病例4
A 6-year-old girl had abdominal pain and vomiting with a vague mass to the left of the umbilicus. The child had had a similar attack lasting for a few hours about 10 days before this second episode. The clinical impression was intussusception. Sonography revealed 2 loops of dilated small bowel to the left of the umbilicus with the zone of transition in the midline. There was a thin membrane covering these 2 loops, which was seen because of minimal fluid in the sac and peritoneal cavity (Figure 7). No further investigation was performed. The clinical situation warranted a laparotomy, which revealed a left paraduodenal hernia containing dilated small-bowel loops due to obstruction of the efferent loop at the neck of the sac.
一6岁大的女孩出现腹痛并呕吐，脐部左上有一不清晰的肿块，此次发作的大约10天前曾有过持续约数小时的类似症状，临床考虑肠套叠。超声显示脐部左侧有2处扩张的肠管，临界区位于中线处，这2处肠管有薄的包膜覆盖—之所以能看到包膜是因为囊内和腹腔存在少量积液（图7）。病人没有做进一步的检查，根据其临床病情进行了腹腔镜检查，发现十二指肠左侧的腹内疝，在疝囊内存在扩张的肠管，这是因为疝囊颈部的输出端肠管梗阻而导致的。
Figure 7. Compound transverse scan of the left side of abdomen showing the dilated loops of bowel within a sac (arrowhead) outlined by fluid on either side of it and the zone of transition at the neck of the sac (arrow).
左侧腹部的组合横向扫描显示疝囊内的扩张肠管（短箭头），疝囊周边的液体表明了其轮廓，过渡区位于疝囊的颈部（箭头）。
讨论
Internal hernia involves protrusion of a viscus, usually the small bowel, through a normal or abnormal aperture within the peritoneal cavity. This hernia may be either congenital or acquired. Congenital internal hernias include paraduodenal, foramen of Winslow, mesenteric, and supravesical hernias. During fetal development, the mesentery of the duodenum, ascending colon, and descending colon becomes fixed to the posterior peritoneum. These segments of the bowel become retroperitoneal. Anomalies of mesenteric fixation may lead to abnormal openings through which internal hernias may occur. This is the likely mechanism of paraduodenal and supravesical hernias. Abnormal mesenteric fixation may lead to abnormal mobility of the small bowel and right colon, which facilitates herniation. During fetal development, abnormal openings may occur in the pericecal, small bowel, transverse colon, or sigmoid mesentery, as well as the omentum, leading to mesenteric hernias.
腹内疝是内脏（通常是小肠）凸入腹腔内正常或异常的裂隙中，它可以是先天性的，也可以是后天性的。先天性腹内疝包括十二指肠旁疝、网膜孔（Winslow孔）疝、肠系膜疝和膀胱上疝。在胎儿发育阶段，十二指肠、升结肠和降结肠的肠系膜固定于腹腔的后壁，这些肠管位于腹膜后。肠系膜的固定异常会导致异常的裂隙，从而产生腹内疝，这有可能就是十二指肠旁疝和膀胱上疝的发病机理。肠系膜固定异常使得小肠和右结肠异常的移动，容易出现疝。在胎儿发育阶段，这种异常的裂隙可能发生在盲肠旁、小肠、横结肠或乙状结肠和网膜，造成肠系膜疝。
Paraduodenal hernias are thought to occur because of anomalies in fixation of the mesentery of the ascending or descending colon. In cases of left paraduodenal hernia, an abnormal foramen (fossa of Landzert) occurs through the mesentery close to the ligament of Treitz, leading under the distal transverse and descending colon, posterior to the superior mesenteric artery. The small bowel may protrude through this fossa. The mesentery of the colon thus forms the anterior wall of a sac enclosing a portion of the small intestine. Mesenteric hernias occur when a loop of intestine protrudes through an abnormal opening in the mesentery of the small bowel or the colon. The most common area for such an opening is in the mesentery of the small intestine, most often near the ileocolic junction. The intestine finds its way through the defects by normal peristaltic activity. Various lengths of intestine may herniate posterior to the right colon into the right paracolic gutter. Compression of the loops may lead to obstruction of the herniated intestine. Strangulation may occur by compression or by torsion of the herniated segment. Obstruction may be acute, chronic, or intermittent. The herniated bowel may also compress arteries in the margins of the mesenteric defect, causing ischemia of nonherniated intestine. Acquired internal hernias may occur as a complication of surgery or trauma if abnormal spaces or mesenteric defects are created.
