Pyloric stenosis

Definition: Pyloric stenosis is a narrowing of the pylorus, the opening from the stomach into the small intestine.Pyloric stenosis, a condition that affects the gastrointestinaltract during infancy, isn't normal  it can cause our baby to vomit forcefully and often and may cause other problems such as dehydration and salt and fluid imbalances.When an infant has pyloric stenosis, the muscles in the pylorus have become enlarged to the point where food is prevented from emptying out of the stomach.

Alternative names: Gastric Outlet Obstruction, Hypertrophic Pyloric Stenosis, Congenital Hypertrophic Pyloric Stenosis

Signs and Symptoms:

Pyloric stenosis is often accompanied by the following signs and symptoms:

v  Vomiting, often projectile in the first 3 - 6 weeks of life (may be intermittent or may occur after each feeding)

v  Persistent hunger

v  Weight loss

v  Dehydration

v  Lethargy

v  Infrequent or absent bowel movements

v  Jaundice (yellowing of the skin and eyes)

Causes :

The exact cause of pyloric stenosis is unknown. However, factors that may contribute to its development include:

Ø  Heredity

Ø  Muscle and nerve abnormalities in the stomach region

Ø  Swelling caused by allergies, leading to enlargement of stomach muscles around the pylorus

Ø  Increased production of the hormone gastrin, which increases cell growth in the stomach muscles

Ø  Chromosomal abnormalities

 

Diagnosis:

v  A careful history and physical examination, often supplemented by radiographic studies are required for diagnosis

v  Most cases of pyloric stenosis are diagnosed/confirmed with ultrasound.

v  Although somewhat less useful, an upper GI series (x-rays taken after the baby drinks a special contrast agent) can be diagnostic by showing the narrowed pyloric outlet filled with a thin stream of contrast material; a "string sign" or the "railroad track sign".

v  The clinician will examine the baby and talk with the parents about their infant's symptoms.

v  If a child has the condition, the doctor should be able to feel a hard mass (about 2 cm wide and olive shaped) in the area above the bellybutton.

v  If the doctor cannot detect the mass, ultrasonography will be done to confirm the diagnosis.

v  A blood test may also be performed to see if the infant is dehydrated, in which case intravenous fluids can be used to correct the problem.

Clinical Manifestation:

Ø  Projectile vomiting

Ø  Feeding hungrily

Ø  Not vomiting after each feeding

Ø  Non-bilious vomitus; may be blood streaked

Ø  Signs of dehydration

Ø  Failure to gain weight

Ø  Loss of fat pads

Ø  Pain behaviors

Ø  Visible peristaltic waves

Ø  Palpable olive-size pyloric tumor during feeding

Pathogenesis:

The gastric outlet obstruction due to the hypertrophic pylorus impairs emptying of gastric contents into the duodenum. As a consequence, all ingested food and gastric secretions can only exit via vomiting, which can be of a projectile nature. The vomited material does not contain bile because the pyloric obstruction prevents entry of duodenal contents (containing bile) into the stomach.

This results in loss of gastric acid (hydrochloric acid). The chloride loss results in hypochloremia which impairs the kidney's ability to excrete bicarbonate. This is the significant factor that prevents correction of the alkalosis.

A secondary hyperaldosteronism develops due to the hypovolaemia. The high aldosterone levels causes the kidneys to:

• avidly retain Na⁺ (to correct the intravascular volume depletion)
• excrete increased amounts of K⁺ into the urine (resulting in hypokalaemia).

The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO₂.

Treatment:

ü  Treatment for pyloric stenosis involves surgery (called a pyloromyotomy) to split the overdeveloped muscles.

ü  In some infants, treatment with atropine sulfate, given intravenously initially and then continued by mouth, has corrected this situation.

ü  A surgical procedure called a Ramstedt pyloromyotomy can cure the disease. The infant should have nothing to eat or drink before surgery and for 12 to 24 hours after surgery.

ü  Prenatal vitamins may also supply some of the vital nutrients that the body needs just before conception and during pregnancy.

ü  A woman's nutritional status just before and during pregnancy helps prevent the occurrence of certain abnormalities at the time of or following birth, including pyloric stenosis.

Possible Complications:

• Vomiting after surgery -- this is very common and generally improves with time
• Failure to gain weight in the newborn period
• Risks associated with any surgery, which include:
• Bleeding
• Infection

 

 

Prevention:

ü  If there is a family history of pyloric stenosis, a new baby should be closely watched for any symptoms.

ü  If treatment is prompt, there are usually no long-term side effects from pyloric stenosis. Recovery depends on the general health of the infant and how quickly a diagnosis and treatment were made.

ü  There are no known ways of preventing pyloric stenosis, although it is possible that breastfeeding might reduce the risk.