Economy Class Syndrome.

I'm learning all about blood clots, one type known as DVT, what medications are out there to treat it, what can be done so as to not have a pulmonary embolism, stuff like that.

I have learned that it is dangerous to fly if you already have DVT

Someone told me that, I didn't know, so I decided to Google it.

I Googled "DVT + airplane".

This is what I found, same answer, thousands of websites.

What is deep vein thrombosis (DVT)?

People who have a history of cardiovascular disease, stroke or thrombotic episodes (blood clots) are at risk of getting blood clots in their legs during airplane flights of 10 hours or more.  But these aren't the only people who can have this problem.  This condition, known as deep vein thrombosis (DVT), also can affect healthy people, even athletes.

What is economy-class syndrome?

Developing DVT after long plane rides is often called "economy-class syndrome" or "coach-class syndrome," because seating and leg room are particularly cramped for passengers in economy class.   However, first-class and business-class passengers also get DVT, so this problem isn't solely due to sitting still in tight quarters for many hours.  Other factors -- such as low cabin pressure, low humidity and dehydration -- all may contribute.   These factors are constant throughout the plane.