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.
Volvulus can also occur in the large bowel, most often in the sigmoid colon. Other possible causes of bowel obstruction include: 1  Impacted stools (poo) from severe constipation. 2  Diseases that affect the intestinal wall such as Crohn's disease or diverticular disease. 3  Gallstones.4  A swallowed item. 5  Intussusception, where part of the intestine folds in on itself.here are a number of causes that could be responsible for a bowel obstruction, both mechanical and non-mechanical. Paralytic ileus refers to a non-mechanical obstruction where the rhythmic muscle contractions of the intestine, known as peristalsis, stops.