Fetal gender and the external genitalia can usually be seen on ultrasound if the fetal position is suitable and oligohydramnios is not present. Fetal testes remain intra-abdominal structures until after 28 weeks gestation.
·Cloacal dysgenesis- This may occur as an isolated lesion or as a part of a spectrum of anomalies involving multiple organ systems. Sonographic diagnostic clues suggesting cloacal dysgenesis include the presence of a single, thick walled septated cyst within the pelvis in the absence of a recognizable fetal bladder.
·Congenital hydeocele- Hydrocele may be either (1) communicating with the peritoneal cavity, or (2) non-communicating; repeat sonographic examination in the latter shows no change in the size of the fluid collection in the scrotum, unlike communicating hydrocele which may change in size. Consecutive scans showing a change in scrotal volume may also raise the possibility of the presence of an inguinal hernia. Hydroceles without evidence of fetal ascites usually resolve spontaneously.
·Megaurethra - The dilated urethra is seen as a fluid filled tube within the penis. Dilated urethra can occur with other urinary tract disorders such as the prune belly syndrome.
·Ambioguous genitalia- Seen when normal male or female anatomy is not apparent.