The radiological assessment of anorectal anomalies

A recently adopted classification of anorectal malformations is given. The methods used in evaluating 34 of these cases are described. The plain inverted film gives much useful information, but prior clinical evaluation is essential for correct interpretation. The radiography employed to show the ischium is discussed. A bony landmark on the ischium, designated the ‘M’ point, was found to be accurate in nominating the high lesions. The ‘M’ point is where the muscle sling of the puborectalis portion of the levator ani muscle acts on the rectum and separates high (supralevator) from low (translevator) lesions. Formerly the pubococcygeal line had been used to divide high from low lesions. This line was found to be difficult to define and inaccurately high. In high lesions, definitive colostomies were performed, and distal colograms defined the sites of fistulas. In low lesions, wide perineal fistulas made air trapping in the rectum less common. Plain films were of less value in this group, but perineal fistulograms often gave useful information. A recently adopted classification of anorectal malformations is given. The methods used in evaluating 34 of these cases are described. The plain inverted film gives much useful information, but prior clinical evaluation is essential for correct interpretation. The radiography employed to show the ischium is discussed. A bony landmark on the ischium, designated the ‘M’ point, was found to be accurate in nominating the high lesions. The ‘M’ point is where the muscle sling of the puborectalis portion of the levator ani muscle acts on the rectum and separates high (supralevator) from low (translevator) lesions. Formerly the pubococcygeal line had been used to divide high from low lesions. This line was found to be difficult to define and inaccurately high. In high lesions, definitive colostomies were performed, and distal colograms defined the sites of fistulas. In low lesions, wide perineal fistulas made air trapping in the rectum less common. Plain films were of less value in this group, but perineal fistulograms often gave useful information.