Purpura and Petechiae

Purpura are reddish-purple lesions which do not blanch with pressure. When less than 1 cm in diameter, they are called petechiae; if larger, they are known as ecchymoses. The problem often presents as ‘bruising easily’ – a common ‘while I’m here’ complaint in primary care. Most cases are normal, with causative minor trauma simply being forgotten or unnoticed.

Published: 2nd August 2022 | Updated: 15th August 2022

Differential diagnosis

Common Diagnoses

  • Trauma
  • Senile Purpura
  • Liver Disease (Especially Alcoholic Cirrhosis)
  • Increased Intravascular Pressure, e.g. Coughing, Vomiting, Gravitational
  • Drugs, e.g. Steroids, Warfarin, Aspirin

Occasional Diagnoses

  • Vasculitis (e.g. Henoch–Schönlein Purpura, Connective Tissue Disorders)
  • Thrombocytopenia (e.g. Idiopathic Thrombocytopenia Purpura [ITP]), Bone Marrow Damage (e.g. Lymphoma, Leukaemia, Cytotoxics), Aplastic Anaemia
  • Renal Failure
  • Infective Endocarditis

Rare Diagnoses

  • Paraproteinaemias (e.g. Cryoglobulinaemia)
  • Inherited Clotting Disorders (e.g. Haemophilia, Christmas Disease, Von Willebrand’s Disease)
  • Infections (e.g. Meningococcal Septicaemia, Rocky Mountain Spotted Fever)
  • Vitamin C and K Deficiency
  • Disseminated Intravascular Coagulation (DIC)
  • Congenital Vessel Wall Abnormalities (e.g. Ehlers–Danlos Syndrome)

Ready reckoner

Key distinguishing features of the most common diagnoses

TraumaSenile PurpuraLiver DiseaseIncreased IV PressureDrugs
Tender BruisingYesNoNoNoNo

Possible investigations

Likely: FBC, ESR/CRP, INR (if on warfarin).

Possible: LFT, U&E, coagulation screen, plasma electrophoresis.

Small Print: Autoimmune testing, further hospital investigations (see below).

  • FBC, ESR/CRP: FBC may reveal thrombocytopenia or evidence of blood dyscrasia. ESR/ CRP and WCC may be raised in blood dyscrasia, connective tissue disorder and infection.
  • LFT, U&E: For underlying liver or renal disease.
  • INR: If on warfarin
  • Autoimmune testing: If possible connective tissue disease causing vasculitis
  • Coagulation screen: To test haemostatic function (e.g. bleeding time, prothrombin time, activated partial thromboplastin time).
  • Plasma electrophoresis: For hypergammaglobulinaemia, paraproteinaemia and cryoglobulinaemia.
  • Further investigations (usually secondary care): To investigate underlying cause, e.g. skin biopsy to confirm vasculitis, bone marrow biopsy if possible marrow infiltrate

Top Tips

  • Multiple bruises of varying ages on the legs of young children who are otherwise well and have no other stigmata of clotting disorder or abuse are likely to be non-pathological.
  • Senile purpura should be easy to diagnose from the history and examination. Reassurance, rather than investigation, is required.
  • A few petechiae on or around the eyelids of a well child can be caused by vigorous coughing or vomiting. If the history is clear, explain the cause to the parents – but emphasise that the appearance of an identical rash elsewhere requires urgent attention.
  • The distribution of purpura can give useful clues to the diagnosis. On the legs, platelet disorders, paraproteinaemias, Henoch–Schönlein purpura or meningococcal septicaemia are likely; lesions on the fingers and toes indicate vasculitis; and senile and steroid purpura tend to affect the back of the hands and arms.
  • Purpura caused by vasculitis tend to be raised palpably above the skin.

Red Flags

  • Remember that the rash of meningococcal septicaemia can appear before a child is obviously systemically unwell. If there is any suspicion that this might be the diagnosis, give parenteral penicillin and admit immediately.
  • The absence of a family history does not exclude a significant inherited bleeding disorder – these disorders can arise spontaneously
  • Take very seriously the pale patient with purpura – a bone marrow problem is likely. Arrange an urgent FBC or admit.
  • Always do a full surface examination of a child with bruising, not forgetting the anogenital area. Keep non-accidental injury in mind.
  • Never give an IM injection if a serious bleeding disorder is suspected.
Report errors, or incorrect content by clicking here.
Website disclaimer

Pulse Reference is based on the best-selling book Symptom Sorter.

The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.

This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.