Clinical Guides
Crohn's Disease
A clinically focused guide to diagnosing, phenotyping and monitoring Crohn's disease, excluding infection and intestinal tuberculosis, and coordinating nutrition, medical therapy, surgery, pregnancy planning and cancer prevention in Indian care settings.
MedNext Academy | 14 min read
Crohn's Disease
A clinically focused guide to diagnosing, phenotyping and monitoring Crohn's disease, excluding infection and intestinal tuberculosis, and coordinating nutrition, medical therapy, surgery, pregnancy planning and cancer prevention in Indian care settings.
Summary
Crohn's disease is a chronic, relapsing inflammatory bowel disease that can involve any part of the gastrointestinal tract, most often the terminal ileum and colon. Inflammation is typically patchy and transmural, so the clinical problem extends beyond diarrhoea: abdominal pain, weight loss, anaemia, growth failure, perianal sepsis, strictures, fistulae and extra-intestinal manifestations may dominate. Location, inflammatory or stricturing or penetrating behaviour, perianal involvement, current activity, accumulated bowel damage and previous treatment response must all be documented. A symptom score alone cannot show mucosal healing or distinguish active inflammation from fibrosis, infection or functional symptoms.
Diagnosis is clinicopathological. It combines history, examination, laboratory and stool testing, ileocolonoscopy with segmental biopsies and small-bowel imaging. No single blood marker, faecal calprotectin value, endoscopic feature or biopsy result proves Crohn's disease in isolation. In India, intestinal tuberculosis and enteric infection can resemble Crohn's clinically, radiologically, endoscopically and histologically. Infection must be investigated before escalating immunosuppression; an empirical diagnostic trial of either anti-tuberculosis treatment or corticosteroid treatment can create delay and harm.
Treatment aims for corticosteroid-free control, restoration of nutrition and function, and prevention of progressive bowel damage. Corticosteroids may induce remission but do not maintain it. Immunomodulators and advanced therapies are selected according to phenotype, prognosis, prior exposure, safety and access. Abscess, obstruction, dysplasia and many fistulating complications require early multidisciplinary surgical input. Objective reassessment, vaccination, infection screening, reproductive counselling and malignancy surveillance are integral rather than optional additions.
How Common Is It?
Crohn's disease occurs worldwide and its incidence is increasing in many newly industrialised regions, including South Asia. Precise Indian estimates vary because population-based registries are limited, diagnostic access is unequal and intestinal tuberculosis or other enteropathies can be misclassified. Hospital cohorts cannot be treated as community prevalence studies. The clinically important point is that inflammatory bowel disease is no longer rare enough in India to be omitted from persistent diarrhoea, abdominal pain, growth failure, perianal disease or unexplained anaemia differentials.
Disease commonly begins in adolescence or early adulthood, but it can present in childhood or later life. Paediatric disease has particular consequences for linear growth, puberty, schooling and bone health. Older-onset disease may coexist with cancer, vascular disease, diverticular disorders and polypharmacy. Some patients have years of intermittent symptoms before diagnosis; others first present with obstruction, abscess or perianal sepsis. Delay matters because transmural inflammation can produce irreversible structural damage even when symptoms fluctuate.
Burden is not captured by stool frequency alone. Pain, urgency, fatigue, iron deficiency, food avoidance, medication toxicity, stoma concerns, infertility fears, anxiety and lost work or education contribute substantially. Repeated steroid courses, emergency admissions, opioid use and unplanned surgery are markers of poor control or fragmented care. Access to endoscopy, cross-sectional imaging, biologic or small-molecule therapy, therapeutic drug monitoring and IBD surgery differs greatly across India. A useful service measures diagnostic delay, steroid exposure, nutrition, objective remission, vaccination and emergency surgery, not simply the number of clinic visits.
