Pediatrics, Pyloric Stenosis Workup
- Author: Jagvir Singh, MD; Chief Editor: Richard G Bachur, MD more...
Laboratory Studies
- Electrolytes, pH, BUN, and creatinine levels should be obtained at the same time as intravenous access in patients with pyloric stenosis.
- Hypochloremic, hypokalemic metabolic alkalosis is the classic electrolyte and acid-base imbalance of pyloric stenosis. Persistent emesis causes progressive loss of fluids rich in hydrochloric acid, which causes the kidneys to retain hydrogen ions in favor of potassium. Electrolyte abnormalities depend on the duration of symptoms in the affected infant.
- The dehydration may result in hypernatremia or hyponatremia and may result in prerenal renal failure.
- Elevated unconjugated bilirubin levels may be present.
Imaging Studies
- If the clinical presentation is typical and an olive is felt, the diagnosis is confirmed and further imaging is not warranted.
- Ultrasonography is the imaging modality of choice when evaluating a child for infantile hypertrophic pyloric stenosis (IHPS).[5] It is both highly sensitive (90-99%) and specific (97-100%) in the hands of a qualified sonographer. The pylorus is viewed in longitudinal and transverse planes. The sonographic hallmark of infantile hypertrophic pyloric stenosis is the thickened pyloric muscle.
- Criteria for making the diagnosis include pyloric muscle thickness greater than 4 mm. The length of the pyloric canal is variable and may range from 14 mm to 20 mm. The pyloric diameter may range from 10-14 mm.
- Infantile hypertrophic pyloric stenosis may be falsely diagnosed in infants who have pylorospasm. Ultrasonography also allows for observation of peristaltic activity, differentiating between pylorospasm and true infantile hypertrophic pyloric stenosis.
- Upper GI imaging (UGI) can help to confirm the diagnosis of infantile hypertrophic pyloric stenosis but is not routinely performed unless ultrasonography is nondiagnostic.
- The "shoulder" sign is a collection of barium in the dilated prepyloric antrum and may be seen in the infant with infantile hypertrophic pyloric stenosis. The "double track" sign (ie, 2 thin tracks of barium compressed between thickened pyloric mucosa), once thought to be pathognomonic of infantile hypertrophic pyloric stenosis, has recently been identified in multiple cases of sonographically confirmed pylorospasm and is shown in the image below.
Lateral view from an upper GI study demonstrates the double-track sign.
Procedures
- Upper GI endoscopy has been used as an adjunct diagnostic tool in select cases of infantile hypertrophic pyloric stenosis when other imaging tests are inconclusive or when the infant presents with atypical clinical features.
Panteli C. New insights into the pathogenesis of infantile pyloric stenosis. Pediatr Surg Int. Sep 16 2009;[Medline].
Rogers IM. The true cause of pyloric stenosis is hyperacidity. Acta Paediatr. Feb 2006;95(2):132-6. [Medline].
Krogh C, Fischer TK, Skotte L, Biggar RJ, Oyen N, Skytthe A. Familial aggregation and heritability of pyloric stenosis. JAMA. Jun 16 2010;303(23):2393-9. [Medline].
[Guideline] Cincinnati Children's Hospital Medical Center. Evidence based clinical practice guideline for hypertrophic pyloric stenosis. Cincinnati (OH): Cincinnati Children's Hospital Medical Center; 2007 Nov 14. [Full Text].
Maheshwari P, Abograra A, Shamam O. Sonographic evaluation of gastrointestinal obstruction in infants: a pictorial essay. J Pediatr Surg. Oct 2009;44(10):2037-42. [Medline].
Aldridge RD, MacKinlay GA, Aldridge RB. Choice of incision: the experience and evolution of surgical management of infantile hypertrophic pyloric stenosis. J Laparoendosc Adv Surg Tech A. Feb 2007;17(1):131-6. [Medline].
Leclair MD, Plattner V, Mirallie E, Lejus C, Nguyen JM, Podevin G. Laparoscopic pyloromyotomy for hypertrophic pyloric stenosis: a prospective, randomized controlled trial. J Pediatr Surg. Apr 2007;42(4):692-8. [Medline].
van den Ende ED, Allema JH, Hazebroek FW, Breslau PJ. Can pyloromyotomy for infantile hypertrophic pyloric stenosis be performed in any hospital? Results from two teaching hospitals. Eur J Pediatr. Jun 2007;166(6):553-7. [Medline].
