Internal hernias after abdominal surgeries: MDCT features

Abstract

As less-invasive treatments for small bowel obstruction, such as laparoscopic surgery or small incision therapy, have become common, there is a growing demand for preoperative assessment of the cause and location of the small bowel obstruction. Thus, the role of computed tomography (CT) in the evaluation of small bowel obstruction is expanding. CT imaging of internal hernias (IHs) has been extensively described and is well established; however, CT imaging of IH after abdominal surgeries is not well recognized because of their anatomical complexity. The aims of this pictorial review are (1) to evaluate the causes of internal IHs in relation to previous abdominal surgery (e.g., IH associated with Roux-en-Y reconstruction, Billroth II reconstruction, peritoneal adhesive band, perineal hernia, and IH after gynecological procedures), (2) to demonstrate the spectrum of imaging findings on multidetector CT (MDCT), and (3) explain the key features for CT diagnosis of IHs related to previous surgical procedures, with emphasis on the multi-planar reformation (MPR) image. We also demonstrate the dynamic changes in the progression of mesenteric strangulation revealed by CT. Understanding the imaging appearance on MDCT can help radiologists guide therapy for patients with a small bowel obstruction after abdominal surgery.

Internal Hernias in the Era of Multidetector CT: Correlation of Imaging and Surgical Findings

“…Although an increasing number of pathognomonic CT findings of internal hernia have been reported, the majority of such reports are individual case reports. Small numbers of review articles (4)(5)(6)(7)(8) and scientific studies (9)(10)(11)(12)(13) have been published.…”

“…Portal venous phase scans are considered to be the most important, with (21). Therefore, routine administration of oral contrast material before CT is considered unnecessary (8,21,22). Multidetector CT scanning protocols differed slightly among the cases described in this article because CT images were collected from multiple institutions.…”

“…Reconstruction of a Roux-en-Y anastomosis is one of the common and increasing procedures in bariatric, gastric, and biliary surgeries (6,8). Internal hernia is a major complication of this anastomosis and results more commonly after laparoscopic gastric bypass surgery than open surgery (11).…”

“…Three subtypes of transmesenteric-type hernias occur with relation to this procedure: transmesocolic, jejunojejunostomy mesenteric, and Petersen hernias (7,8) (Fig 20). Transmesocolic hernia occurs through the surgical defect in the transverse mesocolon where the Roux limb passes.…”

“…Petersen hernia mesenteric root between the superior mesenteric artery and the distal mesenteric arterial branch), the "hurricane eye" sign (distal tubular mesentery with surrounding small bowel loops), a small bowel loop behind the superior mesenteric artery, abnormal position of the jejunojejunostomy, and is a herniation through the potential space called the Petersen defect, which is located between the jejunal mesentery of the Roux limb and transverse mesocolon. A deformed and displaced Roux limb, biliopancreatic limb, and transverse colon may serve as landmarks of these hernias (8).…”