Imaging diagnosis
Case 240
【Progress】
After contrast-enhanced CT, her symptoms worsened. Our surgeon was doing surgery for other patients, and the number of our surgeon was limited. She was transported to other hospital where she could be given service of emergent intraperitoneal laparotomy.
Several days later, our acute care physician got the message from the hospital, saying that she got surgical laparotomy which revealed internal hernia from mesenteric defect, large part of small herniated and its color turned black, indicative of extensive ischemic necrosis. One week after surgical resection of extensive part (240cm in length) of small bowel, she was discharged with no symptoms.
【Discussion】
There are three type hernias in abdomen; diaphragmatic hernia, external hernia and internal hernia. Diaphragmatic hernia includes esophageal hiatal hernia, Bochdalek hernia, Larrey hernia, Morgani hernia. External hernia includes paraumbilical hernia, obturator hernia, inguinal hernia and femoral hernia (1). Meanwhile, internal hernia denotes gut protrusion into aperture (niche) or defect in the walls of abdomen and pelvis. Internal hernia includes right or left para-duodenal hernia, Winslow foramen hernia, omental hernia, trans-mesentery hernia, inter-sigmoid hernia, peri-cecal hernia. For female, hernias of broad ligament, supra-vesical, vesico-uterine, perirectal and Douglas pouch are listed in internal hernia (1- 3).
Abdominal slit or aperture is formed by laparotomy of resection of digestive organ. Then, internal hernia most common occurs after surgical procedure. But internal hernia through congenital defect can occur (2, 4). In our case, she had experienced no surgical repair in the past. Then, congenital mesenteric defect is the cause of small bowel obstruction.
Trans-mesenteric herniation occurs most in children but can occur in adult (5, 6). As mesenteric defect is larger, herniation can be reversible but indicative of less incarceration and less of ischemic damages since the space for mesenteric vessels are preserved. Unlike other internal hernias, trans-mesenteric herniation does not make sac formation because intraperitoneal is limitless (3). However, once trans-mesenteric herniation falls into ischemic damage due to volvulus or strangulation, extensive regions of small bowel necrosis can occur.
On abdomen CT, because trans-mesenteric herniation protrudes to peritoneal cavity, sac formation of accumulated small bowel, namely closed loop sign, is rarely found, (3, 5, 6). In our case, CT showed no localized closed loop sign but two beak signs with mesenteric edema in right and left abdomen. Laparostomy revealed large part of small bowel turned into necrosis corresponded to small bowel with mesenteric edema. Although closed loop sign was not shown on CT, adjacent two beak signs and mesenteric edema are crucial signs implying ischemic change of bowels, strangulation or incarceration of small bowel. Other internal hernias are characteristic of mesenteric edema and two beak signs at the herniation gate, indicative of closed loop sign, while trans-mesenteric hernia might be characteristic of two beak signs and mesenteric edema without closed loop sign. Internal hernia of extensive small bowel causes not only incarceration of small bowel but also tightens the mesentery at the herniation gate, implying occurrence of ischemic damage to the bowel. In our case, although exact diagnosis of trans-mesenteric herniation was not diagnosed, our acute physician judged emergent laparotomy to be needed from severe abdomen rigidity.
【Summary】
We presented a fifty-year-old female with severe abdomen pain. She had no history of having laparotomy. Laboratory test revealed no evidence of abnormality. Abdomen CT showed two beak signs and mesentery edema at upper abdomen. Because her abdominal findings worsened as time progress. She was transported to other hospital where emergent laparotomy would be given. Intraoperative findings revealed trans-mesenteric herniation with bowel necrosis of a large part of small bowel which herniated from mesentery defect into intraperitoneal cavity. It is borne in mind that trans-mesenteric internal hernia is one of the internal hernias. Adjacent two beak signs, mesenteric edema and closed loop sign are found as the triad findings for internal hernia with ischemic damage on CT. However, trans-mesenteric internal hernia might not denote sac or closed loop sign because herniated small bowel enter the unlimited space, intraperitoneal cavity.
【References】
1.Hernias and Abdominal Wall Pathology | Radiology Key。http://om/hhttps://radiologykey.cernias-and-abdominal-wall-pathology
2.Hong SS, et-al. Current diagnostic role of CT in evaluating internal hernia. J Comput Assist Tomogr. 2005;29 (5): 604-9.
3.Doishita S, et-al. Internal Hernias in the Era of Multidetector CT: Correlation of Imaging and Surgical Findings. Radiographics. 2016;36 (1): 88-106
4.Takeyama N, et-al. CT of internal hernias. Radiographics. 2005;25 (4): 997-1015.
5.Katagiri H, et al. Internal hernia due to mesenteric defect. Journal of Surgical Case Reports. 2013; 5: 37
6.Umaparan G, et al. Congenital trans-mesenteric herniation: a rare cause of small intestine strangulation in adults. J Surg Case Rep. 2012;11: 3.
2021.8.10