Yes trichomoniasis can sometimes be missed in a Pap Smear test and you may have trichomoniasis and test negative for it through a Pap Smear.
Some people have trichomoniasis and don't experience any symptoms for awhile so you might have trichomoniasis for a year or so and not even know it.
There's also been cases where someone had a Pap smear done and tested positive for the trichomoniasis and they didn't actually have it.
If you do have trichomoniasis you should take antibiotics to help it clear up faster and keep it from coming back.
It takes around 7 days for metronidazole to cure and treat trichomoniasis.
Once you begin taking metronidazole or any other antibiotics for curing and treating trichomoniasis it should take around 7 days for the trichomoniasis to be cured after taking metronidazole.
If the trichomoniasis doesn't get better within 7 days or isn't cured completely or the condition trichomoniasis seems to be getting worse you should speak with your doctor and let them know.
The last time I had trichomoniasis and took the metronidazole the trichomoniasis cleared up and was cured after 7 days.
Continue taking the metronidazole until you use it all up even though it has cleared up because it keeps it from coming back.