History and exam

Key diagnostic factors

common

abdominal pain

May be cramp or constant pain. Above 70% patients experience abdominal pain at some point during the course of disease.[90][91]

Right lower quadrant and periumbilical regions are common locations if ileitis is present. May be partially relieved by defecation if there is colonic involvement.

Crohn colitis produces diffuse abdominal pain, which may be accompanied by mucus, blood, and pus in the stool.

prolonged diarrhea

Nonbloody or bloody intermittent diarrhea are common complaints in Crohn disease.[10]​

Nocturnal diarrhea may occur.[9]​

perianal lesions

Approximately 25% of patients with Crohn disease may have perianal lesions including skin tags, fistulae, abscesses, scarring, or sinuses.[11]​ Fistulae and abscesses result from penetrating inflammation and are not due to anorectal gland infection.[92]

Other diagnostic factors

common

bowel obstruction

Caused by acute inflammatory edema and spasm of the bowel or chronic scarring and stricture.

Manifests as bloating, distention, cramping abdominal pains, loud borborygmi, vomiting, constipation, and obstipation.

blood in stools

Rectal bleeding is more common in Crohn colitis.

fatigue

Caused by malnutrition, weight loss, and inflammation.

abdominal tenderness

Abdominal tenderness is a common manifestation of Crohn disease. It may be secondary to inflammation, localized collections, strictures causing small bowel or more rarely colonic obstruction, or proximal constipation.

Terminal ileal inflammation may present with localized right lower quadrant pain and tenderness.

weight loss

Unexplained weight loss may be seen.[9]​ Failure to thrive is common in children and may be a very early manifestation of the disease. 

Malabsorption is a later cause of poor nutritional status.

uncommon

fever

Induced by the inflammation of Crohn disease or a complication such as perforation, abscess, or fistula.

oral lesions

Patients with Crohn disease may have oral involvement with recurrent aphthous ulcers and pain in the mouth and gums.​[10][93]​​

abdominal mass

Terminal ileal inflammation may present as a tender mass in the right lower quadrant.

Proximal constipation may also be palpable as irregular stool mass on abdominal exam.

extraintestinal manifestations (e.g., erythema nodosum or pyoderma gangrenosum)

At least one extraintestinal manifestation occurs in about 50% of patients with inflammatory bowel disease.​[8]

Manifestations may include symptoms and signs of arthropathy, cutaneous lesions (e.g., erythema nodosum, pyoderma gangrenosum), and ocular symptoms and signs (e.g., of anterior uveitis or episcleritis). [Figure caption and citation for the preceding image starts]: A patient's arms and hands show the presence of erythema nodosumCDC/ Margaret Renz [Citation ends].com.bmj.content.model.Caption@52c96e6​ The occurrence of thrombotic events in patients with Crohn disease is twice that of the general population.​[8]

Risk factors

strong

white ethnicity

Crohn disease appears to be more common in white people.[11][19][20]

Ashkenazi Jewish ancestry

Crohn disease (CD) appears to be more common in individuals of Ashkenazi Jewish origin.[11]

Ashkenazi Jews have a two- to fourfold increased risk of CD.[56]

age 15-40 or 50-60 years

A bimodal age distribution: the onset of Crohn disease typically occurs in the second to fourth decade of life, with a smaller peak from 50-60 years.[9][11][12][13]​​​

family history of CD

Approximately 12% of patients have a family history of Crohn disease (CD).[57]​ Around 10% to 25% of affected patients have a first-degree relative with CD.[21][22]

use of antibiotics

Studies have reported a significant association between antibiotic use and development of inflammatory bowel disease, particularly Crohn disease (CD).[58][59][60]​​​ One systematic review and meta-analysis found that compared with controls, odds of developing CD were higher in individuals who were exposed to antibiotics during childhood or had a lifetime exposure to antibiotics than in those who were not exposed to antibiotics (odds ratio 1.52 [1.23 to 1.87]; P <0.00001).[60]

weak

cigarette smoking

Smokers are more than twice as likely to develop Crohn disease as nonsmokers.[23][24][25][26]​​ This is in contrast to ulcerative colitis, in which smoking reduces the risk of developing the disease by up to 40%.[61][62]

diet high in refined sugar

Linked with increased incidence of Crohn disease in some studies.​​[22][38]​​​[40]

diet low in fiber

Diet low in fruit, vegetables, and fiber has been associated with increased incidence of Crohn disease.[36][37]

diet high in ultra-processed foods

Large, prospective cohort studies report an association between a higher intake of ultra-processed foods (including soft drinks, processed meat, refined sweetened foods, and salty snacks) and increased incidence of Crohn disease.[38][39][42]

use of oral contraceptives

One meta-analysis of case-controlled and cohort studies reported a 24% increase in risk of developing Crohn disease (CD) in those taking oral contraceptives compared with those not taking them.[35]​ One nested case-control study reported that the use of combined oral contraceptive pills was associated with CD development.[41]​ However, an association with CD was not noted for progesterone-only pills.[41]

not breastfed

Children with Crohn disease were 3-4 times less likely to have been breastfed.[36][37][63]

use of nonsteroidal anti-inflammatory drugs (NSAIDs)

NSAIDs have been shown to increase risk of Crohn disease in some studies.[64][65]

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