Covered exstrophy with anorectal malformation and vaginal duplication.

Covered exstrophy is a rare variant of the exstrophy-epispadias complex. We report a female newborn with covered exstrophy, absent anal opening and duplication of the introitus and the lower vagina. This rare, previously unreported, combination of anomalies highlights the complexity of the embryological events in the caudal area during separation of the hindgut and allantois.

INTRODUCTION

Classical exstrophy of the bladder is a rare anomaly with an incidence of 1 in 30,000-50,000 live births.[1] Covered exstrophy is one of the variants of exstrophy-epispadias complex. There are a few case reports of covered exstrophy with anorectal malformation and the complete duplication of bladder, urethra, and the mullerian structures.[23] However, covered exstrophy associated with duplication of introitus and the lower vagina has not been reported earlier in the English literature. We report one such baby.

CASE REPORT

A 2.6 kg, 2-day-old female child, delivered by cesarean section, was brought to us with malformed external genitalia and a swelling over the lower part of the abdomen and the perineum.

Physical examination revealed a lobulated bowel projection with a skin-covered swelling extending over the lower part of the abdomen and the perineum. The umbilicus was low set, situated just above the upper extent of the swelling. The pubic symphysis was widely separated with a bulging urinary bladder occupying the space in between. The introitus was replaced by the swelling which was continuing on to the lower abdomen. There was duplication of the introitus with two openings, each flanked by the single labia majora located laterally, in the groin area [Figure 1A]. The clitoris was bifid. The two orifices on either side were in communication with each other as a catheter introduced from one orifice exited through the other. The urethral orifice could not be seen from the outside; however, both the introitus openings were discharging urine intermittently. The anal opening was absent. An infantogram and cross-prone-lateral X-ray showed a high type of anorectal malformation and the absence of calcification in the area of accessory bowel loop.

Figure 1

(A) Duplicated introitus, absent anal opening and accessory bowel segment. (B) Neoanus after excision of accessory bowel segment

The baby was resuscitated and undertaken for surgery. A midline laparotomy showed that the small bowel and large bowel were normal and in continuity. The internal genitalia were female type and the uterus was unicornuate with normal fallopian tubes and the ovaries. The urinary bladder was intact although subcutaneous in location. The accessory bowel loop was attached to the lower part of the swelling and the lumen was in continuity with lumen of the terminal part of the rectum. The extra piece of the bowel was excised and the terminal part of rectum fashioned as a neoanus [Figure 1B]. A suprapubic cystostomy (SPC) was also inserted as the anatomy of the bladder neck and urethra was still not clear. The rectus sheath in the upper part of the abdomen was closed primarily and the lower part containing the urinary bladder in subcutaneous location was left as such. The histopathologic examination of the sequestered loop revealed colonic mucosa. The baby was put on oral feeds after 48 h and the SPC was clamped. The baby was decompressing well from the perineal openings and was discharged from the hospital after removal of the SPC catheter. Postoperatively, the baby was put on dilatation program for the neoanus. The ultrasonography and radionuclide scans for the renal tract have shown normal upper tracts. The spine and spinal cord were normal radiologically. At the age of 6 months, the baby underwent genitoscopy examination which showed single urethral orifice with duplication of the lower part of the vagina. Bladder was unremarkable. At present, the patient is waiting for the genital reconstruction at a later age and is continent for urine.

DISCUSSION

Variants of the bladder exstrophy complex are quite uncommon and constitute about 8% of all the cases. These variant lesions, also called “Split symphysis variants”, have all the musculoskeletal findings of classical exstrophy, but the bladder is closed with varying degrees of skin and the subcutaneous covering, and the urethra and sphincter mechanism may be intact.[4] Exstrophy variants have been classified into four major subgroups, namely pseudoexstrophy, superior vesical fissure, duplicate exstrophy, and covered exstrophy with visceral sequestration.[45]

Classical bladder exstrophy is believed to result from the persistence or overdevelopment of an abnormal infraumbilical cloacal membrane that acts as a wedge and prevents the medial progression of the lateral mesoderm between its ectodermal and endodermal layers.[1] The exstrophy variants are explained by the incomplete rupture or persistence of this abnormal infraumbilical cloacal membrane.[6] Mildenberger et al., however, explained the occurrence of exstrophy and its variants to be the consequences of persistence of an abnormal caudal insertion of the body stalk on the embryo.[7]

Covered exstrophy seems to differ from the classical exstrophy not only in the degree of exposure of the bladder and urethra, but also by frequent presence of the abnormalities of the external genitalia. A partial diphallus with incomplete urethral duplication and laterally displaced phallus with widely separated scrotal halves associated with covered exstrophy have been reported by Mildenberger et al.[7] Genital abnormalities observed in females with covered exstrophy included bifid clitoris (67%), labial cleft (11%), hypoplastic labia (11%), and stenosed duplicate vagina (11%).[2] Covered exstrophy with complete duplication of the genital and the lower urinary tract with visceral sequestration have also been reported.[8] The embryological process in variants of exstrophy may not affect the development of the lower urinary tract significantly, but the so-called wedge effect may prevent fusion of superficial paired genital swellings as happened in our case too.[7] The process seems to affect only the superficial perineal structures leading to genital anomalies. The vaginal duplication in our case involved the introitus and the lower part of the vagina only, sparing the developmentally different upper vagina and the uterus.

Covered exstrophy differs from pseudoexstrophy variant in that, there is an associated isolated ectopic bowel segment present on the inferior abdominal wall near the genital area. This segment is usually a segment of the colon and has no communication with the underlying gastrointestinal tract.[1910] However in the present case, the segment was communicating with the rectum and this has not been described earlier in the literature. It has been suggested that this condition is a result of the secondary closure of the cloacal membrane which isolates ectopic embryological colonic cells.[6]

Other associated gastrointestinal anomalies in covered exstrophy include anorectal malformation (40%).[2] Ten cases (six male and four female) of covered exstrophy with visceral sequestration have been reported in the world literature.[811] None of the cases showed the presence of anorectal malformation.

As the continence in these patients is generally good, the treatment is required only for associated gastrointestinal or genital anomalies. Genital reconstruction in such patients is, however, easier than in classical exstrophy.