Help with a Brain Teaser

could be an ectopic pregancy (rare)

could be a full term multiple gestation pregnancy which can cause HCG levels so high that they're unable to be analyzed and must be diluted before they give a positive result (more likely)

I dunno! Sounds like fun stuff though!

In my neck of the woods, she would be sent up to OB where we would do an exam and find her cervix to be, in fact, closed. Some of our ER docs are famously bad at cervical checks! LOL

I am trying to think of a real answer to your question. I assumed the test was urine, since the patient said she had done the same test that morning. HCG levels should still be high enough to make the test positive. Can her urine be too dilute to register HCG for some reason? There probably is something that I'm totally not thinking of...

perhaps she is diabetic, with dilute urine....and later in the day less likely to be positive....i have known of neg testing and actually being preg, but i had thought testing had improved some in 35 years!!

Could it be a molar pregnancy? That's a great brain teaser...Make sure you post the answer once you find out for sure. Thanks.

I saw this post and was very curious as well. I did some searches and came across this article.

http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijgo/vol6n2/test.xml

This woman had many factors contribute to why she was having a negative test.

For the most part I found that the only reason could be that the test was stored in the wrong temperature or some how the test was not done correctly. The only other thing, like others mentioned, was that the urine was diluted. I read that after 12 weeks the HCG goes down but should still register on an OTC test. Interesting post.

I know mine registered at +6m. It's embarrassing, but there ARE laws about poas if you find one, you know. So I found one when I was cleaning out the pantry, and I had to pee on it to avoid prosecution. lol

Still +. *whew*

Danielle,

Did you find out the answer? I'm curious!! :)

No answer yet - it will be a few weeks before he goes over that chapter - as soon as I know I will post. I really appreciate all the good answers and I am researching each of them.

Well, actually hcg falls off as pregnancy proceeds, not goes up. down to the point where an hcg test would read negative at term......pregnancy should be ruled in our out by u/s at this point, not a urine or blood test.

You see, hcg is present in early pregnancy, in order to preserve the pregnancy in early gestation. Once the placenta is fully functioning and "takes over" maintaining the the pregnancy (over the corpus luteum) hcg falls off gradually.

Add to that any thyroid issues, and you can really have a big drop in hcg, fast.......

This is my understanding of how it works, anyhow.

Here is a link detailing HCG levels in pregnancy. It looks like that although they level off they are still incredibly high at the end of pregnancy.

http://www.americanpregnancy.org/duringpregnancy/hcglevels.html

Yes, you are right. But any other problems, like thryoid disorder, can take them down to nearly zero level. The woman is obese. Perhaps she has PCOS or a thryoid disorder that would actually affect her hcg levels, if indeed, she were pregnant. I have a tough time trying to imagine a cervix so dilated (if indeed they are checking correctly) in a non-pregnant woman.

Molar pregnancy was ruled out in my mind as I understood that with molar pregnancy, hcg levels are actually so high, they are hard to quantify. That is why, to my thinking molar pregnancy would rule out. They would want to follow your hcg levels down to zero after a molar pregnancy, just to be sure all is clear.

Anyhow, thyroid comes to mind, so that is why I say, it can fall and read false-negative, esp with a urine test. But you are right; hcg is still present. I do believe I read, however, it differs in different women, so much so that they can have a "negative" pregnancy test after the 2nd trimester.

Anyhow, clearly, I am not the expert here. I am just taking a stab, in the dark.