Irregular Bleeding & Potential Pregnancy: A Medical Evaluation

Question
I am 34 years old and have no childern.  I had one pregnancy that did not go to term when I was 18.   I had my last normal period on Feb 16. I had taken plan B on March 7 due to condom faliure on March 5. On March 16 I bleed for 2 1/2 days. Started taking new brand of birth control pills. Started to have sore breasts and some nausea. I bleed again on April 13 for 2 1/2 days. I took several home pregnancy tests all negative. I went to the dr on april 21 and took a blood test. It came back negative with a level of less than 5. I also had a pelvic exam on that date and the dr said that I was not pregnant. I then bleed again on May 8 for 2 1/2 days.

Is a blood pregnancy test accurate when it was done I would have been 9 weeks. Also can a dr tell if I was pregnant by a pelvic at 9 weeks? I keep reading these stories of women who get there periods and negative test and still end up pregnant. How common is that? I also took another hpt yesterday that would put me at 13 weeks and it was negative.  

Answer
If your last period started on February 16, ovulation would have occurred on  March 1 and you could ONLY have conceived if you had unprotected sex on February 28, March 1,2, or 3.  After Plan B, it is common to have 2-3 days of bleeding. You were due for your next period on April 14, so the bleeding you had on April 13 for 2 1/2 days was your next period. The blood test is quite accurate. Any HCG value of less than 5 is definitely not pregnant. If the hCG value was less than 5 and the pelvic did not demonstrat a pregnancy, you are not pregnant. A 9 weeks pregnancy would be noticed during a pelvic exam. You are not pregnant.