Inter-rater Reliability of Sacral Ratio Measurements in Patients with Anorectal Malformations

State of the Art Bowel Management for Pediatric Colorectal Problems: Anorectal Malformations

Up to 79% of patients with anorectal malformations (ARMs) experience constipation and/or soiling after a primary posterior sagittal anoplasty (PSARP) and are referred to a bowel management program. We aim to report the recent updates in evaluating and managing these patients as part of the manuscript series on the current bowel management protocols for patients with colorectal diseases (ARMs, Hirschsprung disease, functional constipation, and spinal anomalies). The unique anatomic features of ARM patients, such as maldeveloped sphincter complex, impaired anal sensation, and associated spine and sacrum anomalies, indicate their bowel management plan. The evaluation includes an examination under anesthesia and a contrast study to exclude anatomic causes of poor bowel function. The potential for bowel control is discussed with the families based on the ARM index calculated from the quality of the spine and sacrum. The bowel management options include laxatives, rectal enemas, transanal irrigations, and antegrade continence enemas. In ARM patients, stool softeners should be avoided as they can worsen soiling.

Bowel function and associated risk factors at preschool and early childhood age in children with anorectal malformation type rectovestibular fistula: An ARM-Net consortium study

BACKGROUND

Outcome of patients operated for anorectal malformation (ARM) type rectovestibular fistula (RVF) is generally considered to be good. However, large multi-center studies are scarce, mostly describing pooled outcome of different ARM-types, in adult patients. Therefore, counseling parents concerning the bowel function at early age is challenging. Aim of this study was to evaluate bowel function of RVF-patients at preschool/early childhood age and determine risk factors for poor functional outcome.

METHODS

A multi-center cohort study was performed. Patient characteristics, associated anomalies, sacral ratio, surgical procedures, post-reconstructive complications, one-year constipation, and Bowel Function Score (BFS) at 4-7 years of follow-up were registered. Groups with below normal (BFS < 17; subgroups 'poor' ≤ 11, and 'fair' 11 < BFS < 17) and good outcome (BFS ≥ 17) were formed. Univariable analyses were performed to detect risk factors for outcome.

RESULTS

The study included 111 RVF-patients. Median BFS was 16 (range 6-20). The 'below normal' group consisted of 61 patients (55.0%). Overall, we reported soiling, fecal accidents, and constipation in 64.9%, 35.1% and 70.3%, respectively. Bowel management was performed in 23.4% of patients. Risk factors for poor outcome were tethered cord and low sacral ratio, while sacral anomalies, low sacral ratio, prior enterostomy, post-reconstructive complications, and one-year constipation were for being on bowel management.

CONCLUSIONS

Although median BFS at 4-7 year follow-up is nearly normal, the majority of patients suffers from some degree of soiling and constipation, and almost 25% needs bowel management. Several factors were associated with poor bowel function outcome and bowel management.

LEVEL OF EVIDENCE

Level III.

Fetal Sacral Ratio: A Novel Method for Prenatal Sonographic Assessment of Sacral Abnormalities

OBJECTIVES

The sacral ratio (SR) was described as a postnatal X-ray-based method to detect sacral abnormalities and predict functional prognosis for fecal continence in children with anorectal malformations (ARMs). The present study aimed to describe a novel method of assessing sonographic fetal sacral ratio (f-SR) in a normal population of fetuses.

METHODS

Sixty three-dimensional (3D) ultrasound reconstruction images of the sacrum obtained from routine low-risk scans performed between 21 and 26 weeks of gestation served for measurement. The f-SR was calculated in a coronal view as the ratio between lines drawn at the upper and lower levels of the iliac bone and the 5th sacral vertebra. Bland-Altman plots assessed the inter- and intrareader variabilities of measurements.

RESULTS

The f-SR in the normal population of fetuses was 0.913 (±0.094). During the study period, three cases with ARM were examined and had a mean f-SR of 0.55. There was good repeatability of measurements and between readers' agreement.

CONCLUSIONS

The present study introduces a novel prenatal sonographic f-SR that can be reliably calculated on prenatal 3D ultrasound with good reliability and reproducibility. Future research will identify the clinical significance of f-SR abnormalities in ARM and their long-term impact on continence.

Correlation between the lateral and anteroposterior sacral ratios in anorectal malformations

BACKGROUND

The sacral ratio has been used as a tool for evaluating sacral development in patients with anorectal malformations. Sacral ratios can be calculated by obtaining sacral radiographs in the anteroposterior (AP) and lateral planes.

OBJECTIVE

The objective of the study was to determine the correlation and agreement in sacral ratio calculations.

MATERIALS AND METHODS

In this single institution retrospective cohort study, we reviewed medical charts of all pediatric anorectal malformation patients treated between March 2014 and September 2018 who had both AP and lateral images of their sacrum. All sacral ratios were measured by three radiologists. Pearson's correlation coefficients and corresponding 95% confidence intervals (CIs) were used to assess the correlation between the AP and lateral radiographs. A weighted Kappa statistic was used to measure the agreement between how the AP and lateral sacral ratios categorized observations into risk groups.

RESULTS

Our initial cohort consisted of 646 observations from patients with anorectal malformations who had radiographs obtained in both AP and lateral planes. We excluded all observations (n=76) where the radiographs were deemed to be inadequate or not appropriately centered to measure sacral ratio. For a given pair of measurements, the mean lateral sacral ratio was 0.07 units greater than the AP plane (95% CI 0.06-0.09, paired t-test P-value <0.0001). AP and lateral images had a moderate positive correlation (Pearson's r=0.76, 95% CI 0.73-0.79, P<0.0001) and moderate agreement in risk categorization (unweighted kappa = 0.60, P<0.0001). AP and lateral readings conducted by all three radiologists had excellent inter-rater reliability with intraclass correlations for AP and lateral sacral ratios of 0.88 and 0.84, respectively.

CONCLUSION

Even though the AP and lateral sacral ratios had moderate positive correlation, the mean sacral ratio determined by images in the lateral plane was 0.07 units greater than the AP plane. AP and lateral sacral ratios concluded different risk categories relatively often. Future studies are needed to determine whether AP or lateral sacral ratios correlate better with continence in patients with anorectal malformations.