Is visual inspection sufficient to confirm petechiae, or are additional tests needed, particularly if the patient may be attempting to deceive with artificial markings?

Confirming Petechiae: Visual Inspection vs. Additional Testing

Visual inspection by an experienced clinician is sufficient to identify genuine petechiae, with specific attention to characteristic features that distinguish them from artificial markings. 1

Characteristics of True Petechiae

True petechiae have several distinguishing features:

• Small (1-2mm), non-blanching, pinpoint hemorrhagic spots
• Do not blanch when pressure is applied
• Cannot be wiped away
• Often clustered in dependent areas or areas of pressure
• May have a distribution pattern consistent with underlying pathology
• Appear red/purple initially without color evolution in the first hours 1

Distinguishing from Artificial Markings

When suspecting deception with artificial markings:

1. Apply pressure test: True petechiae will not blanch when pressed with a glass slide or transparent object (diascopy)
2. Attempt gentle cleaning: Artificial markings may be partially removed with alcohol swabs while true petechiae remain unchanged
3. Observe borders: True petechiae have well-defined, non-smudged borders
4. Distribution pattern: Evaluate if the distribution is consistent with known causes of petechiae (e.g., dependent areas, pressure points) 2
5. Microscopic examination: In cases requiring definitive confirmation, dermoscopy or magnification can reveal the characteristic appearance of true petechial hemorrhages 3

Clinical Context

The clinical context should guide your suspicion:

• Presence of associated symptoms or conditions known to cause petechiae (thrombocytopenia, coagulopathy, infections)
• Physical examination findings consistent with conditions that cause petechiae
• Location and pattern of the lesions (e.g., above the nipple line in cases of asphyxiation) 4

When Additional Testing May Be Warranted

While visual inspection is usually sufficient, consider additional testing in these scenarios:

• Suspected serious underlying condition (e.g., meningococcemia, thrombocytopenia)
• Rapidly progressing rash
• Petechiae accompanied by fever or systemic symptoms
• Unusual distribution or appearance raising suspicion of deception 1

Common Pitfalls

• Mistaking other skin lesions (cherry angiomas, small insect bites) for petechiae
• Failing to distinguish between petechiae and purpura (larger hemorrhagic lesions)
• Not considering the clinical context when evaluating suspicious markings
• Overreliance on laboratory testing when visual inspection by an experienced clinician is often sufficient 1, 2

In cases of suspected deception, documentation with photographs and detailed descriptions of the appearance, distribution, and results of simple bedside tests (diascopy, cleaning attempts) is recommended to establish the true nature of the lesions.