Risk Factors
Crohn's disease reflects interaction between genetic susceptibility, mucosal immunity, intestinal microbiota and environment; there is no single causal exposure. A first-degree relative with inflammatory bowel disease increases probability, but most patients report no affected relative. Cigarette smoking is associated with a less favourable Crohn's course and is a modifiable risk factor. Previous appendicectomy, antibiotics, diet and urbanisation have epidemiological associations, but these are not diagnostic tests and should not be used to blame a patient. Non-steroidal anti-inflammatory drugs may exacerbate symptoms in some people and should be reviewed.
Once disease is diagnosed, risk stratification focuses on progression. Young age at onset, extensive small-bowel involvement, deep ulcers, severe presentation, perianal or penetrating behaviour, stricturing disease, smoking, growth impairment and early need for corticosteroids can indicate a higher-risk course. Previous resections, short residual bowel, malnutrition and poor treatment response shape future options. Repeated inflammatory activity increases the chance of bowel damage, yet treatment intensity must be balanced against infection and medicine-specific risk.
Before immunosuppression, assess previous or latent tuberculosis, TB contact, hepatitis B and C risk, HIV according to consent and local practice, varicella history, vaccination, recurrent infection and travel or parasite exposure. Diabetes, advanced age, undernutrition, chronic lung disease and combination immunosuppression increase infection consequences. Thiopurine toxicity depends partly on enzyme activity and drug interactions; methotrexate is teratogenic. Cancer risk is influenced by colonic disease duration and extent, persistent inflammation, primary sclerosing cholangitis, family history and some immunosuppressive exposures. Risk review should be repeated as disease, therapy and life plans change.
Diagnosis
History
Define duration, stool frequency and consistency, nocturnal symptoms, blood or mucus, urgency, pain site, vomiting, obstructive episodes, fever, weight trajectory and food restriction. Ask about oral ulcers, joint symptoms, eye pain, skin lesions and perianal pain or discharge. Record growth and puberty in young people. Explore travel, unsafe water, antibiotic exposure, C difficile risk, TB contact, previous TB treatment, family history, smoking and medicines. Prior endoscopy, imaging, pathology and treatment response should be obtained rather than reconstructed from memory.
Examination
Assess vital signs, hydration, weight, body mass index and signs of anaemia or malnutrition. Examine the abdomen for tenderness, distension, mass, scars and peritonism. Inspect the perineum with consent and appropriate chaperoning when perianal symptoms exist; fluctuant swelling, drainage, fissures, tags and fistulous openings alter urgency. Look for oral, ocular, skin and joint manifestations. In children, plot height, weight and growth velocity. Fever, tachycardia, guarding, obstruction or sepsis requires urgent hospital assessment.
Investigations
Use full blood count, ferritin and iron indices, albumin, CRP, electrolytes, liver tests and selected micronutrients to assess inflammation and consequence. Stool testing excludes infection according to context, including C difficile; faecal calprotectin supports intestinal inflammation but is not disease-specific. Ileocolonoscopy should document distribution and severity and obtain biopsies from affected and apparently unaffected segments. MR enterography or intestinal ultrasound, where expertise exists, evaluates small bowel and transmural complications; CT is valuable in acute sepsis or obstruction but adds radiation. Pelvic MRI assesses complex perianal disease. When intestinal TB is plausible, integrate microbiology, histology, imaging, epidemiology and specialist review before immunosuppression.
Differential Diagnosis
Intestinal tuberculosis is a central Indian differential, particularly with ileocaecal disease, constitutional symptoms, ascites, necrotic lymph nodes, pulmonary or disseminated TB evidence, exposure or immunosuppression. Crohn's and TB overlap in pain, weight loss, strictures, ulcers, granulomas and raised inflammatory markers. Histological caseation and microbiological detection support TB, but their absence does not always exclude it. Longitudinal ulcers, cobblestoning, skip lesions and perianal disease may support Crohn's but are not individually decisive. Resolve discordance through gastroenterology, radiology, pathology, microbiology and TB expertise rather than alternating empirical steroid and anti-TB trials.
