| Ulcerative colitis | |
|---|---|
| Classification and external resources | |
Endoscopic image of a bowel section known as the sigmoid colon afflicted with ulcerative colitis. The internal surface of the colon is blotchy and broken in places. |
|
| ICD-10 | K51 |
| ICD-9 | 556 |
| OMIM | 191390 |
| DiseasesDB | 13495 |
| MedlinePlus | 000250 |
| eMedicine | med/2336 |
| MeSH | D003093 |
Ulcerative colitis (Colitis ulcerosa, UC) is a form of inflammatory bowel disease (IBD) . Ulcerative colitis is a form of colitis, a disease of the colon (large intestine), that includes characteristic ulcers, or open sores. The main symptom of active disease is usually constant diarrhea mixed with blood, of gradual onset. IBD is often confused with irritable bowel syndrome (IBS), a troublesome, but much less serious, condition. Ulcerative colitis has similarities to Crohn's disease, another form of IBD. Ulcerative colitis is an intermittent disease, with periods of exacerbated symptoms, and periods that are relatively symptom-free. Although the symptoms of ulcerative colitis can sometimes diminish on their own, the disease usually requires treatment to go into remission Ulcerative colitis occurs in 35–100 people for every 100,000 in the United States,[1] or less than 0.1% of the population. The disease is more prevalent in northern countries of the world, as well as in northern areas of individual countries or other regions. Although ulcerative colitis has no known cause, there is a presumed genetic component to susceptibility. The disease may be triggered in a susceptible person by environmental factors. Although dietary modification may reduce the discomfort of a person with the disease, ulcerative colitis is not thought to be caused by dietary factors. Ulcerative colitis is treated as an autoimmune disease. Treatment is with anti-inflammatory drugs, immunosuppression, and biological therapy targeting specific components of the immune response. Colectomy (partial or total removal of the large bowel through surgery) is occasionally necessary, and is considered to be a cure for the disease.
Contents |
| Crohn's disease | Ulcerative colitis | |
|---|---|---|
| Defecation | Often porridge-like[2], sometimes steatorrhea |
Often mucus-like and with blood[2] |
| Tenesmus | Less common[2] | More common[2] |
| Fever | Common[2] | Indicates severe disease[2] |
| Fistulae | Common[3] | Seldom |
| Weight loss | Often | More seldom |
The clinical presentation[4] of ulcerative colitis depends on the extent of the disease process. Patients usually present with diarrhea mixed with blood and mucus, of gradual onset that persists for an extended period (weeks). They also may have weight loss and blood on rectal examination. The disease may be accompanied with different degrees of abdominal pain, from mild discomfort to painful bowel movements or painful abdominal cramping with bowel movements.
Ulcerative colitis is associated with a general inflammatory process that affects many parts of the body. Sometimes these associated extra-intestinal symptoms are the initial signs of the disease, such as painful, arthritic knees in a teenager and may be seen in adults also. The presence of the disease may not be confirmed immediately, however, until the onset of intestinal manifestations.
Ulcerative colitis is normally continuous from the rectum up the colon. The disease is classified by the extent of involvement, depending on how far up the colon the disease extends:
In addition to the extent of involvement, people may also be characterized by the severity of their disease.[5]
As ulcerative colitis is believed to have a systemic (i.e., autoimmune) origin, patients may present with comorbidities leading to symptoms and complications outside the colon. The frequency of such extraintestinal manifestations has been reported as anywhere between 6 and 47 percent.[6] These include the following:
There are no direct causes for ulcerative colitis, but there are many possible factors such as genetics and stress.
A genetic component to the aetiology of ulcerative colitis can be hypothesized based on the following:[7]
There are 12 regions of the genome which may be linked to ulcerative colitis. This includes chromosomes 16, 12, 6, 14, 5, 19, 1,and 3 in the order of their discovery.[9] However, none of these loci has been consistently shown to be at fault, suggesting that the disorder arises from the combination of multiple genes. For example, chromosome band 1p36 is one such region thought to be linked to inflammatory bowel disease.[10] Some of the putative regions encode transporter proteins such as OCTN1 and OCTN2. Other potential regions involve cell scaffolding proteins such as the MAGUK family. There are even human leukocyte antigen associations which may be at work. In fact, this linkage on chromosome 6 may be the most convincing and consistent of the genetic candidates.[9]
Multiple autoimmune disorders have been recorded with the neurovisceral and cutaneous genetic porphyrias including ulcerative colitis, Crohn's disease, celiac disease, dermatitis herpetiformis, diabetes, systemic and discoid lupus, rheumatoid arthritis, ankylosing spondylitis, scleroderma, Sjogren's disease and scleritis. Physicians should be on high alert for porphyrias in families with autoimmune disorders and care must be taken with potential porphyrinogenic drugs, including sulfasalazine.
