What is the most common cause of small bowel obstruction in patients without a history of abdominal surgery?

The most common cause of small bowel obstruction in patients without a history of abdominal surgery is hernia. Hernias can occur when an organ or tissue protrudes through an opening in the muscle or surrounding tissue. In the case of the small intestine, inguinal hernias (which occur in the groin) and femoral hernias are particularly common and can lead to incarceration or strangulation of the bowel, which results in obstruction.

In contrast, while intussusception is a significant cause of obstruction, especially in children, it is less common overall in adults compared to hernias. Adhesions typically arise from previous surgical procedures and thus are not relevant in patients without such a history. Similarly, while cancer can obstruct the bowel, especially in older adults, hernias remain the leading cause in the absence of surgical history.