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Pediatric Hypertrophic Pyloric Stenosis Clinical Presentation

  • Author: Hisham Nazer, MB, BCh, FRCP, , DTM&H; Chief Editor: Carmen Cuffari, MD  more...
Updated: Aug 14, 2015


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  • Typical presentation of an infant with hypertrophic pyloric stenosis (HPS) is onset of initially nonbloody, always nonbilious vomiting at 4-8 weeks. Although vomiting may initially be infrequent, over several days it becomes more predictable, occurring at nearly every feeding. Vomiting intensity also increases until pathognomonic projectile vomiting ensues. Slight hematemesis of either bright red flecks or a coffee-ground appearance is sometimes observed.
  • Patients are usually not ill-looking or febrile. The baby in the early stage of the disease remains hungry and sucks vigorously after episodes of vomiting.
  • Prolonged delay in diagnosis can lead to dehydration, poor weight gain, malnutrition, metabolic alterations, and lethargy.
  • Parents often report trying several different baby formulas because they (or their physicians) assume vomiting is due to intolerance.


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  • Careful physical examination provides a definitive diagnosis for most infants with hypertrophic pyloric stenosis. However, some of the classic signs that would lead to diagnosis may be absent due, in part, to the early diagnosis of hypertrophic pyloric stenosis.
  • An enlarged pylorus, classically described as an "olive," can be palpated in the right upper quadrant or epigastrium of the abdomen in 60-80% of infants. [5] In order to assess the pylorus, the patient must be calm and cooperative. A pacifier or small amount of dextrose water may help. If the stomach is distended, aspiration using a nasogastric tube is necessary. With the infant supine and the examiner on the child's left side, gently palpate the liver edge near the xiphoid process. Then displace the liver superiorly; downward palpation should reveal the pyloric olive just on or to the right of the midline. To be assured of the diagnosis, the physician should be able to roll the pylorus beneath the examining finger. The tumor (mass) is best felt after vomiting or during, or at the end of, feeding. The diagnosis is easily made if the presenting clinical features are typical, with projectile vomiting, visible peristalsis, and a palpable pyloric tumor.
  • When diagnosis is delayed, the infant may develop severe constipation associated with signs of dehydration, malnutrition, lethargy, and shock.


Despite numerous hypotheses, the exact etiology of HPS is not fully understood. Genetic, extrinsic and hormonal factors have been implicated. In addition, abnormalities of various components of the pyloric muscle, such as smooth muscle cells, growth factors, extracellular matrix elements, nerve and ganglion cells, neurotransmitters, and interstitial cells of Cajal, have been reported. Genetic studies have identified susceptibility loci, and molecular studies have concluded that smooth muscle cells are not properly innervated in this condition.[12]

Bottle-feeding was associated with an increased risk for HPS in a population-based case-control study of 714 infants.[13, 14] After adjustment for sex, race, maternal smoking status, and other factors, bottle-feeding was associated with an increased risk for HPS (odds ratio [OR], 2.31; 95% confidence interval, 1.81-2.95) compared with breast feeding. This effect was most pronounced in the children of older and multiparous mothers.[13, 14]

Infant and maternal use of macrolides also appears to increase the risk of infantile HPS.In an analysis of 999,378 live-born Danish singletons from a nationwide, register-based cohort (1996-2011), Lund et al found that infantile HPS appeared to be associated with the use of macrolide antibiotics in young infants, pregnant women in late pregnancy, and early postpartum (≤2 wk) women.[15, 16] Because macrolide antibiotic treatment of young infants was strongly associated with infantile HPS, the investigators cautioned to only administer these agents if the potential treatment benefits outweigh the risk.[15, 16]

Contributor Information and Disclosures

Hisham Nazer, MB, BCh, FRCP, , DTM&H Professor of Pediatrics, Consultant in Pediatric Gastroenterology, Hepatology and Clinical Nutrition, University of Jordan Faculty of Medicine, Jordan

Hisham Nazer, MB, BCh, FRCP, , DTM&H is a member of the following medical societies: American Association for Physician Leadership, Royal College of Paediatrics and Child Health, Royal College of Surgeons in Ireland, Royal Society of Tropical Medicine and Hygiene, Royal College of Physicians and Surgeons of the United Kingdom

Disclosure: Nothing to disclose.


Dena Nazer, MD, FAAP Assistant Professor of Pediatrics, Wayne State University School of Medicine; Chief, Child Protection Team, Children's Hospital of Michigan

Dena Nazer, MD, FAAP is a member of the following medical societies: Academic Pediatric Association, American Academy of Pediatrics, American Professional Society on the Abuse of Children, Ray E Helfer Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

B UK Li, MD Professor of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Medical College of Wisconsin; Attending Gastroenterologist, Director, Cyclic Vomiting Program, Children’s Hospital of Wisconsin

B UK Li, MD is a member of the following medical societies: Alpha Omega Alpha, American Gastroenterological Association, North American Society for Pediatric Gastroenterology, Hepatology and Nutrition

Disclosure: Nothing to disclose.

Chief Editor

Carmen Cuffari, MD Associate Professor, Department of Pediatrics, Division of Gastroenterology/Nutrition, Johns Hopkins University School of Medicine

Carmen Cuffari, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, Royal College of Physicians and Surgeons of Canada

Disclosure: Received honoraria from Prometheus Laboratories for speaking and teaching; Received honoraria from Abbott Nutritionals for speaking and teaching.

Additional Contributors

Jeffrey J Du Bois, MD Chief of Children's Surgical Services, Division of Pediatric Surgery, Kaiser Permanente, Women and Children's Center, Roseville Medical Center

Jeffrey J Du Bois, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Surgeons, American Pediatric Surgical Association, California Medical Association

Disclosure: Nothing to disclose.


Daniel A Beals, MD Attending Staff, Cornerstone Pediatric Surgery

Daniel A Beals, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Physicians, American Pediatric Surgical Association, American Society for Bioethics and Humanities, Kentucky Medical Association, Society for Fetal Urology, Society of Critical Care Medicine, and Southeastern Surgical Congress

Disclosure: Nothing to disclose.

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