Synopsis
Triage a non-blanching eruption without delay, describe purpura accurately across skin tones, distinguish infection, bleeding, inflammation and occlusion, and direct immediate tests and treatment by physiological risk.
- Non-blanching means colour remains when firm pressure displaces blood from nearby capillaries; it describes extravasated blood or fixed vascular material, not a diagnosis.
- Inspect the whole skin in good light, including conjunctivae, mouth, palms, soles and pressure areas; in brown or black skin, petechiae may be clearer on paler mucosa or by side lighting and palpation.
- Never use a reassuring glass test to overrule an unwell patient: early meningococcal disease may have a blanching, sparse or absent rash, and deterioration can be fast.
- Petechiae are pinpoint lesions, purpura are larger patches and ecchymoses are bruise-sized; more important bedside distinctions are flat versus palpable and round versus angular retiform morphology.
- Fever, toxicity or rapidly multiplying lesions demands immediate sepsis and meningococcal assessment before a dermatological differential or biopsy.
- Flat petechiae with mucosal bleeding favour platelet failure; large ecchymoses and deep bleeding suggest coagulation defects; palpable crops suggest inflamed small vessels.
- Branching retiform purpura, cold skin, severe pain or necrosis indicates vascular occlusion or tissue ischaemia and needs urgent vascular, haematology, renal or dermatology input.
- First-line tests in a stable unexplained presentation are FBC with film, coagulation and fibrinogen, renal and liver profiles, CRP and urinalysis, then phenotype-directed infection, haemolysis, autoimmune or clonal testing.
- Record onset, speed, pain, fever, medicines, infections, bleeding sites and distribution and photograph with consent; do not erase a dangerous trajectory by calling the lesions bruises.
Key red flags
Toxic appearance, rapid lesion spread, fever or hypothermia, altered consciousness, severe limb or abdominal pain, meningism, respiratory compromise, hypotension, delayed refill, oliguria, mucosal bleeding, neurological deficit, pregnancy or immunosuppression requires same-day hospital assessment.
Angular branching non-blanching patches map an obstructed vessel network; pain, coolness, ulceration or black necrosis signals threatened tissue.
Rapid spread with fever, limb pain, reduced responsiveness, poor perfusion or respiratory change is an emergency even if lesions are few or partially blanching.
Investigation priorities
Detect sepsis, shock and limb-threatening vascular compromise before diagnostic sampling.
Management branches
Non-blanching lesions accompany fever, toxicity, rapid progression or impaired perfusion.
- Start ABCDE assessment, record the evolution and summon senior emergency help while checking meningism, limb pain, shock, bleeding and a likely infectious source.
- Obtain cultures, lactate, FBC, coagulation, renal and liver tests if this causes no treatment delay and begin parenteral antibiotics and sepsis resuscitation through the current age-specific protocol.
- Reassess within minutes, document lesion spread and perfusion and coordinate critical care, infection, haematology or vascular support according to shock, coagulopathy and tissue threat.
The person is physiologically stable and the eruption is not rapidly advancing.
- Inspect all skin and mucosa, press representative lesions, palpate elevation and temperature and examine pulses, joints, abdomen, nerves and cardiorespiratory system.
- Build a timed history of infection, medicines, vaccines, trauma, bleeding, travel, pregnancy, systemic symptoms and previous episodes and photograph the distribution with consent.
- Request FBC and film, coagulation and fibrinogen, renal and liver profiles, inflammatory markers and urine, expanding tests only after the initial phenotype is clear.