How should a blue‑purple, bruise‑like lesion on a newborn be evaluated and managed?

Evaluation of Blue-Purple, Bruise-Like Lesions in Newborns

A blue-purple, bruise-like lesion on a newborn requires immediate systematic evaluation to distinguish benign birthmarks (such as Mongolian spots or congenital hemangiomas) from pathologic bruising, which in non-mobile infants is highly suspicious for abuse or bleeding disorders. 1

Initial Clinical Assessment

Age-Specific Red Flags

• Any bruising in infants under 6 months of age requires immediate comprehensive evaluation regardless of location or reported trauma history, as bruising in pre-mobile infants is highly suspicious for inflicted injury 1, 2
• More than half (54.2%) of premobile infants with initially unexplained bruises are ultimately diagnosed with abuse after complete evaluation 2
• Bruising on ears, neck, trunk, buttocks, or genitals has higher specificity for abuse than bruising on bony prominences 1
• Patterned bruising (linear marks, specific shapes) is pathognomonic for inflicted injury 1

Distinguish True Bruising from Benign Lesions

• Mongolian spots are blue-gray pigmented birthmarks commonly found on the lower back and buttocks, present from birth, do not change with palpation, and are not tender 3
• True bruising evolves in color over days (red→purple→green→yellow), is tender to palpation, and may be associated with swelling 3, 4
• Congenital hemangiomas and other vascular birthmarks should be considered but typically have distinct morphologic features 3

Mandatory Evaluation Protocol for True Bruising

History Elements to Document

• Witness accounts: Who observed the lesion first, when it appeared, any reported trauma (however implausible explanations should raise concern for abuse) 1, 2
• Bleeding symptoms: Umbilical stump bleeding, excessive bleeding after circumcision or heel sticks, family history of bleeding disorders 5
• Maternal medications: Anticoagulants, antiplatelet agents, NSAIDs during pregnancy 1, 5
• Vitamin K prophylaxis: Confirm administration at birth, as deficiency causes prolonged PT and increases bruising risk 6
• Multiple or changing versions of history are highly concerning for abuse 7

Physical Examination Priorities

• Complete skin examination to identify additional bruises, particularly in unusual locations (trunk, ears, neck, genitals) 1, 8
• Assess for signs of systemic illness: hepatosplenomegaly (malignancy), joint swelling (hemophilia), skin hyperextensibility (Ehlers-Danlos syndrome) 5, 9
• Document size, location, color, pattern, and tenderness of all lesions 1, 4

Laboratory and Imaging Workup

Initial Laboratory Testing

• Complete blood count with platelet count and peripheral smear 5
• Prothrombin time (PT) and activated partial thromboplastin time (aPTT) 5
• Fibrinogen level if PT or aPTT abnormal 5
• Critical caveat: Normal PT/aPTT does not exclude von Willebrand disease (the most common inherited bleeding disorder, affecting 1 in 1,000) or Factor XIII deficiency, which require specific testing 1, 5, 9

Mandatory Imaging for Occult Injuries

• Skeletal survey is required for all infants under 6 months with bruising concerning for abuse 1
• Research demonstrates that 23.3% of bruised infants under 6 months have occult skeletal injuries, and 27.4% have occult intracranial injuries detected on neuroimaging 8
• 65.4% of abused, bruised infants have occult injuries detected only through systematic imaging and laboratory evaluation 2
• Abdominal imaging should be performed to screen for visceral injury (2.7% prevalence) 8

Management Algorithm

If Benign Birthmark Confirmed

• Reassure parents that Mongolian spots and similar pigmented birthmarks are normal variants, require no treatment, and typically fade over years 3
• Document with photographs for medical record 4
• No further workup needed if clearly a birthmark with no concerning features 3

If True Bruising Present

1. Immediate: Complete history and physical examination as detailed above 1, 2
2. Laboratory: CBC, PT, aPTT, peripheral smear 5
3. Imaging: Skeletal survey and neuroimaging (head CT or MRI) for all infants <6 months 1, 8
4. Consultation: Mandatory child abuse pediatrician consultation for any unexplained bruising in non-mobile infants 1, 2
5. Protective Services: Report to child protective services and law enforcement if abuse suspected 2

Bleeding Disorder Considerations

• If family history of bleeding disorder or significant bleeding symptoms present, add von Willebrand disease panel and Factor XIII assay to initial workup 5, 9
• Vitamin K deficiency should be considered if PT prolonged, particularly if prophylaxis not given at birth 5, 6
• Hematology referral indicated for abnormal initial laboratory results or high clinical suspicion despite normal screening tests 1, 5

Critical Pitfalls to Avoid

• Do not accept implausible trauma explanations in non-mobile infants; newborns cannot self-inflict bruises through normal activity 1, 2
• Do not delay abuse evaluation while pursuing medical workup; both should proceed simultaneously 2, 10
• Do not assume normal PT/aPTT excludes bleeding disorders; specific testing for von Willebrand disease and Factor XIII deficiency is required if clinical suspicion exists 1, 5
• Do not perform limited evaluations; 23.1% of abused infants in one study were not diagnosed until after sustaining subsequent injuries, and some had only a single bruise initially 2
• Clinicians' initial clinical judgment about abuse likelihood is inadequate; systematic evaluation with imaging and laboratory testing is mandatory 2

Disposition

• Hospitalization is warranted for any infant with unexplained bruising pending completion of abuse evaluation and ensuring safe disposition 2, 8
• Outpatient follow-up is appropriate only for confirmed benign birthmarks with no concerning features 3
• Child protective services involvement is mandatory for any case where abuse cannot be excluded 2