Hi.. The hormones which are released by the depot shots can remain from a few weeks to few months.. But the effectiveness of these in preventing pregnancy is still not known.. If you were participating in unprotected sex following the expiry of the depot shots, and you have symptoms, pregnancy has to considered no matter the results of the urine pregnancy test.. Urine pregnancy test is not the confirmatory tests for pregnancy, ultrasound test is the confirmatory test.. Hence untill it is been excluded by ultrasound, then pregnancy has to be considered..