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Pyloric Stenosis

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Description: Pyloric stenosis is a condition in which the passage from the stomach to the small intestine (the pylorus) becomes narrowed due to thickening of the pyloric muscle, causing severe vomiting in infants.
Type: Pyloric stenosis is a congenital condition characterized by the narrowing of the pylorus, which is the opening from the stomach to the small intestine. The type of genetic transmission associated with pyloric stenosis is multifactorial inheritance, meaning it results from a combination of genetic and environmental factors. It can involve multiple genes, and the exact pattern of inheritance is complex and not strictly Mendelian.
Signs And Symptoms: Babies with this condition usually present any time in the first weeks to 6 months of life with progressively worsening vomiting. It is more likely to affect the first-born with males more commonly than females at a ratio of 4 to 1. The vomiting is often described as non-bile stained ("non bilious") and "projectile vomiting", because it is more forceful than the usual spitting up (gastroesophageal reflux) seen at this age. Some infants present with poor feeding and weight loss but others demonstrate normal weight gain. Dehydration may occur which causes a baby to cry without having tears and to produce less wet or dirty diapers due to not urinating for hours or for a few days. Symptoms usually begin between 3 and 12 weeks of age. Findings include epigastric fullness with visible peristalsis in the upper abdomen from the infant's left to right. Constant hunger, belching, and colic are other possible signs that the baby is unable to eat properly.
Prognosis: For pyloric stenosis, the prognosis is generally very good with timely and appropriate treatment. The condition can be effectively treated with a surgical procedure called pyloromyotomy, which involves splitting the muscle of the pylorus to allow food to pass from the stomach to the small intestine. Most infants recover fully and have no long-term complications related to the condition or the surgery.
Onset: Pyloric stenosis typically has an onset within the first few weeks of life, usually between 3 to 6 weeks of age.
Prevalence: The prevalence of pyloric stenosis is approximately 1-3 per 1,000 live births.
Epidemiology: Males are more commonly affected than females, with firstborn males affected about four times as often, and there is a genetic predisposition for the disease. It is commonly associated with people of Scandinavian ancestry, and has multifactorial inheritance patterns. Pyloric stenosis is more common in Caucasians than Hispanics, Blacks, or Asians. The incidence is 2.4 per 1000 live births in Caucasians, 1.8 in Hispanics, 0.7 in Blacks, and 0.6 in Asians. It is also less common amongst children of mixed race parents. Caucasian male babies with blood type B or O are more likely than other types to be affected.Infants exposed to erythromycin are at increased risk for developing hypertrophic pyloric stenosis, especially when the drug is taken around two weeks of life and possibly in late pregnancy and through breastmilk in the first two weeks of life.
Intractability: Pyloric stenosis is not considered intractable. It is a condition that can typically be effectively treated with a surgical procedure called pyloromyotomy, which involves splitting the muscles of the pylorus to allow food to pass from the stomach to the small intestine. This procedure generally results in a complete resolution of symptoms.
Disease Severity: Pyloric stenosis is a condition that typically occurs in infants and is characterized by the narrowing of the pylorus, which is the passage from the stomach to the small intestine.

**Disease Severity:**
The severity of pyloric stenosis can vary, but it generally presents as a serious condition that requires medical intervention. If left untreated, it can lead to severe dehydration, weight loss, and electrolyte imbalances due to persistent vomiting. Early diagnosis and treatment are crucial, often involving surgical intervention to correct the narrowing and allow normal passage of food from the stomach to the intestines.
Healthcare Professionals: Disease Ontology ID - DOID:12639
Pathophysiology: 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. While the exact cause of the hypertrophy remains unknown, one study suggested that neonatal hyperacidity may be involved in the pathogenesis. This physiological explanation for the development of clinical pyloric stenosis at around 4 weeks and its spontaneous long term cure without surgery if treated conservatively, has recently been further reviewed.Persistent vomiting results in loss of stomach acid (hydrochloric acid). The vomited material does not contain bile because the pyloric obstruction prevents entry of duodenal contents (containing bile) into the stomach. The chloride loss results in a low blood chloride level which impairs the kidney's ability to excrete bicarbonate. This is the factor that prevents correction of the alkalosis leading to metabolic alkalosis.A secondary hyperaldosteronism develops due to the decreased blood volume. The high aldosterone levels causes the kidneys to avidly retain Na+ (to correct the intravascular volume depletion), and excrete increased amounts of K+ into the urine (resulting in a low blood level of potassium).The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO2.
Carrier Status: For pyloric stenosis:

Carrier Status: Pyloric stenosis is not typically discussed in terms of carrier status because it is not a single-gene disorder. It is a multifactorial condition influenced by both genetic and environmental factors. Certain genetic predispositions can increase the risk, but there isn't a straightforward carrier status as seen with monogenic diseases.

Nan: Not applicable in this context.
Mechanism: Pyloric stenosis is a condition where the passage from the stomach to the small intestine (the pylorus) becomes narrowed, often due to hypertrophy of the pyloric muscle. This narrowing obstructs the flow of stomach contents into the intestines, leading to severe vomiting and other gastrointestinal symptoms.

