A<unk>  is a loop of the bowel that has twisted on itself or around the axis of the mesentery. The pathophysiology and treatment of<unk>  were established in the 20th century, by William Ladd. However, evidence for cases of<unk>  go as far back as 1550 BC in Egypt.<unk>  can happen at various parts of the gastrointestinal tract.<unk>  can also occur congenitally or acquired in a newborn, an infant or an adult. These include sigmoid<unk> , cecal<unk> , gastric<unk>  and ileal<unk> . Regardless of cause,<unk>  causes symptoms by two mechanisms. One is bowel obstruction, manifested as abdominal distension and vomiting.  The other is  ischemia (loss of blood flow) to the affected portion of intestine. This causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death. Acute<unk>  therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion. Midgut<unk>  occurs in patients (usually in infants) that are predisposed because of congenital intestinal malrotation. Segmental<unk>  occurs in patients of any age, usually with a predisposition because of abnormal intestinal contents (e.g. meconium ileus) or adhesions.<unk>  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.<unk>  must be distinguished from other diseases, as it may be a solitary finding or a feature of another disease. Differential diagnoses include:Crohn's disease, necrotizing enterocolitis, duodenal atresia, pyloric stenosis, toxic megacolon and pseudocolonic obstruction (Ogilvie syndrome). Acute mechanical small bowel obstruction is a common surgical emergency where<unk>  is the cause in 10% of cases. It is estimated that over 300,000 laparotomies are performed per year in the United States for adhesion-related obstructions such as<unk> .<unk>  originating in the colon is the third most common cause of large bowel obstruction. Common risk factors in the development of<unk>  include pregnancy, chronic constipation, age over 50, and long sigmoid colon and mesentery. There is insufficient evidence to recommend routine screening for<unk> . However, there are screening programs in place that utilize an ultrasound to seek out intestinal malrotation, which may be a cause of fatal midgut<unk> . If left untreated, the majority of patients with<unk>  may progress to develop gangrene of the bowel, which can be fatal. Common complications of<unk>  include bowel ischemia, gangrene, and necrosis. Prognosis is generally excellent, so long as the affected part of the bowel is resected or untwisted before ischemia occurs, usually within 48-72 hours. If necrosis of the affected bowel has already occurred then the prognosis is poor and may be fatal. There is no single diagnostic study of choice for the diagnosis of<unk> .<unk>  can be diagnosed based on clinical findings and on the findings on CT scan, plain x-ray or plain x-ray with contrast. The most common symptoms of<unk>  include abdominal pain, abdominal distension, constipation and vomiting. Patients are usually elderly or institutionalized. Patients with<unk>  usually appear in distress. Physical examination of patients with<unk>  is usually remarkable for abdominal distention and abdominal tenderness. An x-ray (with or without contrast) may be helpful in the diagnosis of<unk> . Findings on an x-ray suggestive of sigmoid, cecal and ileal<unk>  include; u-shaped, distended segment of colon seen as an ahaustral collection of gas<unk> . Findings on an x-ray suggestive of gastric<unk>  includes a single, large, spherical gas bubble located in the upper abdomen or chest with an air-fluid level. It is important to rule out pneumoperitoneum before carrying out a barium enema. The initial investigation for<unk>  can be a plain x-ray without contrast, or a CT scan. CT scan is useful in diagnosing<unk>  when x-ray has been unfruitful. CT can also identify the level of obstruction and determine if bowel necrosis has occurred. Laparoscopy may be helpful in the diagnosis of complicated<unk>  when diagnosis is equivocal by other imaging modalities. Surgery is the mainstay of treatment for<unk> . Endoscopic and nasogastric decompression may be used initially in an attempt to detorse the<unk>  when feasible. Subsequently, an open procedure or laparotomy may follow to enter the abdomen, untwist the bowels and restore the blood supply. Necrotic bowel is either resected and re-anastomosed with the remaining bowel or is connected externally by colostomy or ileostomy.
Volvulus
Fecaloma
Rectal foreign body
Anal fissure
Fecal impaction
Vesicointestinal fistula
Anal abscess
Pseudomembranous colitis