A 5 week old male with no significant PMH and an uncomplicated gestational/birth history presents to the ED after multiple episodes of projectile non-bilious vomiting. Vital signs include a HR of 165, Temp of 98.5F, RR 35, SpO2 100%. Exam is notable for a dry mucous membranes but otherwise is unremarkable. You perform an abdominal ultrasound and find the image below. What is the diagnosis?

Pyloric Stenosis:
– It is caused by hypertrophy of the pylorus leading to gastric outlet obstruction
– Presents with non-bilious projectile vomiting
– Can lead to hyperchloremic, hypokalemic, metabolic alkalosis
– Most commonly presents between 3-6 weeks of age
– Physical exam may reveal an “olive” sized mass in the epigastric region
– Patients may appear dehydrated with protracted disease but generally patients appear well without any signs of peritonitis or even abdominal tenderness

Diagnosis: Ultrasound is the test of choice (97-100% sensitivity and specificity of 99-100%)
– Think Pi: 3.14!
– In the longitudinal view: Length greater than 14mm and pyloric muscle wall thickness greater than 3mm is abnormal.

This patient underwent a pylorotomy without any complications and was successfully discharged.

Resources:
https://www.acep.org/sonoguide/advanced/pediatric-pyloric-stenosis#:~:text=Hypertrophic%20pyloric%20stenosis%20is%20an,2%2D12%20weeks%20of%20age.&text=Classic%20findings%20include%20projectile%20non,%25%20of%20the%20time%2C%20respectively.

https://www.emrap.org/corependium/chapter/recZCk7ICgxcy7hbM/Infantile-Hypertrophic-Pyloric-Stenosis#h.whcpdchy1ovf