Hess Test for Petechiae: Procedure and Interpretation
The Hess test (also called the Rumpel-Leede test or tourniquet test) is a clinical maneuver that assesses capillary fragility by applying venous occlusion to the arm and counting petechiae that appear distal to the occlusion site; however, this test has largely fallen out of routine clinical use because it lacks specificity and does not reliably distinguish between different causes of thrombocytopenia or vascular fragility.
How the Test is Performed
The Hess test evaluates capillary fragility through controlled venous stasis:
Apply a blood pressure cuff to the upper arm and inflate it to a pressure midway between systolic and diastolic blood pressure (typically around 100 mmHg or the midpoint between the patient's systolic and diastolic values) 1
Maintain this pressure for 5 minutes while the patient keeps their arm still 1
After 5 minutes, release the cuff and wait 2–5 minutes for the skin to return to baseline color 1
Count the number of petechiae that appear in a defined area (typically a 5 cm diameter circle) on the volar surface of the forearm distal to the cuff 1
Interpretation of Results
Positive Test
More than 10–20 petechiae within the 5 cm diameter circle is generally considered positive, indicating increased capillary fragility 1
A positive test suggests one of the following mechanisms:
Negative Test
- Fewer than 10 petechiae in the defined area is considered negative, suggesting normal capillary integrity and adequate platelet function 1
Histopathologic Findings
Early histologic changes at 2 hours after the test demonstrate:
Focal hemorrhage in the upper dermis with extravasation of red blood cells 1
Perivascular lymphocytic infiltrate with focal areas of lymphocytic epidermal invasion, indicating that lymphocytes may be primary inflammatory cells in early vasopermeability 1
Liquefaction degeneration in some cases, with findings similar to purpura simplex 1
Clinical Utility and Limitations
Why This Test is Rarely Used Today
The Hess test has been largely abandoned in modern clinical practice for several critical reasons:
Poor specificity: A positive test does not distinguish between thrombocytopenia, platelet dysfunction, vasculitis, or simple capillary fragility 1
Superior alternatives exist: A complete blood count with peripheral blood smear provides far more diagnostic information and should be obtained immediately in any patient with petechiae 2, 3
Does not change management: The test result does not guide treatment decisions because the underlying cause still requires laboratory confirmation 2, 3
Time-consuming: The 5-minute occlusion period delays more definitive diagnostic testing 1
When Petechiae Require Urgent Evaluation
In infants and children with petechiae, immediate clinical assessment takes absolute priority over any bedside test:
Ill-appearing infants with fever and petechiae require immediate parenteral antibiotics without waiting for test results, due to the risk of meningococcal disease progressing to purpura fulminans within hours 2, 3
Petechiae on the trunk, face, or ears in a non-cruising infant should raise concern for abusive head trauma and warrant careful examination for scalp bruising, bulging fontanel, subconjunctival hemorrhage, or oral injuries 2
Well-appearing infants with localized petechiae (typically lower extremities, often bilateral) are more likely to have benign etiologies such as tourniquet phenomenon from tight clothing or diapers 4
Essential Diagnostic Workup Instead of Hess Test
The appropriate evaluation for petechiae bypasses the Hess test entirely and proceeds directly to:
Complete blood count with differential and peripheral blood smear reviewed by a hematopathologist to confirm true thrombocytopenia versus pseudothrombocytopenia, assess platelet size, evaluate red and white cell morphology, and identify schistocytes that may indicate thrombotic microangiopathy 2, 3
Coagulation studies (PT, aPTT, fibrinogen, D-dimer) if disseminated intravascular coagulation is suspected 3
Immediate blood cultures and empiric antibiotics if the patient appears ill with fever, before any other testing 2, 3
Common Pitfalls to Avoid
Never delay antibiotics in ill-appearing infants with fever and petechiae while performing bedside tests or awaiting laboratory results, as meningococcal disease can progress to death within hours 2, 3
Do not assume localized petechiae in infants are always benign; consider child abuse in the differential diagnosis, particularly when petechiae appear on the trunk, face, or ears in a non-cruising infant 2
Do not rely on the Hess test to exclude serious pathology; a negative test does not rule out thrombocytopenia, platelet dysfunction, or early vasculitis 1
Recognize that well-appearing infants with localized lower-extremity petechiae often have mechanical causes (tourniquet phenomenon) and may require only observation rather than extensive laboratory workup, though a complete blood count remains appropriate 4