Well wait to go to the doctor and ask questions no one here is going to know for sure.
She's your girlfriend, which suggests the sex that night when she began to have ovarian bleeding was not the first time you had ever had sex, is that right? And now you're saying you think she cheated, because she had an operation on her ovary and you think somehow this would have dislodged any pregnancy? You do know, right, about the difference between an ovary and a uterus? (The uterus is where the egg settles down, not the ovary.) Or do you think that in the excitement (of the ER visit and the surgery) any sperm from your sexual activity that night would have been too scared to find an egg and settle down?
Probably what happened is that her ovary was having trouble because she had an ovarian cyst from having recently ovulated, that was not draining properly, and maybe the sex broke it open. It's possible for an ovary to get bonked during sex, and it is also possible for the cysts to get very big before they drain. Did she have a really complicated surgery, or did they just do a needle drain of the cyst and possibly a stitch or two? Was it a laparoscopy?
It is entirely possible for a pregnancy to make it unbothered through a surgery on an ovary. In fact, women have had appendix surgeries, liver surgeries, kidney surgeries, you name it, while pregnant. It does not bother the embryo in the uterus.
The fact that your girlfriend had what sounds like an ovarian cyst and then turned up pregnant makes it sound a lot like the cyst was from the last time she ovulated. This would suggest she was already pregnant with an embryo just recently embedded in the uterus by the time she had the ovarian bleeding. The blood would not have washed it out, and the pregnancy hormones might not have turned up in a urine test that early.
Hi, healthy. It sounds like it would have been a pretty early pregnancy if the cyst in the ovary was still that new (unless it was an older cyst from an earlier ovulation). I assume that if her period had been noticeably late, she would have said something, so it sounds like this all happened within two weeks after conception. That means, it would not show up yet on an ultrasound, and no positive would appear on a pregnancy test yet (especially if it was a urine-based test). When I was pregnant, I was 8 days after conception and a blood test didn't catch it; it is sure possible for a urine test not to catch it in the first two or three weeks.
If they went in through an incision in the stomach and cleared out blood or fluids, that would make sense in terms of not disrupting an egg or embryo, since the egg could have (or actually, must have, since she is pregnant) been safely traveling down the tubes and into the uterus by then. It is certainly plausible that the embryo would not have been big enough yet to appear on an ultrasound (a new embryo is not visible on ultrasounds until at least three weeks after conception). And hospital urine tests are not often the most sensitive ones. To get a positive on a urine test that early, her urine would have had to be concentrated "first morning" urine, and it would have to be the most sensitive test, and coming in as an emergency case suggests she didn't have those advantages.
The ovary to the uterus is not a closed system. An egg explodes outwards basically loose into the abdomen from the ovary at the moment of ovulation. It then usually gets sucked up by the end of a Fallopian tube (they look like catchers mitts) and then a vacuuming or pulsing motion moves the egg down the tube. If the egg was in that process when the bleeding happened, or if it had happened a couple of days before if you had had sex earlier, it would have been safely out of the way of any surgical action in the abdomen (including the vacuuming of fluids and bloods) by the time they opened her up to see what the pain was about. Like I said, a woman can have appendicitis and have a surgery to remove the appendix all unknowing she is in the early stages of pregnancy, and this doesn't disturb the pregnancy. Your girlfriend's surgery does not sound like they did anything to her uterus at all, or they would not have gone in from the outside but would have gone upwards into the cervix. But why would they have done that, since they knew the problem was a bleeding ovary? They would not. Therefore the uterus doubtless remained undisturbed, with an embryo floating around in it or the tubes.
I assume you had sex before the eventful night when she would up in the ER? Was it unprotected? That would be the time I would be looking at most strongly as producing the pregnancy. You could say this is a baby that weathers all storms. :)
When you go see the doctor, be SURE you ask about the date of conception. Don't just take the doc saying "You're 6 weeks 4 days 'along' or 6 weeks 4 days 'pregnant'" and go home with that. Doctors (all medical people in fact) have a funny way of counting the weeks of pregnancy. They begin on the first day of the woman's last period, day 1 of bleeding, even though a woman is not pregnant on that day. And if her cycles are irregular, they begin on an "assumed" first day of last period. It gets very confusing. So ask for an estimated due date that is based ONLY on ultrasound measurements of the embryo. Don't let them mess with your head about weeks pregnant and just go home, it will be too hard to decide what they were saying. I'll come back in a minute and drop in the explanation of why this happens, but just take my word for it.
