AKT · Musculoskeletal/Inflammatory arthritislow yield

Reactive & enteropathic arthritis

Sterile inflammatory arthritis triggered by a distant GU/GI infection (reactive); or associated with IBD (enteropathic)

Overview

Reactive arthritis is a sterile, HLA-B27-associated inflammatory arthritis arising days to weeks after a urogenital (Chlamydia) or gastrointestinal (Salmonella, Shigella, Campylobacter, Yersinia) infection — the classic triad 'can't see, can't pee, can't climb a tree' (conjunctivitis, urethritis, arthritis). Enteropathic arthritis is the spondyloarthropathy associated with inflammatory bowel disease.

Recognise

Reactive: acute asymmetrical lower-limb oligoarthritis 1–4 weeks after GU/GI infection; enthesitis, dactylitis
Extra-articular: conjunctivitis/anterior uveitis, urethritis, circinate balanitis, keratoderma blennorrhagica, mouth ulcers
Enteropathic: arthritis (peripheral tracks bowel activity; axial independent) with Crohn/UC

Red flags

Exclude SEPTIC arthritis in any acute hot joint — aspirate before labelling it reactive
Anterior uveitis → ophthalmology

Differentials & how to tell them apart

Septic arthritisorganisms on aspirate — must exclude first; reactive arthritis is sterile

Gout/pseudogoutcrystals on aspirate

Other spondyloarthropathypsoriasis, IBD or axial AS pattern

Investigations

Aspirate the joint to EXCLUDE septic arthritis and crystals (reactive arthritis fluid is sterile and inflammatory); identify the trigger (stool culture, chlamydia NAAT); HLA-B27; raised inflammatory markers; assess for IBD in enteropathic arthritis.

Management

Exclude sepsis → NSAIDs ± intra-articular steroid; treat the trigger; sulfasalazine if chronic

1In an acute hot joint, ASPIRATE first to exclude septic arthritis and crystals. Once sterile/reactive → NSAIDs ± intra-articular steroid, and treat any ongoing triggering infection.Gate: Never label a hot joint 'reactive' without excluding septic arthritis by aspiration — the consequences of a missed septic joint are severe.
2Persistent/chronic disease → sulfasalazine; treat the underlying IBD in enteropathic arthritis; manage uveitis with ophthalmology.

NSAIDs ± intra-articular corticosteroid — first-line for the arthritis once sepsis excluded

Treat the triggering infection — antibiotics for ongoing chlamydial urethritis (and partner) — antibiotics do NOT treat the arthritis itself

DMARD (sulfasalazine) for persistent disease — if it becomes chronic; treat IBD in enteropathic arthritis

Manage extra-articular features — uveitis (ophthalmology)

Key points

Asymmetrical lower-limb oligoarthritis 1–4 weeks after a GU/GI infection ('can't see, can't pee, can't climb a tree') = reactive arthritis (HLA-B27). ALWAYS aspirate to exclude septic arthritis first. Arthritis tracking IBD activity = enteropathic.

Monitor & prognosis

Joint resolution (often self-limiting over months), uveitis, IBD activity.

Often self-limiting; a minority become chronic.

Source: NICE NG65; cross-ref gastroenterology (IBD), sexual_health (chlamydia)