出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/03 22:22:35」(JST)
| Volvulus | |
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| Classification and external resources | |
Coronal CT of the abdomen, demonstrating a volvulus as indicated by twisting of the bowel stock
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| ICD-10 | K56.2 |
| ICD-9 | 537.3, 560.2 |
| DiseasesDB | 13996 |
| eMedicine | ped/2415 |
| MeSH | D045822 |
A volvulus is a bowel obstruction[1] of a loop of bowel whose nose has completely twisted around its site of mesenteric attachment.[2]
| This section is in a list format that may be better presented using prose. You can help by converting this section to prose, if appropriate. Editing help is available. (April 2012) |
Regardless of cause, volvulus causes symptoms by two mechanisms:[citation needed]
Depending on the location of the volvulus, symptoms may vary. For example, in patients with a cecal volvulus, the predominant symptoms may be those of a small bowel obstruction (nausea, vomiting and lack of stool or flatus), because the obstructing point is close to the ileocecal valve and small intestine. In patients with a sigmoid volvulus, although abdominal pain may be present, symptoms of constipation may be more prominent.
Volvulus causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed.[2] Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death. This is known as a closed loop obstruction because there exists an isolated ("closed") loop of bowel. Acute volvulus often requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion.[2]
Volvulus occurs most frequently in middle-aged and elderly men.[2] Volvulus can also arise as a rare complication in persons with redundant colon, a normal anatomic variation resulting in extra colonic loops.[3]
Sigmoid volvulus is the most-common form of volvulus of the gastrointestinal tract[4] and is responsible for 8% of all intestinal obstructions.[citation needed] Sigmoid volvulus is particularly common in elderly persons and constipated patients. Patients experience abdominal pain, distension, and absolute constipation.
Cecal volvulus is slightly less common than sigmoid volvulus and is associated with symptoms of abdominal pain and small bowel obstruction.
Volvulus can also occur in patients with Duchenne muscular dystrophy due to the smooth muscle dysfunction.[citation needed]
| This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (April 2012) |
Midgut volvulus occurs in patients (usually in infants) that are predisposed because of congenital intestinal malrotation. Segmental volvulus occurs in patients of any age, usually with a predisposition because of abnormal intestinal contents (e.g. meconium ileus) or adhesions. Volvulus of the cecum, transverse colon, or sigmoid colon occurs, usually in adults, with only minor predisposing factors such as redundant (excess, inadequately supported) intestinal tissue and constipation.
After taking a thorough history, the diagnosis of colonic volvulus is usually easily included in the differential diagnosis. Abdominal plain x-rays are commonly confirmatory for a volvulus, especially if a "bent inner tube" sign or a "coffee bean" sign are seen. These refer to the shape of the air filled closed loop of colon which forms the volvulus. Should the diagnosis be in doubt, a barium enema may be used to demonstrate a "bird's beak" at the point where the segment of proximal bowel and distal bowel rotate to form the volvulus. This area shows an acute and sharp tapering and looks like a bird's beak. If a perforation is suspected, barium should not be used due to its potentially lethal effects when distributed throughout the free infraperitoneal cavity. Gastrografin, which is safer, can be substituted for barium.
The differential diagnosis includes the much more common constricting or obstructing carcinoma. In approximately 80 percent of colonic obstructions, an invasive carcinoma is found to be the cause of the obstruction. This is usually easily diagnosed with endoscopic biopsies.
Diverticulitis is a common condition with different presentations. Although diverticulitis may be the source of a colonic obstruction, it more commonly causes an ileus, which appears to be a colonic obstruction. [5] Endoscopic means can be used to secure a diagnosis although this may cause a perforation of the inflamed diverticular area. CT scanning is the more common method to diagnose diverticulitis. The scan will show mesenteric stranding in the involved segment of edematous colon which is usually in the sigmoid region. Micro perforations with free air may be seen.
Ulcerative colitis or Crohn's disease may cause colonic obstruction. The obstruction may be acute or chronic after years of uncontrolled disease leads to the formation of strictures and fistulas . The medical history is helpful in that most cases of inflammatory bowel disease are well known to both patient and doctor.
Other rare syndromes, including Ogilvie's syndrome, chronic constipation and impaction may cause a pseudo obstruction. [6]
| This section requires expansion. (April 2012) |
Perform sigmoidoscopy for suspected sigmoid volvulus. If the mucosa of the sigmoid looks normal and pink, place a rectal tube for decompression, repair any fluid, electrolyte, cardiac, renal or pulmonary evaluation and repair, and then take the patient to the operating room for repair. If surgery is not performed, there is a high rate of recurrence.
For patients with signs of sepsis or an abdominal catastrophe, immediate surgery and resection is advised.
Laparotomy for other forms of volvulus, especially cecal volvulus.
| Wikimedia Commons has media related to Volvulus. |
CT of an abdomen with sigmoid volvulus
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| 関連記事 | 「intestinal」「volvulus」 |