Many hypotheses have been raised for environmental contributants to the pathogenesis of ulcerative colitis. They include the following:
Some sources list ulcerative colitis as an autoimmune disease,[18] a disease in which the immune system malfunctions, attacking some part of the body. In contrast to Crohn's disease, which can affect areas of the gastrointestinal tract outside of the colon, ulcerative colitis usually involves the rectum and is confined to the colon, with occasional involvement of the ileum. This so-called "backwash ileitis" can occur in 10–20% of patients with pancolitis and is believed to be of little clinical significance.[19] Ulcerative colitis can also be associated with comorbidities that produce symptoms in many areas of the body outside the digestive system. Surgical removal of the large intestine often cures the disease.[5]
Levels of sulfate-reducing bacteria tend to be higher in persons with ulcerative colitis. This could mean that there are higher levels of hydrogen sulfide in the intestine. An alternative theory suggests that the symptoms of the disease may be caused by toxic effects of the hydrogen sulfide on the cells lining the intestine.[20][21]
| Risk factors in Crohn's disease vs. ulcerative colitis. |
||
|---|---|---|
| Crohn's disease | Ulcerative colitis | |
| Smoking | Higher risk for smokers | Lower risk for smokers[22] |
| Age | Usual onset between 15 and 30 years[23] |
Peak incidence between 15 and 25 years |
Ulcerative colitis and Crohn's disease are the main types of inflammatory bowel disease, and may mimic each other to great extent, but differ somewhat in etiology and pathophysiology:
| Pathophysiology in Crohn's disease vs. ulcerative colitis |
||
|---|---|---|
| Crohn's disease | Ulcerative colitis | |
| Autoimmune disease | Widely regarded as an autoimmune disease |
No consensus |
| Cytokine response | Associated with Th17[24] | Vaguely associated with Th2 |
An increased amount of colonic sulfate-reducing bacteria has been observed in some patients with ulcerative colitis, resulting in higher concentrations of the toxic gas hydrogen sulfide. The role of hydrogen sulfide in pathogenesis is unclear. It has been suggested that the protective benefit of smoking that some patients report is due to hydrogen cyanide from cigarette smoke reacting with hydrogen sulfide to produce the nontoxic isothiocyanate. Another unrelated study suggested sulphur contained in red meats and alcohol may lead to an increased risk of relapse for patients in remission.[20]
The initial diagnostic workup for ulcerative colitis includes the following:[1][5]
Although ulcerative colitis is a disease of unknown causation, inquiry should be made as to unusual factors believed to trigger the disease.[5] Factors may include: recent cessation of tobacco smoking; recent administration of large doses of iron or vitamin B6; hydrogen peroxide in enemas or other procedures.
The best test for diagnosis of ulcerative colitis remains endoscopy. Full colonoscopy to the cecum and entry into the terminal ileum is attempted only if diagnosis of UC is unclear. Otherwise, a flexible sigmoidoscopy is sufficient to support the diagnosis. The physician may elect to limit the extent of the exam if severe colitis is encountered to minimize the risk of perforation of the colon. Endoscopic findings in ulcerative colitis include the following:
Ulcerative colitis is usually continuous from the rectum, with the rectum almost universally being involved. There is rarely peri-anal disease, but cases have been reported. The degree of involvement endoscopically ranges from proctitis or inflammation of the rectum, to left sided colitis, to pancolitis, which is inflammation involving the ascending colon.
Biopsies of the mucosa are taken to definitively diagnose UC and differentiate it from Crohn's disease, which is managed differently clinically. Microbiological samples are typically taken at the time of endoscopy. The pathology in ulcerative colitis typically involves distortion of crypt architecture, inflammation of crypts (cryptitis), frank crypt abscesses, and hemorrhage or inflammatory cells in the lamina propria. In cases where the clinical picture is unclear, the histomorphologic analysis often plays a pivotal role in determining the diagnosis and thus the management. By contrast, a biopsy analysis may be indeterminate, and thus the clinical progression of the disease must inform its treatment.
