Anorectal malformations (ARMs) are rare congenital anomalies that comprise a wide spectrum of severity and include cloacal malformations. These patients are commonly managed by pediatric surgeons since they require a diverting colostomy early in life and eventually additional procedures to reconstruct the anal anatomy. However, these patients often have associated urological abnormalities and the incidence of urological abnormalities correlates directly with the severity of ARM, with cloacal malformations being the most severe type of ARM in females.¹ Patients with more severe malformations such as cloaca will have a higher incidence of urological diagnoses including neurogenic bladder, vesicoureteral reflux, hydronephrosis, and renal agenesis among others. These findings and recent other studies have raised the awareness of the importance of a collaborative approach to these patients involving multiple specialties.²

As in many other congenital abnormalities, parents often want to know the long-term prognosis of their children. One of the very important parental concerns regarding patients with ARMs is the ability of the child to achieve both fecal and urinary continence. Information regarding the potential for fecal continence has been available and is based on the ARM index.³ This index is composed of 3 main factors: measure of sacral ratio, presence of a spinal abnormality, and type of malformation. The ARM index has been a valuable tool providing parents with information about the chance for normal fecal continence as well as helping physicians plan for appropriate interventions in patients with low chances of normal fecal incontinence.

To date, no such tool exists to help predict urinary continence in this population. While fecal and urinary continence are often interconnected, no study has evaluated if similar factors such as the ones included on the ARM index could also be used to predict urinary continence. Thus, the goal of our study was to evaluate if the ARM index could be used to predict urinary continence in this group of patients. We queried our large prospectively collected database of children with ARM and included patients older than 4 years of age with adequate information on urinary continence status. This yielded a total of 434 patients that comprise the cohort for the study.

Figure. Continence rates for each subcategory factor.

Patients were classified according to ARM subtype using simple, moderate, and complex severity as described by the Midwest Pediatric Surgery Consortium. Patients were also divided into 3 groups based on the lateral sacral ratio (>7, between 4 and 7, and <4). Finally, the cohort was also categorized based on spinal cord findings in 3 groups (normal, tethered cord, and myelomeningocele). Urinary continence was defined as voiding per urethra volitionally, dry between voids, and ≤1 urinary accident per week. Patients performing clean intermittent catheterization and dry were not considered to be continent as they do not void per urethra.

The study found that each variable independently predicted urinary continence on univariate and multivariable analysis. Patients categorized in the low risk groups (ARM simple, sacral ratio >0.7, and normal spine) had the highest chance of achieving urinary continence. On the other hand, patients in the high risk groups (complex ARM, sacral ratio <0.4, and myelomeningocele) had a lower chance of achieving normal urinary continence. Urinary continence according to each group is shown in the figure.⁴ Given that all cloacal malformation patients are included in the complex ARM category, one can realize that this population does have a lower chance of achieving continence. Yet, considering the other variables, even a cloacal malformation patient can have a good chance for continence if they have a sacral ratio >0.7 and a normal spine.

This recent study showed that ARM type, lateral sacral ratio, and spinal cord status correlate with urinary continence in the ARM patient population including cloacal malformation. These anatomical factors associated with ARM are identifiable at birth and can now be used to help predict a child’s potential to achieve urinary continence. Understanding the relationship between these anatomical findings in this population allows for appropriate patient and family counseling and helps establish appropriate expectations for achieving urinary continence.