Diversities of H-type anorectal malformation: a systematic review on a rare variant of the Krickenbeck classification.

Congenital H-type fistula is a rare congenital rectourogenital connection with an external anal opening in a normal or ectopic position. A systematic review was done to study the anatomical types of congenital H-type fistula, embryology, clinical presentation, relative gender distribution, associated anomalies, investigative modalities, and recent advances in treatment of these lesions. A PubMed search included H-type anorectal malformation; H-type anorectal malformations; H-type anorectal; and H-type congenital anorectal that gave 9;43;76;26 abstracts, respectively. Relevant studies and cited articles were studied omitting duplicate search. The reported incidence is 0.1-16 % of all anorectal malformation. The H-type anorectal malformation is 2.5-6 times more common in females and usually associated with a normal anus. In males, the anomaly is usually a variant with an ectopic anus or a perineal fistula. Anatomical types include anovestibular; rectovestibular; rectovaginal fistula in females and rectourethral (bulbar, prostatic, bladder neck) and rectovesical fistula in males. Variants identified include H-type fistula with perineal fistula, perineal groove, H-type sinus, H-type canal, and acquired H-type fistula. This review compiles the available literature over last six decades. Various surgical corrective procedures have been described. The high recurrence decreases with a learning curve and experience.