Persistent cloaca refers to the continuation of the early embryological stage of a common opening for the rectum, vagina, and urinary tract.
This is an extremely rare abnormality, being seen in only 1 in 50,000 births.
Fetal abdominal cystic masses are the most typical prenatal diagnostic features, usually due to hydrocolpos and associated bladder outlet obstruction.
Following the prenatal diagnosis, targeted fetal ultrasound, amniocentesis, and fetal MRI are helpful in accurately delineating the fetal anatomy.
Postnatal surgical reconstruction is complex and should be undertaken only by a multidisciplinary pediatric surgical team after complete neonatal radiological and endoscopic anatomic evaluation.
Long-term outcome appears favorable after surgical correction with the majority of patients being continent of urine and feces and several having successfully delivered children.
Cloaca, the Latin word for sewer, is aptly named as it represents the persistence of a developmental phase (typically in a female fetus) in which the rectum, vagina, and urinary tract share a common channel. In normal human development, there is a stage during which the cloaca forms from the confluence of the allantois and hindgut (Stephens and Smith, 1971). At 4 to 6 weeks of development, the urorectal septum descends, separating the allantois from the hindgut. Failure of this urorectal septum to descend results in persistent cloaca (Figure 85-1). The infant with persistent cloaca usually presents at birth with abdominal distention and an abnormal perineum. Typically, these children have only a single perineal opening without an anus or a vaginal introitus. The genitalia are ambiguous, often with a hooded phalluslike structure suggesting a masculinized gender, yet their chromosomes are consistently 46,XX and they have two normal ovaries. The length of the common channel to the perineum may vary, from 1 to 12 cm (Canning et al., 1998, Pena et al., 2004). In cases with a common channel <3 cm, there is usually a well-developed sacrum and sphincter complex. In contrast, longer common channels are more likely to have an abnormal sacrum and a poor sphincter complex, and these are usually more complex defects. In more than 50% of cases, there is hydrocolpos due to partial obstruction of the entry of the vagina into the common channel. The hydrocolpos can compress the trigone of the bladder, with resulting bladder outlet obstruction and hydroureteronephrosis. The prenatal sonographic detection of hydronephrosis may be the only indication of cloacal malformation. Duplicated vagina and uterus didelphys are commonly seen in persistent cloaca (Figure 85-2).
Line drawing depicting the anatomic relations typically observed in persistent cloaca with dilated rectum and, in this case, hydrocolpos. (From Pena A. Atlas of Surgical Management of Anorectal Malformations. New York: Springer-Verlag; 1990:60. Lois Barnes Medical Illustrator. Used with permission)
Fetal MRI image in saggittal view ...