Pediatric Surgery, AlSadik Hospital, Qatif, Saudi Arabia
Cloacal exstrophy is an extremely rare and major birth defect representing the severe end of the spectrum of the exstrophy-epispadias complex (Fig. 18.1).
Clinical photograph showing the components of the cloacal exstrophy
It is also called vessico-intestinal fissure.
The exact incidence of cloacal exstrophy is not known but the estimated prevalence ranges from 1 in 50,000 to 250,000 live births.
It is more common in males than females (a male-female ratio of 2:1).
Cloacal exstrophy, is also called the OEIS Complex:
E: Exstrophy of the cloaca
I: Imperforate Anus
S: Spinal Defects
Clinically, patients with cloacal exstrophy present at birth and it is characterized by the followings spectrum of anomalies (Figs. 18.2, 18.3, 18.4, 18.5, and 18.6):
Figs. 18.2 and 18.3
Clinical photographs showing two patients with cloacal exstrophy. Note the difference in the size of omphalocele and also the extent of the exstrophied ileo-cecal region
Figs. 18.4 and 18.5
Clinical photographs showing cloacal exstrophy in two patients. Note the absence of omphalocele in the first one and associated anorectal agenesis in the second one
A clinical photograph showing cloacal exstrophy. Note the associated anorectal agenesis
Two exstrophied hemibladders
These are separated by a foreshortened hindgut or cecum
The hindgut is often blind-ending resulting in an imperforate anus.
This extrophied ileo-cecal region presents between the two hemi bladders (the “elephant trunk” appearance).
The associated omphalocele may be major or minor and sometimes no associated omphalocele.
The symphysis pubis is widely separated
The pelvis is often asymmetrically shaped
The genitalia (ambiguous genitalia):
In males, the penis is divided into two halves usually located separately on either side of the bladder plates with the adjacent scrotal halves.
In females, the clitoris is divided into two haves usually located separately on either side of the bladder plates with the adjacent part.
Duplication of the vagina and uterus
18.2 Etiology and Pathogenesis
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The exact etiology of cloacal exstrophy is not known.
Several theories have been proposed to explain the pathogenesis of cloacal exstrophy but none of them can fully explain the spectrum of anomalies seen in cloacal exstrophy.
The most accepted theory is that cloacal exstrophy results from premature rupture of the cloacal membrane prior to caudal migration of the urorectal septum, and failure of fusion of the genital tubercles.
The urorectal septum divides the cloaca into an anterior urogenital sinus and a posterior anorectal canal.
This occurs around the fourth week of intrauterine life and simultaneously, the cloacal membrane is invaded by lateral mesodermal folds.
It is postulated that if this mesodermal invasion does not occur, the infraumbilical cloacal membrane persists leading to poor lower abdominal wall development.
The cloacal membrane eventually ruptures but if this happens prior to the descent of the urorectal septum which happens at 6–8 weeks of gestation, then cloacal exstrophy results.
Cloacal exstrophy develops as a result of:
Failure of the urorectal septum to develop and divides the urogenital sinus anteriorly from the rectum posteriorly.
Failure of the mesoderm forming the infraumbilical abdominal wall to proliferate and form the lower abdominal wall
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