What are the initial test investigations for a child presenting with petechiae?

Initial Test Investigations for a Child Presenting with Petechiae

For a child presenting with petechiae, the initial test investigations should include a complete blood count (CBC) with peripheral blood smear, coagulation studies (PT, PTT), and assessment for signs of serious illness, while recognizing that well-appearing children with localized petechiae often have benign etiologies. 1

Initial Assessment

• Perform a thorough clinical evaluation including assessment for presence and severity of bleeding symptoms beyond petechiae/purpura, fever history, medication history, and family history of bleeding disorders 1
• Evaluate for physical findings that may indicate serious underlying conditions such as hepatosplenomegaly, lymphadenopathy, or meningeal signs 1
• Assess the distribution of petechiae (localized vs. generalized), as localized petechiae in well-appearing infants without fever often have benign causes 2

Laboratory Investigations

First-line Tests:

• Complete blood count (CBC) with peripheral blood smear examination 3, 1
• Prothrombin time (PT) and activated partial thromboplastin time (PTT) 3, 1
• Review of peripheral blood smear for platelet size, morphology, and to rule out other abnormalities 3

Additional Tests Based on Clinical Presentation:

• If immune thrombocytopenia (ITP) is suspected:

  • No need for bone marrow examination in children with typical features of ITP (isolated thrombocytopenia with normal hemoglobin, white blood cell count, and peripheral smear) 3
  • Testing for HIV and HCV should be considered in cases of suspected ITP 1
  • Measurement of immunoglobulins to exclude common variable immune deficiency (CVID) may be considered, as ITP can be a presenting feature 3

• If infection is suspected:

  • C-reactive protein and blood cultures 2
  • Viral studies if viral infection is suspected 4

Special Considerations

• Meningococcal disease: In children with fever, petechiae/purpura, and ill appearance, immediate administration of parenteral antibiotics is recommended without waiting for test results 1

• Bone marrow examination: Not necessary in children with typical features of ITP, even before initiation of treatment with corticosteroids or before splenectomy 3

• Red flags requiring additional testing:

  • Abnormalities such as fever, bone or joint pain
  • Family history of low platelets or easy bruising
  • Risk factors for HIV infection
  • Skeletal or soft-tissue abnormalities
  • Non-petechial rash
  • Lymphadenopathy
  • Abnormal hemoglobin, white blood cell count, or white cell morphology 3

Management Approach

• Well-appearing children with isolated petechiae and normal laboratory findings may only require observation 2
• Children with ITP who have no bleeding or mild bleeding (defined as skin manifestations only) should be managed with observation alone regardless of platelet count 3
• For children with ITP requiring treatment due to significant bleeding, a single dose of IVIg (0.8-1 g/kg) or a short course of corticosteroids is recommended as first-line treatment 3

Common Pitfalls to Avoid

• Delaying antibiotics in ill-appearing children with fever and petechiae while awaiting test results 1
• Performing unnecessary bone marrow examination in children with typical ITP presentation 3
• Overinvestigating well-appearing infants with localized petechiae who have no fever or other concerning symptoms 2
• Failing to consider viral etiologies, which are frequently associated with petechial rash in children 4