May 172010

“It’s because you don’t drink enough water.” -Midwife to mother who tested faintly positive on a home pregnancy test but negative on a serum blood test, who was in fact pregnant.

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 May 17, 2010  Midwife, prenatal  Add comments

  36 Responses to “"It's Because You Don't Drink Enough Water."”

  1. Um… what? How…? Someone more enlightened inform me how she could draw that conclusion?

  2. I suppose I could see the argument that her urine was super concentrated from dehydration, so the test was able to pick up a small amount of the hormone… But if that were the case, her blood would suffer the effects of dehydration, too… So I’m not sure how that would work, either… ???

    • That would be because the urine concentrates overnight in the bladder, and the HcG collects in it. If the urine IS super-concentrated, the small amount in it is detected as a large amount due to the smaller relative amount of urine it is distributed in, as it is filtered at a constant rate by the kidneys, not at a gradient-determined rate. But in the blood, while it may also suffer the effects of dehydration, this can be corrected in the lab if it is known about(urine is in a cup, so cannot be), and is also based on a concentration within the plasma as a gradient. Usually this is only corrected when there is dehydration illness present, to gauge better what is going on.

      This all said, it is not common for a positive urinalysis to be teamed with a negative blood test. Usually its backwards, because bloodwork is more accurate than a UA. But with newer tests that pick up Pg’s earlier, they are more and more sensitive, so can read positive at levels where individual labs would still deem the test negative. With my last baby, 3 home tests that read 25mmol/L were +ve, but the hospital UA was -ve. Bloods were +ve though. Turned out the hospital test detected 50mmol/L, meaning it needed double the amount of HcG to detect it and turn the reagent pink.

      Hope my technobabble made sense ;)

      • If the blood test were a quantitative hCG, the hydration status of the mother shouldn’t matter at all, since that test measures the actual amount of the hormone present.

      • I had that with my first. Several positive home urine tests and a negative blood test.
        I don’t think the midwife’s statement was off. Unless she was trying to prove to the mother that she is indeed NOT pregnant, that she just got a false positive because of concentrated hormone, then I guess you can write it off as not trusting the mother. Otherwise, if she was explaining the reason for a discrepancy in tests, I see no problem.

  3. Wha …. ?! This source says that dehydration would make the HcG levels appear *higher.*

  4. So how does dehydration cause you to get a positive on an hcg test again? Seriously, that’s how this reads. It looks like the midwife was saying that somehow dehydration would cause the test to appear positive. Silly me. I thought it was the presence of hcg that did that.

    • because HcG is filtered by the kidneys at a constant rate, regardless of hydration. No matter what, in one hour it will be excreted at the same amount. So if your kidneys are only removing 45mL of fluid instead of a normal 90mL in an hour, it is going to have a higher concentration of HcG in it. Not higher amount, but higher concentration.

      Its like if you have a litre of water and half a litre of water, both in a glass. If you drop 3 drops of blue dye in each, the smaller amount will look darker because it has a higher concentration.

      • You’re misreading my sarcasm. I know how concentration works. My statement is more to the fact that the midwife implies that somehow dehydration caused a positive pregnancy test result since the blood test was negative.

        • ummm. no Im not… Dehydration *can* cause a UA to be positive even when the blood results are negative…

          • Okay. Let’s try again. The way I read this, and perhaps it has to do with it being early morning when I got started, was that the midwife concluded that she was not pregnant at all and that her home pregnancy test was invalid, i.e. that dehydration caused the positive home result not a sufficient level of hcg to create a positive result. I’m reading it as a, “There, there, dear, you’re just to dumb to understand this,” based on the ending statement of “…who was in fact pregnant.”

            It really sounds the midwife just completely dismissed her positive pregnancy test as all in her imagination and not something of reality.

            But that’s just my perspective and my impression biased, of course, by my own experiences and a lack of acknowledgement by my OB for a chemical pregnancy.

  5. Dehydration causes the hormone hCG to be concentrated. If the urine stick was more sensitive (meaning it turns positive at a lower level of hCG) than the lab test, then yes, the MW is correct.Some labs test only at a level of 50 (a “qualitative” level) but urine strips can go down to 20. The MW should have ordered a “quantitative” hCG level- which shows even trace levels of hCG.

  6. I just did a search over at where most questions like this are answered and didn’t come up with anything.

    Dehydration clearly wouldn’t *create* hcg, but I’m not aware of what the concentration in a non-pregnant woman’s urine would be ordinarily. When I had a blood test for my second pregnancy, it came up inconclusive because they wanted it to be over 10 and I was merely at 5 (testing two days before my period would have been missed, due to me being stoopid…I mean, impatient).

