Partial urorectal septum malformation sequence: A report of 25 cases

Abstract

We have identi®ed 25 cases with what we are calling the partial urorectal septum malformation (URSM) sequence, which were seen in our institution over the past 27 years. The partial URSM sequence is de®ned as a single perineal/anal opening that drains a common cloaca in combination with an absent (imperforate) anus. In the 25 patients reported here, the partial URSM sequence was more common in females, with a female to male ratio of 18 to 7. Ambiguous genitalia were common in both sexes. Internal pelvic structures typically showed a cloaca with the bladder and rectum (and vagina in females) coalescing into a common canal that connected to the external surface in the perineal or anal area. Abnormalities of the internal genitalia were also common, with 12 females having a bi®d or septate vagina and 11 having a bicornuate uterus. Renal anomalies were frequent in both sexes, with 10 of 25 patients having unilateral cystic renal dysplasia and 7 of 25 patients having unilateral renal agenesis. Twenty-one of 25 patients survived long term. By de®nition, the partial URSM sequence is a milder expression of the full URSM sequence, which is de®ned as having no perineal or anal openings and is typically associated with an internal cloaca. The URSM spectrum, which encompasses the partial and full URSM sequences, is believed to be caused by abnormalities of septation of the primitive cloaca. The URSM spectrum is distinct from the VATER association and conditions caused by sex hormone abnormalities, such as congenital adrenal hyperplasia. ß

Cloaca, Posterior Cloaca and Absent Penis Spectrum

“…Some authors refer to cloacas with a clear embryologic bias, and therefore, they used rather confusing terms such as "urorectal septum malformation sequence" [ 33 ] or "urorectal septal defects" [ 34 ] including variants such as adrenal hyperplasia, as well as male cases [ 35 ]. Others include the cloacas as part of "Müllerian duct anomalies" [ 36 ].…”

Cloacal Malformation

“…7 There are also strong hormonal influences, as evidenced by the association of urogenital sinus malformation with virilization unrelated to congenital adrenal hyperplasia in female fetuses. 8 The common observation of uterine and vaginal duplication has led to speculation that malformation of the cloaca or urogenital sinus interferes with müllerian duct fusion. 9 Persistent urogenital sinus and cloaca are almost exclusively found in female fetuses; however, the cloacal dysgenesis sequence has been reported in male fetuses.…”

“…For example, the partial urorectal septum malformation sequence is synonymous with cloaca. 8 Subtypes described in the surgical literature are based on the anatomic connections as well as the surgical approach and are often grouped under the umbrella of anorectal malformations. The multitude of terms used in the literature and the broad array of possible anatomic connections makes it difficult to develop a useful, simple classification system.…”

Urorectal Septum Malformation Sequence in A Calf

“…Before the introduced the term in human medicine, authors used the terms including 'female pseudohermaphroditism with anorectal malformation, hypoplastic pelvic outlet and persistent cloaca' 2 . The extent of variation in human URSM cases is from complete to partial or milder variant forms characterized by a single openining draining the cloaca might be compatible with life 3 .…”