University:
College
Course:
Medical Laboratory Science
Academic year:

2023
Views:

366

Pages:

1
Author:

Carlo M.

HEMATOLOGY LABORATORY CAPILLARY FRAGILITY TEST SUCTION CUP TECHNIQUE • OUTLINE • Capillary Fragility Test o Tourniquet Test: Principle and Materials o Tourniquet Test: Procedure o Manner of Reporting & Reference Range o Suction Cup Technique o Clinical Significance LABORATORY EVALUATION OF PRIMARY HEMOSTASIS: CAPILLARY FRAGILITY TEST • • • Also called the tourniquet test, Capillary Fragility test is a clinical diagnostic method used to assess the fragility of the capillary walls. The capillary fragility test measures platelet’s ability to maintain capillary integrity. The degree of thrombocytopenia will correlate with the test, as with the bleeding time. In normal patients, none to very few petechiae are formed during this test. A positive test will be found in thrombocytopenia, decreased fibrinogen and in vascular purpura. The capillary or resistance test can be done using the following methods: o Rumpel-Leede/Hess test positive pressure technique/Tourniquet test o Suction Cup/ Petechiometer Method/ Negative Pressure Technique TOURNIQUET TEST: PRINCIPLE AND MATERIALS • • Principle o Appearance of few petechiae after the test indicates a positive test which indicates weakness of the capillary walls or capillary permeability and fragility. Materials o Sphygmomanometer o Timer TOURNIQUET TEST: PROCEDURE 1. 2. 3. 4. 5. Mark a definite area (5cm in a diameter) on the forearm. The upper edge which is 4cm below the bend of the elbow. Count the petechiae (a minute, rounded spot of hemorrhage on the skin) already present in this area. Place a blood pressure cuff on the arm and raise the pressure to 80 mmHg of mercury and leave it for 8 minutes. Remove the cuff, and after 5 minutes, count the number of petechiae in the marked area. Normally, there should be no more than 10 at most, 20 petechiae. MANNER OF REPORTING & REFERENCE RANGE • • Manner of Reporting Grade Petechiae 1+ 1-10 2+ 11-20 3+ 21-50 4+ 50 and above Reference Range: 1 – 10 petechiae • Principle: Employs the use of a suction cup. The cup is applied to the outer surface of the arm for a period of one minute at 200 mmHg and the resistance of thecapillaries is expressed as the negative pressure required to produce a macroscopic petechiae. Normal value: less than 4 Petechiae CLINICAL SIGNIFICANCE • • Increased in Purpura, Dengue Fever and Scurvy