Catherine O'Hara died from a blood clot in her lung, records show

This is one reason why some people take blood thinners (Like Eliquis) to prevent dying from blood clots in the Lungs, the arms, the heart and the brain especially. You cannot live without all these things working right and blood clots in any main organ you need to survive is going to usually kill you.

The downside of Blood Thinners is they usually cannot operate on you until these blood thinners are out of your system for at least 3 days. Otherwise there is a danger you could bleed out and die from loss of blood. So, you only can be operated on after not taking any blood thinners for at least three days. 

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Catherine O'Hara died from a blood clot in her lung, records show

The Emmy Award-winning actor's official cause of death was listed as a "pulmonary embolism" arising from an underlying cause of cancer.

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