Taqi E, Boutros J, Emil S, Dube S, Puligandla P, Flageole H. Evaluation of surgical approaches to pyloromyotomy: a single-center experience. J Pediatr Surg. May 2007;42(5):865-8. [Medline].
Adibe OO, Nichol PF, Lim FY, Mattei P. Ad libitum feeds after laparoscopic pyloromyotomy: a retrospective comparison with a standardized feeding regimen in 227 infants. J Laparoendosc Adv Surg Tech A. Apr 2007;17(2):235-7. [Medline].
Cohen HL, Blumer SL, Zucconi WB. The sonographic double-track sign: not pathognomonic for hypertrophic pyloric stenosis; can be seen in pylorospasm. J Ultrasound Med. May 2004;23(5):641-6. [Medline].
Garcia VF, Randolph JG. Pyloric stenosis: diagnosis and management. Pediatr Rev. Apr 1990;11(10):292-6. [Medline].
Godbole P, Sprigg A, Dickson JA. Ultrasound compared with clinical examination in infantile hypertrophic pyloric stenosis. Arch Dis Child. Oct 1996;75(4):335-7. [Medline].
Hernanz-Schulman M. Infantile hypertrophic pyloric stenosis. Radiology. May 2003;227(2):319-31. [Medline].
Hernanz-Schulman M, Sells LL, Ambrosino MM. Hypertrophic pyloric stenosis in the infant without a palpable olive: accuracy of sonographic diagnosis. Radiology. Dec 1994;193(3):771-6. [Medline].
Huang YC, Su BH. Medical treatment with atropine sulfate for hypertrophic pyloric stenosis. Acta Paediatr Taiwan. May-Jun 2004;45(3):136-40. [Medline].
Irish MS, Pearl RH, Caty MG, Glick PL. The approach to common abdominal diagnosis in infants and children. Pediatr Clin North Am. Aug 1998;45(4):729-72. [Medline].
Kim SS, Lau ST, Lee SL. Pyloromyotomy: a comparison of laparoscopic, circumumbilical, and right upper quadrant operative techniques. J Am Coll Surg. Jul 2005;201(1):66-70. [Medline].
Liacouras CA, Cook-Sather SD, Schreiner MS, Bellah RD. Endoscopic findings in hypertrophic pyloric stenosis: appearance in classic and evolving disease. Gastrointest Endosc. May 1997;45(5):371-4. [Medline].
Nagita A, Yamaguchi J, Amemoto K, et al. Management and ultrasonographic appearance of infantile hypertrophic pyloric stenosis with intravenous atropine sulfate. J Pediatr Gastroenterol Nutr. Aug 1996;23(2):172-7. [Medline].
Schechter R, Torfs CP, Bateson TF. The epidemiology of infantile hypertrophic pyloric stenosis. Paediatr Perinat Epidemiol. Oct 1997;11(4):407-27. [Medline].
Sorensen HT, Skriver MV, Pedersen L. Risk of infantile hypertrophic pyloric stenosis after maternal postnatal use of macrolides. Scand J Infect Dis. 2003;35(2):104-6. [Medline].
Spinelli C, Bertocchini A, Massimetti M. Muscle thickness in infants hypertrophic pyloric stenosis. Pediatr Med Chir. Mar-Apr 2003;25(2):148-50. [Medline].
Sretenovic A, Smoljanic Z, Korac G. [Conservative treatment of hypertrophic pyloric stenosis in children]. Srp Arh Celok Lek. Oct 2004;132 Suppl 1:93-6. [Medline].
Takahashi T. Pathophysiological significance of neuronal nitric oxide synthase in the gastrointestinal tract. J Gastroenterol. 2003;38(5):421-30. [Medline].
van der Bilt JD, Kramer WL, van der Zee DC. Early feeding after laparoscopic pyloromyotomy: the pros and cons. Surg Endosc. May 2004;18(5):746-8. [Medline].
Vasavada P. Ultrasound evaluation of acute abdominal emergencies in infants and children. Radiol Clin North Am. Mar 2004;42(2):445-56. [Medline].

