Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Seek emergency care for trouble breathing, chest pain, fainting, uncontrolled bleeding, or severe and rapidly worsening abdominal or scrotal pain.
Contact your healthcare team promptly for increasing pain, fever, spreading redness, pus, worsening swelling, trouble urinating, persistent vomiting, or an incision that opens.
After vasectomy, report rapidly increasing scrotal swelling or pain that is not improving.
Seek urgent medical care.
And for anyone, someone who:
Routine questions about dressings, activity, semen testing, or returning to work can usually wait for normal clinic hours.
The article also says
After tubal sterilization, a positive pregnancy test with one-sided abdominal pain, shoulder pain, dizziness, or fainting could indicate an ectopic pregnancy.
Every sign above is quoted from the sofidex article on Sterilization surgery - making a decision. If you are not sure, err upward — it is always reasonable to be checked.