The causes of diverticulitis are poorly understood, with approximately 40 percent due to genes and 60 percent due to environmental factors. Conditions that increase the risk of developing diverticulitis include arterial hypertension and immunosuppression. Obesity is another risk factor.

Screening for colonic polyps as well as preventing them has become an important part of the management of the condition. Medical societies have established guidelines for colorectal screening in order to prevent adenomatous polyps and to minimize the chances of developing colon cancer. It is believed that some changes in the diet might be helpful in preventing polyps from occurring but there is no other way to prevent the polyps from developing into cancerous growths than by detecting and removing them.

According to the guidelines established by the American Cancer Society, individuals who reach the age of 50 should perform an occult blood test yearly. Colon polyps as they grow can sometimes cause bleeding within the intestine, which can be detected with the help of this test. Also, persons in their 50s are recommended to have flexible sigmoidoscopies performed once in 3 to 5 years to detect any abnormal growth which could be an adenomatous polyp. If adenomatous polyps are detected during this procedure, it is most likely that the patient will have to undergo a colonoscopy. Medical societies recommend colonoscopies every ten years starting at age 50 as a necessary screening practice for colon cancer. The screening provides an accurate image of the intestine and also allows the removal of the polyp, if found. Once an adenomatous polyp is identified during colonoscopy, there are several methods of removal including using a snare or a heating device. Colonoscopies are preferred over sigmoidoscopies because they allow the examination of the entire colon; a very important aspect, considering that more than half of the colonic polyps occur in the upper colon, which is not reached during sigmoidoscopies.

It has been statistically demonstrated that screening programs are effective in reducing the number of deaths caused by colon cancer due to adenomatous polyps. While there are risks of complications associated with colonoscopies, those risks are extremely low at approximately 0.35 percent. For comparison, the lifetime risk of developing colon cancer is around 6 percent. As there is a small likelihood of recurrence, surveillance after polyp removal is recommended.

It is unclear what role dietary fibre plays in diverticulitis. It is often stated that a diet low in fibre is a risk factor; however, the evidence to support this is unclear. There is no evidence to suggest that the avoidance of nuts and seeds prevents the progression of diverticulosis to an acute case of diverticulitis. It appears in fact that a higher intake of nuts and corn could help to avoid diverticulitis in adult males.

The prevalence of diverticulosis progressively increases with age. Approximately 50% of people over the age of 60 and 70% of people over the age of 80 have diverticulosis. This disease is common in the U.S., Britain, Australia, Canada, and is uncommon in Asia and Africa. Large-mouth diverticula are associated with scleroderma. Diverticular disease is more common in collagen disorders such as Ehlers Danlos Syndrome.

The risks of progression to colorectal cancer increases if the polyp is larger than 1 cm and contains a higher percentage of villous component. Also, the shape of the polyps is related to the risk of progression into carcinoma. Polyps that are pedunculated (with a stalk) are usually less dangerous than sessile polyps (flat polyps). Sessile polyps have a shorter pathway for migration of invasive cells from the tumor into submucosal and more distant structures, and they are also more difficult to remove and to ascertain. Sessile polyps larger than 2 cm usually contain villous features, have a higher malignant potential, and tend to recur following colonoscopic polypectomy.

Although polyps do not carry significant risk of colon cancer, tubular adenomatous polyps may become cancerous when they grow larger. Larger tubular adenomatous polyps have an increased risk of malignancy when larger because then they develop more villous components and may become sessile.

It is estimated that an individual whose parents have been diagnosed with an adenomatous polyp has a 50% greater chance to develop colon cancer than individuals with no family history of colonic polyps. At this point, there is no method to establish the risks that patients with a family history of colon polyps have to develop these growths. Overall, nearly 6% of the population, regardless of the family history, is at risk of developing colon cancer.

The U.S. National Institutes of Health notes that, although the low-fiber theory of the cause of diverticulosis is the leading theory, it has not yet been proven.

Laparotomy for other forms of volvulus, especially anal volvulus.

Fundic gland polyps are found in 0.8 to 1.9% of patients who undergo esophagogastroduodenoscopy, and are more common in middle aged women.

The most important consideration in evaluating patients with FGPs is distinguishing between sporadic form (patients without any other gastrointestinal condition, usually in middle age with female prevalence) and syndromic form. This is to ascertain the risk of development of gastric cancer, and to ascertain the risk of concomitant colon cancer.

