TY - CHAP M1 - Book, Section TI - Hypertrophic Pyloric Stenosis A1 - Shah, Ashish A1 - Sobolewski, Brad A1 - Mittiga, Matthew R. A2 - Knoop, Kevin J. A2 - Stack, Lawrence B. A2 - Storrow, Alan B. A2 - Thurman, R. Jason Y1 - 2021 N1 - T2 - The Atlas of Emergency Medicine, 5e AB - Hypertrophic pyloric stenosis (HPS) is characterized by progressive postprandial, nonbilious vomiting that steadily increases in frequency and amount due to hypertrophy of the pyloric musculature and edema of the pyloric canal, producing gastric outlet obstruction. It is usually diagnosed in infants from birth to 5 months, most commonly at 2 to 8 weeks of life. The vomiting may become forceful and is then described as projectile (although this pattern is not always present). There is a familial tendency, and white males (especially firstborn) are more frequently affected. During the physical examination, peristaltic waves may be observed traveling from the left upper to right upper quadrants. The hypertrophy of the antral and pyloric musculature produces the “olive” to palpation (best palpated in the epigastrium or right upper quadrant after emesis, following feeding, or after emptying the stomach with a nasogastric tube). As a result of persistent vomiting, hypochloremic, hypokalemic metabolic alkalosis with varying degrees of dehydration and failure to thrive may occur when the diagnosis is not made early in the course. SN - PB - McGraw-Hill CY - New York, NY Y2 - 2024/03/29 UR - accessemergencymedicine.mhmedical.com/content.aspx?aid=1181044300 ER -