Hypertrophic pyloric stenosis in infants: US evaluation of vascularity of the pyloric canal.
To determine if there is increased flow to the pylorus in infants with hypertrophic pyloric stenosis (HPS) and, if so, whether the flow is localized to the muscle layer, mucosal layer, or both. Seventy-five infants examined for clinical suspicion of HPS were prospectively recruited for the study. Color scale was standardized at 4.2-4.4 cm/sec. Color Doppler flow at ultrasonography (US) was graded as follows: Grade 1 meant no signal; grade 2, two to five flow signals; and grade 3, extensive or continuous flow. Flow to the muscle or mucosal layer was documented and confirmed with spectral analysis. Infants without HPS served as control patients. Descriptive analyses were conducted to assess the demographic data and US results. Significance was assessed with chi2 or t tests. P <.05 was considered to indicate a significant difference. HPS was present in 41 infants with a mean age of 5 weeks +/- 2.0 (SD). Their mean flow grade was 2.80 +/- 0.4 in muscle and 2.88 +/- 0.4 in mucosa. HPS was not present in 34 infants with a mean age of 5.9 weeks +/- 4.5. Their mean flow grade was 1.26 +/- 0.5 in muscle and 1.15 +/- 0.5 in mucosa (P <.001). There was no significant difference in flow grades when the dimensions of the pyloric muscle and mucosa were compared. There was no significant difference in age between the HPS and control patient groups. Increased flow accompanies and may conceivably represent an integral component of the changes that occur with infantile HPS.