Posterior cloaca: A urogenital rather than anorectal anomaly

'Persistent Cloaca' refers to one of the major groups of anorectal anomalies in the female when a single perineal orifice is located at the normal site of the urethra draining both urogenital and alimentary tracts. However, 'posterior cloaca' is a new term developed by Pena to describe a unique defect in females in which a common urogenital sinus is deviated posteriorly to open into normally located anorectum (type A) or in the perineum slightly anterior to the anus (type B).

The study included seven girls diagnosed as posterior cloaca. Their age at presentation ranged from 1 to 108 months (median 12 months). The main presentation was abnormal external genitalia, while two cases underwent colostomy (±vaginostomy) at birth. Surgical reconstruction varied according to the degree of deviation from normal anatomy. Partial urogenital sinus mobilization (PUM) was used to correct minor forms; while at the other end of the spectrum (absent urinary bladder), continent urinary diversion was performed. Due to the high incidence of renal and urological anomalies, regular follow up at paediatric nephrology/urology clinics was advised for affected cases.

All seven cases had a common urogenital confluence characteristically deviated posteriorly. The degree of backward deviation of the common urogenital orifice was variable ranging from mild to severe posterior displacement. In six cases (85%), the common urogenital orifice was shifted backwards in the perineum approaching the anal verge (type B). In one case, the common urogenital orifice opened internally into the anorectum (type A). Major urinary tract anomalies were quite common (5 of 7 cases; 71%): absent urinary bladder (2 cases); single kidney (2 cases); crossed ectopic kidney (1 case); hydroureteronephrosis (2 cases).

Posterior cloaca is a rare anomaly in the female essentially affecting the lower urogenital tract with a high incidence of associated renal anomalies. Management should be tailored according to the degree of developmental defect.