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Look Up > Conditions > Pyloric Stenosis
Pyloric Stenosis
Overview
Definition
Etiology
Risk Factors
Signs and Symptoms
Differential Diagnosis
Diagnosis
Physical Examination
Laboratory Tests
Imaging
Other Diagnostic Procedures
Treatment Options
Treatment Strategy
Drug Therapies
Surgical Procedures
Complementary and Alternative Therapies
Other Considerations
Prevention
Complications/Sequelae
Prognosis
References

Overview
Definition

Pyloric stenosis is characterized by hypertrophy and hyperplasia of the muscular layers in the pylorus. It is the most common cause of gastrointestinal obstruction in infants and is also called infantile hypertrophic pyloric stenosis (IHPS). It appears in approximately 2 per 1,000 live births, presenting in the first few months of life with persistent and often projectile vomiting. If not treated quickly, dehydration and electrolyte imbalance will ensue. The condition was first described in detail by the Danish pediatrician Hirschsprung in 1887. In recent years, prompt use of ultrasonography to establish a diagnosis followed by surgical intervention has reduced the incidence of alkalosis and resulted in a shorter clinical course.


Etiology

The proximate cause of IHPS is hypertrophy and hyperplasia of both the circular and longitudinal muscle layers of the pylorus. The pyloric canal lengthens and its walls thicken, leading to a narrowing of the gastric antrum.

The etiology is unknown; however, the condition appears to be multifactorial in origin. Investigators have hypothesized the following causes:

  • Primary muscle disorder leading to postnatal hypertrophy
  • Allergy-induced edema leading to narrowing of the pyloric opening and causing hypertrophy of stomach muscles due to the work against the narrow foramen
  • Infantile hypergastrinemia, associated with prostaglandin elevation and nitric oxide deficiency; however, this may be secondary to gastric stasis and distention
  • Abnormal muscle innervation
  • Trisomy 18 has been associated with pyloric stenosis
  • Maternal stress in third trimester of pregnancy

Risk Factors
  • Age: Approximately 95% of cases are diagnosed in infants aged 3 to 12 weeks.
  • Sex: It is 4 to 5 times more prevalent in males and more common in firstborn males.
  • Race: It is most common in Caucasians (2.4 per 1,000 live births, vs. 1.8 in Hispanics, 0.7 in African-Americans, 0.6 in Asians).
  • Birth weight: Low birth weight is associated with a lower rate of occurrence of IHPS.
  • Maternal age: Older maternal age as well as higher maternal educational level is associated with a lower incidence of IHPS.
  • Oral erythromycin given to the neonate

Signs and Symptoms
  • Progressive nonbilious emesis, often becoming projectile. May be intermittent or may occur after each feeding
  • Persistent hunger
  • Weight loss
  • Dehydration
  • Lethargy
  • Diminished stools
  • Marasmus and protein calorie malnutrition (in severe cases)
  • Jaundice (in 5% of cases)

Differential Diagnosis
  • Peptic ulcer
  • Gastroenteritis
  • Gastroesophageal reflux
  • Pyloric atresia
  • Pyloric antral web
  • Pyloric diaphragm
  • Poor feeding practices
  • Hiatal hernia

Diagnosis
Physical Examination

Consideration of IHPS should not be delayed due to the potential for dangerous fluid and electrolyte imbalance. Examine for epigastric distention and visible gastric peristaltic waves moving across the epigastrium from left to right. Firm, nontender, mobile 2-to-3-cm mass ("olive") may be palpated deep in the epigastrium to the right of midline; present in 60% to 80% of cases. Palpation is best attempted after emesis when infant is calm.


Laboratory Tests
  • pH, electrolytes, BUN, creatinine: Hypochloremic, hypokalemic alkalosis is often seen as a result of dehydration and loss of hydrochloric acid
  • Elevated conjugated bilirubin

Imaging
  • Ultrasonography: Method of choice due to its accuracy and noninvasive nature. Criteria for diagnosis include pyloric muscle thickness greater than 4 mm, pyloric length greater than 14 mm, or pyloric ratio (wall thickness: pyloric diameter) >0.27. The pyloric ratio has the advantage of being a weight-independent indicator.
  • Upper gastrointestinal imaging: Barium study indicated if sonography is unavailable or inconclusive, or if an alternative diagnosis such as gastroesophageal reflux is being considered. Signs include elongated pyloric channel ("string sign") and pyloric muscle bulging into antrum ("shoulder sign").
  • X rays: indicated only to rule out presence of free air.