Infectious mimics include bacterial enterocolitis, C difficile, amoebiasis, giardiasis, Yersinia where epidemiologically relevant, cytomegalovirus in immunosuppressed patients and other parasites. Ulcerative colitis usually has continuous mucosal colonic inflammation beginning at the rectum, yet IBD-unclassified remains appropriate when evidence is mixed. Coeliac disease, microscopic colitis, drug injury, Behcet disease, eosinophilic disease, common variable immunodeficiency and ischaemic enteritis are selected alternatives. NSAID enteropathy can cause ulcers and strictures.
Symptoms in established Crohn's do not always mean inflammatory relapse. Consider fibrostenotic obstruction, abscess, bile-acid diarrhoea after ileal disease or resection, small-intestinal bacterial overgrowth, lactose intolerance, coeliac disease, pancreatic insufficiency and irritable bowel syndrome overlap. Anaemia, infection and depression can drive fatigue despite controlled gut inflammation. Malignancy should be considered with a new mass, progressive obstruction, unexplained systemic decline or longstanding colonic disease. Objective reassessment prevents both undertreatment of active disease and unsafe escalation when inflammation is absent.
Management
Management should be multidisciplinary and goal-directed. Treat dehydration, electrolyte disturbance, venous-thromboembolism risk, anaemia and infection while defining disease activity and complication. Dietitian assessment is essential when weight loss, restricted intake, growth failure, micronutrient deficiency, short bowel or surgery is present. Exclusive enteral nutrition is an established induction option in paediatric Crohn's and may be used in selected adults with expert support. There is no single exclusion diet that cures Crohn's; unnecessary restriction can worsen malnutrition. Smoking cessation reduces a modifiable driver of adverse course.
For active luminal disease, induction choice depends on location, severity and prognosis. Systemic corticosteroids or selected ileal-release budesonide can induce remission in appropriate phenotypes, but repeated courses indicate treatment failure. Conventional immunomodulators are not rapid induction monotherapy; thiopurines or methotrexate have selected maintenance roles. Advanced options include anti-TNF, anti-integrin, anti-interleukin and other licensed targeted treatments. Comparative evidence is incomplete for every sequence, so selection should combine efficacy, prior biologic exposure, fistula phenotype, infection risk, pregnancy plans, monitoring capacity, patient preference and affordability.
Abscess usually requires antibiotics and image-guided or surgical drainage before immunosuppression. Complex perianal disease needs pelvic imaging, examination under anaesthesia when indicated, drainage or seton strategy and coordinated medical therapy. Obstructive symptoms require distinction between inflammatory oedema and fixed fibrosis; short accessible strictures may suit dilation, whereas complex, long, penetrating or suspicious strictures need surgery. Early elective surgical discussion is not failure. After remission, use objective markers and endoscopy or imaging at planned intervals because symptoms may underestimate inflammation. Postoperative recurrence prevention begins with risk assessment, smoking cessation and timely surveillance.
Prescribing Information
Corticosteroids are induction drugs, not maintenance therapy. Before use, exclude uncontrolled infection and assess glucose, blood pressure, bone risk, mood and gastrointestinal protection according to the individual. Plan a taper and a steroid-sparing strategy from the start; abrupt cessation after prolonged exposure risks adrenal insufficiency. Budesonide has lower systemic exposure but is location-specific and is not harmless. Avoid routine opioids for chronic abdominal pain because dependence, ileus and worse outcomes can follow. NSAIDs may aggravate disease in some patients.
Before thiopurines, assess TPMT or NUDT15 according to local availability and population practice, baseline blood count and liver function, interactions and infection status. Normal enzyme activity does not remove the need for serial blood and liver monitoring. Thiopurines act slowly and do not induce remission as monotherapy. Methotrexate requires blood, liver and renal monitoring, folate support and strict pregnancy prevention for the patient receiving it; it is contraindicated in pregnancy. Aminosalicylates have limited efficacy in Crohn's compared with their role in ulcerative colitis.