The following conditions may present in a similar manner as ulcerative colitis, and should be excluded:
The most common disease that mimics the symptoms of ulcerative colitis is Crohn's disease, as both are inflammatory bowel diseases that can affect the colon with similar symptoms. It is important to differentiate these diseases, since the course of the diseases and treatments may be different. In some cases, however, it may not be possible to tell the difference, in which case the disease is classified as indeterminate colitis.
| Findings in diagnostic workup in Crohn's disease vs. ulcerative colitis |
||
|---|---|---|
| Sign | Crohn's disease | Ulcerative colitis |
| Terminal ileum involvement | Commonly | Seldom |
| Colon involvement | Usually | Always |
| Rectum involvement | Seldom | Usually[22] |
| Involvement around the anus |
Common[3] | Seldom |
| Bile duct involvement | No increase in rate of primary sclerosing cholangitis | Higher rate[25] |
| Distribution of Disease | Patchy areas of inflammation (Skip lesions) | Continuous area of inflammation[22] |
| Endoscopy | Deep geographic and serpiginous (snake-like) ulcers | Continuous ulcer |
| Depth of inflammation | May be transmural, deep into tissues[9][3] | Shallow, mucosal |
| Stenosis | Common | Seldom |
| Granulomas on biopsy | May have non-necrotizing non-peri-intestinal crypt granulomas[3][26][27] | Non-peri-intestinal crypt granulomas not seen[22] |
Standard treatment for ulcerative colitis depends on extent of involvement and disease severity. The goal is to induce remission initially with medications, followed by the administration of maintenance medications to prevent a relapse of the disease. The concept of induction of remission and maintenance of remission is very important. The medications used to induce and maintain a remission somewhat overlap, but the treatments are different. Physicians first direct treatment to inducing a remission which involves relief of symptoms and mucosal healing of the lining of the colon and then longer term treatment to maintain the remission and prevent complications.
Ulcerative colitis can be treated with a number of medications including aminosalicylates such as sulfasalazine, corticosteroids such as prednisone, immunosuppressive medications such as azathioprine, and biological agents such as infliximab.
Sulfasalazine has been a major agent in the therapy of mild to moderate UC for over 50 years. In 1977, Mastan S. Kalsi et al. determined that 5-aminosalicylic acid (5-ASA and mesalazine) was the therapeutically active in sulfasalazine. Since then many 5-ASA compounds have been developed with the aim of maintaining efficacy but reducing the common side effects associated with the sulfapyridine moiety in sulfasalazine.[28]
Unlike Crohn's disease, ulcerative colitis has a lesser prevalence in smokers than non-smokers. Patients who choose to use smoking as a treatment should keep a record regarding smoking cessation and the onset or relapse of ulcerative colitis to verify associations.[29][30] Studies using a transdermal nicotine patch have shown clinical and histological improvement.[31] In one double-blind, placebo controlled, study conducted in the United Kingdom 48.6% of patients who used the nicotine patch, in conjunction with their standard treatment, showed complete resolution of symptoms. Another randomized, double-blind, placebo-controlled, single-center clinical trial conducted in the United States showed that 39% of participants showed significant improvement vs. 3% of placebo.[32] Use of a transdermal nicotine patch without the addition of other standard treatments such as mesalazine has relapse occurrence rates similar to standard treatment without the use of nicotine.
| Management in Crohn's disease vs. ulcerative colitis |
||
|---|---|---|
| Crohn's disease | Ulcerative colitis | |
| Mesalazine | less useful[33] | More useful[33] |
| Antibiotics | Effective in long-term[34] | Generally not useful[35] |
| Surgery | Often returns following removal of affected part |
Usually cured by removal of colon |
Unlike Crohn's disease, ulcerative colitis can generally be cured by surgical removal of the large intestine, also known as a colectomy. This procedure is necessary in the event of: exsanguinating hemorrhage, frank perforation or documented or strongly suspected carcinoma. Surgery is also indicated for patients with severe colitis or toxic megacolon. Patients with symptoms that are disabling and do not respond to drugs may wish to consider whether surgery would improve the quality of life.
Ulcerative colitis (UC) is a disease that affects many parts of the body outside the intestinal tract. In rare cases the extra-intestinal manifestations of the disease may require removal of the colon.[5]
Another surgical option for ulcerative colitis that is affecting most of the large bowel is called the ileo-anal pouch procedure. This procedure is a two to three step procedure in which the large bowel is removed, except for the rectal stump and anus, and a temporary ileostomy is made. The next part of the surgery can be done in one or two steps and is usually done at six to twelve month intervals from each prior surgery. In the next step of the surgery an internal pouch is made of the patients' own small bowel and this pouch is then hooked back up internally to the rectal stump so that patient can once again have a reasonably functioning bowel system, all internal. The temporary ileostomy can be reversed at this time so that the patient is now internalized for bowel functions, or in another step to the procedure, the pouch and rectal stump anastamosis can be left inside the patient to heal for some time, while the patient still uses the ileostomy for bowel function. Then on a subsequent surgery the ileostomy is reversed and the patient has internalized bowel function again.
