We present a case of persistent cloaca.

Our ultrasound images demonstrate the following:

• Image 1, Video 1: nonspecific cystic structure below the stomach and to the left of the bladder. On repeat ultrasound in the 2nd trimester, this structure disappeared.
• Image 2, Video 2: Due to patient habitus (>110kg), our ultrasound images displayed poor definition. At the 3rd trimester scan, we identified a macrocystic structure in the pelvis of a female fetus with internal echoic deposits. Our differential diagnosis included ovarian cyst. We also identified an unusual septum within the structure, possibility due to a blood clot. We then performed an MRI to further evaluate.
• Images 3-20
  • The macrocystic structure was located in the midline and extended into the pelvis towards the perineal area. It displayed an incomplete midline septum. Hypointense deposits are seen within the structure. Its shape and location in the midline, behind the bladder are suggestive of a hydrometrocolpos with a partial uterine septum.
  • The bladder was best seen on the sagittal and axial views. It was pushed to the front by what appeared to be a hydrometrocolpos, and was less than half-full. In addition, there was dilation of bilateral ureters and bilateral hydronephrosis proximal to the hydrometrocolpos. Either there was a mass effect of the hydrometrocolpos on both ureters, or there was a low-urinary-tract-obstruction (LUTO) with "valve-effect" towards the colpos.
  • The meconium has a remarkable T1 hyperintense physiologic 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 4cm above the perineal skin, suggesting a high-type anorectal malformation. There was no bowel dilation or enterolithiasis.
  • Spine and spinal cord showed normal MRI appearance.

The combination of an hydrometrocolpos, an anorectal malformation and bilateral ureter and kidney pelvis dilation was very suggestive of a persistent cloaca. Some differences in this case compared to others presented on TheFetus.net include:

• Oddly there was an atypical cystic pelvic image on first trimester ultrasound, which is non specific. Some may believe it represents a communication between the bladder and bowel (Prof. R. Chaoui).
• Maternal obesity limits ultrasound examination, thus the anal muscle hypoechoic ring could not be assessed.
• There was no fetal ascites.
• The uterine septum was partial.

The diagnosis was confirmed at birth. On exam, the neonate had a distended abdomen and pelvis with an imperforate anus. Upon surgical exploration, the large bowel was connected to the uterus through a cloacal channel. Anatomic repair is difficult in the neonatal period, therefore a colostomy was performed and drains were placed in both bladder and uterus.

References

[1] Gupta A, Bischoff A, Peña A, et al. The great divide: septation and malformation of the cloaca, and its implications for surgeons. Pediatr Surg Int. 2014 Nov;30(11):1089-95.
[2] Bischoff A, Calvo-Garcia MA, Baregamian N, et al. Prenatal counseling for cloaca and cloacal exstrophy-challenges faced by pediatric surgeons. Pediatr Surg Int. 2012 Aug;28(8):781-8.
[3] Alfred Z. Abuhamad, Rabih Chaoui. First Trimester Ultrasound Diagnosis of Fetal Abnormalities. (2017) ISBN: 9781451193725
[4] Fayard C, Blondiaux E, Grigorescu R, et al. AIRP best cases in radiologic-pathologic correlation: prenatal and postmortem imaging of a complex cloacal malformation.  Radiographics. 2014 Nov-Dec;34(7):2056-63.