The Validity of Ultrasound in Diagnosing Hypertrophic Pyloric Stenosis

Objectives: To evaluate the validity of ultrasound for diagnosis and exclusion of pyloric stenosis in the infants with nonbilious vomiting. Methodology: In a cross-sectional study, 444 consecutive infants with clinical suspicion of pyloric stenosis were evaluated by ultrasound (US) and categorized as pyloric stenosis or not according measuring parameters as muscle thickness, muscle width and canal length of pylorus. Positive findings were confirmed at surgery; Negative findings were confirmed by means of follow up. Sensitivity, specificity and accuracy were calculated. Results: Sensitivity, specificity and accuracy of ultrasound were 100% if pyloric muscle thickness of >3mm was chosen as diagnostic. When muscle thickness more than 4mm was used, sensitivity, specificity and accuracy were 96%, 100% and 99.32% respectively. Conclusions: Ultrasound is highly sensitive and specific if pyloric muscle thickness 3 mm is used as cut off point. By virtue of direct visualization of the pyloric muscle, ultrasound is method of choice for both the diagnosis and exclusion of pyloric stenosis in infants.