Pediatric emergency medicine trisk 4509 4509
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Technique
The high-frequency linear probe, preferably with a large footprint, should be
placed in the right lower quadrant in the transverse plane. The colon is then traced
from right to left, rotating the probe to the longitudinal plane at the level of the
transverse colon to maintain a short-axis view of the bowel. This focused
investigation identifies ileocolic intussusception, the most common type. The
appearance of the intussusception is noted to be alternating hyperechoic and
hypoechoic rings representing the telescoping bowel wall. In the center may be
noted hyperechoic mesenteric fat and/or hypoechoic lymph nodes which served
as lead point ( Video 131.18 ). Sometimes referred to as the target or donut
sign, the rings of bowel occupy up to 3 to 4 cm. In long axis, the invaginated
loops appear similar to the layers of a sandwich, with alternating hyperechoic and
hypoechoic layers ( Video 131.19 ).
Pitfalls
Overlying bowel gas can obscure visualization of the bowel and can prevent
identification of intussusception. Small bowel intussusception can also occur but
is typically self-resolving and often will decompress during observation on
ultrasound. This entity does not typically require reduction and should be
differentiated from ileocolic intussusception.
Appendicitis
Anatomy
The normal appendix arises from the cecum in the right lower quadrant. In
patients with abnormal anatomy this position can be variable. Normal intestine
appears as alternating hyperechoic and hypoechoic rings representing the
histologic layers of the intestinal wall, also known as gut signature. A
noninflammed appendix is compressible, measuring less than 6 mm.
Technique
With the patient in the supine position, the high-frequency linear or curvilinear
probe should be placed in the right lower quadrant to identify the appendiceal
body. In a patient with significant pain, narcotic analgesia is necessary to perform
graded compression to displace overlying bowel gas and facilitate visualization of
the underlying bowel. In the longitudinal plane, the cecum should be identified,
with its fluid-filled haustra and inferior termination into the ileum. The appendix
will extend from the cecum just proximal to the junction with the ileum. In the
transverse plane, identification of the psoas muscle laterally and the iliac vessels
