Patients suffering from IHPS presents with signs and symptoms within three to six weeks from birth. The following signs and symptoms are commonly seen among infants with IHPS:

• Projectile vomiting: Babies with IHPS will have forceful vomiting of ingested milk after 30 minutes of intake [5]. The severity of the infant’s vomiting increases with the pyloric narrowing of the lumen.
• Persistent hunger: Infants with IHPS who frequently vomit will feel hungry more often.
• Dehydration: The incessant vomiting may cause fluid and electrolyte imbalance that may lead to life-threatening dehydration.
• Constipation: Patients diagnosed with IHPS may have obvious changes with their bowel movement due to the inadequate emptying gastric contents to the lower intestinal tract.
• Weight changes: The pyloric stenosis in infant may prevent the infant from gaining weight and may also cause weight loss in advanced cases.
• Abdominal contractions: Infants suffering from IHPS will show signs of wave-like contractions in the upper abdominal area due to the stomach propulsive force that pushes the food contents through a narrowed pyloric opening.

A detailed clinical history of the infant may give away the diagnosis of IHPS. Physical examination of the abdomen will reveal a wave-like motion of the stomach area during ingestion of milk. An olive size lump will be palpable at the area of the gastric outlet reflecting the hypertrophic muscle of the disease. Blood tests are ordered to determine the presence of electrolyte imbalance and uncover early signs of dehydration. Imaging studies like abdominal ultrasound, computed tomography (CT scan), and magnetic resonance imaging (MRI) confirm the diagnosis pyloric stenosis [6].

Infantile hypertrophic pyloric stenosis should always be treated as a medical emergency in the emergency room setting. It is imperative that the acid-base balance and the electrolyte deficiency should be corrected promptly to avoid grave complications [7]. Signs of shock due to dehydration are immediately treated with an intravenous bullous of crystalloid fluids at 20 mL/Kg. Infants presenting with milder symptoms are given intravenous fluids at 1.5 to 2 times the normal maintenance rate with 5% dextrose in 0.33% or 0.25% sodium chloride admixed with 2-4 mEq of Potassium Chloride per 100 ml solution.

Urine output and acid base balance are continually monitored while in the patient is admitted in the hospital. The definitive treatment for pyloric stenosis is the surgical correction of the obstruction by pyloromyotomy. This procedure may be performed through laparoscopic surgery for shorter hospital stay and for cosmetic reasons [8]. A cohort study in the United Kingdom, demonstrated that laparoscopic pyloromyotomy shortens time until full feedings, lessens incidence of emesis, and lowers the requirement of analgesia among IHPS patients [9]. Post-operative infants are regularly monitored for the recurrence of persistent vomiting which is a sign of an inadequate pyloromyotomy procedure [10].

Patients suffering from infantile hypertrophic pyloric stenosis carry an excellent prognosis after surgical intervention. In fact, infants may be given small portion of feedings in increasing frequency a few hours post operatively. Patients subjected to laparoscopic pyloromyotomy will have faster recovery, better cosmesis, and lesser post-operative emesis compared to those exposed to the traditional surgical approach [4]. Untreated patients may develop dehydration and serious malnutrition problems in the future.

The definitive etiology of pyloric stenosis is still unknown, although studies have been focusing on the active role of genes and environment on its occurrence and prevalence. Parents with pyloric stenosis are most like to give birth to children with IHPS. Pyloric stenosis in adults and may be idiopathic or secondary to ulcers, tumors or inflammatory diseases. 

In the United States, the current incidence of infantile hypertrophic pyloric stenosis is 2 to 4 cases per 1000 live births. Mortality rate is usually very low and unexpected. Deaths usually occurs with the late diagnosis of the pyloric stenosis due to dehydration and hypovolemic shock. IHPS has predilection with the white race compared to the black, Hispanic and Asian races. They appear less common among siblings with mixed racial lineages.

Males are predisposed to IHPS more than females with 4 is to 1 ratio, with 30% of cases occurring among first born males. Pyloric stenosis begins to manifest within the first 3 weeks of life where it is usually diagnosed at that age group. 

The pathogenesis of pyloric stenosis is primarily due to the marked hypertrophy and hyperplasia or the circular and longitudinal muscle layer of the pylorus. These cellular changes leads to the lengthening of the pyloric canal and the pyloric sphincter becomes thickened. The soft tissue mucosa becomes grossly edematous and thick leading to the mechanical obstruction of the gastric outlet to the small intestine. Advanced cases of pyloric stenosis may lead to stomach dilatation due to long standing partial obstruction.

The etiology of IHPS is described to be multifactorial involving hereditary factors and extrinsic factors [1]. Other etiologic factors like infantile hypergastrinemia, exposure to macrolide antibiotics [2], abnormal myenteric plexus innervation, and neuron devoid of nitric oxide synthase. Children who bottle fed are at risk in developing IHPS during infancy [3].

IHPS is a congenital defect of the pylorus that presents within the third to sixth weeks of life; thus, no modifiable activities or lifestyle modifications can be afforded to prevent its occurrence. It genetic nature, may prompt attending pediatricians to carefully examine the abdomen and note for early signs of pyloric stenosis among siblings of parents with IHPS. There are no guidelines for the prevention of aquired pyloric stenosis.

Pyloric stenosis is an uncommon medical condition that results from the muscular thickening of the gastric pylorus. Pyloric stenosis is commonly seen among infant patients presenting with forceful vomiting, dehydration, and weight loss. Infantile pyloric stenosis is the most common cause of intestinal obstruction among infants. Pyloric stenosis rarely occurs in adults and may be caused by ulcers, tumors or inflammatory diseases.

Definition

Pyloric stenosis is a clinical condition characterized by the partial or complete obstruction of the pyloric lumen usually due to muscular hypertrophy or hyperplasia of the luminal walls.

Cause

Genetic transmission is implicated for most of the cases. Environmental factors like maternal macrolide therapy, infant bottle feeding, and infantile gastrinemia play a role. Rarely pyloric stenosis may be aquired. 

Symptoms

Infants will frequently present with post prandial projectile vomiting 30 minutes after feeding. They will appear to be hungry a few minutes after vomiting. Patients will have signs of dehydration and weight loss. A wave-like movement of the stomach will be physically observable among infants.

Diagnosis

A detailed clinical examination and history will clinch the diagnosis. Blood tests for acid-base balance and electrolytes are monitored. Imaging studies can definitively establish its diagnosis.

Treatment and follow-up

The condition is a medical emergency that will require immediate fluid resuscitation, and correction of the acid-base and electrolyte imbalance. The definitive treatment is surgical pyloromyotomy.

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