1. Infantile Hypertrophic Pyloric Stenosis
By : Dani Mamo

2. Introduction
Infantile pyloric stenosis is a relatively common condition that causes severe projectile non-bilious vomiting in the first few weeks of life.
It results from hypertrophy of the muscles surrounding the pylorus leading to its narrowing and gastric outlet obstruction.

3. Epidemiology
Infantile pyloric stenosis occurs in the first 3–6 weeks of life.
Infantile pyloric stenosis has also been reported in the first few days of life and in utero.
Males are more commonly affected than females, with firstborn males affected about four times as often.
It is commonly associated with people of Jewish ancestry.
Pyloric stenosis is more common in Caucasians than Hispanics, Blacks, or Asians.

4. Epidemiology
The incidence of infantile hypertrophic pyloric stenosis is variable. It is:
2.4 per 1000 live births in Caucasians.
1.8 per 1000 live births in Hispanics.
0.7 per 1000 live births in Blacks.
0.6 per 1000 live births in Asians.
Less common among children of mixed race parents.
Caucasian babies with blood type B or O are more likely than other types to be affected.

5. Etiology The exact cause is not known.
It appears to be inherited in a multifactorial manner.
Infantile hypertrophic pyloric stenosis has been reported in twins and several members of the same family suggesting genetic predisposition or familial component.
There is a fivefold increase in the risk of developing infantile hypertrophic pyloric stenosis in first degree relatives if one member of the family is affected.
Nitric oxide is an essential chemical transmitter responsible for relaxation of the pyloric sphincter muscles. Studies have shown deficiency in nitric oxide synthase in the myenteric plexus in patients with infantile hypertrophic pyloric stenosis.

9. Dani mamp

10. Pathophysiology
There is hypertrophy and hyperplasia of the two (circular and longitudinal) muscular layers of the pylorus. This leads to narrowing of the pyloric canal and gastric outlet obstruction.
The pyloric canal becomes lengthened, and the whole pylorus becomes thickened. The mucosa is usually edematous and thickened.
Infantile pyloric stenosis is characterized by persistent, non-bilious projectile vomiting due to gastric outlet obstruction.
This results in loss of gastric acid with subsequent hypochloremia (chloride loss) and metabolic alkalosis (acid loss).
Prolonged vomiting leads to loss of large quantities of gastric secretions rich in hydrogen and chloride. As a result of dehydration, the kidneys attempt to conserve Na+ to maintain volume by exchanging Na+ for K+ and hydrogen secreted as KHCO3 and H2CO3 (paradoxical aciduria). There is a metabolic alkalosis, but instead of having an alkalotic urine, it is acidic.

11. Pathophysiology

12. Signs and Symptoms
There is progressively projectile and non-bile-stained vomiting. The child remains hungry and takes food immediately after vomiting.
Poor weight gain and malnutrition .
95% percent have a palpable pyloric mass (olive sign) which is felt in the right upper abdomen, especially after vomiting and during a test feed.
May be dehydrated.
Visible peristalsis in the epigastrium travelling from left to right .
Indirect hyperbilirubinemia may be seen in 1–2 % of affected infants.

13. a and b Clinical photograph of patients with infantile hypertrophic pyloric stenosis with poor weight gain,malnutrition, dehydration, and epigastric fullness

14. Diagnosis
history and physical examination, often supplemented by radiographic studies.
Abdominal radiographs are not necessary and may show a fluid-filled or air-distended stomach, suggesting the presence of gastric outlet obstruction. A markedly dilated stomach with exaggerated incisura (caterpillar sign) may be seen.
ultrasonography, are noninvasive and accurate for identification of infantile hypertrophic pyloric stenosis. Ultrasonography is the method of choice for the diagnosis of hypertrophic pyloric stenosis.

15. Diagnosis
Ultrasonography confirms hypertrophic pyloric stenosis when the pyloric muscle thickness is > 4 mm and the pyloric channel length is > 15 mm.
An upper gastrointestinal (GI) series is also not necessary and should be done only in doubtful cases when other imaging tests are inconclusive or when the infant presents with atypical clinical features. It is diagnostic when showing the narrowed pyloric canal filled with a thin stream of contrast material, a “string sign” or the “railroad track sign” .
Blood tests will reveal hypokalemic, hypochloremic metabolic alkalosis.

16. Differential Diagnoses
Bowel Obstruction in the Newborn
Emergent Treatment of Gastroenteritis
Intestinal Malrotation
Nutritional Considerations in Failure to Thrive
Pediatric Adrenal Insufficiency (Addison Disease)
Pediatric Duodenal Atresia
Pediatric Gastroesophageal Reflux
Pediatric Metabolic Alkalosis
Sandifer Syndrome

17. Treatment
The mortality and morbidity of infantile pyloric stenosis comes from the dehydration and electrolyte disturbance. Therefore, the infant must be initially stabilized by correcting the dehydration and hypochloremic alkalosis with IV fluids. This can usually be accomplished in about 24–48 h using ½ normal saline with K+ supplements.
Infantile pyloric stenosis is typically managed with surgery.

18. Treatment
Intravenous and oral atropine has been used to treat pyloric stenosis; 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.

19. Treatment
The Ramstedt pyloromyotomy remains the standard procedure for pyloric stenosis.
Pyloromyotomy can be done by open procedure or laparoscopically depending on the surgeon’s experience and preference. Care should be taken to avoid duodenal perforation during the procedure and, if this happens, the perforation should be closed and covered with an omental patch .
Traditionally, the pyloromyotomy is performed through a right upper quadrant transverse incision.

20. Treatment
The laparoscopic pyloromyotomy has been found to be safe and effective, with shorter operative times and hospital stay.
Feeding can be initiated 4–8 h after recovery from anesthesia. Infants who are fed earlier than 4 h do vomit more frequently and more severely, leading to significant discomfort for the patient and anxiety for the parents.
As many as 80 % of patients continue to regurgitate after surgery; however, patients who continue to vomit 5 days after surgery may warrant further radiologic investigation.
Patients should be observed for surgical complications:
Incomplete pyloromyotomy
Mucosal duodenal perforation
Bleeding

22. a and b Abdominal X-ray showing markedly dilated stomach

23. Erect abdominal X-ray showing dilated stomach with air fluid level in a patient with infantile hypertrophic pyloric stenosis. Note the scanty gas in the distal bowel

24. Barium meal in a patient with infantile hypertrophic pyloric stenosis showing dilated stomach and pyloric stenosis. Note the string sign

25. Dani mamo