FGPs can be found in association with the following genetic conditions:

- familial adenomatous polyposis

- attenuated familial adenomatous polyposis syndromes

- Zollinger-Ellison syndrome

- gastric adenocarcinoma associated with proxymal polyposis of the stomach (GAPPS): this condition, described in three families is characterized by development of antral adenomas and FGPs, with early development of severe dysplasia and gastric cancer, in absence of overt intestinal polyposis. This condition has been recently characterized by a point mutation in exon 1B of APC gene.

Sporadic FGPs have been associated with:

- chronic use of proton pump inhibitors (proposed by some authors, denied by others)

- "Helicobacter pylori" infection: there is a reverse relationship between infection and fundic gland polyps, and infection by "H pylori" causes polyps regression.

Risperidone, an anti-psychotic medication, can result in megacolon.

This is a very rare phenomenon (50 years of age), and more commonly in women than men (5:1). There is an increased frequency in Okinawa, Japan, but this may be a reporting bias.

The tumor develops very specifically in the subscapular or infrascapular area, deep to the muscle, sometimes even attached to periosteum of ribs. It is usually between the shoulder blade and the lower neck, with rare tumors reported in the chest wall.

Also called Hirschsprung's disease, it is a congenital disorder of the colon in which nerve cells of the myenteric plexus in its walls, also known as ganglion cells, are absent. It is a rare disorder (1:5 000), with prevalence among males being four times that of females. Hirschsprung’s disease develops in the fetus during the early stages of pregnancy. A genetic predisposition to Hirschsprung's disease has been linked to chromosome 13 where a missense mutation at an ultraconserved region impairs functionality of the W276C receptor. Seven other genes seem to be implicated, however. If untreated, the patient can develop enterocolitis.

Lipomatosis is believed to be a hereditary condition in which multiple lipomas are present on the body.

Adiposis dolorosa (Dercum disease) is a rare condition involving multiple painful lipomas, swelling, and fatigue. Early studies mentioned prevalence in obese postmenopausal women. However, current literature demonstrates that Dercum disease is present in more women than men of all body types; the average age for diagnosis is 35 years.

Benign symmetric lipomatosis (Madelung disease) is another condition involving lipomatosis. It nearly always appears in middle-aged males after many years of alcoholism. But, non-alcoholics and females can also be affected.

In a cecal volvulus, the cecum may be returned to a normal position and sutured in place, a procedure known as cecopexy. If identified early, before presumed intestinal wall ischemia has resulted in tissue breakdown and necrosis, the cecal volvulus can be detorsed laparoscopically.

Lipomas are rarely life-threatening and the common subcutaneous lipomas are not a serious condition. Lipomas growing in internal organs can be more dangerous; for example lipomas in the gastrointestinal tract can cause bleeding, ulceration and painful obstructions (so-called "malignant by location", despite being a benign growth histologically). Malignant transformation of lipomas into liposarcomas is very rare and most liposarcomas are not produced from pre-existing benign lesions. A few cases of malignant transformation have been described for bone and kidney lipomas, but it is possible these few reported cases were well-differentiated liposarcomas in which the subtle malignant characteristics were missed when the tumour was first examined. Deep lipomas have a greater tendency to recur than superficial lipomas, because complete surgical removal of deep lipomas is not always possible.

The presence of multiple lipomas is known as lipomatosis and is more commonly encountered in men. Some superficial lipomas can extend into deep fascia and may complicate excision. Liposarcoma is found in 1% of lipomas and are more likely in lesions of the lower extremities, shoulders and retroperitoneal areas. Other risk factors for liposarcoma include large size (>5 cm), associated with calcification, rapid growth and/or invasion into nearby structures or through fascia into muscle tissue.

The tumor is rare, affecting adults in the 4th decade most commonly. Patients are usually younger than those who present with a lipoma. There is a slight male predominance. Hibernoma are most commonly identified in the subcutaneous and muscle tissue of the head and neck region (shoulders, neck, scapular), followed by thigh, back, chest, abdomen, and arms. In rare cases hibernoma may arise in bone tissue, however it is an incidental finding.

There is a risk of development of cancer with fundic gland polyposis, but it varies based on the underlying cause of the polyposis. The risk is highest with congenital polyposis syndromes, and is lowest in acquired causes. As a result, it is recommended that patients with multiple fundic polyps have a colonoscopy to evaluate the colon. If there are polyps seen on colonoscopy, genetic testing and testing of family members is recommended.

