My tubes have been tied for 3 years now. and my period normally lasts 5 days, this time it only lasted 2.5 days. is there any way i could be pregnant?

Unreated: It would be extremely rare. I would be more concerned if you missed a. Period completely. It is not uncommon for the link of the cycle to vary occasionally.

Highly unlikely.: The fact you had a period at all means it is highly unlikely that you are pregnant; women that are pregnant usually realize it because they miss a period entirely.

Yes: Pregnancy can occur following a tubal ligation, especially if the ends of the cut tubes were not folded back and attached so they could not rejoin. Get a prenancy test and seek prenatal exam/care.

Very very unlikely: You had tubes tied and had a period which may be of shorter duration than normal, but was a period eventhough there have been very rare reports of failure of tubal ligation but in your case the odds are almost none that you could be pregnant, but if you still have doubts, do a home pregnancy test to satisfy your curiosity.

Very small chance: After tying the tubes there is a small chance of getting pregnant even many years later. I tell my patients to check a pregnancy test if they miss a period or think they might be pregnant. That's because if you get pregnant after a tubal ligation about 1/2 the time the pregnancy is in the tube, which requires treatment. That being said, your short period is likely normal variation.