Other Diagnostic Procedures

Upper GI endoscopy may be used if imaging is inconclusive or atypical clinical features are present.


Treatment Options
Treatment Strategy

IHPS is a medical emergency. Immediate attention must be given to correcting fluid loss, electrolytes, and acid-base balance. Surgery is the curative treatment.


Drug Therapies

Some infants have responded to treatment with atropine sulfate, 0.04 mg/kg/day IV, with the dose increasing by 0.01 mg/kg/day until vomiting ceased (1 to 8 days). Then the atropine was continued orally at twice the effective intravenous dose for two weeks. The infants began gaining weight before regression of pyloric thickening was established ultrasonographically. Normalization of pyloric muscle caliber was shown by ultrasonography 4 to 12 months later. Investigators have suggested that the pyloric muscle hypertrophy might be worsened by the spasms that occur in IHPS.


Surgical Procedures

The Ramstedt pyloromyotomy is the treatment of choice. The antropyloric mass is split, leaving the mucosal layer intact. The procedure is performed through a short transverse incision or laparoscopically. Newer approaches include supra-umbilical skin-fold or umbilical incisions for better cosmetic results. The infant should have nothing to eat or drink before surgery and for 12 to 24 hours after surgery.

Endoscopic balloon dilatation of the pylorus has provided short-term symptomatic relief for some patients but is not curative.


Complementary and Alternative Therapies

Periconceptional nutrition has benefits in the prevention of congenital hypertrophic pyloric stenosis. Therefore, periconceptional counseling should include discussion of diet and folic acid intake.


Nutrition

Nutrition, multivitamins, and folic acid play a role in reducing the incidence of congenital defects, including congenital hypertrophic pyloric stenosis, although the underlying biologic mechanisms of these protective effects are still not understood (Czeizel 1995). Synthetic folic acid (monoglutamate) is preferred over natural folate because of its rapid absorption and stability. Food folate is fragile and easily destroyed by heat. In addition, dietary folate consists of polyglutamates which must be converted into monoglutamate before they can be absorbed (Hall and Solehdin 1998).

A multicenter study in the greater metropolitan areas of Boston, Philadelphia, and Toronto from 1993 to 1996 evaluated the benefit of periconceptional multivitamin use. Infants with and without birth defects and aborted fetuses with birth defects were divided into eight case groups representing common congenital anomalies. Mothers of infants six months old or less were interviewed about vitamin use. Controls were 521 infants without birth defects and 442 infants with defects other than those being investigated. Data assessment revealed that periconceptional multivitamin supplementation may extend benefits beyond protection against neural tube defects and may reduce the incidence of other congenital anomalies, including congenital hypertrophic pyloric stenosis. However, other than folic acid, it was not clear which nutrient or nutrient combinations might affect non-neural tube defects (Werler et al. 1999).

A review of recent studies finds confirmation of these results and concludes that periconceptional daily folic acid supplementation plays a key role in reducing the incidence of neural tube defects and other congenital anomalies, including congenital hypertrophic pyloric stenosis. A dose of 0.4 mg folic acid per day should be supplemented in the periconceptional period to reduce the morbidity and mortality due to these birth defects. High risk mothers, mothers with a child previously affected by neural tube defects, mothers with diabetes mellitus, and women on anti-epileptic medications and other folate antagonists are advised to take 4 to 5 mg periconceptional folic acid daily. Because 50% of pregnancies are not planned, women of childbearing age, especially women considering pregnancy, should be advised of the need for periconceptional folic acid supplementation (Hall and Solehdin 1998).

While unproven, re-establishing normal bowel flora following antibiotic treatment and eliminating allergenic foods from the diets of the infant and breast-feeding mother may alleviate gastric irritability and inflammation. Common allergenic foods include dairy products, peanuts, soy, eggs, fish, and wheat, among others (Marks and Marks 1993). The breast-feeding mother should consider avoiding other foods such as caffeine, spicy foods, beans, and Brassica vegetables (e.g., broccoli), which can stimulate colic or general gastric upset in the neonate. Formula-fed infants may benefit from a change to a soy preparation or an easily digested hydrosylate formula. Normal bowel flora may be re-established by supplementing with lactobacilli such as L. acidophilus and especially Bifidus spp. The breast-feeding mother can take one capsule with meals; alternatively, one capsule per day in three divided doses may be administered to the newborn (using the powder inside an opened capsule) (Vaughan and Mollet 1999).


