I wonder if she is pregnant or not

Patient: I had sex with my girlfriend after 15 days of her period and she was bleeding for 3-4 days since sex. just as we decided to visit doctor bleeding stopped but now it has been about 8 days since she is waiting for period.she made pregnancy test and answer was negative. can you help with an advice?

Doctor: Hello,If you have had sex while she was in her fertile period so the chances of pregnancy remains increased, but now as the pregnancy test is negative, it is possible that the 3 days she bleed after sex could have been an early menses and she would have had a change of dates possibly. If she is already 8 days post missed period and pregnancy is ruled out then she may wait for another week to look if the menses resume, else she should get an ultrasound pelvis done to look for the endometrial thickness. If its less as compared to the phase of cycle then it is likely that the 3 day bleed was her fresh early period and her dates have changed, else if the ET is more than 10mm, then she can opt for a withdrawal bleed with progestins to resume her menses.I hope I have answered your query in detail,wishing good health,regards