Infantile hypertrophic pyloric stenosis 浙江大学医学院附属儿童医院 江米足

Gastric outlet obstruction Hallmark is non-bilious vomiting Other symptoms include abdominal pain and nausea Other signs include abdominal distention and bleeding from secondary inflammation Most common cause of non-bilious vomiting is infantile hypertrophic pyloric stenosis Similar symptoms including pyloric atresia, antral webs, gastric duplications, and gastric volvulus

Pyloric Stenosis First described by Hirschsprung in 1888 Ramstedt described an operative procedure to alleviate the condition in 1907 – the procedure used to this day to treat pyloric stenosis Harald Hirschsprung (1830-1916)

Infantile hypertrophic pyloric stenosis Description: thickening of the pyloric portion of the stomach causing obstruction of gastric outflow(1, 2, 4) Also called: infantile hypertrophic pyloric stenosis hypertrophic pyloric stenosis congenital pyloric stenosis

Epidemiology age distribution almost always between age 3-8 weeks 4-5 times more common in boys than girls highest incidence in first-born infants less common in black and Asian patients than white patients in United States more common in Western world reported incidence 1-5 per 1,000 births(1, 2, 4)

Causes unknown(3, 4) hypotheses include(1, 3) abnormal neurophysiology in muscular layer including decreased nerve terminal number reduced nitrous oxide reduced number of interstitial cells of Cajal bacteria infection, such as Helicobacter pylori genetic factors pyloroduodenal duplication cysts as cause of neonatal gastric outlet obstruction in case report

Pathogenesis circular muscle of pylorus becomes hypertrophied(4) pyloric sphincter fails to open causing obstruction of gastrointestinal tract(3) stomach cannot drain, becomes fuller and stretches until emesis occurs(3) jaundice seen in 1%-2% of infants with hypertrophic pyloric stenosis(1, 2)

Complications dehydration(1, 4) starvation(1) hyperbilirubinemia(1) jaundice(2)

History Chief concern (CC): History of present illness (HPI): projectile nonbilious vomiting(1, 2, 3, 4) voracious appetite despite inability to tolerate feeds(1) may also present with dehydration or weight loss(1, 3, 4) History of present illness (HPI): non-vomiting at birth followed by gradual onset of nonbilious vomiting until emesis follows every feeding(1, 3, 4) median duration of symptoms 10 days median age at operation 40 days

Physical:General physical only 14% infants with pyloric stenosis present with all 3 signs of "classic triad" (nonbilious projectile vomiting, visible peristalsis, palpable "olive") signs of dehydration may include(4) acute body weight change poor mucous membrane hydration decreased capillary refill time absence of tears

Abdomen palpable mass in epigastrium or right upper quadrant(1, 2, 3, 4) olive-sized, 1.5-2 cm may require experience and persistence to find due to presence of gastric distention and need for calm infant with relaxed abdominal muscles less prevalent with earlier diagnosis distended stomach may be identifiable in hypochondrium with visible peristalsis (1, 3)

Making the diagnosis: diagnosis suspected in infant with(1, 4) forceful (projectile) nonbilious vomiting good appetite visible peristalsis hypochloremic alkalosis diagnosis often confirmed by palpation of olive-shaped pyloric muscle mass but may be difficult to appreciate by inexperienced examiners and requires calm infant with relaxed abdominal muscles(1, 4)

Making the diagnosis: ultrasound is preferred imaging test to confirm diagnosis with commonly used diagnostic criteria of(1, 3, 4) pyloric muscle thickness > 3 mm (threshold in various studies ranges from > 2.5 mm to > 4.5 mm) pyloric length > 15-18 mm (threshold in various studies ranges from > 14 mm to > 20 mm) upper gastrointestinal study used with atypical presentation or when ultrasound negative(4)

Testing overview: imaging studies ultrasound upper gastrointestinal imaging blood tests to assess for dehydration and metabolic alkalosis serum electrolytes arterial blood gas blood glucose

Ultrasound considered test of choice for pyloric stenosis due to absence of ionizing radiation exposure and oral contrast use (4) ultrasound using gray-scale and color Doppler techniques by experienced sonography appears highly sensitive and specific for diagnosis of IHPS negative ultrasound required pylorus muscle wall thickness < 3 mm pylorus canal length < 14 mm pylorus diameter < 12 mm absent or minimal vascular flow pyloric muscle thickness ≥ 2.5 mm on ultrasound may be most sensitive finding for diagnosis of IHPS had 98.8% sensitivity and 85% specificity

Upper gastrointestinal (UGI) study UGI used when(4) presentation atypical (bilious emesis, emesis present since birth, patient age extreme) ultrasound negative

UGI study UGI may show(1, 2, 4) prepyloric antrum failure to relax, seen as "elongation" of pyloric canal pyloric canal outlined by string of contrast material ("string sign") contrast material as linear tracts separated by mucosa ("double-track sign") thickened pylorus causing external impression on gastric antrum ("shoulder sign") ancillary findings of gastric hyperperistalsis, large volume gastric residue, delayed gastric emptying

（1）幽门管细长,呈“线样征” 十二指肠球底见“蕈伞征” （2）幽门管内可见“双轨征” （3）胃窦部幽门前区“鸟嘴征

Treatment overview preoperative management infant should have nothing by mouth(3) correction of dehydration and alkalosis preoperative antibiotics for prophylaxis (4) surgery is treatment of choice pyloromyotomy (Ramstedt procedure) laparoscopic pyloromyotomy for pyloric stenosis associated with fewer complications,

Ramstedt Pyloromyotomy

Follow-up postoperative analgesia(4) discharge following surgery(4) Underlying pyloric mass is split without cutting the mucosa and the incision is closed Post-op vomiting occurs in ½ the patients and thought to be due to edema of the pylorus Feedings can usually be initiated within 12-24 hours ad libitum feeding may be as safe and effective as standardized feeding regimen after pyloromyotomy