Before advanced therapy, document disease activity objectively and screen for TB and other infections according to agent and local epidemiology. Anti-TNF and JAK-pathway treatments particularly demand TB risk assessment; treat latent or active infection with specialist coordination. Check hepatitis B status and immunisations, and give indicated non-live vaccines ideally before immunosuppression. Live vaccines are generally avoided during significant immunosuppression. Monitor response, adverse effects and loss of response rather than continuing automatically. Biosimilars may improve access when procurement and pharmacovigilance are reliable. All dosing and combination decisions belong to an experienced IBD team using current labels and local policy.
When to Refer
Emergency surgical and gastroenterology assessment is required for peritonitis, suspected perforation, complete obstruction, toxic systemic illness, uncontrolled bleeding, severe dehydration, a tender mass with sepsis, or a perianal abscess with systemic compromise. Resuscitate, obtain appropriate cultures and imaging, start indicated antimicrobial treatment and involve surgery early. Do not administer escalating immunosuppression to undrained sepsis. A patient with persistent vomiting, increasing distension, inability to pass stool or flatus and colicky pain may have obstruction even if diarrhoea occurred earlier.
Urgent specialist evaluation is appropriate for suspected new inflammatory bowel disease with weight loss, nocturnal diarrhoea, iron-deficiency anaemia, hypoalbuminaemia, raised inflammatory markers, growth failure, perianal fistula or abnormal imaging. In India, diagnostic uncertainty between Crohn's and intestinal TB warrants coordinated expert review before immunosuppressive treatment. Known disease needs expedited review for steroid dependence, repeated relapse, progressive anaemia, malnutrition, fistula, obstructive symptoms, new extra-intestinal manifestations or discordance between symptoms and biomarkers.
Early colorectal or IBD surgical referral is appropriate for a symptomatic fibrotic stricture, penetrating disease, recurrent abscess, complex perianal fistula, medically refractory localised ileal disease, dysplasia or suspected cancer. Elective discussion permits nutrition, infection and steroid optimisation and is safer than waiting for an emergency. Refer for specialist obstetric and gastroenterology planning before conception when possible, and involve paediatric teams for growth or transition concerns. A referral should include phenotype, prior pathology and imaging, infection and TB work-up, cumulative steroid exposure, medicine history, nutritional status and the specific decision required.
Red Flags
Acute red flags are shock, high fever with toxicity, guarding or rebound, rigid abdomen, severe distension, persistent bilious vomiting, absent output with colicky pain, major bleeding, syncope, altered consciousness and rapidly worsening perianal pain or swelling. These suggest perforation, obstruction, abscess, sepsis or major haemorrhage and require hospital care. Immunosuppressed patients may have muted fever or inflammatory markers, so deterioration, tachycardia and localising symptoms deserve particular weight. New chest symptoms or hypoxaemia raise infection and thromboembolism concerns.
During immunosuppressive treatment, urgent review is required for persistent fever, cough, night sweats, weight loss, jaundice, severe sore throat, bruising, neurological symptoms or exposure to varicella or another significant infection. In a TB-endemic setting, constitutional or respiratory symptoms during anti-TNF or other immunosuppression must not be labelled a Crohn's flare without evaluation. Severe cytopenia or liver injury can be medicine toxicity. Patients should know whom to contact and which medicines, if any, need to be withheld while assessment occurs; blanket unsupervised cessation can also cause harm.
Longer-term red flags include repeated steroid courses, falling weight or albumin, growth faltering, progressive anaemia, nocturnal symptoms, a new abdominal mass, change in a known stricture, unexplained obstruction or persistent inflammation despite few symptoms. New dysplasia, longstanding extensive colonic disease and primary sclerosing cholangitis alter cancer surveillance. Severe depression, food avoidance, inability to afford therapy or loss to follow-up can be as consequential as a laboratory abnormality. Safe care identifies these problems before emergency surgery or irreversible malnutrition develops.
