What Is the Lesser Omentum?

It is the part where the visceral peritoneum migrates from the stomach to the hilum, and is formed by a double-layer peritoneum, which is connected between the lower part of the liver and the small curvature of the stomach and the upper part of the duodenum. Divided into two parts, one is located between the liver and stomach, called the liver-gastric ligament; the other is located between the liver and the upper duodenum, called the liver-duodenal ligament. There is no clear demarcation between the two parts. The right edge of the small omentum is a free edge, and there is an omentum hole (Winslow hole) behind the edge. The border of the omentum: the front border is the free border of the small omentum, the upper border is the liver, the posterior border is the inferior vena cava (via the peritoneum), and the lower border is the upper duodenum. The omentum hole is used to lead to the omental sac, and the right omentum hole is connected to the large peritoneal sac. The anterior border of the omental foramen, that is, the hepatoduodenal ligament contains portal veins, hepatic arteries, and common bile ducts that enter and exit the hepatic portal.

It is the part where the visceral peritoneum migrates from the stomach to the hilum, and is formed by a double-layer peritoneum, which is connected between the lower part of the liver and the small curvature of the stomach and the upper part of the duodenum. Divided into two parts, one is located between the liver and stomach, called the liver-gastric ligament; the other is located between the liver and the upper duodenum, called the liver-duodenal ligament. There is no clear demarcation between the two parts. The right edge of the small omentum is a free edge, and there is an omentum hole (Winslow hole) behind the edge. The border of the omentum: the front border is the free border of the small omentum, the upper border is the liver, the posterior border is the inferior vena cava (via the peritoneum), and the lower border is the upper duodenum. The omentum hole is used to lead to the omental sac, and the right omentum hole is connected to the large peritoneal sac. The anterior border of the omental foramen, that is, the hepatoduodenal ligament contains portal veins, hepatic arteries, and common bile ducts that enter and exit the hepatic portal.

Chinese name

Small omentum

Foreign name

lesser omentum

Location

Between hilar and small stomach, upper duodenum

Structure

Double peritoneal structure

Application area

anatomy

Small omentum hernia

Intraabdominal hernia formed by intestinal hernia into the small omental sac is called small omental sac hernia. It is relatively rare clinically, and there is no obvious specificity in the age and gender of onset.

Causes and classification of small omentum

It can be divided into four types according to the cause of the disease, the path of the hernia ring or intestinal diaphragmatic hernia into the small omental sac.

1. Winslow hernia is formed by abdominal organs entering the small omental sac through the Winslow foramen. The Winslow hole is also called the small omental hole. It is located behind the hepatoduodenal ligament. It is the port of the small omentum and other parts of the abdominal cavity. Therefore, the Winslow hole hernia is also called the small omental hernia. The disease was first reported by Blandin (1834), accounting for 0.08% of all hernias and 8% of internal hernias. Clinically, it is very common in men. Hernia contents are 63% in the small intestine, 30% in the terminal ileum and / or cecum, 7% in the transverse colon, and very few in the gallbladder and omentum. Review of the literature, only 2 cases were reported in China. Because of no specific manifestations, the patient was diagnosed or suspected of having less than 10% of the disease before surgery, and the mortality rate was as high as 49%.

The causes are as follows.

(1) The Winslow hole is too large: Except for a few unusual cases, almost all individuals have an open Winslow hole. Under normal circumstances, this hole is small. If it is too large for some reason, it may provide a "hernia port" for hernia in the intestine. Some people believe that the Winslow hole is too large to pass or accommodate more than two fingers, is the first condition for the formation of Winslow hole hernia.

(2) Excessive swimming of the intestine: Excessive swimming of the intestine is another important condition for the internal hernia to pass through the Winslow hole. Common causes of excessive bowel movements are: the mesentery of the small intestine is too long; congenital intestinal malrotation, which can be accompanied by poor fixation of the midgut. Free, high cecum, incomplete omentum attachment, enlarged duodenal crypts, etc., cause excessive intestinal motility, in addition to causing intestinal torsion, but also an important cause of intraabdominal hernia.

