Intra-abdominal abscess Transmural bowel inflammation results in bowel perforation and intra-abdominal and pelvic abscess formation in up to 30% of Crohn’s patients.14 Abdominal pain, fever, rigors, and elevated WBC count can indicate abscess formation. CT is generally diagnostic.13 Treatment involves antibiotics, CT or ultrasound-guided drainage and, occasionally, surgical resection.14

Bowel cancer Crohn’s disease carries an increased risk of bowel cancer.2,12,15 The incidence of small-intestinal cancer is about 100 times higher in the presence of long-standing small-bowel Crohn’s disease. Risk of colon cancer is increased in colonic disease, which has prompted the recommendation of annual colonoscopies for this patient population.12

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Thromboembolism A number of factors are potential contributors to the increased risk of thromboembolism seen in Crohn’s. Factor V Leiden mutation, thrombocytosis, increased clotting factors, and elevated homocysteine levels have all been noted in the disease.2,14 While the risk is highest during periods of disease exacerbation, clots are also known to occur during disease remission.14

Nutritional deficiencies/anemia Nutritional deficiencies are multifactorial. A simple but often overlooked cause is decreased caloric intake, usually resulting from decreased appetite and abdominal pain. This combination leads to malnutrition in up to 50% of Crohn’s patients.16 Rapid intestinal transit, small-bowel bacterial overgrowth, and fistulas can all lead to malabsorption. Protein loss through the inflamed intestine also contributes to nutritional deficiencies.16

Disaccharidase and lactase deficiencies often occur, further leading to malabsorption and decreased intake secondary to gas and bloating.16 Since the terminal ileum is the site of vitamin B12 absorption, severe disease or surgical resection of that area often results in deficiency, with subsequent pernicious anemia.12 Bile salts are also reabsorbed in the terminal ileum; disease in this area results in bile-salt deficiencies, which lead to malabsorption of fats and fat-soluble vitamins.12 Chronic GI bleeding frequently results in iron deficiency anemia.

Careful monitoring of nutritional deficiencies is of utmost importance, particularly in children and adolescents. In addition, vitamin and protein deficiencies should be addressed with oral supplementation when possible. In the case of B12 deficiency, parenteral replacement may be necessary. With severe disease, or in preparation for surgery, total parenteral nutrition may be warranted.2

Liver disease Abnormal liver enzymes are seen in up to 30% of people with Crohn’s disease, regardless of degree of disease activity.17 In the majority of cases, the abnormalities are mild and do not generally lead to liver disease.2 There are, however, a number of chronic liver diseases that occur with increased frequency in Crohn’s disease. These include primary sclerosing cholangitis, cirrhosis, gallstones, cholangiocarcinoma, fatty liver, liver cancer, amyloidosis, liver abscess, autoimmune hepatitis, and drug-induced hepatitis secondary to pharmacologic therapy.2,18

While most of these hepatic complications are rare, it is important to know that they are possible. Liver enzymes and CT scanning should be considered if signs of liver disease (e.g., jaundice, ascites, pruritus, right upper-quadrant abdominal pain, acholic stools, or dark urine) occur.

Arthritis Joint pains and stiffness, as well as arthritis, are associated with Crohn’s disease. Symptoms often occur as a result of a flare and resolve with treatment of the underlying disease.2

Treatment involves management of the Crohn’s disease, although this may not alleviate arthritis symptoms. Nonsteroidal anti-inflammatory drugs can cause exacerbation and are contraindicated.19 Referral to a rheumatologist is recommended. In addition, sulfasalazine is often helpful for management of both Crohn’s disease and arthritis.19

Ocular pathology Ocular abnormalities, such as episcleritis, uveitis, scleritis, and iritis, may occur in up to 13% of patients with Crohn’s.2,19 Topical steroids generally control the problem. Since loss of vision is rare but possible, a close relationship with an ophthalmologist is ideal.

Skin lesions A number of skin lesions are known to occur in conjunction with Crohn’s disease, with pyoderma gangrenosum and erythema nodosum topping the list.2 Pyoderma gangrenosum generally starts out as small blisters that grow and ulcerate.20 They can occur on any area of skin but most commonly appear on the lower extremities. 20,21 Treatment of the underlying Crohn’s disease generally results in remission of both pyoderma and erythema nodosum. Oral aphthous ulcers, vasculitis and polyarteritis nodosa also occur concurrently with Crohn’s disease.2, 20

Kidney disorders Kidney stones are commonly seen in association with Crohn’s disease.2 The previously described malabsorption of fat plays a role in the formation of stones. Fatty acids that are normally absorbed are free to attach to calcium that is present in the bowel. The inactivated calcium, which generally binds to luminal oxalate, is unable to do so, resulting in enhanced absorption of oxalate. This is ultimately secreted by the kidneys, resulting in oxalate stone formation.2 In addition, fistulizing disease to the bladder, glomerulonephritis and membranous nephropathy are rare complications of Crohn’s disease.2