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Persistent cloaca with hydrometrocolpos

Case contributed by Fabien Ho
Diagnosis certain


Familial and obstetrical backgrounds, as well as lab screenings were non relevant.

Patient Data

Age: 35 weeks gestation
Gender: Female

1st trimester


Non-specific cystic structure below the stomach and to the left of the bladder.
This image then disappeared upon follow-up, including 2nd trimester US exams.

34 weeks gestation


Unfortunately, our US scans displayed poor definition due to patient's weight (over 110 kilograms).
Macrocystic structure in the pelvis of a female fetus, with internal echoic deposits. Ovarian cyst ? 
Unusual septum within the image: due to blood clot?

We quickly performed an MRI as soon as possible because we had numerous possible differential diagnoses in mind...

35 weeks gestation


The macrocystic structure was located in the midline and extended way down into the pelvis towards the perineal area. It displayed an incomplete midline septum. Hypointense deposits are seen within. Its shape and location on the midline, behind the bladder, are very suggestive of a hydrometrocolpos with a partial uterine septum.

The bladder was best seen on sagittal and axial view. It was pushed to the front by what appears to be a hydrometrocolpos and was less than half-full. In contrast, there was dilation of both ureters and both kidney pelvis above the hydrometrocolpos. Either there was a mass effect on both ureters, either there was a low-urinary-tract-obstruction (LUTO) with "valve-effect" towards the colpos.

The meconium has a remarkable T1 hyperintense physiological signal, which is very handy to follow the large bowel. On axial, sagittal, and coronal view, no hyperintense T1 meconium was seen in the pelvis. The large bowel likely ended 4 centimeters above the perineal skin: most likely a high-type anorectal malformation. There was no bowel dilation nor enterolithiasis.

Spine and spinal cord showed normal MRI appearance.

Case Discussion

This case is very similar to one of our previous cases, except:

  • oddly there was an atypical cystic pelvic image on first trimester US, which was non-specific. Some may believe it does represent communication between the bladder and the bowel (Prof. R. Chaoui).
  • maternal weight really limited US examination, thus the anal muscle hypoechoic ring could not be assessed. 
  • there was no fetal ascites
  • the uterine septum was partial

The combination of a hydrometrocolpos, an anorectal malformation and bilateral ureter and kidney pelvis dilation in a female fetus was very suggestive of a persistent cloaca.

The diagnosis was confirmed at birth: distended abdomen and pelvis with an imperforate anus were seen. Upon surgery, the large bowel was connected to the uterus by an atretic cloacal channel.  Anatomic repair is hardly doable in the neonatal period. Therefore, colostomy was performed, and drains were put in both bladder and uterus.

For more information about cloaca, refer to the references below.

Dr Fabrice Cuillier contributed to the US images, and of course, the neonatal pediatric team and the pediatric surgical team also contributed to this case. 

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