Reasoning GP · Algorithm · 1-page summary
Purpura and petechiae
For: children and adults with a non-blanching rash, petechiae or purpura, in hours or OOH. Not for: ongoing specialist care of ITP, ANCA vasculitis or meningococcal survivors (haematology-, rheumatology- or hospital-led; detail in the full algorithm).
Core rule: an unwell patient with a non-blanching rash has suspected meningococcal disease: 999 first, never wait for blood results. The glass test helps, but a rash that fades excludes nothing.
0Stop — call 999 now — and pre-alert
- Non-blanching rash + fever + unwell; purpura >2 mm, a rapidly spreading non-blanching rash, or meningitis features with a non-blanching rash → 999
- Purpura with haemodynamic compromise (pale, mottled, cold peripheries, prolonged capillary refill, altered consciousness): purpura fulminans / DIC → 999
- Suspected TTP/HUS (low platelets + anaemia/haemolysis, renal impairment or neurology); major GI, intracranial or concealed bleeding; febrile neutropenia or severe pancytopenia; meningism, severe headache or seizures → 999
- While waiting: meningococcal disease strongly suspected → IV/IM ceftriaxone (preferred) or benzylpenicillin as soon as possible, unless it delays transfer or severe allergy to that drug (benzylpenicillin <1 yr 300 mg · 1–9 yrs 600 mg · ≥10 yrs 1200 mg; doses per BNF/BNFC). No test may delay transfer.
1Triage — well or unwell decides first
| Patient | Action |
|---|---|
| Unwell | Petechiae or purpura anywhere, or any abnormal vital sign → 999 |
| Child | Unexplained petechiae or hepatosplenomegaly → Same-day immediate specialist assessment (NG12) |
| FBC | Platelets <20 × 10⁹/L, blasts or pancytopenia → Same-day haematology; significant bleeding → 999 |
| Safeguarding | Pre-mobile infant, unexplained or implausible lesions → Urgent paediatric / safeguarding assessment; body map |
| Well | Face/neck only after coughing, vomiting or crying → possible Valsalva; exclusion diagnosis (block 5) |
2Screen — one row is enough
- Leukaemia: child with pallor, persistent fatigue, unexplained fever, persistent infection, generalised nodes, bone pain, unexplained bruising or bleeding; adult with purpura + pallor, nodes or hepatosplenomegaly → Very urgent FBC ≤48 h
- IgA vasculitis with severe abdominal pain, GI bleeding, cannot mobilise, hypertension, significant proteinuria or haematuria, renal impairment, dehydration → Same-day paediatrics
- Palpable purpura with renal, respiratory, neurological or systemic features (ANCA vasculitis) → Urgent assessment
- On heparin, suspected HIT → stop heparin now, non-heparin anticoagulant → Same-day haematology
3Assess — observations before anything else
☐ Temperature, HR, BP, RR, SpO₂, capillary refill, peripheral temperature, mental state ☐ Glass test; conjunctivae and all skin incl. nappy area (harder to see on brown or black skin) ☐ Palpable? Spreading? Mucosal bleeding? ☐ Nodes, liver, spleen, joints, fundi
Well: FBC + film; clotting if bleeding significant or unexplained; urinalysis + renal function if vasculitis possible. No routine ANCA/ANA/EBV panels.
4Classify — only if blocks 0–2 are negative
- ITP — well, isolated low platelets, normal Hb, white cells and film. Exclude leukaemia, drugs, TTP/HUS; haematology-led.
- IgA vasculitis — age 3–15, palpable purpura on buttocks and legs, joint and abdominal pain. BP + urinalysis every review.
- Valsalva / viral — well child; face and neck after a clear trigger, or palatal petechiae.
- Actinic purpura — older adult, sun-exposed forearms and hands, normal FBC. Reassure; review medication.
- Uncertain — say so. Diagnostic uncertainty with low platelets → same-day specialist discussion.
5Treat today — only these
- Valsalva petechiae: only if observations normal, whole child examined, rash not spreading, drugs, platelets and safeguarding considered → reassure; review within 24 h.
- IgA vasculitis, well: analgesia, fluids; avoid ibuprofen (or discuss) if renal impairment, dehydration, GI bleeding or significant proteinuria. No routine steroids.
- Low platelets: avoid NSAIDs and aspirin; activity advice per haematology.
- Drug cause: stop essential medicines only after assessing risk (except HIT). Doses: NICE/SPC, BNF, local formulary.
6Refer routinely
- IgA vasculitis: urine and BP over several months; persistent proteinuria, hypertension or renal impairment → nephrology.
- Unexplained thrombocytopenia not clearly ITP → haematology (suspected cancer pathway).
- After meningococcal disease: audiology within 4 weeks of being well enough; notify the HPT, which arranges contact prophylaxis.
7Never reassure by
- A rash that fades, or a negative or unclear glass test.
- No fever in an infant or immunocompromised patient, or no rash.
- Petechiae confined to the face and neck, on distribution alone.
- An earlier label of ITP, viral petechiae or vasculitis once new fever or deterioration appears.
- Waiting for blood results in an unwell patient.
- A possible bleeding disorder when there are safeguarding concerns.
8Safety-net — say it, write it, document it
999 “Call 999 if a fever starts, the rash spreads or the spots get bigger, your child becomes drowsy, pale or unwell, or there is a severe headache, a fit, heavy bleeding, or dark urine or no urine.” Same day “Contact us today for new bleeding, tummy pain, joint pain, less urine, or pink or red urine with IgA vasculitis.”
A rash that fades does not rule out serious illness. On brown or black skin, check paler areas and inside the eyelids.
✓Safe to leave primary care only if — all five, documented
Observations normal; whole skin examined
No block 0–2 row applies
Cause explains the rash, or uncertainty discussed the same day
Safeguarding considered and recorded
Written safety-net given; review booked
Summary of the full Reasoning GP purpura and petechiae algorithm, which holds the detail, examination, differential and evidence. Sources: NICE NG240, NG12 (updated April 2026), NG143, CG89; BSH ITP and child-protection bleeding guidance; UKHSA meningococcal guidance and Green Book. Clinical reference — follow local emergency-transfer and safeguarding policies and check doses: NICE/SPC, BNF.