(3) Abnormal bowel movements and sudden increase in intra-abdominal pressure: The bowel can easily enter the small intestine from the Winslow foramen under the influence of abnormal bowel movements or overeating, part of the weight of the intestine increases, the patient's position changes suddenly, and abdomen pressure rises suddenly. A small omental hernia is formed inside the omental sac. The anterior wall of the hernia ring is the hepatoduodenal ligament, which contains the common bile duct, the portal vein, and the hepatic artery; the inferior vena cava and the spine are behind. The structure forming the hernia ring is strong and has a small expansion property, and it is easy to compress the intestine through the hernia ring, making it difficult to recover, and easily incarcerating and narrowing the contents of the hernia.

2. Transverse mesenteric hiatal hernia: The intestinal canal enters the small omental sac from the transverse mesenteric hiatus.

3. hiatal hernia of the hepatogastric ligament: the intestinal canal enters the small omentum sac from the hiatus of the hepatogastric ligament (small omentum).

4. Gastric colon ligament hiatal hernia: The intestinal canal enters the small omental sac from the gastrocolic ligament hiatus.

Small omentum (3 photos)

Omentum clinical manifestations

The main clinical manifestations of this disease are acute intestinal obstruction. Patients may have symptoms such as upper abdominal pain, vomiting, and anal exhaustion.

1. Abdominal pain: It is acute onset colic, which is more severe and unbearable. Because the anterior wall of the hernia ring (hepatoduodenal ligament) is relatively loose when the patient's body flexes, abdominal pain can be reduced when the patient sits on the bed or knees are bent to the jaw or flexed in a chair, and some patients can also feel the lower back pain. Some scholars believe that the reduction of abdominal pain during body flexion is a characteristic manifestation of Winslow foramen.

2. The degree of vomiting and bloating is related to the organs that are hernias. If it is an intestine, the vomiting is more severe; if it is the omentum, the vomiting may be mild. If the hernia into the organ is the upper part of the jejunum, vomiting occurs early and frequently, and abdominal distension is generally not obvious; if the hernia into the organ is the ileum or colon, the vomiting occurs late and the degree of abdominal distension is also obvious.

3. Physical examination can find that the patient's upper abdomen is full, and the left upper abdomen can often touch soft cystic masses with tenderness fixed. Early percussion was drum sounds, mostly dull sounds after exudation, and hyperintestinal sounds or sounds of water over the breath could be heard. If the bowel sounds disappear, or the symptoms of peritoneal irritation, or hemorrhagic turbid fluid is drawn through the abdominal puncture, it indicates that the hernia enters the intestinal canal to be strangulated or necrotic. In severe cases, there may be shock performance. A small number of patients may develop obstructive jaundice due to compression of the common bile duct in the anterior wall of the hernia ring.

4. Imaging examination

(1) X-ray examination of the abdomen

a. An upright or supine abdominal plain film such as the contents of the hernia is an intestinal canal. You can see the curved intestinal gas and gas-liquid plane in the small omentum sac area and shift the left front of the stomach. A small bowel crest may be seen in the right abdomen that rises to the Winslow hole below the liver. If the hernia contains ascending colon, intestinal qi and fecal accumulation cannot be seen on the right abdomen.

b. Upper gastrointestinal angiography can show that the stomach is pushed to the left. Delayed angiography shows that the intestine is located in the small omental sac.

c. When the barium enema hernia is colon, it can be shown that the colon is located in the small omental sac.

d. The main signs of CT scan are: the mesentery is located between the inferior vena cava and the portal vein; there is a gas-liquid plane in the small omentum sac, and it is pointed at the omental foramen; Two or more bowels can be seen in the inferior space.

(2) An abnormal intestinal echo was seen in the sub-hepatic, small omental sac foramen, common bile duct and portal vein, and small omental sac area.

(3) 99mTc-HIDA cholangiography When the hernia is the gallbladder, 99mTc-HIDA cholangiography can show abnormal gallbladder and biliary tract position.