A high-fiber diet and fiber supplements are advisable to prevent constipation. The American Dietetic Association recommends 20–35 grams each day. Wheat bran has been shown to reduce intra colonic pressure.

The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says foods such as nuts, popcorn hulls, sunflower seeds, pumpkin seeds, caraway seeds, and sesame seeds have traditionally been labeled as problem foods for people with this condition; however, no scientific data exists to prove this hypothesis. The seeds in tomatoes, zucchini, cucumbers, strawberries, raspberries, and poppy seeds, are not considered harmful by the NIDDK.

One study found that nuts and popcorn do not contribute positively or negatively to patients with diverticulosis or diverticular complications.

Many people with diverticulosis have minimal to no symptoms, and do not require any specific treatment. Colonic stimulants should be avoided. Treatments, like some colon cleansers, that cause hard stools, constipation, and straining, are not recommended.

People may be placed on a low fibre diet. It was previously thought that a low-fibre diet gives the colon adequate time to heal. Evidence tends to run counter to this with a 2011 review finding no evidence for the superiority of low fibre diets in treating diverticular disease and that a high-fibre diet may prevent diverticular disease. A systematic review published in 2012 found no high quality studies, but found that some studies and guidelines favour a high-fibre diet for the treatment of symptomatic disease. While it has been suggested that probiotics may be useful for treatment, the evidence currently neither supports nor refutes this claim.

Most cases of simple, uncomplicated diverticulitis respond to conservative therapy with bowel rest.

Laparotomy for other forms of volvulus, especially anal volvulus.

Treatment for sigmoid volvulus may include sigmoidoscopy. If the mucosa of the sigmoid looks normal and pink, place a rectal tube for decompression, correct any fluid, electrolyte, cardiac, renal or pulmonary abnormalities and then take the person to the operating room for repair. If surgery is not performed, there is a high rate of recurrence.

For people with signs of sepsis or an abdominal catastrophe, immediate surgery and resection is advised.

Diverticular disease is when problems occur due to diverticulosis, a condition defined by the presence of pouches in the wall of the large intestine (diverticula). This includes diverticula becoming inflamed (diverticulitis) or bleeding. Colonic perforation due to diverticular disease may be classified using the Hinchey Classification.

Conditions such as ulcerative colitis or certain types of relapsing infectious diarrhea can vary in severity over time, and FOBT may assist in assessing the severity of the disease. Medications associated with gastrointestinal bleeding such as Bortezomib are sometimes monitored by FOBT.

Safety regulations from US accreditor the Joint Commission may have unintentionally decreased digital rectal examination and FOBT in hospital settings such as Emergency Departments.

If small and asymptomatic, no treatment is necessary. Larger, symptomatic cases of Zenker's diverticulum have been traditionally treated by neck surgery to resect the diverticulum and incise the cricopharyngeus muscle. However, in recent times non-surgical endoscopic techniques have gained more importance (as they allow for much faster recovery), and the currently preferred treatment is endoscopic stapling (i.e. diverticulotomy with staples ). This may be performed through a diverticuloscope. Other methods include fibreoptic diverticular repair.

Other non-surgical treatment modalities also exist, such as endoscopic laser, which recent evidence suggests is less effective than stapling.

Prevention of radiation injury to the small bowel is a key aim of techniques such as brachytherapy, field size, multiple field arrangements, conformal radiotherapy techniques and intensity-modulated radiotherapy. Medications including ACE inhibitors, statins and probiotics have also been studied and reviewed.

Acute appendicitis is typically managed by surgery. However, in uncomplicated cases, antibiotics are effective and safe. While antibiotics are effective for treating uncomplicated appendicitis, 26% of people had a recurrence within a year and required eventual appendectomy. They work less well if an appendicolith is present. Cost effectiveness of surgery versus antibiotics is unclear.

In people presenting with symptoms compatible with radiation enteropathy, the initial step is to identify what is responsible for causing the symptoms. Management is best with a multidisciplinary team including gastroenterologists, nurses, dietitians, surgeons and others.

Medical treatments include the use of hyperbaric oxygen which has beneficial effects in radiation proctitis or anal damage. Nutritional therapies include treatments directed at specific malabsorptive disorders such as low fat diets and vitamin B12 or vitamin D supplements, together with bile acid sequestrants for bile acid diarrhea and possibly antibiotics for small intestinal bacterial overgrowth. Probiotics have all been suggested as another therapeutic avenue.

Endoscopic therapies including argon plasma coagulation have been used for bleeding telangiectasia in radiation proctitis and at other intestinal sites, although there is a rick of perforation. Sucralfate enemas look promising in proctitis.

Surgical treatment may be needed for intestinal obstruction, fistulae, or perforation, which can happen in more severe cases. These can be fatal if patients present as an emergency, but with improved radiotherapy techniques are now less common.

Optimal treatment usually produces significant improvements in quality of life.

