Pyloric Stenosis


Pyloric stenosis is characterized by hypertrophy of the circular muscle fibers of the pylorus, with a severe narrowing of the lumen.

What is Pyloric Stenosis? 

Pyloric stenosis, also known as infantile hypertrophic pyloric stenosis (IHPS), is the most common cause of intestinal obstruction in infancy.

  • Pyloric stenosis is characterized by hypertrophy of the circular muscle fibers of the pylorus, with a severe narrowing of the lumen.
  • The pylorus is thickened to as much as twice its size, is elongated, and has a consistency resembling cartilage; as a result of this obstruction at the distal end of the stomach, the stomach becomes dilated.


In 1717, Blair first reported autopsy findings of pyloric stenosis.

  • Marked hypertrophy and hyperplasia of the 2 (circular and longitudinal) muscular layers of the pylorus occurs, leading to narrowing of the gastric antrum.
  • The pyloric canal becomes lengthened, and the whole pylorus becomes thickened.
  • The mucosa is usually edematous and thickened; in advanced cases, the stomach becomes markedly dilated in response to near-complete obstruction.

Statistics and Incidences

The incidence of infantile hypertrophic pyloric stenosis is 2-4 per 1000 live births.

  • Death from infantile hypertrophic pyloric stenosis is rare and unexpected; the reported mortality rate is very low and usually results from delays in diagnosis with eventual dehydration and shock.
  • Infantile hypertrophic pyloric stenosis is more common in whites than Hispanics, blacks, or Asians; the incidence is 2.4 per 1000 live births in whites, 1.8 in Hispanics, 0.7 in blacks, and 0.6 in Asians.
  • Infantile hypertrophic pyloric stenosis has a male-to-female predominance of 4-5:1, with 30% of patients with infantile hypertrophic pyloric stenosis being first-born males.
  • The usual age of presentation is approximately 2 – 6 weeks of life.
  • Approximately 95% of infantile hypertrophic pyloric stenosis cases are diagnosed in those aged 3-12 weeks.


The causes of infantile hypertrophic pyloric stenosis are multifactorial.

  • Exposure to antibiotics. A cohort study found that treatment of young infants with macrolide antibiotics was strongly associated with infantile hypertrophic pyloric stenosis (IHPS).
  • Genetic factors. A nationwide study of nearly 2 million Danish children born between 1977 and 2008 shows strong evidence for familial aggregation and heritability of pyloric stenosis.
  • Nitric oxide. Impairment of this neuronal nitric oxide synthase (nNOS) synthesis has been implicated in infantile hypertrophic pyloric stenosis, in addition to achalasia, diabetic gastroparesis, and Hirschsprung disease.

Clinical Manifestations

Pyloric stenosis is rarely symptomatic during the first days of life; it has occasionally been recognized shortly after birth, but the average affected infant does not show symptoms until about the third week of life.

  • Vomiting. Classically, the infant with pyloric stenosis has nonbilious vomiting or regurgitation, which may become projectile (in as many as 70% of cases), after which the infant is still hungry.
  • Jaundice. The infant may develop jaundice, which is corrected upon correction of the disease.
  • Dehydration and malnutrition. As the obstruction becomes more severe, the infant begins to show signs of dehydration and malnutrition, such as poor weight gain, weight loss, marasmus, decreased urinary output, lethargy, and shock.
  • Palpable pylorus. In as many as 60-80% of the infants with infantile hypertrophic pyloric stenosis (IHPS), a firm, nontender, and mobile hard pylorus that is 1-2 cm in diameter, described as an “olive,” may be present in the right upper quadrant at the lateral edge of the rectus abdominis muscle.
  • Gastric peristalsis. Clinicians may also observe gastric peristalsis just prior to emesis as the peristaltic waves try to overcome the obstruction.

Assessment and Diagnostic Findings

Pyloric Ultrasound showing thickened pyloric muscle in a 4-week-old infant with pyloric stenosis.

Diagnosis is usually made on the clinical evidence.

