Pyloric Stenosis and Gastroenteritis in infants

Pyloric stenosis (also referred to as infantile hypertrophic pyloric stenosis) is a thickening of the pylorus, a muscular valve that facilitates the movement of food from the stomach into the intestine. It is most commonly seen in infants between 3-6 weeks of age, where the muscle stops milk from leaving the stomach and babies become sick after every feed as a result of muscle hypertrophy that narrows the pyloric canal. Neonates affected by the condition will often vomit forcefully, become increasingly lethargic and constipated as a result of little or no food reaching the bowel.

If left untreated, the baby will also become increasingly dehydrated and have less frequent wet nappies. Babies with the condition may also develop a sunken fontanel (the soft spot on the top of the head). It is an urgent condition that requires immediate medical attention as a result of the harms that can occur if left untreated.

What children are prone to this disorder?

A number of genetic studies have identified susceptibility loci (a gene mutation that increases an individual’s susceptibility or predisposition to a certain disease or disorder) for pyloric stenosis (1). The studies have shown that children who have abnormalities of the pyloric muscle, and smooth muscle cells that are not innervated, have a much greater chance of developing the condition. 

If a parent has had pyloric stenosis, there is an estimated 20% chance that their child will also develop it.

How common is pyloric stenosis?

The most recent studies suggest that pyloric stenosis affects approximately 1 in every 500 live births (2). However, there is a relatively limited evidence base regarding the epidemiology of the condition and its true prevalence remains unclear. It is known that the condition is more common in males than females, with first born male children believed to be at a higher risk of developing the disease. Early exposure to oral erythromycin has been hypothesised as a potential cause for increased incidence, although these findings are based on a single study rather than a well developed evidence base (3).

How is pyloric stenosis diagnosed?

Babies presenting with the symptoms of pyloric stenosis will often be given an ultrasound as the main investigation due to its high sensitivity and specificity (4).

However, some physicians will be able to feel a thickened pylorus muscle during the examination of a baby’s abdomen. As the symptoms of the disease are very similar to a range of other symptoms, babies may occasionally be given differential diagnoses of gastroenteritis, oesophageal atresia, intestinal malrotation, gastro-oesophageal reflux, or feeding problems/milk intolerance.

Treatment options for pyloric stenosis

Babies who have been unwell for sometime will often be dehydrated and require admission to hospital, with fluid given via a cannula to restore the chemical balance of the baby’s blood (fluid deficiency and electrolyte imbalance). Surgery is often required for children who have the condition, with a procedure called a pyloromyotomy cutting through the thickened muscles of the pylorus to relieve the blockage that results in pyloric stenosis. The procedure is considered low risk, and is easily performed with minimal complications (5). It is generally carried out via keyhole surgery, with three small incisions in the abdomen. Following surgery, babies are able to return to regular feeding patterns within around 3-4 hours. However, because of swelling around the surgery site the child may still continue to vomit small amounts for several days after the procedure. Pyloric stenosis very rarely recurs after surgery, and on the rare occasions it does it is often as a result of an incomplete pyloromyotomy.

Complications as a result of late/non-treatment

Babies who do not receive a timely diagnosis may experience significant discomfort as a result, as prolonged pyloric stenosis can result in severe dehydration, weight loss and electrolyte disturbance. Foveolar cell hyperplasia - a condition in which the cells that produce mucus in the stomach to prevent it from being harmed by gastric acid grow abnormally and affect the function of the stomach itself – has been identified as a very rare cause of persistent gastric obstruction in patients with pyloric stenosis (6).

Although all surgical interventions carry a risk of harm, the procedure to correct pyloric stenosis is generally safe and rarely causes harm. In rare cases, operative complications may result in some postoperative bleeding, mucosal perforation, and persistent vomiting as a result of incomplete surgery.

Long term prognosis 

The long term prognosis for children who receive a pyloromyotomy is very good, with the condition causing no further complications in the future following a successful surgery.

Prognosis is always better when a timely diagnosis is made, as prolonged severe dehydration can be avoided. Babies who receive a successful pyloromyotomy can expect to experience no more complications related to pyloric stenosis throughout their lives.

References

1. Panteli C (2009) New insights into the pathogenesis of infantile pyloric stenosis Pediatr Surg Int 25(12):1043-52
2. de Laffolie J, Turial S, Heckmann M, et al (2012) Decline in infantile hypertrophic pyloric stenosis in Germany in 2000-2008 J Pediatrics 129(4):e901-6
3. Lozada LE, Royall MJ, Nylund CM, et al (2013) Development of pyloric stenosis after a 4-day course of oral erythromycin Pediatr Emerg Care 29(4):498-9
4. Sivitz AB, Tejani C, Cohen SG (2013) Evaluation of hypertrophic pyloric stenosis by pediatric emergency physician sonography Acad Emerg Med 20(7):646-51
5. Aspelund G, Langer JC (2007) Current management of hypertrophic pyloric stenosis Semin Pediatr Surg 16(1):27-33)
6. Tan HL, Blythe A, Kirby CP, et al (2009) Gastric foveolar cell hyperplasia and its role in postoperative vomiting Eur J Pediatr Surg 19(2):76-8