Extra-intestinal manifestations of IBD

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Extra-intestinal disease arises through shared immune pathways, chronic inflammation, altered absorption and treatment effects. Its relationship to intestinal activity varies. Erythema nodosum and some peripheral arthritis commonly parallel a flare, while axial spondyloarthritis, uveitis, PSC and pyoderma can progress despite quiet bowel disease. This distinction prevents two errors: escalating intestinal therapy for an independently active organ disease, and ignoring the bowel when control would treat both. A joint IBD-rheumatology, ophthalmology, dermatology or hepatology plan is preferable to competing isolated prescriptions.

The differential diagnosis remains broad. Septic arthritis can resemble inflammatory monoarthritis; infection or drug reaction can resemble a rash; anti-TNF can paradoxically cause psoriasiform disease; mesalazine, thiopurines, methotrexate and biologics can injure liver, pancreas, kidney, marrow or lung. Nutritional deficiencies cause fatigue, neuropathy, mouth lesions and bone disease. Assessment should establish onset relative to bowel activity and medicines, organ threat, objective intestinal state and treatment compatibility. Systemic corticosteroid may suppress several problems briefly but can worsen infection and bone risk, so an organ-specific, steroid-sparing strategy remains the goal.

Key points

Extra-intestinal manifestations can involve joints, eyes, skin, liver, blood, bone, kidneys, lungs and nervous system, and some appear before IBD is diagnosed.
Peripheral arthritis associated with active colitis may improve when bowel inflammation is controlled, whereas axial spondyloarthritis often follows an independent course and needs rheumatology care.
A painful photophobic red eye or reduced vision is uveitis until urgently assessed; simple episcleritis is usually less painful and does not impair vision.
Erythema nodosum usually presents as tender shin nodules and often tracks bowel activity; pyoderma gangrenosum causes rapidly progressive painful ulceration and can worsen after trauma.
Persistent cholestatic liver tests require assessment for primary sclerosing cholangitis and other hepatic causes; PSC changes colorectal and biliary cancer surveillance.
Active IBD, hospitalisation and surgery increase venous-thromboembolism risk, so formal prophylaxis assessment is essential even when non-major rectal bleeding is present.
Anaemia, osteoporosis, gallstones and renal stones may reflect inflammation, malabsorption, ileal disease, resection or corticosteroid exposure rather than a separate coincidence.
Before calling a new syndrome extra-intestinal IBD, exclude infection, medicine toxicity and unrelated disease because immunosuppression can make these presentations atypical.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Shared immune inflammation

Cross-reactive immune pathways and trafficking of activated lymphocytes link intestinal disease with joints, eyes, skin and hepatobiliary tissues.

Activity-linked systemic effects

Peripheral arthritis, episcleritis and erythema nodosum often track bowel inflammation, while axial spondyloarthritis and PSC may progress independently.

Treatment and deficiency effects

Immunosuppression, corticosteroids, malabsorption and chronic inflammation produce infection, drug toxicity, anaemia and bone disease that can resemble primary manifestations.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Gut-derived immune activation
Loss of mucosal tolerance activates cytokines and immune cells that recognise related antigens or adhesion signals outside the bowel.
2
Organ-specific inflammation
Recruited inflammatory cells damage synovium, uvea, skin or bile ducts, with clinical behaviour varying by target organ.
3
Systemic prothrombotic and catabolic state
Active inflammation increases coagulation, endothelial activation and bone or muscle loss, compounding direct immune injury and medicine effects.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Peripheral arthropathy

Acute asymmetric large-joint inflammation may parallel active IBD, while a more persistent polyarticular pattern can continue independently; true synovitis needs separation from mechanical pain.

Axial spondyloarthritis

Back pain beginning young, morning stiffness, night waking and improvement with movement suggests axial inflammation; normal plain radiography does not exclude non-radiographic disease.

Erythema nodosum

Tender warm subcutaneous nodules, classically over shins, occur with active inflammation but infection, sarcoidosis and medicines remain alternative causes.

Pyoderma gangrenosum

A painful pustule or nodule can rapidly ulcerate with undermined violaceous edges; trauma or debridement may worsen pathergy and should be avoided until expert review.

PSC pattern

Persistent alkaline phosphatase or gamma-glutamyl transferase elevation, pruritus, fatigue, recurrent cholangitis or jaundice suggests cholangiopathy, though many patients are initially asymptomatic.

Hypercoagulability

Deep-vein thrombosis, pulmonary embolism, portal or cerebral venous thrombosis may occur during severe inflammation but can also present outside an obvious flare.