  • Laboratory studies. Electrolytes, pH, BUN, and creatinine levels should be obtained at the same time as intravenous access in patients with pyloric stenosis.
  • Ultrasonography. If the clinical presentation is typical and an olive is felt, the diagnosis is almost certain; however formal ultrasonography is still recommended to evaluate the pylorus and confirm the diagnosis.
  • Radiography. Radiographic studies with barium swallow show an abnormal retention of barium in the stomach and increased peristalsis.

Medical Management

Treatment of a child with pyloric stenosis includes:

  • Prehospital care. As with all pediatric resuscitations, prehospital care in patients with pyloric stenosis should be consistent with pediatric advanced life support (PALS) recommendations for infants who are dehydrated or in shock.
  • Correction of dehydration. If significant dehydration has occurred, immediate treatment requires correction of fluid loss, electrolytes, and acid-base imbalance, starting with an initial fluid bolus (20ml/kg) of isotonic crystalloid.
  • Diet. Feeding can be initiated 4-8 hours after recovery from anesthesia, although earlier feeding has been studied; infants who are fed earlier than 4 hours do not have a worse total clinical outcome; however, they do vomit more frequently and more severely, leading to significant discomfort for the patient and anxiety for the parents.
  • Pyloromyotomy. A surgical procedure called a pyloromyotomy, also known as a Fredet-Ramstedt operation, is the treatment of choice.

Pharmacologic Management

Medications used to treat pyloric stenosis symptomatically are:

  • IV atropine. The intravenous dose of atropine for treatment of pyloric stenosis ranges in studies from 0.04 to 0.225mg/kg/day and is given for 1 – 10 days.
  • Oral atropine. Oral atropine (0.08 – 0.45mg/kg/day) is continued, after IV therapy has been deemed successful, for 3 weeks to 4 months.

Nursing Management

Nursing management in a child with pyloric stenosis include:

Nursing Assessment

Assessment in a child with pyloric stenosis include:

  • Assess the child’s history of vomiting. Ask when the vomiting started and determine the character of the vomiting.
  • Assess for the child’s elimination. Ask the caregiver about constipation and scanty urine.
  • Physical exam. Physical exam reveals an infant who may show signs of dehydration; obtain the infant’s weight and observe skin turgor and skin condition, anterior fontanelle, temperature, apical pulse rate, irritability, lethargy, urine, lips and mucous membranes of the mouth, and eyes; observe for visible gastric peristalsis when the infant is eating.

Nursing Diagnoses

Based on the assessment data, the major nursing diagnoses are:

Nursing Care Planning and Goals

The major nursing care planning goals for a child with pyloric stenosis are:

  • Improving nutrition and hydration.
  • Maintaining mouth and skin integrity.
  • Relieving family anxiety.

Nursing Interventions

Nursing interventions are:

  • Maintain adequate nutrition and fluid intake. If the infant is severely dehydrated and malnourished, rehydration with intravenous fluid and electrolytes is necessary; feedings of formula thickened with infant cereal and fed through a large-holed nipple may be given to improve nutrition; feed the infant slowly while he or she is sitting in an infant seat or being held upright.
  • Provide mouth care. The infant needs good mouth care as the mucous membranes of the mouth may be dry because of dehydration and omission of oral fluids before surgery; a pacifier can satisfy the baby’s need for sucking because of the interruption in normal feeding and sucking habits.
  • Promote skin integrity. The infant is repositioned, the diaper is changed, and lanolin or A and D ointment is applied to dry skin areas.
  • Promote family coping. Include the caregivers in the preparation for surgery and explain the importance of  added IV fluids, the reason for ultrasonographic or barium swallow examination, and the function of the NG tube and saline lavage; describe the surgical procedure to be performed; and explain what to expect and how long the operation will last.


Goals are met as evidenced by:

  • Improved nutrition and hydration.
  • Maintained mouth and skin integrity.
  • Relieved family anxiety.

Documentation Guidelines

Documentation in a child with pyloric stenosis include:

  • Individual findings, including factors affecting, interactions, nature of social exchanges, specifics of individual behavior.
  • Intake and output.
  • Characteristics of vomitus.
  • Cultural and religious beliefs, and expectations.
  • Plan of care.
  • Teaching plan.
  • Responses to interventions, teaching, and actions performed.
  • Attainment or progress toward desired outcome.

