to know the sex of the fetus, 24 (6.8%) scans were inconclusive, 319 (97%) were correctly identified, and ten (3%) were incorrectly identified (six male, four female). There were no terminations of pregnancy. The majority of prospective parents wish to know the sex of their child, and, in most cases, it is possible to determine the fetal sex at the time of the routine anomaly scan. During the time allowed, the fetal sex was undetermined in one in ten cases, and 3% were sexed incorrectly. If parents wish to know the gender of their fetus, it would appear reasonable to provide this information, provided that the parents are aware of the failure and error rates of sex identification using ultrasound.