Pediatric emergency medicine trisk 4507 4507
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Pediatric Abdomen
Pediatric patients often present to the ED for evaluation of vomiting and/or
abdominal pain. In infants less than 2 months of age, there is often concern for
hypertrophic pyloric stenosis (HPS), requiring ultrasound for definitive diagnosis.
In the toddler age group, colicky abdominal pain with associated emesis can be
signs of intussusception, a pathology that is also diagnosed with sonography. In
children of all ages, abdominal pain that is localized to lower right side of the
abdomen raises concern for appendicitis. Ultrasound has become the first-line
diagnostic modality for appendicitis but sensitivity depends on patient
characteristics and sonographer skill. Recent literature has demonstrated the
ability of pediatric emergency medicine providers to identify pyloric stenosis,
intussusception, and appendicitis on bedside sonography.
Hypertrophic Pyloric Stenosis
Anatomy
The gastric outlet in infants abuts the medial portion of the hepatic contour. The
pyloric channel connects the antrum of the stomach to the first portion of the
duodenum and is surrounded by muscle. The position of the pylorus is dependent
upon the fullness of the stomach, but is typically adjacent to the gall bladder and
anteromedial to the right kidney.
Technique
A high-frequency linear probe, preferably with a large footprint, positioned on the
upper abdomen to the right of midline, will allow visualization of the pylorus as it
extends from the stomach, deep to the liver. The probe is oriented longitudinally
with the marker angled slightly toward the right shoulder for the short-axis view
and then rotated 90 degrees in the transverse plane to obtain the long-axis view.
In the long axis, the inner channel appears as a narrow canal flanked by the linear
hyperechoic walls that are surrounded by the hypoechoic muscular pylorus (Fig.
131.20 ).
As the pylorus thickens, it often extends superiorly toward the gall bladder and
when the channel has become obstructed, absence of passage of liquids can be
seen as retrograde peristalsis into the stomach. Measurements of the pylorus
should be performed to assess for hypertrophy with an abnormal muscle thickness
measuring greater than 3 mm and an abnormal channel length measuring greater
than 17 mm.
Pitfalls