Regarding your scepticism (suspicions that your girlfriend cheated because you imagined no pregnancy could make it through the surgery) -- if you have different reasons to be suspicious, there is nothing wrong with doing a DNA test when the baby comes. But the surgery followed by the discovery she is pregnant is NOT a valid reason. In other words, if you had already been wondering if she is being exclusive with you, you are not obliged to fall into the assumption that this baby is from you. But watch what you say and how you act, because nothing about this situation suggests she has been cheating. I mean, nothing. Please be very careful not to offer her such an insult as to imply she must have been cheating.
Will come back with the discussion of doctor's count of "weeks pregnant." You really need to know this one before you go in.
Ok, here is the stuff about "weeks pregnant."
If a doctor, nurse, or any medical person, or a medical textbook, or anything medical, says someone is 6 weeks "pregnant", it is not a figure that counts back to conception. All medical counts of pregnancy (the so-called GA or gestational-age number -- "6 weeks 3 days" or "11 weeks 4 days") begin on the first day of the last period the woman had before getting pregnant. If a doctor says to a woman, "Congratulations, you are 6 weeks pregnant!" he means 6 weeks since her last period began and only about 4 weeks since conception.
The count is done this way because it has been counted this way since great-grandma's day. The period is a big, obvious signal, and ovulation and conception are hidden and unknown. It is not counted like this because the doctor thinks the woman was pregnant when she was on day 1 of her cycle. (The doctor knows she was not pregnant then -- she was having a period!) But that is why pregnancy, which takes 38 weeks, is counted as being 40 weeks long. They add a spare two weeks at the front end, to be able to calibrate the count to the presumed first day of the last period.
That two-week gap is also an average. Sometimes a woman's GA count given to her by a doctor does not align perfectly with when the real first day of her last period was. This is because a lot of women have irregular cycles and don't ovulate neatly two weeks after the first day of their last period. The ultrasound sees and measures the actual embryo, so a woman who gets a GA count from an ultrasound should date the conception as being the GA count less two weeks, no matter when her real last period came. Ultrasounds, if done early, trump the actual first day of last cycle for determining conception.
So when you're at the doctor's, ask for an ultrasound if they don't seem ready to offer it (though they should be since she had surgery recently). Say you're concerned because she had this surgery and it seems to be right around the first couple of weeks of pregnancy and you want to try to pinpoint when conception was. Use the specific word "conception," not "how far along she is," because the minute you say "far along" or other vague terms, the doctor will lapse into the "weeks" count that does not really help things.
If the doc will not commit to a guess at the conception date, just get an estimated due date based on the measurements of the embryo and its developmental markers. Then take the due date home, and plug it into an online conception calculator to find out the estimated conception date. (Or just count back from it 266 days manually on a calendar.)
If the doctor says insurance won't cover an ultrasound this early, pay out of pocket. The closer she is to around her seventh week GA (which I hope by now you understand is her fifth week since conception) the more accurate. If you wait a long time for an ultrasound, its usefulness for determining a conception date diminishes. The sweet spot is between the 6th and 8th week (GA). Earlier is not helpful because ultrasounds can't see pregnancies in the third or fourth or even fifth week, and later is not that helpful because by week 12, there is a margin for error of a week, and since you were so fast to be sceptical that you were the father, I think you would like to have as much accuracy as possible.
One thing you haven't said is how long ago this surgery was. I am assuming it was recent but not so recent that you would be too early to get a clear ultrasound view of the embryo. If she would only be in her fifth week now (three weeks since conception) it might be too early to get a really definite answer.
The reason to push for an ultrasound in the 6th, 7th or 8th week and not later, is that babies can grow at different rates. Many doctors, by week 12, will say +/- 7 days if using an ultrasound to determine a conception date. And it gets more and more wide -- by the 40th week, the margin for error is 3 weeks.
Be sure the doc does not use the actual first day of your girlfriend's last period to determine the due date, especially if her cycles are irregular. A doctor counting from a little cardboard wheel or just counting forward 280 days on a calendar is not going to be accurate if the woman's cycles are not totally regular/ just like clockwork/ every 28 days a new period comes. If she does tell them when her first day of her last period was, ask them not to use that when giving an estimated due date but instead to base the due date on the crown-to-rump measurements of the embryo and its developmental markers, as seen on the ultrasound.
I just wanted to thank you for all the explanations and let you know that it helped me understand many things. The weeks count were indeed in this way, 9 weeks counted on old way, 7 weeks since conception. :)