 [ Symptoms ] if a woman had her tubes tied 13 years ago can she still get pregnant now i havent had a period in four months [ Disease ] marijuana can remain in the body for weeks since it can be bound to body fat some hair tests can show thc for months there are really no medical conditions including pregnancy that would cause a false positive thc so most clinicians and law enforcement agencies would consider her test positive regardless of her conviction that she has not been using marijuana or around people who are being pregnant and showing positive thc can be very problematic for her