A few comments in English regarding "operation" and "surgery" (and "procedure")
The topic of surgery came up at the medical conference.
Tom underwent 3 surgeries on his left knee before he could Tango again.
Both uses of surgery are correct. In one usage, it is an "uncountable noun," but it can also be used in the plural.
Examples: brain surgery, heart surgery, carpal tunnel surgery
"Operate" is a good medical verb and both "operate" and "operation" have plenty of uses beyond the medical field, in addition to "operator" (telephone operator, smooth operator).
It was a covert operation.
The way that man operates, he can close a deal in 5 minutes.
"Surgery" and its "derivatives" do not really have a lot of different uses and are pretty much confined to medical subjects.
Where an operation takes place is usually called the "operating room" (OR), and the "performing" doctor, the "surgeon," sometimes the "operating surgeon."
3. PROCEDURE (and "surgical procedure")
The word "procedure" is also frequently used in medical literature and often certain types of operations are formally named using "procedure."
Example: A "Bankart procedure" is a common type of shoulder operation.
"Surgical" can be used with "procedure" also and is commonly used in the medical field: a surgical procedure.
Common phrase: The risks and benefits of the surgical procedure were explained to the patient.
Obviously, "procedure" has many different uses other than medical, like "operation," cited above.
All of the examples in Rick's post are great. It would take me 3 days to try to write this in Portuguese, so I hope you'll forgive my English :)