Objectives : To determine the accuracy of two main radiologic tools currently employed in the clinical management of anorectal malformations, the invertogram and the distal colostogram. The data will be useful as a basis for quality assurance as well as for future comparisons in case there are innovations to be considered.
Material and Method : Radiological materials and clinical records of infants with anorectal malformations operated on in Songklanagarind Hospital from 1995 to 2001 were retrieved. Each record was blindly reviewed by two radiologists and one pediatric surgeon. Using operative findings as the gold standard, the accuracy of an invertogram in diagnosing low anomalies and the accuracy of a distal colostogram in
screening cases that needed a laparotomy and in detecting internal fistulas were determined. The quality of the films was also categorized and poor quality studies were excluded from the analysis. Cases of common cloaca were not included in the level reading analysis.
Results : Radiologic materials from 59 patients were examined, including 26 invertograms and 49 distal colostograms. Among 52 cases whose neonatal history could be traced, 29 (55.8%) cases exhibited clinical evidence of anomalies level. Two invertograms and 5 colostograms were graded as poor quality and excluded from the analysis. The overall sensitivity of invertograms in detecting low anomalies was 33.3%, whereas,
specificity was 66.7%. Analyzing only infants with a blind rectal pouch, the sensitivity and specificity to detect low anomalies were 33.3% and 75.0%, respectively. The sensitivity of distal colostograms in detecting a fistula was 60.0% in males and 62.5% in females. Distal colostograms diagnosed ‘high-type anomalies’ in 7 cases and correctly detected 2 cases of vesical fistula which needed APSARP. No prostetic-urethral fistulas showed a radiological high level.
Conclusion : The study found poor diagnostic sensitivity of invertograms in detecting low type anomalies which deserved primary anoplasty. However, the data support the role of a distal colostogram in diagnosing high anomalies, despite its low sensitivity in detecting urethral fistulas.

Keywords : Anorectal malformations, Invertogram, Colostogram