I can see where you went with how you would like to market this domain -- using it as a platform similar to what you may find on other crowdfunding websites -- and tailor it directly to Surgical Procedures and Medical Requests for funding.
The industry is by and large reacting to the heavy amounts of new TLD's that are coming out. Some of these extensions will stay, while others may be lost in time.
With this in mind, it is hard to give an accurate appraisal on the domain at this current time, as related .surgery sales are few and far between since the inception in 2014.
Was it worth your 20$? If marketed correctly with a pitch to a startup that is willing to crowdfund medical emergencies -- you may be looking at a high XX to low XXX appraisal if marketed to the correct end user.
Is there a use and need for the domain? Absolutely. However, I feel like fine wine -- newer TLD's will only gain value in time with increased use among the industry and the internet as a whole. Or end up as a bottle of "two buck chuck".
With your acquisition, I would say it will hold value in time -- the appraisals will be very subjective or biased to how people feel over new TLD's. However, your 20$ investment is safe.
A decent acquisition!