Preoperative sonographic diagnosis of McSwain type V appendiceal intussusception: A case report (with video).

RATIONALE: Appendiceal intussusception is a rare disease. The definite preoperative diagnosis of appendiceal intussusception is rare and challenging. Here, we present a case of McSwain type V appendiceal intussusception in a 10-year-old boy. To our best knowledge, this is the first case report of a type V appendiceal intussusception that was preoperatively confirmed with sonography. Here, we have described in detail the ultrasound features and differential diagnosis of this rare disease.

PATIENT CONCERNS: A 10-year-old boy presented with 3 days of recurrent intermittent mild abdominal pain. The result of ultrasonography suggested an ileocolic intussusception and a therapeutic air-contrast enema was requested to reduce the intussusception but failed at a local hospital.

DIAGNOSES: Physical exam revealed mild tenderness in the lower right quadrant of the abdomen. However, ultrasonography showed a target-sign in cross section and a finger-like appearance in the longitudinal view. A diagnosis of McSwain type V appendiceal intussusception was made.

INTERVENTIONS: The patient underwent an appendectomy after successful manual reduction on laparotomy. The appendix was successfully resected.

OUTCOMES: Intraoperatively, the appendix was completely inverted in the cecum, and the preoperative sonographic findings were confirmed. During follow-up, there were no signs of recurrence.

LESSONS: Pre-operatively, on ultrasound a type V appendiceal intussusception is usually misdiagnosed as an ileocolic intussusception. Radiologists must execute caution to avoid over reliance on the sonographic findings of intussusception, especially when there is a mismatch with clinical symptoms. It is especially important to accurately understand the surgical-anatomic configuration of type V appendiceal intussusception that creates a "target-sign" and a "finger-like" layout on ultrasonography.