Hypertropic pyloric stenosis

IHPS

1. Hypertropic Pyloric Stenosis Dr Hammad ur Rehman PGR Paeds Surgery Ward

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 and Etiology Infantile pyloric stenosis occurs in the first 2–8 weeks of life .(Peak incidence 3-5 weeks) Infantile pyloric stenosis has also been reported in the first few days of life and in utero . No definitive causative factors have been identified. Both genetic and environmental factors seem to play a role in the pathophysiology.

4. Genetic Predisposition A mong races, more common in Caucasians M ale preponderance, A n increased risk to first-born infants (4 times) P ositive family history C ertain ABO blood types . (B and O)

5. Environmental factors Environmental factors associated with IHPS include the M ethod of feeding (breast-feeding versus formula feeding ) S easonal variability Erythromycin exposure T ranspyloric feeding of premature infants .

6. Growth Factors and GIT Peptides Nitric oxide is an essential chemical transmitter responsible for relaxation of the pyloric sphincter muscles . D eficiency in nitric oxide synthase in the myenteric plexus Hypertrophied circular muscle did not demonstrate any NO synthase activity, but the activity in the longitudinal muscle was normal.

7. Growth Factors and GIT Peptides Substance P , a neurotransmitter responsible for enteric muscle contraction, could produce pylorospasm leading to muscle hypertrophy. This peptide is present in higher concentration in the pyloric muscle of patients with IHPS.

8. Growth Factors and GIT Peptides Neurotrophins , which are important for nerve differentiation and survival, have been noted to be decreased in IHPS . Specific receptors for these neurotrophins , the tyrosine kinase A receptor c-kit, is not present in IHPS tissue.

9. 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 . Immunohistochemical analysis of the hypertrophic muscle reveals an increase in fibroblasts, fibronectin , desmin , elastin and collagen.

10. Pathophysiology of IHPS

11. Clinical Presentation Persistent , non-bilious projectile vomiting. Blood in the emesis that gives it a brownish discoloration or a coffee-ground appearance Infants with IHPS remain hungry after emesis and are otherwise not ill appearing or febrile A significant delay in diagnosis leading to severe dehydration, however, results in a lethargic infant. Indirect hyperbilirubinemia may be seen in 1–2 % of affected infants.

12. Differential Diagnosis of Non bilious Vomiting Medical GERD Gastroenteritis Increased intracranial pressure Metabolic disorders. Surgical Pylorospasm Antral webs P yloric atresia D uplication cyst of the antropyloric region E ctopic pancreatic tissue within the pyloric muscle

13. Examination Visible peristaltic waves in the left upper part of the abdomen Seventy-five percent have a palpable pyloric mass (olive sign) which is felt in the right upper abdomen While examination Infant must be calm, warm, and cooperative Use of a pacifier or a small feeding (5% dextrose in water) may be helpful. If the stomach is distended, aspiration with a nasogastric tube The examiner should be willing to commit 5 to 15 minutes of uninterrupted time One should be able to roll the hypertrophied pylorus under the fingertips to be convinced of the diagnosis.

14. Investigations CBC S/E ABGs Metabolic alkalosis CUE Paradoxical aciduria

15. Abdominal X Ray Abdominal radiographs are not necessary May show a fluid-filled or air-distended stomach A markedly dilated stomach with exaggerated incisura (caterpillar sign) may be seen

16. Abdominal USG Most common initial imaging technique for the diagnosis Gold standard for diagnosing IHPS . Dependent on the level of experience and expertise of the ultrasonographer The generally accepted criteria for a positive US study are a P yloric muscle thickness of 3.5 (in premature infants) to 4 mm or more P yloric channel length of 16 mm or greater

17. UGI Contrast Study Barium is generally preferred compared with water-soluble contrast to avoid the chemical pneumonitis It shows narrowed pyloric canal filled with a thin stream of contrast material, a “string sign” or the “railroad track sign” Residual barium from the stomach should be aspitated If barium does not leave the stomach, it is not possible to confirm the diagnosis of IHPS because pylorospasm can also produce transient complete gastric outlet obstruction .

18. Preoperative Preparation P repare the infant adequately for anesthesia and surgical correction of IHPS. The length of preparation depends on the severity of the fluid and electrolyte abnormalities. Three levels of severity primarily on the basis of the serum carbon dioxide content S light , <25 mEq /L; moderate , 26 to 35 mEq /L severe, >35 mEq /L

19. Preoperative Preparation Oral feedings should be discontinued . A nasogastric tube should not be placed routinely because it removes additional fluid and hydrochloric acid from the stomach. Most infants with IHPS should be able to be resuscitated within a 24-hour period . Aggressive resuscitation should be avoided because it can produce rapid fluid and electrolyte shifts, possible leading to seizures 5% dextrose in 0.45 normal saline containing 20 mEq /L of potassium chloride is the optimal resuscitation fluid

20. Preoperative Preparation An initial rate for fluid resuscitation is 1.25 to 2 times the normal maintenance rate until adequate fluid resuscitation and urine output are achieved . Serum bicarbonate level should be below 30 mEq /L to avoid respiratory depression and prolonged postoperative intubation Hyperbilirubinemia invariably resolves postoperatively .

21. Operative Procedure The operative procedure of choice remains the Ramstedt pyloromyotomy . Two Technigues Minimal Laparotomy (“Open”) Technique Laparoscopic Procedure

22. Minimal Laparotomy (“Open”) Technique Two incisions (supra umbilical transverse and supra umbilical curved skin ) The pylorus can be stabilized by the index finger of the operating surgeon standing to the right of the patient . The serosa on the anterior wall of the hypertrophied pylorus is incised just proximal to the hypertrophied muscle extending just proximal to the pyloric vein B luntly splitting the hypertrophied muscle down to the submucosa Leave a few pyloric muscle fibers intact at the duodenal end to reduce the risk for duodenal perforation

23. Before closure, check for a leak from the stomach or duodenum If leak occurs, the submucosa should be approximated absorbable suture and a portion of omentum placed over this site. A lternative technique is to reapproximate the myotomy site, rotate the pylorus 180 degrees, perform a myotomy on the posterior wall of the pylorus.

24. Laproscopic Technique

25. Comparison Of The Open Versus Laparoscopic Approach A dvocates Faster recovery time Q uicker return to full feeding E arlier postoperative discharge D ecrease in postoperative emesis Decrease in pain Proponants Greater complication rate including perforation, missed perforation incomplete myotomy increase in operative time increased expense

26. Non Operative Management Intravenous and oral atropine has been used to treat pyloric stenosis It requires Prolonged hospitalization S killed nursing C areful follow-up during treatment

27. Postoperative Management Feeding can be started within 4 hours after the surgical procedure . 80 % of patients continue to regurgitate after surgery P atients who continue to vomit 5 days after surgery may warrant further radiologic investigation.

28. Complications Perforation Missed perforation Incomplete myotomy Vomiting Bleeding Wound infections