Mysterious Intussusception in an Adult Without a Lead Point

Abstract

Introduction: Intussusception is defined as telescoping or prolapsing of the proximal bowel segment into the distal segment. The mechanism is not fully understood in primary or idiopathic intussusception; however, secondary intussusception is believed to result from a lesion in the bowel wall that alters the peristaltic pattern of the bowel causing invagination. This is a very rare phenomenon. Case Report: A 40-year-old male with history of GERD, gastritis, cholecystectomy, and appendectomy presented to the emergency department with 1-year history of intermittent abdominal pain located in the mid-epigastric area described as squeezing and non-radiating pain, associated with bilious, non-bloody vomiting, and weight loss of 20 lbs for the past 3 months. The patient denies any hematemesis, diarrhea, constipation, hematochezia, or melena. Because of recent weight loss, CT with contrast was obtained, which revealed small bowel intussusception of 6 cm length without any obvious small bowel lesions or lead points causing the intussusception. He underwent exploratory laparotomy with segmental small bowel resection. Pathology of the resected bowel showed normal mucosa and muscular intestinal wall without any lead points or lesions. Discussion: Intussusception in adult patients represents 5% of all intussusceptions. This pathology can be explained 90% of the time to be due to an origination of lead point such as a carcinoma, polyp, diverticula, stenosis, or benign neoplasm. Thus, most surgeons agree that intussusceptions in adults require surgical resection due to intraluminal lesions as lead points, and therefore, its risk of malignancy. In adult patients, 90% of intussusceptions occur with a lesion of the intestinal wall or any irritant factor in its lumen that alters normal peristaltic activity, which serves as a trigger to start an intussusception of 1 bowel segment over another. In cases where no lead points are identified, intussusception may be due to submucosal bowel edema, fibrous adhesions, or dysrhythmic contractions. However, 8-20% of cases are idiopathic, without a lead point lesion. Transient non-obstructing intussusception without a lead point has been described in patients with celiac disease and Crohn’s disease, but is more frequently idiopathic and resolves spontaneously without any specific treatment. Conclusion: Intussusceptions in adults is a rare and challenging diagnosis. It is often initially missed or delayed due to its vague, non-specific symptoms. Abdominal CT is the most sensitive imaging modality, and can be helpful in distinguishing the presence or absence of a lead point. Treatment in adult intussusception is almost always by surgery due to frequent association with malignant organic lesions.