Petechiae are minute hemorrhages into the skin. Purpura are larger areas of bleeding into the skin that begin as red areas that become purple and later brownish-yellow. The identification of petechiae can be done by demonstrating the absence of blanching and this can be accomplished by placing a slide over the areas and pushing down. 

Evaluation of Patients with Petechiae and Purpura

1. History
1. Age of child and age at initial presentation
2. Has the child been ill, febrile, coughing , vomiting? 
3. Has there been a recent viral illness?
4. Has the child been taking any medications?
5. Has there been any recent trauma?
6. Any family history of similar condition?
7. Has there been any bone pain?
8. Has there been bleeding elsewhere, abdominal pain, joint symptoms, urine color changes or jaundice?
9. If it is a newborn, have there been previous newborns with similar problem, has the mother been ill, has the mother been on any medications or suffering from hypertension? Did the mother ever have ITP? Lupus?
2. Physical Examination
1. Distribution of the petechiae and purpura
2. Paleness? Icterus?
3. Check for liver and spleen enlargement
4. Fever, blood pressure, general appearance of toxicity
5. Hemangiomas
6. Examination of the thumbs and forearm
7. Other skin rashes including eczema
8. Evidence of trauma and other areas of hemorrhage.

Normal Platelet Count

1. Vasculitis- HSP would be the most common
2. Trauma- area of bruising should be consistent with the history. Suspicion of abuse if findings are inconsistent.
3. Localized increase pressure- hard coughing, vomiting, strangulation, suction to skin
4. Viral illnesses- especially enteroviral infections during warm weather months.

1. ITP- usually associated with preceding viral -like illness and child often not ill appearing. and physical examination normal. Petechiae most common on dependent areas such as the lower extremities , chest, and trunk. May have epistaxis, gum bleeding, and mucous membrane bleeding. 
2. Hereditary syndromes
1. Wiscott-Aldrich- sex linked recessive with eczema and immunologic deficiencies
2. TAR syndrome-radial anomalies as well as heart and renal abnormalities
3. Kasabach Merritt- giant hemangiomas
4. Fanconi's anemia- absent or hypoplastic thumbs
3. Meningococcemia
4. Drugs- Tegretol, Dilantin, Chloramphenicol, Sulfonamides, Trimethoprim-sulfamethazole
5. Malignancies including leukemia, lymphomas, and any other process that may replace the bone marrow. 
6. Sepsis- usually will be other findings as well as skin hemorrhaging
7. Newborn
1. Mother has antibodies that cross the placenta- history of ITP, lupus, previously sensitized against fetus' platelet type
2. Alloimmunization- fetus has Ags different that mother on the platelets
3. Infections- TORCH

1. After careful evaluation of the patient, simple laboratory investigations should be performed. This would include a CBC with platelet count, urinalysis, and cultures that may be appropriate,. A bone marrow aspirate may be necessary in cases where the above evaluations did not delineate the etiology.
2. In ITP, the bone marrow should have adequate numbers of megakaryocytes. 

1. Buchanan, George. ITP: How much treatment is enough? Contemporary Pediatrics. May 1995
2. Chu Y, Korb J, and Sakamoto KM. Idiopathic Thrombocytopenic Purpura  Pediatrics in Review. 2000; 21:91-104.
3. Murphy S, Nepo A and Sills R. Thrombocytopenia. Pediatrics in Review. 1999; 20(2):64-69.
4. Buchanan George  ITP: How Much Treatment is Enough?  Contemporary Pediatrics April 2000
5. Cines Douglas, and Blanchette Victor. Immune Thrombocytopenic Purpura NEJM Vol 346 No. 13 March 28, 2002
6. NEJM Case 37-2010:A 16 year-old-Girl with Confusion, Anemia, and Thrombocytopenia.  Dec 9, 2010
7. Consolini D. Thrombocytopenia in Infants and Children.  Pediatrics in Review.  April 2011
8. Neunert C. et. al. American Society of Hematology 2011 evidence-based practice guidelines for immune thrombocytopenia.  Blood April 2011http://bloodjournal.hematologylibrary.org/content/117/16/4190.full.html