8 Medical management of Crohn’s disease

Treatment of Crohn’s disease not only depends on disease activity and site, as in ulcerative colitis, but also needs to be tailored according to the individual’s clinical presentation and its dominant underlying pathological explanation. Inflammation, obstruction, abscess and fistula require different therapeutic approaches, and they often need to be distinguished by appropriate investigation before specific treatment is begun. Drug therapy in Crohn’s disease is generally less effective than in ulcerative colitis, and dietary and surgical treatment correspondingly more important.

General measures

Explanation, psychosocial support and hospital care. Newly diagnosed patients with Crohn’s disease need a full explanation of their illness, preferably assisted by the written information provided by patient support groups (see Table 6.1 and Useful resources). A substantial minority of patients are sufficiently disturbed psychologically by the chronically disabling nature of their illness to need more formal psychosocial help. Out- and inpatient care is best undertaken by a specialist multidisciplinary hospital team.

Dietary advice and nutritional support. All patients should be carefully assessed in relation to their nutritional intake and status, the latter by measurement of weight and height and calculation of body mass index (BMI = weight [kg]/height [m]²; normal BMI 19–25).

Patients with stricturing small-bowel Crohn’s disease should avoid high-residue foods (e.g. citrus fruit, nuts, sweetcorn, uncooked vegetables) that might cause bolus obstruction. Special dietary and nutritional modifications are needed for those with extensive small-bowel Crohn’s disease, or short-bowel syndrome (see Chapter 2). Sick inpatients may need enteral or parenteral nutrition to restore nutritional deficits, while liquid formula diets provide a primary therapy option for some with active small-bowel Crohn’s disease.

Non-specific drugs. Diarrhea in Crohn’s disease has a number of different causes, each requiring a different therapeutic approach (see Table 2.1). Codeine phosphate and loperamide are often useful for the symptomatic control of diarrhea that is due to active disease or previous bowel resection. As in active ulcerative colitis, however, they should be avoided in active Crohn’s colitis in case they provoke colonic dilation.

Colestyramine (cholestyramine) sachets, 4 g one to three times daily, or colesevalam tablets, which are more palatable, often help patients with Crohn’s disease complicated by bile-salt-induced diarrhea as a result of extensive terminal ileal disease or resection (see ‘Bile-salt malabsorption’, pages 31 and 136). By binding bile salts, these agents may, however, exacerbate or induce steatorrhea and malabsorption of fat-soluble vitamins; they may also directly bind with and prevent the absorption of other drugs and should not, therefore, be given simultaneously with other therapies.

Hematinics (oral or intravenous iron, oral folate and intramuscular vitamin B₁₂), calcium, magnesium, zinc and fat-soluble vitamins (A, D, E and K) may be needed for the replacement of particular deficiencies, as may appropriate drugs for incipient or established osteoporosis (see Chapter 3).

Subcutaneous heparin to reduce the risk of arterial and venous thrombosis is recommended for those admitted with active Crohn’s disease.

Drugs to avoid. Non-steroidal anti-inflammatory drugs (NSAIDs) may precipitate relapse of Crohn’s disease and should, if possible, be avoided. Likewise, in patients with small-bowel stricturing due to Crohn’s disease, delayed-release drugs should not be prescribed in case they cause bolus obstruction. Anecdotal evidence suggests that oral iron can exacerbate relapses, and its prescription is best postponed until remission has been achieved. In those who are frequently hospitalized because of pain, use of opioids should be minimized to avoid narcotic addiction.

Treatment of active Crohn’s disease

Who needs hospital admission? The heterogeneous presentation of Crohn’s disease makes assessment of disease activity more complicated than in ulcerative colitis. For clinical trials, a large number of multifactorial clinical and/or laboratory-based scoring systems, such as the Crohn’s Disease Activity Index (CDAI) and Harvey-Bradshaw Index, have been devised, but none is suitable for ordinary clinical use. The working definitions of the American College of Gastroenterology (Table 8.1) are more practical. Many patients with active Crohn’s disease can be looked after as outpatients, but those with moderate-to-severe and severe-to-fulminant disease need prompt, and in the latter instance immediate, hospital admission. In patients with Crohn’s colitis, indications for admission resemble those for acute severe ulcerative colitis (see Chapter 7).

