To explore the clinical significance of abnormal fetal genitalia detected by routine prenatal ultrasound.

In Peking University Third Hospital from January 2014 to January 2016, the ultrasonic diagnosis and sonographic features in 14 suspected cases of abnormal fetal genitalia were analyzed retrospectively and compared with postpartum morphological and pathological characteristics.

The fetal ultrasound findings and clinical outcomes in 14 cases were: (1) There were 4 cases of partial penoscrotal transposition (28.6%, 4/14), in which all fetus hadshort penis and hypospadias. In 2 termination cases, unilateral hydronephrosis and anal atresia was found in one case, while ventricular septal defect was found in the other case. In 2 term-birth cases, there was one case of recessive spina bifida. In the 4 cases, prenatal ultrasonographic manifestation showed that the short penis was located between the division of the scrotum, named as ″tulip sign″. (2) There were 2 cases (14.3%, 2/14) of complete penoscrotal transposition, in which all the pregnancies were terminated. On prenatal ultrasound of external genitalia, the location of the penis and scrotum was reversed. In one case, anal atresia and small eye malformation were found. In one case, the tetralogy of Fallot, duodenal atresia and anal atresia were found. (3) There were 4 cases of the micropenis (28.6%, 4/14). On prenatal ultrasound, the penis was difficult to demonstrated and was shown merely as an echoic dot. Among 2 cases of FGR, one infant dies for unexplained reasons after birth, and one infant has hypospadias after birth. The pregnancy was terminated in two cases of 18-trisomia and microdeletion in chromosome 9. (4) There were 2 cases of penis absence (14.3%, 2/14), in which all pregnancies were terminated. The sonographic manifestations show the absence of penis and bladder eversion. (5) In 2 cases, sex couldn`t be identified (14.3%, 2/14). In one case, the 46 xy infant showed a female external genitalia appearance after birth. In one case, the clitorism and congenital adrenal cortical hyperplasia were found in a 46 xx infant after birth.

Prenatal ultrasonography is effective and feasible in detecting genitalia abnormalities, especially for penis scrotal transposition and penis absence. When the fetal gender cannot be identified on ultrasound, chromosome examination is warranted. For indeterminable cases, ultrasound follow-up in 2^nd and 3^rd trimester is necessary.