Cloacal Malformations

Updated: Dec 09, 2015
  • Author: Marc A Levitt, MD; Chief Editor: Eugene S Kim, MD, FACS, FAAP  more...
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Overview

Background

A persistent cloaca is defined as a confluence of the rectum, vagina, and urethra into a single common channel. This defect is one of the most formidable technical challenges in pediatric surgery. The etiology of persistent cloaca is unknown.

Cloacal anomalies occur in 1 per 20,000 live births. They occur exclusively in girls and comprise the most complex defect in the spectrum of anorectal malformations. Families and physicians dealing with a newborn baby girl who has a cloacal malformation have three main concerns, as follows:

  • Urinary control
  • Bowel control
  • Sexual function (menstruation, intercourse, obstetric issues)

The goals of treatment include an anatomic reconstruction and achieving bowel and urinary control, as well as normal sexual function.

Diverse treatments for the management of persistent cloaca have been proposed in the past. The most common approach consisted of repairing the rectal component of the malformation without repairing the urogenital sinus or planning its repair in a second stage. A combined abdominal, perineal, vaginal, and simultaneous rectal pull-through was also used.

Some treatments were adequate for certain cloacae but not for others. The perineal approach to urogenital sinus repair may be useful in patients with low defects, but not in those with higher defects. Similarly, the abdominal approach is required for some anomalies but not for others. Traditional approaches were limited in their exposure and, thus, could not clearly define the complex anatomy of the defect, and the urinary sphincter and anorectal sphincter were matters of speculation.

In 1982, the posterior sagittal approach, which was used to repair an imperforate anus, was first performed for a cloacal malformation. [1] It was ideally suited for the more complex repair of cloacae and led to the operation described as the posterior sagittal anorectovaginourethroplasty (PSARVUP). This approach allowed for direct exposure to the complex anatomy and an excellent visualization of the voluntary muscles of urinary and fecal continence.

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Pathophysiology

Genitourinary defects

More than 80% of all patients with a cloaca experience an associated urogenital anomaly.

  • Persistent cloaca - 90%
  • Rectobladderneck fistula - 84%
  • Rectoprostatic urethral fistula - 63%
  • Rectovestibular fistula - 47%
  • Rectobulbar urethral fistula - 46%
  • Rectoperineal fistula - 26%
  • Anorectal malformation with no fistula - 31%

All patients must be evaluated at birth for an associated urologic problems; the most valuable screening test is abdominal and pelvic ultrasonography.

Urologic evaluation, either by a pediatric surgeon experienced with pediatric urology or in consultation with a pediatric urologist, is necessary before proceeding with colostomy. This provides the surgeon the necessary information needed to address the urologic problem at the time of the colostomy. In addition, drainage of a distended vagina (hydrocolpos) may be required.

Tethered cord

A tethered spinal cord refers to an intravertebral fixation of the phylum terminale.

Tethered cord has a known association with anorectal malformations and is particularly common in patients with persistent cloaca.

Motor and sensory disturbances of the lower extremities may result.

Patients with anorectal malformations and tethered cord have a worse functional prognosis regarding bowel and urinary function. However, they also have higher anorectal defects, less-developed sacra, associated spinal problems, and less-developed perineal musculature; thus, the actual impact of tethered cord alone on the functional prognosis is unclear.

Untethering of the cord to avoid motor and sensory problems is indicated in the neurosurgical literature. No definitive evidence suggests that this operation affects the functional prognosis of a patient with anorectal malformation. Some evidence in the urologic literature indicates that this operation may improve urodynamics.

Anomalies of the sacrum, particularly hypodevelopment, sacral hemivertebrae, and hemisacra, are associated with tethered cord and most likely comprise the spectrum of caudal regression, of which spinal anomalies are a part.

Spinal ultrasonography in the first 3 months of life and MRI thereafter are useful in diagnosis.

Sacrum and spine anomalies

The sacrum is the most frequently affected bony structure. Traditionally, to evaluate the degree of sacral deficiency, the number of sacral vertebral bodies was counted. A more objective assessment of the sacrum can be obtained by calculating a sacral ratio. The sacrum is measured, and its length is compared with bony parameters of the pelvis (see the image below).

Calculation of sacral ratio. Calculation of sacral ratio.

The distance from the coccyx to the sacroiliac joint divided by the distance from the sacroiliac joint to the top of the pelvis provides the sacral ratio. Lateral radiography is more accurate than the anteroposterior view because its calculation is not affected by the tilt of the pelvis.

The assessment of the hypodevelopment of the sacrum correlates with the patient's functional prognosis. Normal sacra have a ratio of greater than 0.7. Bowel control has rarely been observed in patients with ratios less than 0.3.

A hemisacrum is almost always associated with a presacral mass, commonly teratomas, or anterior meningoceles. The Currarino triad, which includes an anorectal malformation, a hemisacrum, and a presacral mass, has been described.

Hemivertebrae may also affect the lumbar and thoracic spine, leading to scoliosis.

Patients may have spinal anomalies other than tethered cord, such as syringomyelia and myelomeningocele.

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Epidemiology

The literature reports that the incidence rate of cloacal malformations is approximately 1 per 20,000-25,000 live births. However, the literature often contains reports of rectovaginal fistula, which are most likely cloacal malformations in which the rectal problem was corrected but the urogenital sinus was not. Therefore, cloacal malformations are probably more common than previously thought.

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Prognosis

Functional prognosis with regard to achieving fecal continence depends on the complexity of the defect and the status of the spine and sacrum.

Fecal continence is more likely in patients with a benign cloaca and in those who have a normal sacrum. Approximately 70% of patients can achieve voluntary movements (for comparison with patients with other anorectal anomalies, see Imperforate Anus).

Postoperative monitoring of bowel function is similar to that in patients with imperforate anus (see Imperforate Anus: Surgical Perspective).

Urinary control varies based on the length of the common channel (see the image below).

Repair of persistent cloaca with 4-cm common chann Repair of persistent cloaca with 4-cm common channel.

Intermittent catheterization is required in 69% of patients with persistent cloaca who have a common channel longer than 3 cm, compared with 20% in the group with a common channel shorter than 3 cm.

In most patients, the bladderneck is competent, and the patients who require catheterization remain dry between voids. If catheterization is not performed, overflow incontinence occurs. Occasionally, the bladderneck is not competent or is nonexistent; in these patients, urinary diversion, such as a Mitrofanoff procedure, with bladder neck tightening may be needed.

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