QuestionHi Catherine,
Once again, thank you for taking the time to answer my questions. You mentioned that an ultrasound taken at 6 week or earlier is not that accurate, so at 6 weeks or earlier, up to how many days can the margin or error be? Can it be a month or more, since it is so early on? It's also interesting that you mentioned Pitocin, since that is what my doctor gave me to speed up the contractions. My water had broke, but I didn't have contractions for awhile. Perhaps the Pitocin or the wrapping of the umbilical cord can explain the decrease in heart rate. When this happened several times, my doctor gave me oxygen and asked me to lie on my left side, which seemed to help. Have you ever heard of this before? Once again, thanks for your help.
AnswerHilary,
Once again, *NO*, an early ultrasound cannot be off by a month or more. There is nothing to see in a regular ultrasound that early if it was off by a month - that would mean showing 2 weeks rather than 6 - at 2 weeks, you're not even pregnant yet! Pregnancy is calculated as 40 weeks from the first day of your last period, which means you're not even pregnant for at least the first two weeks, until ovulation and conception occur - the average pregnancy is 38 weeks from conception, 40 from LMP.
Just to close this discussion, look at a picture of a 6 week ultrasound vs. a 10 week:
http://www.ob-ultrasound.net/images/us25.jpg - 6 weeks
http://www.ob-ultrasound.net/images/scan11.jpg - 10 weeks
There can be no doubt between the two - the first is a gestational sac - you can barely see anything yet in the sac and the second shows a recognizable fetus. You'd have to be the worst u/s tech in the world to confuse the two.
I already gave you the margin of error for ultrasound in the first trimester in your previous question: +/-8% of the estimate.
But the real point you seem to be missing is that ultrasounds should not be done at that early a stage - there's too little development to come to reliable conclusions. Waiting until 8-10 weeks is preferable for dating and I've already given you the stats and references on that. Please review them.
In any case, as I also already stated, your 9 week ultrasound is the most reliable one you had. Worrying about the 6 week one will not change the results of the 9 or 11 week ones, which clearly point to conception in October.
Now regarding pitocin (a man-made version of oxytocin, the hormone that causes contractions), yes, it's entirely possible it caused the drop in heart rate.
Here's why:
When the body produces oxytocin, it is released in spurts, meaning there's a burst of it, then a rest period, then another burst, etc.
This natural burst-rest pattern allows the uterus and the baby to rest and recover between contractions - when the uterus is contracting, the baby's oxygen can be a bit reduced from the pressure, which is why it's normal for the heart rate to dip during contractions, then rise after them.
However, when pitocin is given, it is administered as a steady drip-drip-drip - with no rest period for the uterus or baby. It makes contractions unnaturally longer, stronger, and closer together, without break periods between them. If the dose is set too high or too fast, then this can hyperstimulate the uterus, decreasing blood flow and sending the baby into distress.
It's actually called Pit-to-Distress - it's unfortunately so common it has a name.
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But here's the most important point: this is an inflicted condition from a too-aggressive management of labor. It doesn't have to and shouldn't happen - but is sometimes ordered deliberately.
It's a common occurrence when doctors want you to deliver as fast as possible, not for your benefit or your baby's (faster doesn't mean safer/better), but for their convenience. It's preventable by either avoiding pitocin altogether or starting and maintaining a low dose of pitocin, or turning it off/down once a regular pattern of contractions has begun. Many doctors will just leave it on or order it at the maximum dose, trying to make your labor that much faster whether it's really needed or not.
It's a leading cause of preventable c-sections: the pitocin is set too high/fast, the baby can't handle the stress, the heart rate drops, and an "emergency c-section" is ordered to save the baby - from the complications the doctor *caused*.
Then, mothers who don't know better are thanking the doctor for "saving the baby", when the doctor is the one that *caused* the problem in the first place.
He's cleaning up his mistake with a major abdominal surgery and the mother, who doesn't know better, is thanking him for it.
Reviews of medical-malpractice claims by the non-profit Institute for Healthcare Improvement show pitocin is involved in more than 50 percent of situations leading to birth trauma.
Here are some good discussions of pit-to-distress with additional links:
http://vbacfacts.com/2009/07/10/pit-to-distress-a-significant-risk-of-hospital-b...
http://www.theunnecesarean.com/blog/2009/7/6/pit-to-distress-your-ticket-to-an-e...
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Now, does this mean that's what happened in your case? NO.
You haven't provided enough details to determine anything for certain - I'd basically need to see your chart as there are too many unknown factors - how long your water was broken before the pit was started, what was your temperature, what dose of pitocin was given, at what point was it started, how dilated/effaced were you, what position were you in, what station was the baby at, was your movement restricted, etc. All these questions and a few more would need to be answered before a reliable answer could be given.
All I can do is speculate at this point - there are not just not enough facts to say for certain.
However, I can say that either the pitocin or the cord, or a combination of both, could have caused the drop in heart rate. Again, without more information, it's impossible to determine if either or both did reliably.
You were asked to lie on your left side and given oxygen - this is because lying on your left side reduces pressure on the uterus and maximizes blood flow and thereby oxygen to the baby. If the cord is actually compressed, not just wrapped around the baby's neck, this is a fast, easy way to take any pressure off it so the baby's heart rate will return to normal. The oxygen helps your own oxygen levels rise, which then increases the amount of oxygen sent to the baby.
But, if the pitocin was never turned off/down, then that could have been causing the heart rate decels and stopping/reducing it could have been all that was needed to bring the heart rate back up. It's more common for pitocin to cause problems during labor than for a cord to be truly compressed, so turning it off/down could have been an appropriate step to resolving the heart decels.
Also, just because your water had broken didn't necessarily mean your contractions had to start immediately. The safest course is to wait for your uterus to start contracting on its own. There is a risk of infection if your waters have been broken for too long without active labor starting on its own, so at that point, some form of labor augmentation such as pitocin is typically given. But before this time, it's not needed in most cases.
In summary:
It's not possible for an early ultrasound to be off a month. If a 6 week u/s was off by a month, you would not even be pregnant yet. Please review the previous references given for further information.
The pitocin or the cord, or a combination of both, could have caused the heart rate decels. Without detailed information, i.e. reading your chart, it's impossible to say for certain.
Best,
Catherine
