I have had tendonitis at the elbow and at the wrist. The tennis elbow was from windsurfing and stuck around for more than a year until I found a very simple physical therapy thing (using the Thera-Band Flexbar) that cured it in just a few days. I've been fine ever since, and have had to use the Flexbar only a few times when I felt very mild symptoms come back. Original report at
boardsurfr.blogspot.com/2010/05/no-more-tennis-elbow.html My wrist tendonitis (carpal tunnel) went undiagnosed/misdiagnosed for about a year, despite doctor visits. When I finally discovered what it was, wearing a wrist support cured it in a few weeks.
Neither one of these applies directly to your problem, but I'm mentioning it because I think there is hope that you'll find something that will work. Many physical therapists don't know about using the Flexbar for eccentric exercises to cure tennis and golfer elbow. I used it after reading about a clinical study where it worked extremely well; in my case, it worked even better than in the study. Maybe someone has developed a similar exercise for De Quervain. Or perhaps arnica or something else works for you. Try a few things before surgery, and good luck.
I did a quick Google search, and here is one publication that describes eccentric exercises for De Quervain:
www.ncbi.nlm.nih.gov/pmc/articles/PMC3364060/It's just a single-patient case report, but it helped. It was published by a chiropractor. I've had extremely good and extremely questionable experiences with chiropractors, but even the questionable one seemed to help.
Also, check out this video:
It describes an exercise that worked for the guy who posted. It's also an eccentric exercise (lengthening under load), similar to the Flexbar exercises, but for De Quervain. You may want to start with very low weights, and do the exercise even slower than shown in the video. Definitely worth trying! I just hope you're not already doing it in physio.