**Mechanism:**
1. **Hypertrophy and Hyperplasia**: The primary mechanism involves hypertrophy (increase in size) and hyperplasia (increase in number) of the smooth muscle cells of the pyloric sphincter. This muscle thickening constricts the pyloric canal, making it difficult for stomach contents to pass through.
2. **Obstruction**: The thickened muscle can cause functional obstruction at the pyloric channel, leading to gastric outlet obstruction.

**Molecular Mechanisms:**
1. **Genetic Factors**: There is a significant hereditary component to pyloric stenosis, suggesting a polygenic inheritance pattern. Several genes are believed to be involved, though specific gene mutations have not been conclusively identified.
2. **Growth Factors**: Abnormalities in cellular signaling pathways, including those involving growth factors like epidermal growth factor (EGF) and transforming growth factor-beta (TGF-β), may contribute to muscle hypertrophy and hyperplasia.
3. **Neurotransmitter Imbalance**: Dysregulation in the innervation of the pyloric muscle, particularly involving neurotransmitters like nitric oxide, which is crucial for muscle relaxation, may also play a role.
4. **Hormonal Influences**: Elevated levels of certain hormones, such as prostaglandins or motilin, could potentially contribute to abnormal muscle contraction and growth.

Investigations are ongoing to further elucidate the precise molecular mechanisms underlying pyloric stenosis.
Treatment: Infantile pyloric stenosis is typically managed with surgery; very few cases are mild enough to be treated medically.
The danger of pyloric stenosis comes from the dehydration and electrolyte disturbance rather than the underlying problem itself. Therefore, the baby must be initially stabilized by correcting the dehydration and the abnormally high blood pH seen in combination with low chloride levels with IV fluids. This can usually be accomplished in about 24–48 hours.Intravenous and oral atropine may be used to treat pyloric stenosis. It has a success rate of 85–89% compared to nearly 100% for pyloromyotomy, however it requires prolonged hospitalization, skilled nursing and careful follow up during treatment. It might be an alternative to surgery in children who have contraindications for anesthesia or surgery, or in children whose parents do not want surgery.
Compassionate Use Treatment: Pyloric stenosis typically requires surgical intervention, specifically a procedure called pyloromyotomy, which has a high success rate. There aren't widely recognized compassionate use treatments specifically for pyloric stenosis as it is generally promptly and effectively treated with surgery.

However, in terms of experimental or off-label treatments, there have been limited explorations of alternative approaches. For instance, some studies have looked into the use of atropine sulfate, a cholinergic antagonist, which can be administered either orally or intravenously to temporarily relieve symptoms by relaxing the pyloric muscle. This treatment, though not standard, has shown some effectiveness in mild cases or when surgery is contraindicated or delayed.

It's important to note that these alternative treatments should only be considered under strict medical supervision and in specific clinical contexts, as they are not a replacement for the surgical standard of care.
Lifestyle Recommendations: Pyloric stenosis primarily affects infants and is characterized by the narrowing of the pylorus, which blocks food from entering the small intestine. Since this condition typically arises in early infancy and requires medical or surgical intervention for treatment, lifestyle modifications are not usually a core component of managing pyloric stenosis. The standard treatment is a surgical procedure called pyloromyotomy, which corrects the narrowing.

However, parents and caregivers can help manage the condition and support recovery by ensuring proper hydration and nutrition through appropriate feeding techniques. This may involve:

- Monitoring feeding times and ensuring the infant is getting enough nutrition.
- Offering smaller, more frequent feedings to avoid overloading the stomach.
- Keeping the infant upright during and after feedings to help with digestion.
- Being attentive to signs of dehydration or complications and seeking medical care promptly.

Once treated, infants generally recover well and can continue with normal feeding practices as per pediatric guidance.
Medication: Pyloric stenosis is typically treated with surgery rather than medication. The standard procedure is called pyloromyotomy, which involves cutting the muscle of the pylorus to widen the passage from the stomach to the intestines. Medications are generally not used to treat this condition.
Repurposable Drugs: For pyloric stenosis, medications such as atropine sulfate have been studied for potential nonsurgical treatment. They work by relaxing the pyloric muscle. However, the primary and most effective treatment remains surgical intervention via pyloromyotomy. Always consult a medical professional for advice regarding treatment options.
Metabolites: In pyloric stenosis, the primary metabolic disturbance is hypochloremic hypokalemic metabolic alkalosis. This occurs due to the loss of gastric acid (hydrochloric acid, HCl) from persistent vomiting, which leads to a decrease in chloride and hydrogen ions and subsequently causes alkalosis. The body compensates by retaining bicarbonate, which exacerbates the alkalosis, and potassium levels decrease as the kidneys attempt to compensate for the altered pH balance.
Nutraceuticals: Nutraceuticals are not typically considered a standard treatment for pyloric stenosis, a condition where the opening from the stomach to the small intestine narrows, causing vomiting and feeding difficulties in infants. The primary treatment for pyloric stenosis is surgical intervention, specifically a procedure called pyloromyotomy. Nutraceuticals have not been shown to have any significant impact on the management or treatment of this condition.
Peptides: Peptides are not directly related to the diagnosis or treatment of pyloric stenosis, which is a condition that affects the opening between the stomach and the small intestine in infants, causing projectile vomiting. The primary treatment for pyloric stenosis is a surgical procedure called pyloromyotomy.