Herbs

Traditional colic formulas may be beneficial in easing gastrointestinal spasm and preventing hypertrophy/hyperplasia of the pylorus. Formulas typically include dill (Anethum graveolens) and/or chamomile (Matricaria recutita), given to the infant by drops or to the breast-feeding mother. (These herbs have traditionally been used for treatment of dyspepsia (Blumenthal et al. 1998)). Catnip (Nepeta cateria) may also be included.


Homeopathy

While homeopathic remedies for prevention or treatment of pyloric stenosis have not been investigated in scientific studies, the following remedies are used clinically by homeopathic doctors for this condition:

  • Antimonium crudum for vomiting of curdled milk after breast-feeding; the baby for whom this remedy is appropriate may be irritable and refuse to nurse.
  • Phosphoros indicated for violent vomiting as soon as feeding is completed. The infant for whom this treatment is appropriate tends to be mild mannered and generally with a good appetite despite the symptoms described.
  • Silica for vomiting in breast-fed infants who have a delicate constitution and slow development.

Acupuncture

Acupuncture may well play a role in alleviating causative factors that would otherwise lead to pyloric stenosis and/or helping in recovery from surgery. These mechanisms have not yet been explored in scientific research.


Massage

Touch is an important part of infant well being. While it is plausible that massage relieves gastrointestinal spasm and reduces stress, this application in the treatment of pyloric stenosis has not been investigated in scientific studies.


Other Considerations
Prevention
  • Caution should be exercised in prescribing oral erythromycin to neonates (see section entitled Risk Factors).
  • Stress reduction during pregnancy, particularly the third trimester (see section entitled Etiology).

Complications/Sequelae
  • Emesis persisting after surgery suggests incomplete pyloromyotomy, gastritis, hiatal hernia, or another cause for obstruction.
  • Postoperative complications include duodenal perforation or small bowel obstruction secondary to adhesions.

Prognosis

Fast diagnosis and treatment are necessary to avoid life-threatening fluid and electrolyte imbalance. If IHPS is detected quickly, the prognosis for recovery and catch-up growth is very good. Surgery is curative and mortality is very low (less than 0.5%).


References

Ballard RB, Rozycki GS, Knudson MM, Pennington SD. The surgeon's use of ultrasound in the acute setting. Surg Clin North Am. 1998;78(2):337-364.

Beers MH, Berkow R, eds. The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck & Co.; 1999:2213.

Blumenthal M, Busse WR, Goldberg A, et al., eds. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, Mass: Integrative Medicine Communications; 1998:107, 121.

Czeizel AE. Nutritional supplementation and prevention of congenital abnormalities. Curr Opin Obstet Gynecol. 1995;7(2):88-94.

Hall J, Solehdin F. Folic acid for the prevention of congenital anomalies. Eur J Pediatr. 1998;157(6):445-450.

Honein MA, Paulozzi LJ, Himelright IM, et al. Infantile hypertrophic pyloric stenosis after pertussis prophylaxis with erythromycin: a case review and cohort study. Lancet. 1999;354(9196):2101-2105.

Hulka F, Campbell TJ, Campbell JR, Harrison MW. Evolution in the recognition of infantile hypertrophic pyloric stenosis. Pediatrics. 1997;100(2):E9.

Lowe LH, Banks WJ, Shyr Y. Pyloric ratio: efficacy in the diagnosis of hypertrophic pyloric stenosis. J Ultrasound Med. 1999;18(11):773-777.

Marks DR, Marks LM. Food allergy. Manifestations, evaluation, and management. Postgrad Med. 1993;93(2):191-196, 201.

Nagita A, Yamaguchi J, Amemoto K, Yoden A, Yamazaki T, Mino M. Management and ultrasonographic appearance of infantile hypertrophic pyloric stenosis with intravenous atropine sulfate. J Pediatr Gastroenterol Nutr. 1996;23(2):172-177.

Singh J. Pediatrics, Pyloric Stenosis. In: Adler J, Brenner B, Dronen S, et al., eds. Emergency Medicine: An On-line Medical Reference. Accessed at www.emedicine.com/cgi-bin/foxweb.exe/showsection@d:/em/ga?book=emerg&sct=PEDIATRIC on August 18, 2000.

Vaughan EE, Mollet B. Probiotics in the new millennium. Nahrung. 1999;43(3):148-153.

Werler MM, Hayes C, Louik C, Shapiro S, Mitchell AA. Am J Epidemiol. 1999;150(7):675-682.


Copyright © 2000 Integrative Medicine Communications

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