Regardless of cause,<unk>  causes symptoms by two mechanisms: * Bowel obstruction manifested as abdominal distension and bilious vomiting. * Ischemia (loss of blood flow) to the affected portion of intestine. Depending on the location of the<unk> , symptoms may vary. For example, in patients with cecal<unk> , the predominant symptoms may be those of 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 sigmoid<unk> , although abdominal pain may be present, symptoms of constipation may be more prominent.<unk>  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. This is known as a closed-loop obstruction because there exists an isolated ("closed") loop of bowel. Acute<unk>  often requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion.<unk>  occurs most frequently in middle-aged and elderly men.<unk>  can also arise as a rare complication in persons with redundant colon, a normal anatomic variation resulting in extra colonic loops. Sigmoid<unk>  is the most-common form of<unk>  of the gastrointestinal tract. and is responsible for 8% of all intestinal obstructions. Sigmoid<unk>  is particularly common in elderly persons and constipated patients. Patients experience abdominal pain, distension, and absolute constipation. Cecal<unk>  is slightly less common than sigmoid<unk>  and is associated with symptoms of abdominal pain and small bowel obstruction.<unk>  can also occur in patients with Duchenne muscular dystrophy due to smooth muscle dysfunction. Gastric<unk>  causes nausea, vomiting, and pain in the upper abdomen. The Borchardt triad is a group of symptoms that help doctors to identify gastric<unk> . The symptoms are intractable retching, pain in the upper abdomen and inability to pass nasogastric tube into the stomach.
Volvulus
Diverticulum
Rectal foreign body
Anal fissure
Rectitis
Fecal impaction
Vesicointestinal fistula
Proctocolitis