Red flags requiring action

A painful photophobic red eye, reduced vision or abnormal pupil needs same-day ophthalmology assessment to prevent irreversible visual damage.
A hot swollen single joint with fever is septic arthritis until excluded and must not be treated as routine IBD arthropathy with more immunosuppression.
Rapidly progressive painful skin ulceration should prompt dermatology review before surgical debridement because pyoderma gangrenosum can worsen through pathergy.
Jaundice with fever, right upper-quadrant pain, hypotension or confusion suggests acute cholangitis and requires urgent sepsis, biliary and hepatology management.
New dyspnoea, pleuritic pain, unilateral swelling, focal neurology or severe headache requires emergency thrombosis assessment.
Focal spinal pain, height loss or fracture after corticosteroid exposure needs urgent structural and bone review, not analgesia alone.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Objective IBD activity assessmentFirst step
Why
Determine whether the extra-intestinal syndrome tracks uncontrolled bowel inflammation.
Interpretation and limitations
Use symptoms with calprotectin, CRP, endoscopy or imaging; quiet luminal disease does not exclude axial arthritis, uveitis, PSC or pyoderma.
02
Slit-lamp ophthalmic examination
Why
Distinguish uveitis and define the site and severity of ocular inflammation.
Interpretation and limitations
Visual acuity and slit-lamp findings guide topical or systemic specialist treatment; do not delay urgent referral while waiting for gastrointestinal tests.
03
Joint examination, inflammatory markers and targeted imaging
Why
Identify synovitis or axial inflammation and exclude structural or septic disease.
Interpretation and limitations
Use ultrasound, MRI sacroiliac imaging or aspiration according to presentation; HLA-B27 supports susceptibility but neither confirms nor excludes enteropathic spondyloarthritis.
04
Liver profile and magnetic resonance cholangiopancreatography
Why
Assess cholestasis and map possible primary sclerosing cholangitis.
Interpretation and limitations
Exclude medicine, fatty liver, viral, autoimmune and obstructive causes; MRCP can show multifocal biliary stricturing, while a new dominant or relevant stricture needs specialist exclusion of malignancy.
05
Full blood count, ferritin and transferrin saturation
Why
Characterise anaemia from iron deficiency, inflammation, bleeding or medicine toxicity.
Interpretation and limitations
Ferritin rises with inflammation, so combine indices with CRP, red-cell pattern, vitamin B12, folate, haemolysis or marrow assessment as indicated.
06
Bone risk and DEXA assessment
Why
Identify osteoporosis in patients with steroid, malnutrition, inflammatory or fracture risk.
Interpretation and limitations
Use age, fracture history, steroid exposure, body mass, vitamin D and current national thresholds; a normal scan does not justify repeated unnecessary corticosteroid.
07
Skin biopsy and microbiology
Why
Support difficult dermatological diagnosis and exclude infection or vasculitis.
Interpretation and limitations
Biopsy the appropriate edge under dermatology guidance because histology may be non-specific and traumatic sampling can aggravate suspected pyoderma.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Infection

Fever, focal sepsis, positive cultures or immunosuppression-related exposure requires assessment before attributing joint, skin or eye symptoms to sterile IBD inflammation.

Medicine toxicity

Temporal association, class-specific laboratory changes and improvement after supervised withdrawal suggest adverse therapy effects rather than uncontrolled extra-intestinal disease.

Independent autoimmune disease

Organ-specific antibodies, imaging or specialist criteria may establish rheumatoid, connective-tissue, dermatological or hepatobiliary disease requiring its own treatment pathway.

Additional chapter-specific clues

Uveitis versus episcleritis

Uveitis causes deeper pain, photophobia, ciliary redness or visual change, whereas episcleritis more often causes superficial discomfort without visual loss; uncertain cases need urgent eye examination.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01TRIAGEIdentify the threatened organFirst stepA patient with known or suspected IBD presents with a new joint, eye, skin, liver, neurological or cardiorespiratory syndrome.

1Assess vision, sepsis, joint destruction, thrombosis, biliary obstruction and neurological function first, using emergency specialist pathways when an organ is threatened.
2Relate onset to bowel symptoms, objective IBD activity, recent infection, immunosuppression, corticosteroid changes and newly introduced medicines.
3Obtain targeted examination and investigations rather than labelling the syndrome from association alone, actively excluding infection and drug toxicity.
4Contact the relevant specialty and IBD team early so one treatment plan does not worsen the other disease domain.

02JOINT-EYE-SKINCoordinate inflammatory treatmentArthritis, uveitis, erythema nodosum or pyoderma is confirmed after urgent mimics are addressed.

1Determine whether the manifestation tracks gut activity and treat active bowel inflammation, while not delaying direct ophthalmic, dermatological or rheumatological therapy.
2Select local treatment when adequate and use systemic therapy that can control both domains when possible, checking current IBD and specialty licensing.
3Avoid routine NSAIDs when bowel flare risk is substantial and avoid debridement of suspected pyoderma without expert confirmation.
4Monitor organ-specific outcomes such as vision, joint function and wound dimensions separately from stool or calprotectin response.

03LIVERInvestigate persistent cholestasisLiver tests show a sustained cholestatic pattern or symptoms suggest biliary disease.

