Labs may show hypokalemia and hypochloremic metabolic alkalosis
Primary test of choice
Ultrasound: thickened (>3 mm) and elongated (>17 mm) pylorus ~ 95% Sn/Sp
Other tests that may show findings
Abdominal x-ray: may show large stomach bubble with absence of air in small bowel or colon
Characteristic caterpillar sign (gastric contractions against hypertrophied pylorus)
Upper GI: string sign (narrowed<unk>  lumen), double track sign (duplicated mucosa), beak sign (abnormality of<unk>  opening)
Characteristic caterpillar sign (gastric contractions against hypertrophied pylorus)
Pyloric stenosis
Emergent
Gastric volvulus
Necrotizing Enterocolitis
Duodenal atresia
Volvulus
Achalasia
Testicular torsion