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Transomental Hernia
网膜疝

Transomental hernias constitute approximately 1%–4% of all internal hernias. There are two types: In the first type, herniation occurs through a free greater omentum; this type is more common, and no sac is present. In the second type, which is rare, herniation into the lesser sac occurs through the gastrocolic ligament (33,35,36).
网膜疝约占所有腹内疝的1-4%，分为两型：第一种类型是经游离的大网膜疝，这种类型比较常见，不存在疝囊；另一种类型很少见，是经胃结肠韧带疝入一小囊内。

In the first type, the hernial orifice on the greater omentum is located in the periphery near the free edge (Fig 10) and is usually a slitlike opening from 2 to 10 cm in diameter (1–4,37). The cause of the omental defect has not been identified, but it has been suggested that most have a congenital origin, although inflammation, trauma, and circulation may also cause omental perforations. Small bowel loops, the cecum, and the sigmoid colon are involved in this defect. The clinical and radiologic findings are almost identical to those of transmesenteric hernias (Fig 11) (1,3,38).
在第一种类型中，大网膜上的疝孔位于近游离缘的外周，通常呈裂隙样开口，直径2-10cm。网膜缺损的原因不是很明确，尽管感染、创伤和循环异常也能导致网膜穿孔，但大多数有先天性的因素。这种缺损可累及小肠、盲肠和乙状结肠。临床和影像学表现和肠系膜疝的表现几乎一样（图11）。

Figure 10. Transomental hernia in a 76-year-old woman with a 6-day history of lower abdominal pain. (a) Contrast-enhanced CT scan of the pelvis shows a cluster of fluid-filled small bowel loops (arrowheads) with poor or absent enhancement of bowel walls adjacent to the midabdominal wall. The mesenteric vascular pedicle (arrow), which is crowded and engorged with vessels, is observed at the hernial orifice. Laparotomy was performed 3 hours after CT. (b) Diagram (coronal view) of the surgical findings shows that the hernial orifice (arrow) is in the periphery of the greater omentum. (c) Intraoperative photograph shows the hernial orifice (arrowhead). Approximately 80 cm of ileum, located 70 cm from the ileocecal valve, was herniated through the defect; 55 cm was resected due to gangrene (arrows).
图10 一76岁妇女的网膜疝，有下腹疼痛6天的病史。（a）盆腔增强造影CT显示小肠积液堆积（短箭头），邻近中腹壁的小肠管壁轻度或没有强化。疝孔处的肠系膜血管蒂（箭头）拥挤，血管充盈。CT检查3小时后进行了手术。（b）手术所见的示意图（冠状面）显示疝孔（箭头）位于大网膜的外周部。（c）术中图片显示疝孔（短箭头）。距回盲瓣70cm的回肠有约80cm经缺损疝出，55cm的肠管因为坏疽而被切除（箭头）。

Figure 11. Transomental hernia in a 78-year-old man with acute epigastric pain of 24 hours duration. At admission, the vital signs, laboratory values, and results of physical examination were normal with the exception of mild epigastric pain. On the second hospital day, laboratory investigations showed a white blood cell count of 20,300/mm3 (20.3 x 109/L). (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled closed bowel loops (S) surrounded by massive ascites (arrowheads). Engorged and crowded mesenteric vessels (arrow) are seen at the hernial orifice, which is adjacent to the abdominal wall. Laparotomy was performed 2 hours after CT. (b) Diagram (coronal view) of the surgical findings shows that the hernial orifice (arrow) is 3 cm in diameter with a firm and fibrous edge. (c) Intraoperative photograph shows approximately 90 cm of gangrenous jejunal loops (arrows), located 120 cm from the Treitz ligament, which were resected.
图11 一78岁男性患者的网膜疝，表现为持续24小时的急性上腹部疼痛，住院时的生命体征、实验室检查结果和体格检查均正常，仅表现为中上腹疼痛。住院第二天，实验室检查发现白细胞计数20300/mm³（20.3×10⁹/L）。（a）中腹部增强CT扫描显示闭合肠管（S）积液扩张，周围见大量腹水（短箭头）。与腹壁相邻的疝孔处可见肠系膜血管充盈拥挤（箭头）。CT检查后2小时进行了手术。（b）手术所见的示意图（冠状面）显示疝孔直径3cm（箭头），其边缘牢固呈纤维性。（c）术中图片显示距Treitz韧带120cm的空肠有约90cm发生坏疽（箭头），被手术切除。