Pain medications (such as morphine) do not appear to affect the accuracy of the clinical diagnosis of appendicitis and therefore should be given early in the patient's care. Historically there were concerns among some general surgeons that analgesics would affect the clinical exam in children, and some recommended that they not be given until the surgeon was able to examine the person.

Pain relief is administered concomitantly to the treatment of the primary disease causing tenesmus. Methadone has been shown to be an effective pain-reliever.

Tenesmus is characterized by a sensation of needing to pass stool, accompanied by pain, cramping, and straining. Despite straining, little stool is passed. Tenesmus is generally associated with inflammatory diseases of the bowel, which may be caused by either infectious or noninfectious conditions. Conditions associated with tenesmus include:

- Amebiasis

- Coeliac disease

- Chronic arsenic poisoning

- Colorectal cancer

- Anal melanoma

- Cytomegalovirus (in immunocompromised patients)

- Diverticular disease

- Hemorrhoid, which are prolapsed

- Inflammatory bowel disease

- Irritable bowel syndrome

- Ischemic colitis

- Kidney stones, when a stone is lodged in the lower ureter

- Pelvic floor dysfunction

- Radiation proctitis

- Rectal gonorrhoea

- Rectal lymphogranuloma venereum

- Rectal lower gastrointestinal parasitic infection, particularly "Trichuris trichiura" (whipworm)

- Shigellosis

- Ulcerative colitis

Tenesmus (rectal) is also associated with the installation of either a reversible or non reversible stoma where rectal disease may or may not be present. Patients who experience tenesmus as a result of stoma installation can experience the symptoms of tenesmus for the duration of the stoma presence. Long term pain management may need to be considered as a result.

More than half of people with Crohn's disease have tried complementary or alternative therapy. These include diets, probiotics, fish oil and other herbal and nutritional supplements.

- Acupuncture is used to treat inflammatory bowel disease in China, and is being used more frequently in Western society. At this time, evidence is insufficient to recommend the use of acupuncture.

- A 2006 survey in Germany, found that about half of people with IBD used some form of alternative medicine, with the most common being homeopathy and a study in France found that about 30% used alternative medicine. Homeopathic preparations are not effective for treating any condition, with large-scale studies finding them to be no more effective than a placebo.

- There are contradicting studies regarding the effect of medical cannabis on inflammatory bowel disease.

Zenker's diverticulum mainly affects older adults. It has an incidence of 2 per 100,000 per year in the UK, but there is significant geographical variation around the world.

Crohn's may result in anxiety or mood disorders, especially in young people who may have stunted growth or embarrassment from fecal incontinence. Counselling as well as antidepressant or anxiolytic medication may help some people manage.

As of 2017 there is a small amount of research looking at mindfulness-based therapies, hypnotherapy, and cognitive behavioural therapy.

In histology, cryptitis refers to inflammation of an intestinal crypt.

Cryptitis is a non-specific histopathologic finding that is seen in several conditions, e.g. inflammatory bowel disease, diverticular disease, radiation colitis, infectious colitis.

Mortality is indirect and caused by complications. After cholangitis occurs, patients typically die within 5–10 years.

Some people will have an active infection when they present with a fistula, and this requires clearing up before definitive treatment can be decided.

Antibiotics can be used as with other infections, but the best way of healing infection is to prevent the buildup of pus in the fistula, which leads to abscess formation. This can be done with a seton.

There are several stages to treating an anal fistula:

Definitive treatment of a fistula aims to stop it recurring. Treatment depends on where the fistula lies, and which parts of the internal and external anal sphincters it crosses.

There are several options:

- Doing nothing — a drainage seton can be left in place long-term to prevent problems. This is the safest option although it does not definitively cure the fistula.

- Lay-open of fistula-in-ano — this option involves an operation to cut the fistula open. Once the fistula has been laid open it will be packed on a daily basis for a short period of time to ensure that the wound heals from the inside out. This option leaves behind a scar, and depending on the position of the fistula in relation to the sphincter muscle, can cause problems with incontinence. This option is not suitable for fistulae that cross the entire internal and external anal sphincter.

- Cutting seton — if the fistula is in a high position and it passes through a significant portion of the sphincter muscle, a cutting seton (from the Latin "seta", "bristle") may be used. This involves inserting a thin tube through the fistula tract and tying the ends together outside of the body. The seton is tightened over time, gradually cutting through the sphincter muscle and healing as it goes. This option minimizes scarring but can cause incontinence in a small number of cases, mainly of flatus. Once the fistula tract is in a low enough position it may be laid open to speed up the process, or the seton can remain in place until the fistula is completely cured. This was the traditional modality used by physicians in Ancient Egypt and formally codified by Hippocrates, who used horsehair and linen.

- Seton stitch — a length of suture material looped through the fistula which keeps it open and allows pus to drain out. In this situation, the seton is referred to as a draining seton. The stitch is placed close to the ano-rectal ring – which encourages healing and makes further surgery easy.

