Just to correct a typo in the first answer: the total number of nodes for a tree of depth L is (N^(L+1)-1) / (N-1)... (that is, to the power L+1 rather than just L). This can be shown as follows. First, take our theorem: 1 + N^1 + N^2 + ... + N^L = (N^(L+1)-1)/(N-1) Multiply both sides by (N-1): (N-1)(1 + N^1 + N^2 + ... + N^L) = N^(L+1)-1.
Malignancy is the most common cause of large bowel obstruction in older patients. Colon carcinoma without obstruction does not usually cause acute abdominal pain. Diverticulitis and colonic volvulus (i.e., narrowed, twisted lumen with a birdâs beak appearance) are less common causes of large bowel obstruction.4,5,14,35.
Mechanical causes of an acute abdomen include such obstructive conditions as incarcerated hernia, post-operative adhesions, intussusception, malrotation of the gut with volvulus, congenital atresia or stenosis of the gut. The most common cause of large bowel mechanical obstruction is carcinoma of the colon. Vascular entities producing an acute abdomen include mesenteric arterial thrombosis or embolism. When the blood supply is cut off, necrosis of tissue results, with gangrene of the bowel.