Which instrument did Wright develop to measure coagulation?

• A. Hematocytometer
• B. Centrifuge
• C. Coagulometer
• D. Spectrophotometer

Answer: (C)

Measuring how quickly a clot forms and how the clot develops is the key idea here. Wright’s instrument for this purpose is the coagulometer, which quantifies coagulation rather than just observing it. It works by monitoring a plasma sample after triggering the clotting cascade with reagents. The device detects clot formation either by a mechanical change (such as a moving element or torque that reflects increasing viscosity) or by optical means (changes in light transmission as fibrin forms). The result is an objective measurement of clotting time and the rate of clot development, which underpins standard coagulation tests like PT and aPTT.

Hematocytometer measures cell counts, a centrifuge separates components of blood, and a spectrophotometer gauges how much light is absorbed by a solution to determine concentration. These tools serve different purposes, whereas the coagulometer is specifically designed to quantify the coagulation process.