Muscle thickness in hypertrophic pyloric stenosis: sonographic determination.

Abdominal sonography was performed in 169 infants with vomiting. The hypertrophied circular muscle of the pylorus and distal antrum could be seen as a thick, hypoechoic cylinder in all cases of hypertrophic pyloric stenosis. The thickness of each wall of this cylinder was 4 mm or more in 86 of 93 patients subsequently shown to have hypertrophic pyloric stenosis at surgery. None of the patients without stenosis displayed this finding on sonography. Although technically demanding, sonographic imaging with a high-frequency system (7 MHz or more) can be an accurate initial examination for hypertrophic phyloric stenosis.