Postoperative Changes of Ultrasonographic Pyloric Mass in Infantile Hypertrophic Pyloric Stenosis

Kim, Bo Gyoon; Kim, Jong Jun; Park, Ung Chae; Choi, Young Chil

Abstract

BACKGROUND: Infantile hypertrophic pyloric stenosis (IHPS) is a well-recognized cause of vomiting in infancy and is easily cured by a Ramstedt pyloromyotomy. However there have been no reports on the postoperative appearance of a pyloric mass in Korea.
METHODS
Twenty infants with IHPS and 20 control infants were studied ultrasonographically during the first year of life at a regular interval. According to examination intervals, the IHPS infants (n=20) were divided into three groups: Group A (3 months, n=6), B (6 months, n=7), and C (12 months, n=7). At each examination, measurements were obtained concerning the length of the pyloric canal and the muscular thickness.
RESULTS
The mean preoperative length of the pylorus of the IHPS group was 19.4+/-3.64 mm, ranging from 17 to 30 mm (control: 7.73+/-2.67 mm) (p<0.0001). The mean pyloric muscle thickness of the IHPS group was 5.08+/-0.67 mm, ranging from 3.5 to 6 mm (control: 2.37+/-0.58 mm) (p<0.0001). The preoperative and postoperative measurements were subsequently compared. Postoperatively, the length of the pylorus averaged 22.0+/-2.66 mm, and the muscular thickness was 6.53+/-1.68 mm (p<0.0001). The reduction rates in pyloric length were 23.5%, 46.3%, and 53.4% for the respective groups. Also, the muscle-thickness reduction rates were 31.8%, 48.9%, and 57.8% respectively. At 6 months after the operation, the pyloric muscular thickness was in the normal control range, and the pyloric length was reduced to the normal range after 12 months.
CONCLUSIONS
This prospective study suggests that the pyloric mass undergoes a rapid reduction in size in the first 6 months, followed by a more gradual reduction to a normal value by 12 months after a pyloromyotomy.