Brief Answer: You can not be pregnant as vasectomy is a permanent method of birth control. You should check your thyroid hormone levels. If they are within normal range, you should see a gynecologist. Detailed Answer: Hello, Thank you for using HCM. Tapazole may cause: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, yellowing eyes/skin, dark urine, severe stomach/abdominal pain, persistent nausea/vomiting, joint/muscle pain, change in the amount of urine. This medication may rarely cause very serious blood disorders, during the first few months of treatment (such as a low number of red cells, white cells, and platelets), that may lead to unusual bleeding or bruising, but not lack of menstruation s. Vasectomy is considered a permanent method of birth control. A vasectomy prevents the release of sperm when a man ejaculates. This means that you can not be pregnant. I suggest you to check the thyroid hormones level in blood(TSH, fT3, ft4), because the treatment may have lowered fT3, fT4 levels below the normal range, causing lack of menstruations. If the TSH, fT3, fT4 levels are within normal range, than you should see a gynecologist. Hope this is helpful. Let me know if you need more clarifications. Otherwise please close and rate the answer. Kind Regards, Dr. Juarda