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Features
特征

Transmesenteric and transmesocolic hernias account for 8% of all internal hernias (1–3). Because of the absence of a limiting hernial sac, mechanical SBO usually occurs in cases of transmesenteric hernia (Fig 8), and it is impossible to differentiate closed-loop obstructions caused by herniation through the mesenteric defect from those caused by prolapse of the intestine under adhesive bands. A volvulus may further complicate the process and cause rapid hernial strangulation and intestinal gangrene (Fig 9) (1,3,32). A transmesenteric hernia usually manifests in association with proximal small bowel dilatation, with a transition zone to a normal or collapsed intestine. Because the bowel mesenteric defect itself is not visualized, observation of the clustering of small bowel loops and abnormalities of the mesenteric vessels plays an important role in diagnosis of transmesenteric hernia. CT shows that the mesenteric vascular pedicle is characteristically engorged, stretched, and crowded; in addition, converging mesenteric vessels are located at the entrance of the hernial sac (34) and there is displacement of the main mesenteric trunk (9,10,32).
肠系膜疝和结肠系膜疝占所有腹内疝的8%。由于后者没有局限性的疝囊，机械性SBO通常发生在肠系膜疝的病例中（图8），而且不能区分经肠系膜缺损疝导致的闭合性肠梗阻与粘连带下的肠脱垂导致的闭合性肠梗阻。肠扭转是进一步的并发症，从而导致迅速的疝性绞窄和肠坏疽（图9）。肠系膜疝通常显示为近端小肠的扩张，与正常或塌陷肠管间存在过渡区。由于小肠系膜缺损本身不能显示，堆积的小肠肠管的梗阻和肠系膜血管的异常是诊断肠系膜疝的重要所在。CT表现为特征性的肠系膜血管蒂充盈、拉长和拥挤，另外，汇聚的肠系膜血管位于疝囊的入口处，肠系膜的主干发生移位。

Figure 8. Transmesenteric hernia in a 36-year-old woman with lower abdominal pain of 10 days duration. She was treated conservatively for 20 days by means of decompression with a nasogastric tube or long intestinal tube, intravenous fluids, and antibiotics because of an undiagnosed SBO. However, the SBO developed despite treatment. (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled small bowel loops (S) and crowded and stretched vessels (arrow). (b) CT scan of the pelvis shows crowded and converging vessels (arrow) at the hernial orifice. (c) Image obtained with enteroclysis performed through the intestinal tube shows the SBO (arrow). (d) Diagram (coronal view) of the surgical findings shows that approximately 180 cm of strangulated ileum (arrows), located 5 cm from the ileocecal valve, was herniated through the mesenteric defect (arrowheads). At laparotomy, a segment of gangrenous ileum was resected. (e) Intraoperative photograph shows the hernial orifice, which is oval and 4 cm in diameter.
图8 一36岁妇女的肠系膜疝，持续10天下腹痛。给予了20天的保守治疗，包括经鼻胃管或肠管减压、静脉输液和抗生素。然而尽管经过治疗还是出现了SBO。（a）增强CT扫描显示中腹部小肠肠管积液扩张（S），血管汇聚并拉长（箭头）。（b）盆腔CT扫描显示疝孔处的血管拥挤汇集（箭头）。（c）经肠管行肠道造影的图像显示SBO（箭头）。（d）手术所见的示意图（冠状面）显示距回盲瓣5cm的回肠有大约180cm发生绞窄，是经肠系膜上的缺损（短箭头）导致的疝。术中将坏疽的回肠段予以切除。（e）术中图片显示疝孔，呈卵圆形，直径4cm。

Figure 9. Transmesenteric hernia in a 12-year-old girl who experienced 36 hours of diffuse abdominal pain and sudden development of cramps. Abdominal examination showed severe distention and tenderness at the midabdomen. Laboratory investigations revealed a hemoglobin level of 8.4 g/dL. (a) Nonenhanced CT scan of the midabdomen shows diffuse mesenteric fluid and haziness (arrows) and mildly dilated small bowel loops. The attenuation of the intraluminal fluid is increased (arrowheads) because red blood cells may have been released in the lumen. Laparotomy was performed 12 hours after CT. (b) Intraoperative photograph shows the hernial orifice (arrow), which is 3 cm in diameter. Approximately 260 cm of small intestine, located 100 cm from the ileocecal valve, was herniated through the mesenteric defect and twisted 360°; 230 cm was gangrenous and was thus resected.
一12岁女孩的肠系膜疝，表现为弥漫性腹疼36小时后突发绞疼。腹部检查发现中腹部严重膨隆并且敏感。实验室检查发现血红蛋白8.4g/dL。（a）中腹部非强化CT扫描显示弥漫性的肠系膜积液并模糊不清（箭头），小肠肠管轻度扩张。由于红细胞进入管腔内，腔内的积液衰减增加。CT检查12小时后进行了手术。（b）术中图片显示疝孔（箭头），直径3cm。距回盲瓣100cm处的小肠约有260cm经肠系膜缺损疝出并旋转360°，230cm的肠管发生坏疽并被切除。