Pyloric stenosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mohamadmostafa Jahansouz M.D.[2]
Overview
Infantile pyloric stenosis is a condition that causes severe vomiting in the first few months of life.There is narrowing (stenosis) of the opening from the stomach to the intestines, due to spasm and hypertrophy of the muscle surrounding this opening (the pylorus). It is uncertain whether there is a real congenital narrowing or whether there is a functional hypertrophy of the muscle which develops in the first few weeks of life.
Pyloric stenosis also occurs in adults where the cause is usually a narrowed pylorus due to scarring from chronic peptic ulceration. This is a completely different condition from the infantile form.
Historical Perspective
In 1717, Dr. Patrick Blair reported autopsy findings of pyloric stenosis for first time. In 1912, Conrad Ramstedt witnessed complete recovery of a patient with pyloric stenosis after undergoing pyloroplasty.
Classification
There is no established system for the classification of pyloric stenosis. It may be subclassified as infantile pyloric stenosis and adult-onset hypertrophic pyloric stenosis.
Pathophysiology
The pathogenesis of infantile hypertrophic pyloric stenosis is not completely understood. However, infantile hypertrophic pyloric stenosis may result from abnormal innervation of the pyloric smooth muscle.The chloride loss due persistent vomiting results in hypochloremia which impairs the kidney's ability to excrete bicarbonate. This is the significant factor that prevents correction of the alkalosis.[1] The secondary hyperaldosteronism develops due to the hypovolaemia.The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO2.
Causes
The causes of infantile pyloric stenosis are unknown, but genetic and environmental factors might play a role in pathogenesis of infantile pyloric stenosis. common causes of adult-onset hypertrophic pyloric stenosis (HPS) include persisting duodenal hyperacidity, inheritance of a parietal cell mass (PCM) at the upper end of the normal range which causes persisting duodenal hyperacidity.
Differentiating Pyloric stenosis overview from Other Diseases
Infantile hypertrophic pyloric stenosis must be differentiated from other diseases that cause vomiting, poor feeding and dehydration, such as adrenal insufficiency, gastroenteritis, UTI, Inborn errors of metabolism and acute renal failure.
Epidemiology and Demographics
The incidence of infantile pyloric stenosis is approximately 400 per 100,000 individuals worldwide and it is four times more common in males.It usually affects individuals of the Caucasian race. Asians individuals are less likely to develop Infantile pyloric stenosis. The prevalence of infantile pyloric stenosis in the course of 11 years (1989-1999) was approximately 7.3 per 100,000 individuals in one study.[2] Studies showed the mortality rate of pyloric stenosis is very low and usually results from delays in diagnosis that causes sever dehydration and shock.
Risk Factors
The most potent risk factors in the development of infantile pyloric stenosis are male gender, Caucasian race, bottle feeding, caesarean section delivery, first-born infant, preterm birth, and exposure to macrolides, nitrofurantoin, penicillins and trimethoprim-sulphamethoxazole during pregnancy.
Screening
Screening for pyloric stenosis is not recommended.
Natural History, Complications, and Prognosis
The gastric outlet obstruction due to the hypertrophic pylorus impairs emptying of gastric contents into the duodenum that causes projectile vomiting. The vomited material does not contain bile because the pyloric obstruction prevents entry of duodenal contents (containing bile) into the stomach. Vomiting after surgery is the most common complication of infantile hypertrophic pyloric stenosis. Failure to gain weight in newborn, Bleeding and Infection after surgery are the other complications of infantile pyloric stenosis. Vomiting after surgery is the most common complication of infantile hypertrophic pyloric stenosis. Failure to gain weight in the newborn ,Bleeding and Infection after surgery are the other complications of infantile pyloric stenosis.
Diagnosis
Ultrasonography is the the modality of choice for the diagnosis of infantile pyloric stenosis.
History and Symptoms
The hallmark of infantile pyloric stenosis is progressively worsening vomiting within the first few weeks to months of life. A positive history of bottle feeding and cesarean section delivery is suggestive of infantile pyloric stenosis. The most common symptoms of infantile pyloric stenosis include vomiting, belching, persistent hunger. Less common symptoms of infantile pyloric stenosis include failure to gain weight or weight loss, jaundice, lethargy and Decreased urine output. The hallmark of adult type pyloric stenosis is progressively worsening projectile vomiting. A positive history of chronic peptic ulcers and fibrosis near the gastric outlet is suggestive of adult type pyloric stenosis. The most common symptoms of adult type pyloric stenosis include vomiting with occasional relief after vomiting, belching, epigastric pain. Less common symptoms of adult type pyloric stenosis include failure to gain weight or weight loss and symptoms of dehydration like increased thirst, dry mouth and decreased urine output.
Physical Examination
Patients with infantile pyloric stenosis usually appear ill. Physical examination of patients with infantile pyloric stenosis is usually remarkable for palpation of an abdominal mass in epigastrium.This mass, which consists of the enlarged pylorus, is referred to as the olive. Hypothermia and tachycardia with regular pulse and tachypnea may be present. In skin examination cyanosis, poor skin turgur, jaundice and pallor may be present.
Laboratory Findings
Most common laboratory findings consistent with the diagnosis of infantile pyloric stenosis and adult type pyloric stenosis include hypokalemia, hypochloremia, and metabolic alkalosis.
Electrocardiogram
There are no ECG findings associated with pyloric stenosis.
Xray
Abdominal x-ray findings are non-specific for pyloric stenosis but a distended stomach with minimal distal intestinal bowel gas may be seen .
CT scan
There are no CT scan findings associated with infantile pyloric stenosis but CT scan may be helpful in the diagnosis of adult type hypertrophic pyloric stenosis.
MRI
There are no MRI findings associated with infantile pyloric stenosis.
Ultrasound
Ultrasonography demonstrates the thickened prepyloric antrum bridging the duodenal bulb and distended stomach and it is the modality of choice for the diagnosis of infantile pyloric stenosis.
Other Imaging Findings
Ultrasonography demonstrates the thickened prepyloric antrum bridging the duodenal bulb and distended stomach and is the best imaging for diagnosis of infantile pyloric stenosis.
Other Diagnostic Studies
Upper gastrointestinal series (barium meal) may be helpful in the diagnosis of infantile pyloric stenosis. Findings on an upper gastrointestinal series suggestive of infantile pyloric stenosis include delayed gastric emptying, elongated pylorus with a narrow lumen (string sign), and the pylorus indents the contrast-filled antrum (shoulder sign).
Treatment
Medical Therapy
Correcting the dehydration and hypochloremic alkalosis and IV fluids therapy is very important in treatment of pyloric stenosis.
Surgery
Infantile pyloric stenosis is typically managed with surgery. Ranstedt's extramuscular pyloromyotomy is the gold standard of treatment.
Primary Prevention
There are no established measures for the primary prevention of pyloric stenosis.
Secondary Prevention
There are no established measures for the secondary prevention of pyloric stenosis.
References
- ↑ Kerry Brandis, Acid-Base Physiology. Retrieved December 31, 2006.
- ↑ Mukhin VN, Moskalenko VZ, Grona VN, Sopov GA, Linchevskiĭ GL (2001). "[Population prevalence of congenital hypertrophic pyloric stenosis in the Donetsk region of Ukraine]". Tsitol Genet. 35 (5): 60–4. PMID 11944318.