Pediatric Surgery

Pyloric Stenosis

May 01, 2020
Dr. Bhargava Mullapudi, Pediatric Surgeon at Cincinnati Children’s, and Dr. Gillian Goddard, Pediatric Surgery Research Fellow at Cincinnati Children's, joins Dr. Rae Hanke to review the essentials of pyloric stenosis in this videocast.

Pyloric Stenosis

·      Definition: Acquired gastric outlet obstruction in infants

·      Epidemiology:

o   1-4/1000 Caucasian live births. (less common in other races)

o   M:F 2-5:1,

o   First born infants

o   Genetic predisposition, but not related to a specific genetic syndrome/mutation

·      Etiology: multifactorial. Hypothesis related to absence of Nitric oxide synthase in circular muscular layerto muscle spasm hypertrophy of pyloric sphincter hypertrophic pyloric stenosis

·      Pathophysiology:

o   Hypertrophy and hyperplasia of inner circular layer with associated mucosal hypertrophy.

o   Leads to GOO in infants 2-10 of age.

·      Presentation:

o   Infant with Nonbilious “projectile” vomiting aged 2-10 weeks of life.  Hungry vomiters. Dehydration, lethargy.

o   Timeline: 1-3 weeks from onset of symptoms to hospital presentation. Electrolyte abnormalities and dehydration worse the longer symptoms have been present

o   Hyperbilirubinemia, down regulation of hepatic enzymes associated with starvation. Reversible with rehydration and nutrition.

·      Differential diagnosis:

o   Gastric esophageal reflux

o   Pyloric spasm

o   Gastroenteritis

o   Duodenal/antral web

o   Pyloric atresia

o   Duplications

o   Bilious emesis must w/u for midgut volvulus!

·      Work up

o   History: onset and duration, character/nature of emesis

o   Physical exam: palpable epigastric mass, dehydration (depressed fontanelle, dry MM, decreased cap refill, low UOP), lethargy (sign of dehydration)

o   Labs: CMP for electrolytes (bicarb, chloride, potassium)

o   Ultrasound: pyloric measurements are diagnostic (thick 3mm, length 15mm)

o   Extraneous TestingUpper GI  used in resource poor countries (previously Gold standard)

§  Barium needs to be seen emptying to rule out atresia/web

o   Acid/Base Presentation: hypokalemic, hyperchloremic metabolic alkalosis

§  GOO leads to persistent vomiting, loss of HCl hypochloremia, loss of H

§  Kidneys try to compensate, increase Na/K pump urinary excretion of K to preserver Na and H20 hypokalemia

§  Paradoxical aciduria later stage, excretion of protons worse alkalosis

·      Treatment

o   Resuscitate to correct dehydration and electrolytes

§  Fluid bolus, mIVF, repeat lab draws

§  CCHMC Protocol: Bolus strategy 20ml/kg NS separated by 1hr, then recheck labs

·      Resuscitate based on chloride levels

o   <85, give 3bolus

o   85-97 2 bolus,

o   >97 1 bolus

·      If chloride normalResuscitate based on bicarb

o   >40 3 bolus

o   >33 2 bolus

·      If chloride and bicarb is normal resuscitate based on potassium

o   lowgive 1 bolus.

·      1-1.5 times mIVF w/ dextrose 

o   NGT discouraged at presentation worsens dehydration and electrolyte derangements

§  Place NG just prior to induction of anesthesia, to reduce aspiration risk on induction

o   Non surgical treatment: rehydrate w/ frequent feedings NOT recommended. Higher mortality

o   Surgery: Pyloromyotomy is standard of care in US AFTER resuscitation

§  Pyloromyotomy Surgical Technique:

·      Anatomic landmarks for LONGITUDINAL incision:

o   Proximal edge antrum transitions to thick pylorus

o   Distal edge vein of mayo, white line, pyloro duodenal junction

o   Pyloric spreader, extend to submucosa (gently)

·      When is it an adequate myotomy?: Submucosa bulges into the myotomy site.

·      Low incidence of complications both Laparoscopic and Open approach

·      Post Op Considerations

o   Feed immediately after the operation ad lib once alert and awake (decrease LOS)

o   Persistent vomiting post op is expected keep feeding, MCC is stomach irritation/swelling.

§  Other DDX for post op vomiting

·      Incomplete myotomy (rare)

·      Leak from mucosal perforation expect tachycardia/abdominal tenderness

·      GERD should obtain this history prior to OR

·      Complications

o   Incomplete myotomy rare, would require return to OR

o   Perforation

§  If noticed in OR close mucosa with full thickness repair of myotomy, can do second myotomy on posterior side of pylorus

§  Leave NGT for decompression, consider upper GI study

o   Apnea: risk of post op apnea, increased incidence with narcotic use. Most cases only need Tylenol post operatively.

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