In dengue, the 'tourniquet test' (Rumpel-Leede phenomenon) is performed by inflating a blood pressure cuff to the midpoint between systolic and diastolic pressure for 5 minutes. A positive test is defined as:

• A ≥5 petechiae per square inch (2.5 cm²) on the forearm
• B ≥10 petechiae per square centimetre (1 cm²) on the forearm
• C Any visible petechiae regardless of number
• D ≥20 petechiae per square inch on the forearm ✓

Explanation

A positive tourniquet test in dengue fever is defined as ≥20 petechiae per 2.54 cm² (1 square inch) area on the forearm, distal to the cuff. This reflects capillary fragility due to thrombocytopaenia and dengue-induced vasculopathy. The WHO dengue clinical criteria include a positive tourniquet test as supportive diagnostic evidence. A threshold of 10 petechiae per 2.5 cm² is used for general capillary fragility; the dengue-specific cut-off is 20 per square inch.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.