Sonographic Layers in Infantile Hypertrophic Pyloric Stenosis seen on High Resolution Sonography

Sonography is a conclusive method in the diagnosis of infantile hypertrophic pyloric stenosis(IHPS). However, previous reports incompletely described the sonographic layers. This study was performed to define the layers seen on high resolution sonography. We performed high resolution sonography with 10-5 MHz linear transducer in 8 patients with IHPS. The layers seen on sonography were correlated with histopathologic findings by obtaining thin section of thickened gastric wall during surgery. All cases showed typical sonographic findings that were previously described. The thickened pyloric wall consisted of 5 sonographic layers : extremely echogenic mucosal interface, hypoechoic mucosa, hyperechoic submucosa, mixed echogenic circular muscle layer, and hypoechoic longitudinal muscle layer. On longitudinal scan of pylorus,circular muscle fiber directions were identified as alternating bands of hyper-and hypoechogenicity with the appearance of zebra skin. Clear delineation of the layers of gastric wall and the muscle fiber directions of hypertrophied circular muscle in IHPS showed by high resolution sonography. Our results are contradictory to the previous reports that defined the sonolucent double tracks as collapsed lumen and the echogenic lines as mucosa. We believe that the multiple hypoechogenic bands seen in longitudinal scan represent the folded mucosal layers and that the echogenic lines are from the mucosal interface