In the gastric adenocarcinoma associated with proximal polyposis of the stomach (GAPPS), there is a high risk of early development of proximal gastric adenocarcinoma.

It is still unclear which patients would benefit with surveillance gastroscopy, but most physicians recommend endoscopy every one to three years to survey polyps for dysplasia or cancer. In the event of high grade dysplasia, polypectomy, which is done through the endoscopy, or partial gastrectomy may be recommended. One study showed the benefit of NSAID therapy in regression of gastric polyps, but the efficacy of this strategy (given the side effects of NSAIDs) is still dubious.

With early intervention, morbidity and mortality of cases of intestinal obstruction is low. The outcome is in part dependent upon congenital comorbidities and delays in diagnosis and management.

An increasing number of people are now surviving cancer, with improved treatments producing cure of the malignancy (cancer survivors). There are now over 14 million such people in the US, and this figure is expected to increase to 18 million by 2022. More than half are survivors of abdominal or pelvic cancers, with about 300,000 people receiving abdominal and pelvic radiation each year. It has been estimated there are 1.6 million people in the US with post-radiation intestinal dysfunction, a greater number than those with inflammatory bowel disease such as Crohn's disease or ulcerative colitis.

It is a serious medical disorder and the mortality rate can be as high as 30%. The high mortality rate is likely a measure that this syndrome is seen in critically ill patients, rather than this syndrome being in itself lethal, although it can also present in otherwise healthy individuals (especially if the disorder was induced by pharmacologic agents). Drug induced megacolon (i.e. from Clozapine) has been associated with mortality as high as 27.5%.

Complete removal of a SSA is considered curative.

Several SSAs confer a higher risk of subsequently finding colorectal cancer and warrant more frequent surveillance. The surveillance guidelines are the same as for other colonic adenomas. The surveillance interval is dependent on (1) the number of adenomas, (2) the size of the adenomas, and (3) the presence of high-grade microscopic features.

An ileosigmoid knot is a form of volvulus in which ileum wraps around the base of the sigmoid and passes beneath itself forming a knot.

The exact cause of this condition is not known. Patients usually present with clinical features of colonic obstruction. Vomiting, abdominal distension, abdominal pain, blood stained stools are frequent symptoms. It is difficult to diagnose this condition before surgery. Raveenthiran described a triad which may be useful in preoperative diagnosis. The triad includes 1). Clinical features suggestive of small bowel obstruction, 2). Radiological features suggestive of large bowel obstruction, 3). Inability to negotiate sigmoidoscope or a flatus tube. This is a surgical emergency that requires urgent resection of gangrenous bowel and untwisting of the volvulus.

An adipose tissue neoplasm is a neoplasm derived from adipose tissue.

An example is lipoma.

Villous adenoma is a type of polyp that grows in the colon and other places in the gastrointestinal tract and sometimes in other parts of the body. These adenomas may become malignant (cancerous). Villous adenomas have been demonstrated to contain malignant portions in about one third of affected persons, and invasive malignancy in another one third of removed specimens. Colonic resection may be required for large lesions. These can also lead to secretory diarrhea with large volume liquid stools with few formed elements. They are commonly described as secreting large amounts of mucus, resulting in hypokalaemia in patients. On endoscopy a "cauliflower' like mass is described due to villi stretching. Being an adenoma, the mass is covered in columnar epithelial cells.

In most cases, the cause of acoustic neuromas is unknown. The only statistically significant risk factor for developing an acoustic neuroma is having a rare genetic condition called neurofibromatosis type 2 (NF2). There are no confirmed environmental risk factors for acoustic neuroma. There are conflicting studies on the association between acoustic neuromas and cellular phone use and repeated exposure to loud noise. In 2011, an arm of the World Health Organization released a statement listing cell phone use as a low grade cancer risk. The Acoustic Neuroma Association recommends that cell phone users use a hands-free device.

Meningiomas are significantly more common in women than in men; they are most common in middle-aged women. Two predisposing factors associated with meningiomas for which at least some evidence exists are exposure to ionizing radiation (cancer treatment of brain tumors) and hormone replacement therapy.

According to a 1984 study conducted in Maryland, Hirschsprung's disease appears in 18.6 per 100,000 live births. In Japan, it occurs at a similar rate of about one in 5,000 births (20 per 100,000). It is more common in male than female (4.32:1) and in white rather than nonwhite. Nine percent of the Hirschsprung cases were also diagnosed as having Down syndrome. Most cases are diagnosed before the patient is 10 years of age.