Indian Clinical Context
The central diagnostic challenge is distinguishing Crohn's disease from intestinal tuberculosis and other infection without stereotyping either condition. Evaluate epidemiology, pulmonary and extra-intestinal findings, endoscopic distribution, cross-sectional imaging, histology and microbiology together. Send tissue or other appropriate samples for mycobacterial testing when suspicion warrants, coordinating with pathology so all material is not placed in fixative. Neither a negative molecular test nor absence of caseation excludes every case, while granulomas alone do not prove TB. Diagnostic uncertainty should be documented and discussed in a multidisciplinary forum before high-risk immunosuppression.
TB screening before anti-TNF or other substantial immunosuppression is particularly important in India. History and examination should be combined with chest imaging and latent-infection testing according to current specialist and national practice, recognising reduced test sensitivity during immunosuppression. Symptoms suggesting active TB require a disease-diagnostic pathway, not latent-TB treatment alone. Hepatitis B, HIV with consent, strongyloides or other locally relevant infection risks are assessed according to exposure and planned therapy. Update inactivated vaccines where possible before treatment and plan live vaccines before immunosuppression when clinically safe.
Access influences every choice. Endoscopy, MR enterography, intestinal ultrasound expertise, biologics, drug-level testing and colorectal surgery may be distant or unaffordable. Use the best validated available test, preserve original images and pathology, and coordinate referral rather than repeating low-yield studies. Biosimilars and public schemes may improve access, but interrupted supply can undermine a regimen. Nutrition advice must use affordable local foods and avoid unnecessary exclusion. Care plans should specify monitoring locations, abnormal-result responsibility, medicine storage, pregnancy contact, emergency access and what happens if the preferred therapy is unavailable.
NMC Competency Mapping
Crohn's disease integrates NMC CBME competencies across general medicine, surgery, paediatrics, pathology, microbiology, pharmacology, radiology, nutrition and AETCOM. At Know level, learners should describe discontinuous transmural inflammation, common ileocolonic distribution, inflammatory, stricturing and penetrating behaviour, extra-intestinal manifestations and complications. They should compare Crohn's with ulcerative colitis, intestinal TB, infectious enterocolitis and malabsorption while recognising that no isolated feature is definitive.
At Know How level, the learner should select inflammatory markers, stool infection testing, faecal calprotectin, ileocolonoscopy with biopsies and cross-sectional imaging for specific questions. They should explain how abscess, fibrosis and fistula alter treatment; why corticosteroids do not maintain remission; and why infection screening, vaccination and laboratory monitoring precede immunomodulators or biologics. Indian clinical reasoning includes safe tissue handling and integrated evaluation for intestinal and pulmonary TB. Nutrition competence includes growth assessment, iron and vitamin deficiencies and indications for specialist enteral support.
At Show How level, case-based assessment can test a focused diarrhoea and perianal history, abdominal examination, interpretation of an ileal stricture, counselling before thiopurine or biologic therapy and structured escalation for obstruction or sepsis. At Perform level, endoscopy, immunosuppressive prescribing and operative decisions remain within supervised scope and institutional policy. AETCOM outcomes include shared decisions about chronic therapy, fertility, stoma concerns, cost and uncertain diagnosis. This guide is educational and cannot certify independent colonoscopy, pathology interpretation, TB exclusion or biologic prescribing.
Key Exam Pearls for NEET PG
Crohn's can involve mouth to anus, characteristically with skip lesions and transmural inflammation; terminal ileum and colon are common sites. Transmural disease explains fistulae, abscesses and strictures. Histology may show non-caseating granulomas, but they are absent in many patients and require distinction from intestinal TB. Cobblestoning, longitudinal ulcers, creeping fat and perianal disease are classic associations, not stand-alone diagnostic tests. Ileal disease or resection can cause vitamin B12 deficiency and bile-acid diarrhoea; extensive resection risks short-bowel syndrome and nutritional deficiency.
