Significant use of the Recto-sigmoid Index in Prediction of Hirschsprung Disease in the Newborn Period

Objective: There has been a debate regarding the accuracy of contrast enema (CE) in the diagnosis of Hirschsprung disease (HD) in the newborn period when a transitional zone (TZ) was not well demonstrated. The aim of this study is to determine the optimal cut-point that will improve the accuracy of the recto-sigmoid index (RSI) and other positive CE signs in predicting aganglionosis in the newborn period. Material and Method: A retrospective review of newborn patients who underwent CE for suspected HD during a 3-year period (2005 through 2008) was conducted. The RSI and other positive contrast enema signs were evaluated and compared with pathological reports. Data were analyzed by Chi-square. Results: Thirty-five neonates (20 M: 15 F, mean age: 19.5 days) underwent 37 preoperative CE. Aganglionosis was histologically confirmed in 20 patients (54%). The most common site of proximal extent of aganglionosis was recto-sigmoid colon (9 patients, 45%). The results of pathology and CE were concordant in 91% of the patients for transitional zone (TZ) and 68% for other CE findings. From the ROC curve, the most accurate diagnostic cut-point was RSI of the lateral view of <0.7 (sensitivity of 60% and specificity of 88.2%), whereas radiographic TZ had 50% sensitivity and 94% specificity. The combination of radiographic TZ and/or RSI increased the sensitivity up to 70% and specificity to 82.4%. The inter-rater reliability was 0.83 and 0.7 for 2 observers, while the intra-observer variation was 0.1. Conclusion: RSI can improve the accuracy of CE for the diagnosis of HD in the newborn period. Further studies with larger sample size are required to better confirm these findings.