十二指肠旁疝的发生被认为是由于升结肠或降结肠的肠系膜固定异常。在上面的左侧的十二指肠旁疝的病例中的肠系膜有一异常的裂隙（Landzert窝），它靠近Treitz韧带，在远端的横结肠和降结肠的下方，肠系膜上动脉的后方，而小肠就是进入了这个裂隙中。结肠系膜就成为了包绕部分小肠的疝囊的前壁。如果一部分肠管经过小肠或结肠的肠系膜上的异常裂隙凸出就形成了肠系膜疝，而这种裂隙最常发生于小肠系膜，最常见于邻近回结肠的交界处。肠管在正常蠕动就可从这个缺损穿过。不同长度的肠管从右结肠后方疝入右侧结肠旁沟。疝入的肠管受到挤压就可能导致肠梗阻，也可因为受压或发生扭转而出现绞窄，导致急性的、慢性的或者间歇性的梗阻。疝入的肠管也可以压迫肠系膜缺损边缘的动脉导致非疝入部分肠管的局部缺血。后天性腹内疝也可能是因为手术或外伤时出现异常的空腔或肠系膜缺损时出现的并发症。
Any of the various forms of internal hernias may cause symptoms of acute or chronic intermittent intestinal obstruction. The diagnosis is difficult among patients with chronic symptoms and is rarely made preoperatively among patients with acute obstruction. About half of patients with paraduodenal hernias have intestinal obstruction, which may be low grade, chronic, and recurrent or may be high 3–5 grade and acute. In acute bowel obstruction, patients have colicky abdominal pain with vomiting. Features of internal hernia on a barium meal study and CT scan are available, but reports are very scanty. Barium radiographs may show the small bowel to be bunched up or agglomerated, as if it were contained in a bag, and displaced to the left or right side of the colon. The small bowel is often absent from the pelvis. The colon may be deviated by the internal hernia sac. The bowel proximal to the hernia may be dilated.
任何类型的腹内疝均可出现急性或慢性间歇性肠梗阻的症状，而存在慢性症状的病人的诊断很困难，急性梗阻的病人中也很少能在术前做出诊断。约一半的十二指肠旁疝的病人发生肠梗阻，这种梗阻可以是程度较轻的、慢性的和复发的，也可以是程度很重的、急性的。急性肠梗阻的病人出现腹部绞痛和呕吐。钡餐检查或CT扫描中可发现有价值的腹内疝征象，但极少有此报道。钡餐透视可表现为小肠堆积成团或聚集成块，似乎像是被袋子包绕着一样，并移向结肠的左侧或右侧，盆腔内常看不到小肠，而结肠可因腹内疝而出现偏移。邻近疝囊的肠管出现扩张。
However, barium radiographic findings may be normal if the hernia has spontaneously reduced. There are a few reports of features of internal hernia on CT. The largest series was a retrospective review of 17 patients by Blachar et al. They put forth the following CT findings in internal hernia: (1) evidence of small-bowel obstruction, (2) a cluster of small-bowel loops, (3) a saclike mass of small bowel, (4) crowding of mesenteric vessels, and (5) displacement of the mesenteric trunk. 7 Schaffler et al described a pathognomonic anterior and upward displacement of the inferior mesenteric vein in paraduodenal internal hernia. A barium meal study of the small bowel involves more time and may delay the diagnosis. The clinical condition of the patient may preclude a time-consuming investigation. A CT scan is the investigation of choice at present, but it has the disadvantage of cost and nonavailability, particularly in developing nations. In contrast, sonography is more readily available and affordable in this part of the world. Sonography is