About 21% of inflammatory bowel disease patients use alternative treatments.[40] A variety of dietary treatments show promise, but they require further research before they can be recommended.[41]
In vitro research, animal evidence, and limited human study suggest that melatonin may be beneficial.[42]
Dietary fiber, meaning indigestible plant matter, has been recommended for decades in the maintenance of bowel function. Of peculiar note is fiber from brassica, which seems to contain soluble constituents capable of reversing ulcers along the entire human digestive tract before it is cooked.[43] Oatmeal is also commonly prescribed.
| Complications of Crohn's disease vs. ulcerative colitis |
|||
|---|---|---|---|
| Crohn's disease | Ulcerative colitis | ||
| Nutrient deficiency | Higher risk | ||
| Colon cancer risk | Slight | Considerable | |
| Prevalence of extraintestinal complications[48] |
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| Iritis/uveitis | Females | 2.2% | 3.2% |
| Males | 1.3% | 0.9% | |
| Primary sclerosing cholangitis |
Females | 0.3% | 1% |
| Males | 0.4% | 3% | |
| Ankylosing spondylitis |
Females | 0.7% | 0.8% |
| Males | 2.7% | 1.5% | |
| Pyoderma gangrenosum |
Females | 1.2% | 0.8% |
| Males | 1.3% | 0.7% | |
| Erythema nodosum | Females | 1.9% | 2% |
| Males | 0.6% | 0.7% | |
Patients with ulcerative colitis usually have an intermittent course, with periods of disease inactivity alternating with "flares" of disease. Patients with proctitis or left-sided colitis usually have a more benign course: only 15% progress proximally with their disease, and up to 20% can have sustained remission in the absence of any therapy. Patients with more extensive disease are less likely to sustain remission, but the rate of remission is independent of the severity of disease.
There is a significantly increased risk of colorectal cancer in patients with ulcerative colitis after ten years if involvement is beyond the splenic flexure. Those with only proctitis or rectosigmoiditis usually have no increased risk.[5] It is recommended that patients have screening colonoscopies with random biopsies to look for dysplasia after eight years of disease activity.[49]
Ulcerative colitis has a significant association with primary sclerosing cholangitis (PSC), a progressive inflammatory disorder of small and large bile ducts. As many as 5% of patients with ulcerative colitis may progress to develop primary sclerosing cholangitis.[50]
The effect of ulcerative colitis on mortality is unclear, but it is thought that the disease primarily affects quality of life, and not lifespan.
Changes that can be seen in chronic ulcerative colitis include granularity, loss of the vascular pattern of the mucosa, loss of haustra, effacement of the ileocecal valve, mucosal bridging, strictures and pseudopolyps.[51]
The incidence of ulcerative colitis in North America is 10–12 cases per 100,000 per year, with a peak incidence of ulcerative colitis occurring between the ages of 15 and 25. Prevalence is 1 per 1000. There is thought to be a bimodal distribution in age of onset, with a second peak in incidence occurring in the 6th decade of life. The disease affects females more than males.[4]
The geographic distribution of ulcerative colitis and Crohn's disease is similar worldwide,[52] with highest incidences in the United States, Canada, the United Kingdom, and Scandinavia. Higher incidences are seen in northern locations compared to southern locations in Europe[53] and the United States.[54]
As with Crohn's disease, the prevalence of ulcerative colitis is greater among Ashkenazi Jews and decreases progressively in other persons of Jewish descent, non-Jewish Caucasians, Africans, Hispanics, and Asians.[19] Appendectomy prior to age 20 for appendicitis[55] and tobacco use[56] are protective against development of ulcerative colitis.
Helminthic therapy using the whipworm Trichuris suis has been shown in a randomized control trial from Iowa to show benefit in patients with ulcerative colitis. The therapy tests the hygiene hypothesis which argues that the absence of helminths in the colons of patients in the developed world may lead to inflammation. Both helminthic therapy and fecal bacteriotherapy induce a characteristic Th2 white cell response in the diseased areas, which is somewhat paradoxical given that ulcerative colitis immunology was thought to classically involve Th2 overproduction.[57]
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