Definition

Stenosis refers to narrowing, and the pylorus is a muscle that acts as a valve between the stomach and the small intestine. In pyloric stenosis, the narrowing occurs due to thickening and enlargement of the pyloric muscle, which abnormally blocks food from entering the small intestine.

The pylorus is a sphincter muscle located at the end of the stomach, connecting it to the small intestine. It closes while food and fluids are being digested in the stomach and opens afterward to allow further digestion in the small intestine.

When the pyloric muscle becomes too thick, it narrows the digestive pathway, preventing fluids and food from moving from the stomach to the small intestine. Pyloric stenosis is typically diagnosed in newborns and is considered a rare disorder, affecting 3 out of 1000 births.

Pyloric stenosis can cause forceful vomiting because breast milk or formula cannot pass into the small intestine. This may lead to dehydration, fluid deficiency, and weight loss in affected babies. Babies with pyloric stenosis often appear hungry all the time. Fortunately, pyloric stenosis can be cured with surgery.

Causes

The exact cause of pyloric stenosis is still unknown, but genetic and environmental factors are suspected to play a role. Pyloric stenosis is typically not present at birth but develops over several days.

Pylorus narrowing can also occur in older children, although it is rare. Causes of pylorus narrowing in older children may include conditions such as peptic ulcers or wounds on the stomach wall and rare conditions like eosinophilic stomach inflammation.

Risk factor

Risk factors of stenosis pyloric include:

• Gender: Pyloric stenosis is more common in male infants, especially first-borns, than in female infants.
• Race: Pyloric stenosis is more prevalent in individuals of Northern European descent, less common in individuals of Black descent, and rare in Asians.
• Premature birth: Pyloric stenosis is more likely to occur in premature babies compared to full-term babies.
• Family history: Studies have indicated that the risk of this condition is higher in certain families. Pyloric stenosis occurs in 20% of male descendants and 10% of female descendants of mothers with the condition.
• Smoking during pregnancy: This behavior increases the risk of pyloric stenosis by up to 2 times.
• Early antibiotic use: Babies given certain antibiotics in the first weeks of life, such as erythromycin to treat pertussis, have a higher risk of pyloric stenosis. Additionally, babies born to mothers who consumed certain antibiotics late in pregnancy also have a risk of pyloric stenosis.

Symptoms

The symptoms of pyloric stenosis typically appear between 3-5 weeks after birth, and it rarely occurs in babies older than 3 months. While babies may be able to breastfeed properly initially, they may exhibit the following symptoms:

• Vomiting after feeding: Babies may experience projectile vomiting, which can start mildly and progressively worsen as the pylorus opening narrows. Vomit may sometimes contain blood.
• Constant hunger: Babies with pyloric stenosis often feel hungry immediately after vomiting.
• Abdominal contractions: Wave-like contractions (peristalsis) in the upper abdomen occur after feeding and before vomiting as the abdominal muscles attempt to force food through the narrowed pylorus.
• Palpable lump: A lump resembling a sausage or olive may be felt in the upper abdomen.
• Dehydration: Signs include crying without tears, appearing lethargic, or decreasing urination frequency (e.g., changing diapers less frequently).
• Changes in bowel movements: Babies with this condition may experience constipation.
• Weight issues: Pyloric stenosis can hinder weight gain and sometimes lead to weight loss.
• Irritability.
• Small, pellet-like stools.

Many babies with pyloric stenosis appear healthy, leading parents to be unaware of the disorder until dehydration or malnutrition occurs.

Diagnosis

In diagnosis, the doctor will inquire about the symptoms and the baby's condition and perform a physical examination. When examining the baby's abdomen, the doctor can sometimes feel an olive-shaped lump on the enlarged pylorus muscle.

To support the diagnosis, the doctor may recommend:

• Blood tests to check for dehydration or electrolyte imbalance
• Ultrasound (USG) to assess the condition of the pylorus and confirm the diagnosis of pyloric stenosis
• X-ray of the baby's digestive system if the ultrasound results are unclear

Management

Surgery is necessary to treat pyloric stenosis. The pyloromyotomy procedure, which involves repairing the narrowed pylorus, is typically scheduled promptly after the diagnosis is confirmed. If the baby experiences dehydration or electrolyte imbalance, they will receive fluid therapy first before the surgery.

During pyloromyotomy, the doctor only cuts the thickened outer layer of the pylorus muscle, allowing the inner layer to bulge. This provides a pathway for food to flow into the small intestine.

Pyloromyotomy is often performed using laparoscopy, a minimally invasive surgery resulting in faster recovery and smaller scars compared to traditional surgery.

After surgery, some conditions that may be observed include:

• The baby will receive intravenous fluids for several hours. Breastfeeding can typically resume 12-24 hours post-surgery.
• The baby may want to breastfeed more frequently.
• The baby may still experience vomiting for several days.

In rare cases, the pylorus may remain too narrow even after surgery. In such cases, a second surgery may be needed. Potential complications of pyloric stenosis surgery include bleeding and infection. However, such complications are rare, and surgery outcomes are generally favorable.

Complications

Pyloric stenosis can lead to several complications, including:

• Growth and developmental delays in the baby.
• Dehydration: Repeated vomiting can lead to dehydration and electrolyte imbalance. Electrolytes are essential for regulating many vital body functions.
• Stomach irritation: Repeated vomiting may irritate the baby's stomach, possibly causing mild bleeding.
• Jaundice: Although rare, this complication involves the accumulation of bilirubin, a substance secreted by the liver, resulting in a yellowish discoloration of the skin and eyes.

Prevention

If there is a family history of pyloric stenosis, it's important to consult a doctor. The doctor will assess your baby for signs or symptoms of pyloric stenosis. Prompt identification of these signs and symptoms allows for early treatment, which can help prevent complications such as malnutrition and dehydration. 

When to see a doctor?

If your baby experiences any of the following symptoms, it's important to seek medical attention:

For babies experiencing pyloric stenosis:

• Projectile vomiting after feeding
• Appearing less active or very irritable
• Urinating less frequently or having fewer bowel movements
• Failure to gain weight or even weight loss

If your baby has already undergone surgery for pyloric stenosis, consult a doctor if any of the following occur:

• Bleeding
• Abdominal bloating
• Swelling at the surgical site
• Fever
• Decreased urination
• Repeated vomiting
• Dark green vomit or vomit containing blood
• Severe abdominal pain
• Redness or leakage at the surgical site