Faecal calprotectin indicates intestinal inflammation but is not specific for Crohn's and can rise with infection or other disease. Ileocolonoscopy with segmental biopsies assesses mucosa; MR enterography evaluates small bowel and transmural complications without ionising radiation. CT is useful in acute obstruction or sepsis. A suspected abscess is drained and treated before intensifying immunosuppression. Fixed fibrotic strictures generally do not resolve with corticosteroids, and selected short accessible strictures may be dilated.
Corticosteroids induce but do not maintain remission. Thiopurines and methotrexate are slow maintenance agents in selected patients, while biologic and targeted therapies are chosen by phenotype and risk. Before anti-TNF treatment, screen for TB and hepatitis B and update vaccination. Avoid live vaccines during significant immunosuppression. Methotrexate is teratogenic. Smoking worsens Crohn's outcomes. Surgery treats complications or selected localised disease but is not curative, because postoperative recurrence can occur. Longstanding colonic involvement requires risk-based dysplasia surveillance.
Frequently Asked Questions
How can clinicians distinguish Crohn's disease from intestinal tuberculosis in India?
No single symptom, endoscopic sign or test is sufficient. Use a composite assessment: TB exposure and systemic or pulmonary features; disease distribution and lymph-node pattern on imaging; ileocolonoscopy; biopsies from multiple sites; histology; and mycobacterial microbiology on correctly handled tissue or other samples when indicated. Caseation or microbiological confirmation strongly supports TB, but sensitivity is imperfect. Skip lesions, longitudinal ulcers, transmural complications and perianal disease may favour Crohn's but overlap occurs. Discordant cases require gastroenterology, radiology, pathology, microbiology and TB input. Empirical corticosteroids can disseminate unrecognised TB, while an uncritical anti-TB trial can delay Crohn's treatment, so uncertainty should be explicit and managed rather than concealed.
Why should corticosteroids not be continued to maintain Crohn's remission?
Corticosteroids can suppress active inflammation relatively quickly, but they do not provide safe durable maintenance and cumulative exposure causes infection, diabetes, hypertension, osteoporosis, cataract, mood disturbance, growth suppression and adrenal insufficiency. A patient who relapses during taper or repeatedly needs another course has steroid-dependent or inadequately controlled disease and needs objective reassessment plus a steroid-sparing strategy. The next step may involve an immunomodulator, an advanced therapy, nutrition, treatment of a complication or surgery, depending on phenotype and evidence of inflammation. A taper must be planned and prolonged therapy should not be stopped abruptly. Infection, including TB, must be excluded before escalation.
Can a person with Crohn's disease have a healthy pregnancy?
Yes. Many people have successful pregnancies, especially when conception occurs during stable remission with coordinated gastroenterology and obstetric care. Active disease itself increases pregnancy risk, so stopping effective treatment without advice can be more dangerous than continuing an appropriate medicine. Review every drug before conception: methotrexate is contraindicated and requires specialist discontinuation planning, while the safety and timing of biologics and immunomodulators depend on the agent and individual circumstances. Correct anaemia and nutritional deficiency, update suitable vaccines, stop smoking and discuss thrombosis risk. Infant live-vaccine timing may need adjustment after some in-utero biologic exposures. Decisions should use current drug-specific guidance rather than a blanket rule.
When does Crohn's disease require surgery, and does surgery cure it?
Surgery is required urgently for perforation, uncontrolled sepsis, complete obstruction or major bleeding, and is considered electively for fibrotic stricture, recurrent abscess, complex fistula, dysplasia, cancer or medically refractory localised disease. Drainage and control of sepsis often precede definitive resection. Selected short, straight, endoscopically accessible strictures may be dilated, whereas long, complex, penetrating or suspicious strictures usually need surgical management. Surgery can restore health and quality of life and should not be framed as failure, but it does not cure the underlying tendency to Crohn's inflammation. Postoperative recurrence is possible, so risk-based preventive treatment, smoking cessation and objective endoscopic follow-up remain necessary.
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