Purpose: Pyloric muscle thickness (PMT) equal to or greater than 4mm and canal length equal to or greater than 16mm are widely accepted for diagnosis of idiopathic hypertrophic pyloric stenosis (IHPS). However, up to 25% of IHPS patients show discordant ultrasonic parameters compared to current diagnostic criteria. We analyzed the ultrasonic parameters of pylorus of IHPS patients to discover their correlation to patient characteristics and aimed to find a new diagnostic value.
Method: Medical records of 131 IHPS patients who received pyloromyotomy from 1994 to 2016 were reviewed. All patients presented with characteristic clinical symptoms. The patients were divided into two groups according to their eligibility for current criteria as Discordance group (n=32) and Concordance group (n=99). Baseline characteristics were reviewed and ultrasonic parameters were measured, and then the volume of the pylorus was estimated by calculation using the parameters.
Results: The proportion of neonates were higher in Discordance group (43.8% vs.13.1%, p<0.001). Mean postconceptional age of Concordance group was 19.4 days older than that of Discordance group at the time of US examination (p<0.001). Average weight of Concordance group was 4.29 0.74kg while that of Discordance group were 3.76 0.91kg. Also, the median chronological age at the time of US was 28.0 [21, 35] days in Discordance group and 44.0 [29.5, 54.5] days in Concordance group (p<0.001). In Discordance group, proportion of PMT over PD was 31.87 3.24%, while it was 35.06 3.61 % in Concordance group. Postconceptional age and being neonate were remained as significant variables after multivariate linear regression (R2=0.390).
Conclusion: Pyloric volume of IHPS patients were strongly related to their postconceptional age, and it suggested that the diagnostic criteria may differ according to the patient’s size and time of diagnosis. Future diagnostic criteria for IHPS should reflect the dynamic nature of the patients.
