Embryological Development of Persistent Cloaca. Hypothesis

Introduction: While some authors suggest that anorectal malformations (ARMs) arise from abnormal development of the cloaca, only the true cloaca arises because of the cessation of the division of the cloaca stopping at the stage of development characteristic of female birds and reptiles.It is characterized by the confluence of the rectum, uterus, and bladder into a wide space, resulting in the complete absence of the urethra, vagina, and anal canal.Currently, following the articles by Hendren and Pea, persistent cloaca is the name given to the pathology that was previously called ARM with vaginal fistula.These patients have a urethra, vagina, and anal canal that supposedly merge into a common narrow channel.These patients are operated on as if they were patients with a true cloaca.Results: As a result of an analysis of literature and our own research, it has been shown that with all types of ARMs, except for the true cloaca, the pathology develops at a later embryonic period because of impaired development of the exodermal rudiment of the anal canal.By this time, normal development of the anal canal occurs up to the subcutaneous tissue.When the IAS does not encounter the ectodermal rudiment, as evidenced by the absence of the anus, it deviates forward and upward, forming a narrow, rigid fistula.This process leads to the ectopic positioning of the anus on the perineum, vestibule, urethra, or vagina.What surgeons typically remove during the pull-through procedure, under the guise of a fistula, is a functioning anal canal.A short, rigid fistula forms in the wall of the organ through which the IAS penetrates.Conclusion: Unlike a true cloaca, a persistent cloaca develops due to the penetration of the IAS through the vaginal wall before a cavity has formed within the vagina.As a result, the IAS creates a narrow long fistula that, in some cases, obstructs the emptying of the upper part of the vagina, leading to hydrocolpos.These patients typically have a normally functioning bladder and urethra, and in some cases, a functioning anal canal has been documented.Poor outcomes are the result of unnecessary and mutilating surgeries.