Hello, 
Thank you for the query.

Since you have marked the query complete, I am not able to access it and hence I am replying via email.

Anvar - Oxandrolone is an anabolic steroid. It is rather OK to take the drug Anvar even if you have a surgery scheduled, but you must inform this to Anaesthetist during the pre op examination. 

Being said that, this is not an absolute Yes. There are a number of side effects that can occur due to anabolic steroids, ranging from heart muscle hypertrophy to liver toxicity. So this naturally increases surgical risk. But again, this is just a possibility and there is no absolute contraindication. 

In my opinion you have two options here :
 

1. Take the drug, inform the Anaesthetist during the pre surgery check up.

2. Taper and stop the drug (in consult with your Physician) now. Use alternative measure like Nutritional supplementation. 

Both are ok choices and none will put in a major surgical risk. Hope this helps. Thank you