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 to 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 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