Why must the blood be allowed to clot for at least 30 minutes when obtaining serum?

A thrombus can block the flow of blood through a vein or arteryIf it detaches from the vessel wall and lodges in the lungs or other vital organs, it can become a life-threatening embolus1,2The coagulation system depends on a delicate balance between:
Natural coagulant and anticoagulant factorsThe coagulation and fibrinolytic systemA pathological thrombus forms when there is an imbalance in the blood coagulation system leading to a number of serious health conditions, including heart attacks and cardioembolic stroke in patients with AF, and VTE1,3,4VTE can manifest as DVT and/or PE – two distinct but related aspects of the same disease
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It will dry out with less sunlight

Plants, sunlight, growth and artificial sunlight