A 3-week-old male born to a 23-year-old Caucasian primigravida develops projectile non-bilious vomiting after every meal. Abdominal inspection reveals prominent peristalsis in the epigastrium and an olive-sized mass is felt on deep palpation of the right upper abdomen. The mass most likely represents:

Question

A 3-week-old male born to a 23-year-old Caucasian primigravida develops projectile non-bilious vomiting after every meal.  Abdominal inspection reveals prominent peristalsis in the epigastrium and an olive-sized mass is felt on deep palpation of the right upper abdomen.  The mass most likely represents:

Quizplus · Accepted Answer

Congenital pyloric stenosis is a relatively common disorder that is encountered primarily in male infants (at a 3:1 ratio) and characterized by a multifactorial pattern of inheritance. Infants typically present with recurrent projectile nonbilious vomiting, and physical examination demonstrates visible peristalsis and the presence of an olive-sized mass in the distal stomach or pyloric region. The mass is thought to develop secondary to hypertrophy of the pyloric muscularis mucosae. The narrowing of the pyloric channel is thought to be exacerbated by localized edema and inflammation. The stenosis is relieved by surgical splitting of the muscle. (Choices A, D, and E) Infection, pancreatic juice accumulation, and biliary duct distension are not associated with pyloric stenosis. (Choice B) Acquired pyloric stenosis occurs in adults and is associated with gastritis, peptic ulcers in the pylorus, or a neoplastic process (eg, carcinoma of the pyloric region or lymphoma). Neoplasm in this area would not be expected in an infant, however. Educational Objective: Congenital pyloric stenosis arises secondary to hypertrophy of the pyloric muscularis mucosae.

A 3-Week-Old Male Born to a 23-Year-Old Caucasian Primigravida Develops