Maternity Department, Al-Hammadi Hospital, Riyadh, Saudi Arabia.

The following images present a case of a persistent urogenital sinus (persistent cloaca).

A 22-year-old G3P2 with noncontributory personal or family history presented to our department for the ultrasound scan at 33 weeks. We discovered the anechogenic cyst measuring 52x50 mm, localized in the lower abdomen. There was a moderate amount of free fluid in the abdomen. Urinary bladder was anterior and adjacent to the cystic lesion. Both kidneys were of normal morphology but showed signs of mild hydronephrosis.
The consecutive ultrasound at 38 weeks revealed polyhydramnios (max. vertical pool, 11 cm). The cyst measured 100x65 mm and reduced to the size of 70x65 mm after urination.

The female baby was born at 38 weeks and its postnatal adaptation was normal. There was a significant swelling of the labia majora. Small opening was found in the vagina, we inserted a feeding tube through this opening and it got easily into the cystic mass. We drained 180 ml of fluid, which turned out to be the urine after confirmation from the laboratory.

According to the ultrasound and MRI examinations, persistent urogenital sinus was diagnosed. The neonate underwent surgery afterwards which confirmed the diagnosis.

Images 1,2: Images show a abdominal cystic mass which is actually dilated vagina and uterus; Image 2 shows a urinary bladder anterior to the hydrocolpos, * indicates the communication between bladder and vagina.

Images 3,4: Image 3 shows the upper portion of the cyst-hydrocolpos with dilated uterine cavity, Image 4 shows a kidney.

Images 5,6: The following are the MRI images; Image 5 shows a transverse view of the abdomen, bladder is in front of the hydrometrocolpos; Image 6 shows a sagittal view of the abdominal cavity, note grossly enlarged vagina with uterus on the top. 

Images 7,8: Images show a sagittal view of the abdomen, bladder (yellow), vagina (blue) and uterus (red).

Conclusion

A persistent urogenital sinus or persistent cloaca is a rare anomaly affecting female fetuses.

Prevalence: 1:20,000 female deliveries.

Both urethra and vagina open into a common channel. In our case urethra opened into the anterior aspect of the vagina. Hydrometrocolpos (vagina and uterus filled with fluid) is present due to a vaginal obstruction and reflux of urine from the urinary bladder into vagina and uterus. There is usually an ascites due to the retrograde flow of fluid from the uterus into the abdominal cavity.

Persistent urogenital sinus can be associated with ambiguous genitalia in case of 45 X/46 XY mosaicism. There are other conditions which can cause hydrometrocolpos. Any form of vaginal obstruction, such as transverse septum, imperforate membrane and cloacal malformation. Hydrometrokolpos in McKusic-Kaufman syndrome is due to cervical or vaginal atresia.