Findings: Pyloric channel measures 19mm in length while pyloric thickness is 3.8mm.

Diagnosis: Pyloric Stenosis.

Discussion: Hypertrophic pyloric stenosis is generally considered an acquired condition that develops in infants between 2 and 8 weeks after birth. The precise etiology is unknown, but evidence supports prolonged spasm which leads eventually to muscular hypertrophy. Symptoms typically include vomiting (at times projectile), feeding difficulty and weight loss. Vomitus is characteristically non-bilious. The diagnosis can often be made on clinical grounds in a patient with projectile vomiting and a hypertrophied muscle mass (olive) on physical exam. If there is any doubt as to the diagnosis, an imaging study should be obtained, of which an ultrasound is the current study of choice. The classic appearance of HPS on ultrasound is that of 1) elongation of the pyloric channel 2) little fluid entering the duodenum 3) persistent thickening of the pyloric muscle. Muscle thickness greater than 3 to 4 mm is generally considered diagnostic, especially if associated with a canal length greater than 18mm. If the pyloric canal length is less than 18mm, then the diagnosis of HPS should be in doubt. In the usual case of pyloric stenosis, pyloromyotomy is the preferred mode of therapy, and in most cases is successful.

References:
Swischuk LE. Imaging of the Newborn Infant and Young Child.
3rd edition. Williams and Wilkins Inc., Baltimore, MD, 1989:396-404.

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