Children's Hospital Colorado

Anorectal Malformation Rectobladder Neck Fistula

Research background

Traditional classifications of anorectal malformations in children are categorized as low, intermediate or high. This classification fails to distinguish among different types of anorectal malformations, which may be included in the same category even though they may require different surgical approaches and have different prognoses.

Rectobladder neck fistula is the highest and most complex anorectal malformation in boys. It carries a poor prognosis for bowel control and is the only anorectal malformation that requires open or laparoscopic abdominal repair. Its features should identify it as a separate entity due to anatomic variants in the genitourinary tract.

The lead author of this study, Alberto Peña, MD, of the International Center for Colorectal and Urogenital Care at Children’s Hospital Colorado proposed a more practical classification in a 1995 study titled “Anorectal Malformations” published in Seminars in Pediatric Surgery, which was based on anatomic features of the malformations. 

This research study aimed to describe the distinct characteristics of anorectal malformations with rectobladder neck fistula that warrant special attention and to describe associated anatomic variants in the genitourinary tract.

1980 To 2011 Study Period
111 Patients in Study
89% With Associated Genito-Urologic Anomalies

Research methods

All patients treated for rectobladder neck fistula in a database of a tertiary medical center from 1980 to 2011 were included in a review of associated anorectal malformations, type and characteristics of colostomy at birth, sacral ratio, type of main repair surgery and outcome.

There were 111 patients in the study cohort, accounting for 10 percent of 1,069 pediatric male patients operated on for anorectal malformation during the study period.

Research results 

Associated urologic malformations

There were 99 patients (89 percent) with an anatomic or functional urologic malformation. The most common anatomic malformation was a single kidney, found in 37 patients, and the most common functional disorder was vesicoureteral reflux (VUR) in 40 patients. Forty-two patients with urologic malformations also had non-urologic anomalies. 

Without treatment, these abnormalities can lead to significant upper urinary tract complications and lifelong morbidity. 

Ectopic verumontanum (VM)

There were 16 patients with a VM located in a higher than normal anatomic position. This group accounted for 40 percent of children who underwent cystoscopy, which was an unexpected finding.

A potential consequence is infertility, and assisted reproduction techniques should be discussed with patients.

Associated non-urologic malformations 

There were 47 patients with non-urologic anomalies; 23 patients of whom had more than one of the associated anomalies. Twenty-nine had cardiac anomalies and 25 had gastrointestinal malformations. 

Sacrovertebral anomalies

The most common sacrovertebral anomaly was hemivertebra, occurring in 25 patients. The average sacral ratio (SR) was .59 (calculated from available data on 95 patients). 

Colostomy opening

All but one patient underwent colostomy at birth at other institutions. The stoma was located too distally in 20 patients, limiting the bowel for a pull through. Four underwent revision before main repair and 13 needed special treatment maneuvers during the main repair.  

Placement of a proper stoma during the newborn period is essential to prevent unnecessary complications. 

Surgical approach

The main repair in the 98 patients operated on at the study authors’ institution was posterior sagittal anorectoplasty (PSARP) with laparotomy (80 patients), laparoscopic assisted PSARP (8 patients) and PSARP alone (10 patients). 

For surgical repair, the abdominal approach is recommended with a posterior sagittal incision and the laparoscopic approach is particularly indicated.

Research functional results

Relationship between sacral ratio (SR) and outcome (SR was divided into three groups)

Infographic showing fecal control data for 69 patients (9 had fecal control, 8 had partial fecal control, 52 had no fecal control and required bowel management with enemas) and urinary control data for 61 patients (40 had full urinary control, 3 had partial control, 18 had no urinary control and required clean intermittent catheterization).

Infographic showing recto bladderneck data for the 69 pediatric patients that had fecal control data. 12 had a sacral ratio value of 0-0.4; 26 had a sacral ratio value of 0.41-0.69 and 21 had a sacral ratio value of 0.7 or higher.
Infographic showing recto bladderneck data for the 61 pediatric patients that had urinary control data. 13 had a sacral ratio value of 0-0.4; 22 had a sacral ratio value of 0.41-0.69 and 19 had a sacral ratio value of 0.7 or higher.

Research discussion and conclusion

Among the many findings, here are several key takeaways:

  • All pediatric patients with anorectal malformations should undergo an early kidney ultrasound to evaluate the renal status and identify obstruction.
  • A bifid scrotum is a common urologic malformation associated with rectobladder neck fistula and may serve as a sign for diagnosis.
    • The higher the malformation, the more likely a bifid scrotum will develop.
  • Rectobladder neck fistula is associated with poor functional prognosis.
    • The prognosis worsens for pediatric patients who require procedures after failed repairs.
  • Close urological follow-up is required.
  • Correct colostomy construction should be addressed.

The full paper was published in the June 2016 issue of the Journal of Pediatric Surgery.

Dr. Peña close-up in scrubs with a surgical mask on preparing for surgery.