General measures. As for those with ulcerative colitis, patients with active Crohn’s disease should be looked after by a multidisciplinary team with special expertise in IBD in a specialist gastroenterology clinic or ward (see Table 6.1). Options for treatment (medical, nutritional, surgical) are wider than in ulcerative colitis, and it is essential that the patient with Crohn’s disease is kept fully informed about his or her illness, and takes a place at the center of the therapeutic decision-making process.

Establishing the diagnosis, clinicopathological problem and severity. For many patients, the diagnosis of Crohn’s disease and identification of its principal site will have been made before he or she presents with a relapse. Investigations, therefore, are directed primarily at clarifying the dominant clinicopathological process so as to optimize subsequent treatment. In individuals presenting acutely for the first time, the diagnosis must be established (Table 8.2; see also Tables 4.1 4.2, 4.3, 4.4).

Clinical evaluation. Symptoms of active terminal ileal and ileocecal Crohn’s disease are described in Chapter 2. Where the diagnosis of Crohn’s disease has not yet been made, acute appendicitis with a mass may be particularly hard to differentiate from Crohn’s disease, except with laparoscopy or laparotomy. In elderly patients presenting de novo, cecal carcinoma and lymphoma need careful consideration, while in some ethnic groups, for example South Asians, ileocecal tuberculosis must be excluded.

In Crohn’s colitis, diarrhea is a more prominent symptom than pain; questions to be asked of previously undiagnosed patients are outlined in the section on acute severe ulcerative colitis in Chapter 7. External abdominal or perianal fistulas are usually clinically obvious, but direct questions may be necessary to identify enterovesical or enterovaginal fistulas (see page 28).

Blood tests. As in ulcerative colitis, the main value of blood tests is in assessing and monitoring disease activity, which is related directly to the platelet count and C-reactive protein, and inversely to serum albumin. However, in very sick patients, particularly those with extensive small-bowel disease and steatorrhea, there may be laboratory evidence of malnutrition and malabsorption (anemia and low levels of serum iron, folate, B₁₂, albumin, calcium, magnesium, vitamin D, zinc and essential fatty acids). A raised neutrophil count suggests intra-abdominal abscess, but corticosteroids also cause leukocytosis by demarginating intravascular neutrophils.

Stool microbiology. As in ulcerative colitis (see page 95), diarrhea in Crohn’s disease may be due to intercurrent infection, particularly with Clostridium difficile toxin. Stool samples should therefore be sent for microbiological analysis in all patients presenting with a recent onset of diarrhea.

Endoscopy and biopsy. In those with right iliac fossa pain where the diagnosis of Crohn’s disease is in doubt, colonoscopy to the terminal ileum, with appropriate biopsies, can be helpful. It can also be used to balloon-dilate short strictures. In established Crohn’s colitis, colonoscopy during acute relapse is not routinely necessary and may be unsafe, as in active ulcerative colitis (see Chapter 7). In previously undiagnosed patients, digital rectal examination and cautious sigmoidoscopy may show rectal induration or ulceration, or the presence of perianal disease. Furthermore, biopsies of macroscopically normal rectal mucosa may reveal epithelioid granulomas in a minority of patients with more proximal Crohn’s disease.

Plain abdominal X-ray. A plain film is essential if intestinal obstruction is suspected. It may also show a mass in the right iliac fossa and, in active Crohn’s colitis, provide information about disease extent and severity.

Barium radiology. As indicated in Chapter 4, barium follow-through has been largely superseded by MRI scanning for small-bowel imaging, but contrast fistulography remains useful occasionally in patients with abdominal sinuses or fistulas.

Radiolabeled leukocyte scans. ⁹⁹Technetium-labeled hexamethylpropyleneamine oxime (⁹⁹Tc-HMPAO) scanning can help to identify, non-invasively, not only sites of intestinal inflammation, as in ulcerative colitis, but also intra-abdominal abscesses in those with fever and/or an abdominal mass (see Chapter 4); again, this test is being replaced now by MRI, ultrasound and CT scan.

Ultrasound, CT scan and MRI. Abdominal ultrasound and CT scanning can be very useful in active Crohn’s disease for the evaluation and percutaneous drainage of localized collections (see Chapter 4); the last should be used selectively because of its high radiation dosage. Endoluminal ultrasound and MRI (Figure 8.1) are useful for the anatomic delineation of perianal abscesses and fistulas.

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Principles of management Prognosis Surgery Extraintestinal manifestations and complications Medical management of ulcerative colitis Diagnosis

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