- Fistulotomy — till anorectal ring

- Colostomy — to allow healing

- Fibrin glue injection is a method explored in recent years, with variable success. It involves injecting the fistula with a biodegradable glue which should, in theory, close the fistula from the inside out, and let it heal naturally. This method is perhaps best tried before all others since, if successful, it avoids the risk of incontinence, and creates minimal stress for the patient.

- Fistula plug involves plugging the fistula with a device made from small intestinal submucosa. The fistula plug is positioned from the inside of the anus with suture. According to some sources, the success rate with this method is as high as 80%. As opposed to the staged operations, which may require multiple hospitalizations, the fistula plug procedure requires hospitalization for only about 24 hours. Currently, there are two different anal fistula plugs cleared by the FDA for treating ano-rectal fistulae in the United States. This treatment option does not carry any risk of bowel incontinence. In the systematic review published by Dr Pankaj Garg, the success rate of the fistula plug is 65-75%.

- Endorectal advancement flap is a procedure in which the internal opening of the fistula is identified and a flap of mucosal tissue is cut around the opening. The flap is lifted to expose the fistula, which is then cleaned and the internal opening is sewn shut. After cutting the end of the flap on which the internal opening was, the flap is pulled down over the sewn internal opening and sutured in place. The external opening is cleaned and sutured. Success rates are variable and high recurrence rates are directly related to previous attempts to correct the fistula.

- LIFT Technique is a novel modified approach through the intersphincteric plane for the treatment of fistula-in-ano, known as LIFT (ligation of intersphincteric fistula tract) procedure. LIFT procedure is based on secure closure of the internal opening and removal of infected cryptoglandular tissue through the intersphincteric approach. Essential steps of the procedure include, incision at the intersphincteric groove, identification of the intersphincteric tract, ligation of intersphincteric tract close to the internal opening and removal of intersphincteric tract, scraping out all granulation tissue in the rest of the fistulous tract, and suturing of the defect at the external sphincter muscle. The procedure was developed by Thai colorectal surgeon, Arun Rojanasakul, The first reports of preliminary healing result from the procedure were 94% in 2007. Additional ligation of the intersphincteric fistula tract did not improve the outcome after endorectal advancement flap.

- Fistula clip closure (OTSC Proctology) is the latest surgical development, which involves the closure of the internal fistula opening with a superelastic clip made of nitinol (OTSC). During surgery, the fistula tract is debrided with a special fistula brush and the clip is transanally applied with the aid of a preloaded clip applicator. The surgical principle of this technique relies on the dynamic compression and permanent closure of the internal fistula opening by the superelastic clip. Consequently, the fistula tract dries out and heals instead of being kept open by continuous feeding with stool and fecal organisms. This minimally-invasive sphincter-preserving technique has been developed and clinically implemented by the German surgeon Ruediger Prosst. First clinical data of the clip closure technique demonstrate a success rate of 90% for previously untreated fistulae and a success rate of 70% for recurrent fistulae.

- PERFACT Procedure is another latest addition to the armamentarium to treat complex and highly complex fistula-in-ano. It is a minimally cutting procedure as both the anal sphincters (internal and external sphincters) are not cut/damaged at all. Therefore, the risk of incontinence is minimal. PERFACT procedure (proximal superficial cauterization, emptying regularly fistula tracts and curettage of tracts) entails two steps: superficial cauterization of mucosa at and around the internal opening and keeping all the tracts clean. The principle is to permanently close the internal opening by granulation tissue. This is achieved by superficial electrocauterization at and around the internal opening and subsequently allowing the wound to heal by secondary intention. Early results of this procedure are quite encouraging for complex fistula-in-ano (86.4% in highly complex anal fistulae). The procedure is effective even in fistula associated with abscess, supralevator fistula-in-ano and fistula where the internal opening is non-localizable.

A number of preventative measures are recommended, including avoiding straining while attempting to defecate, avoiding constipation and diarrhea either by eating a high-fiber diet and drinking plenty of fluid or by taking fiber supplements, and getting sufficient exercise. Spending less time attempting to defecate, avoiding reading while on the toilet, and losing weight for overweight persons and avoiding heavy lifting are also recommended.

After diagnosing rectovaginal fistula, it is best to wait for around 3 months to allow the inflammation to subside. For low fistulae, a vaginal approach is best, while an abdominal repair would be necessary for a high fistula at the posterior fornix.

A circular incision is made around the fistula and vagina is separated from the underlying rectum with a sharp circumferential dissection. The entire fistulous tract, along with a small rim of rectal mucosa is incised. The rectal wall is then closed extramucosally.

Most rectovaginal fistuals will need surgery to fix. Medications such as antibiotics and Infliximab might be prescribed to help close the rectovaginal fistula or prepare for surgery.