1Repeat and fractionate the pattern, review alcohol, metabolic risk, viral infection and hepatotoxic medicines, and perform abdominal ultrasound for common obstruction.
2Refer for hepatology assessment and MRCP when PSC remains possible, avoiding diagnostic ERCP unless intervention or tissue is required.
3For a clinically important stricture, cholangitis or worsening jaundice, coordinate urgent biliary drainage, cytology or further malignancy assessment in an expert service.
4If PSC is confirmed, establish hepatobiliary follow-up and intensified colitis surveillance according to current BSG and local specialist pathways.

04PREVENTReduce thrombotic, bone and deficiency harmActive inflammation, admission, surgery, corticosteroid exposure, ileal disease or chronic blood loss creates preventable systemic risk.

1Perform venous-thromboembolism risk assessment on admission and prescribe pharmacological prophylaxis unless a genuine bleeding or other contraindication is documented.
2Identify and treat iron, vitamin B12, folate, vitamin D, calcium and nutritional deficits through disease control and route-appropriate replacement.
3Minimise systemic corticosteroid and assess fracture risk, exercise, smoking, alcohol and bone-protective treatment using current national guidance.
4Recheck correction and symptoms, because persistent deficiency can indicate ongoing inflammation, bleeding, malabsorption or medicine toxicity.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Controls selected anterior ocular inflammation rapidly and protects vision alongside broader disease treatment.

Topical ocular corticosteroid

Ophthalmologist-directed preparation, frequency and taper after slit-lamp diagnosis of uveitis.

Do not initiate prolonged treatment without eye assessment; infection, glaucoma, cataract and posterior disease require specialist monitoring and sometimes systemic therapy.

Can control intestinal inflammation and selected axial, peripheral, ocular or dermatological manifestations.

Monoclonal anti-TNF therapy

Licensed specialist induction and maintenance regimen chosen for both IBD and extra-intestinal phenotype.

Drain infection first and screen tuberculosis and hepatitis; not every anti-TNF formulation has equivalent evidence across manifestations, and paradoxical psoriasis can occur.

Reduces venous-thromboembolism during active IBD admission, immobility and perioperative care.

Pharmacological thromboprophylaxis

Hospital prophylactic regimen adjusted for renal function, body weight and bleeding risk.

Major active haemorrhage, severe thrombocytopenia and renal impairment need individual review; minor rectal bleeding alone is not always a reason to withhold protection.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Sight-threatening uveitis

Painful photophobia or reduced vision can indicate uveal inflammation and requires urgent ophthalmology assessment to prevent permanent visual loss.

Venous thromboembolism

Active IBD, admission, dehydration and surgery increase deep-vein thrombosis and pulmonary embolism risk, supporting appropriate prophylaxis.

Chronic organ damage

Axial disease can impair mobility, PSC increases biliary and colorectal cancer risk, and osteoporosis raises fracture risk despite bowel symptom control.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Track extra-intestinal activity with organ-specific measures rather than assuming calprotectin represents joint, eye, skin or bile-duct control.
Ask directly about eye pain, vision, inflammatory back pain, skin ulcers, pruritus, jaundice, chest pain and limb swelling during routine IBD review.
For PSC, follow hepatology-led liver, imaging, biliary and cancer-surveillance plans and investigate clinical change rather than relying on one stable enzyme value.
Recheck anaemia and micronutrient response after replacement, using failure to correct as a signal of ongoing bleeding, inflammation, loss or non-adherence.
Record cumulative steroid exposure and reassess fracture and adrenal risk whenever another course is considered.
Reconcile therapies across specialties because duplicate immunosuppression, NSAID exposure or incompatible biologic choices can arise when care is fragmented.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Activity coupling varies

Some peripheral joint and skin inflammation improves with bowel control, while axial disease, PSC and uveitis may require treatment despite intestinal remission.

The red eye has levels

Superficial redness without visual change differs from deeper pain and photophobia, but uncertainty should favour urgent slit-lamp assessment because missed uveitis threatens vision.

Pathergy changes wound care

Pyoderma gangrenosum may expand after trauma. Surgical cleaning that is appropriate for infection can be damaging until dermatology excludes an inflammatory ulcer.

PSC changes colitis surveillance

The combination carries higher colorectal neoplasia risk and often requires a more intensive colonoscopic programme independent of bowel symptoms.

Rectal bleeding and thrombosis coexist

Active colitis can cause visible blood and simultaneously create marked thrombosis risk; prophylaxis decisions require haemorrhage severity, not a reflex binary rule.

11Common pitfallsFrequent interpretation and management errors.

01
Calling a hot swollen joint IBD arthritis before excluding septic arthritis.
02
Treating a painful photophobic eye as conjunctivitis without checking vision and obtaining urgent ophthalmology assessment.
03
Debriding a rapidly progressive suspected pyoderma ulcer before dermatology review and thereby provoking pathergy.
04
Assuming axial pain will resolve when bowel calprotectin normalises and omitting rheumatology referral.
05
Attributing every liver-test abnormality to PSC without reviewing fatty liver, gallstones, viral disease and medicine toxicity.
06
Withholding thromboprophylaxis from every admitted flare because some rectal blood is present.
07
Escalating gut-selective therapy for an extra-intestinal manifestation it is unlikely to control.