the first investigation requested for patients with abdominal symptoms. Hence, recognition of sonographic features of internal hernia will be an advantage, and it will be useful in the treatment of such patients, especially in developing countries. An acute occurrence of an internal hernia is due to obstruction of the small bowel. Sonographic features of small-bowel obstruction are well described. There are dilated small-bowel loops showing active peristalsis. The peristalsis is usually pendular, with to-and-fro movement of fluid on the lumen. This is because of reverse peristalsis occurring due to distal obstruction. Sonography is useful in differentiating mechanical obstruction from paralytic ileus. In the absence of peristalsis, passive to-and-fro movement of the fluid in the lumen with respiration, widespread distri-bution of dilated bowel loopswithout a demonstrable level, uniformity of bowel obstruction, and demonstration of the cause of ileus are the features of paralytic ileus. The sensitivity and specificity of sonography for the diagnosis of small-bowel obstruction are as high as 83% and 100%, as reported by Suri et al. The level of obstruction is correctly predicted by sonography in 70% of patients, but sonography is poor (23%) in showing the etiology of obstruction. The difficulty is caused by gas in the obstructed bowel, which makes sonography difficult. This can be partly overcome by compression of the bowel loop, displacing the air; thus, the bowel can be traced distally to identify the level and cause of obstruction. This technique may be difficult in very obese patients. So far, to my knowledge, there is only 1 report of sonographic features of internal abdominal hernia, which describes an abdominal mass with the presence of changing cystic or tubular internal components and a surrounding membrane.
然而，如果腹内疝出现自发复位，钡餐检查可以表现正常。有几篇关于腹内疝CT表现的报道，其中最大的研究是由Blachar等人对17例病例所作的回顾性分析，他们提出以下的腹内疝CT表现：（1）小肠梗阻的证据；（2）小肠肠管堆积；（3）小肠的囊性团块；（4）肠系膜血管拥挤；（5）肠系膜蒂的移位。Schaffler等人提出了十二指肠旁疝中肠系膜下静脉向前上移位的特异性表现。小肠钡餐检查需要很多的时间，可能会延误诊断，而病人的病情不允许费时的检查。CT扫描是目前可选的检查方法，但其不足之处是价格昂贵，尤其是在疾病的进展阶段效果不佳，而超声更具价值，价格也可以承受，它是腹痛病人所需的首选检查方法，因而，识别腹内疝的超声特征很有必要，同时对病人的治疗也有益处，尤其是处于进展阶段的病人。腹内疝的急性病变是由于小肠梗阻导致的，而超声能明确的分辨小肠梗阻的特征。扩张的小肠肠管存在蠕动活跃，蠕动通常呈摆动状，肠管内的液体内容物来回运动，这是由于远端的肠管梗阻而导致的反向蠕动。超声可以区分机械性梗阻和麻痹性梗阻。麻痹性肠梗阻的特征包括蠕动的消失、肠管的液性内容物随呼吸而被动的来回运动、远端肠管梗阻但其梗阻水平不能确定、肠管梗阻程度不一致、梗阻的病因明确。据Suri等报道，超声诊断小肠梗阻的敏感性和特异性高达83%和100%，超声能对70%的病人准确的判断出梗阻的水平，但超声显示梗阻病因的能力很有限（23%），梗阻肠管内的气体是造成超声诊断困难的原因，而通过对梗阻肠管的挤压赶走空气可以部分的克服，从而可以沿着肠管的走形确定梗阻的水平和原因，但这种方式对非常肥胖的病人还是存在困难。据我们所知，到目前为止仅有1例关于腹内疝超声特征的报道，将其描述为腹部的团块，表现为不断变化的囊性或管状的内部成分和外周包膜。
