Coagulum pyelolithotomy: the determination of optimal conditions for clot formation

Summary

Strong, elastic clots are required for the removal of renal calculi by coagulum pyelolithotomy. An in vitro study was performed to establish the optimal conditions for the formation of clots. A thrombelastograph was used to measure the clotting time and elasticity. For tensile strength measurements, a special apparatus was constructed. The use of platelet-rich plasma as a source of fibrinogen resulted in weak clots. Cryoprecipitate proved to furnish good clots, especially when clotting was induced by calcium. The addition of thrombin had an adverse effect on the strength and elasticity of the clot. In our hands, optimal clots were obtained by mixing 15 ml of regular bloodbank cryoprecipitate with 1 ml of 10% calcium laevulate or 0.5 ml of 10% calcium chloride at room temperature and waiting for a period of 10 min. Preheating to 37°C offered no advantage and a limited degree of dilution with urine had no adverse effect on the clot properties. Clot particles dissolve in urine within 1.5 days.