4th June 2025

Diagnosis

Petechiae, purpura and ecchymoses are diagnosed via a thorough history and clinical examination. Once diagnosed, the underlying cause may require further investigation. This will initially involve blood tests such as FBC, clotting studies and vitamin K levels – or a septic screen if infection is suspected.

https://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Petechia_lower_leg.jpg/640px-Petechia_lower_leg.jpg

https://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Petechial_rash.JPG/640px-Petechial_rash.JPG

https://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Pferdekuss.jpg/640px-Pferdekuss.jpg

Livedo reticularis is diagnosed via history and examination; if there are features suspicious of an underlying coagulation disorder, initial investigations will involve blood tests including:

• Full blood count
• Clotting studies
• Antibody panel (e.g. lupus anticoagulant, anticardiolipin antibodies)
• Occasionally, punch biopsies of the rash may be taken for histopathology and diagnosis