Practice Quiz: Pyloric Stenosis

Here’s a 5-item quiz for Pyloric Stenosis study guide. Please visit our nursing test bank page for more NCLEX practice questions.

1. Nurse Nancy is assessing a child with pyloric stenosis; she is likely to note which of the following?

A. “Currant jelly” stools.
B. Regurgitation.
C. Steatorrhea.
D. Projectile vomiting.

1. Answer: D. Projectile vomiting.

  • Option D: Projectile vomiting is a key sign of pyloric stenosis.
  • Option B: Regurgitation is seen more commonly with gastroesophageal reflux.
  • Option C: Steatorrhea occurs in malabsorption disorders such as celiac disease.
  • Option A: “Currant jelly” stools are characteristic of intussusception.

2. A school-aged patient asks a nurse to recommend strategies to prevent constipation. Which of the following suggestions would be helpful? Note: More than one answer may be correct.

A. Get moderate exercise for at least 30 minutes each day.
B. Drink 6-8 glasses of water each day.
C. Eat a diet high in fiber.
D. Take a mild laxative if you don’t have a bowel movement every day.

2. Answers: A, B, and C.

  • Options A and B: Moderate exercise, such as walking, encourages bowel health, as does generous water intake.
  • Option C: A diet high in fiber is also helpful.
  • Option D: Laxatives should be used as a last resort and should not be taken regularly. Over time, laxatives can desensitize the bowel and worsen constipation.

3. A 2-year-old female with constipation due to pyloric stenosis is assessed by the nurse for a bowel training regimen. Which factor indicates further information is needed by the nurse?

A. The client’s dietary habits include foods high in bulk.
B. The client’s fluid intake is between 1500-2000 ml per day.
C. The client engages in moderate exercise each day.
D. The client’s bowel habits were not discussed.

3. Answer: D. The client’s bowel habits were not discussed.

  • Option D: A routine for bowel elimination should be based on the client’s previous bowel habits and alterations in bowel habits that have occurred because of illness or trauma.
  • Option A: Foods high in bulk are appropriate.
  • Option B: The client and the family should assist in the planning of the program which should include foods high in bulk, adequate exercise, and fluid intake of 2500-3000 ml.
  • Option C: Exercise should be a part of a bowel training regimen.

4. An infant diagnosed with pyloric stenosis is admitted with history of vomiting for several days. Which nursing diagnosis would be the priority?

A. Deficient fluid volume related to prolonged vomiting.
B. Ineffective airway clearance related to impaired swallowing.
C. Imbalanced nutrition: less than body requirements related to prolonged vomiting.
D. Anxiety related to loss of body control.

4. Answer: A. Deficient fluid volume related to prolonged vomiting.

  • Option A: Infants with pyloric stenosis usually have some degree of dehydration; replacing fluids and electrolytes would be priority actions for this diagnosis.
  • Option B: Swallowing is not impaired with pyloric stenosis.
  • Option C: Imbalanced nutrition is an appropriate nursing diagnosis as well, but not the priority at this time.
  • Option D: Infants do not experience body control anxieties.

5. A child with a poor nutritional status and weight loss is at risk for a negative nitrogen balance. To help diagnose this problem, the nurse in charge anticipates that the doctor will order which laboratory test?

A. Total iron-binding capacity.
B. Hemoglobin.
C. Total protein.
D. Serum transferrin.

5. Answer: C. Total protein.

  • Option C: A negative nitrogen balance may result from inadequate protein intake and is best detected by measuring the total protein level.
  • Options A, B, and D: Measuring total iron-binding capacity, hemoglobin, and serum transferrin levels would help detect iron-deficiency anemia, not a negative nitrogen balance.

Marianne is a staff nurse during the day and a Nurseslabs writer at night. She is a registered nurse since 2015 and is currently working in a regional tertiary hospital and is finishing her Master's in Nursing this June. As an outpatient department nurse, she is a seasoned nurse in providing health teachings to her patients making her also an excellent study guide writer for student nurses. Marianne is also a mom of a toddler going through the terrible twos and her free time is spent on reading books!
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