    According to that site’s faq, “A “regular” pregnancy test usually detects 40-50 mIU/mL. An “early” test will detect 25 mIU/mL or less. ”

    from days 0 to 7 after conception, a woman has 0 to 5 hCG in mIU/mL in singleton pregnancy, and from days 8 to 14 (when we can assume this woman tested) it would be 3 to 426. In order to raise the concentration from 0 to 5 up to the threshold level of 25 (assuming an early-detect kind of test) the woman would have to be so dehydrated she would be barely able to function. Unless the midwife said this as she was starting an IV bag, I don’t think it’s possible.

    But I’m not a medical professional. LOL!

    • No, that makes perfect sense. I tested and tested and tested early this last time because I knew I was pregnant and was waiting to hit the point where it would show. Dehydration would cause the urine to concentrate as the body sucks liquid back into itself. And if the woman happens to produce a slightly higher than average count, it would be easier to get an early positive. I don’t know how the two tests came back different unless she tested and got an evaporation line or something and both were negative at that time.

      But we have to remember that these numbers we quote as the gospel, are in fact, averages. As someone that has to argue over body temperature, I get frequent reminders. My normal body temp is 97.4 and by the time I’m hitting the average 98.6, I’m running a fever. Yet I have to argue with medical professionals over whether I’m really sick or not.

      But from what’s listed up here, the midwife dismissed her as not pregnant at all.

      • She could also have been slightly dehydrated when she took the test (esp if it was first thing in the morning) and have had plenty to drink between then and when the blood test was done. Was the midwife being snippy, and/or saying she wasn’t possibly pregnant, or was she just trying to explain the discrepancy?

        • That’s the other possibility, but I would think that it would have to be significant dehydration because the blood test is supposed to be more sensitive than the urine test.

          I have entirely too much time on my hands with this staycation I’ve got going on, though, obviously.

    • there is usually a concentration of up to 5mmol/L in a womans blood no matter what.

  7. With my first, I KNEW I was pregnant. I had missed my period 3 weeks previously and taken lots of pregnancy tests that said negative. I had to use first pee of the morning after hardly drinking anything for 2 days and finally got a very faint positive, so faint that I almost threw it away because I thought I was seeing an evaporation line.

  8. I just want to throw this out there…does anyone else think the “need” for a positive pregnancy test is just another way to shift the focus from the mother to the technology? I never had a positive pee test because there didn’t seem to be much point in buying more tests after I’d had luteal-phase temperatures for 18 days. At 8 weeks my clueless brother-in-law looked at my still unimpressive abdomen and said “Do you actually KNOW you’re pregnant? You’ve been to a doctor, right?” What does this prevailing attitude say to women about their ability to be aware of their own bodies? (And yes, my in-laws don’t get to find out so early next time… ;) )

    • In the olden days when they started knitting booties, that’s when they knew they were pregnant.

    • There are very very very rare situations where a luteal cyst can cause high temps and a luteal phase with no end in sight. But yeah, for most of us, 21 days of high waking basal temps will tell us we’re preggers.

      I was told my insurance company wouldn’t pay for pregnancy care if the doctor didn’t prove I was pregnant by having me pee on a stick. :-) That’s shifting care away from the woman and toward the money, I guess, but I didn’t care because I liked having my insurance pay for things.

      We could also wait until 8 weeks and then have pregnancy confirmed by the doctor/midwife finding the heartbeat.

      I knew at 10 DPO, before I even took a pregnancy test, four days before I “should have” missed my period. That happened all five times.

      • Hmm–yet another way insurance distorts our perceptions of what we do and do not need! ;)

        What I was trying to ask is, why do we need anyone else to confirm our pregnancy for us? If the reasons don’t actually have anything to do with maintaining a healthy pregnancy, then isn’t this just one more way of telling women they can’t do _anything_ related to bearing children without a doctor’s and/or insurance company’s permission?

        • Including *be* pregnant?

          Yes, possible. Pregnancy tests do force us to resort to the first test in a cascade of tests later on, and maybe that does insulate women from trusting their own bodies. I know I’m pregnant, but I require this technology to say I’m really pregnant. Later I’ll require this technology to tell me the baby is growing, the baby is alive, the baby is doing well, the baby is descending, and that the baby has been born (because again, what’s the first thing they used to do after birth? Weight, measurements, APGAR assessment. Oh, and then Mom got to hold the baby. THat, fortunately, has changed, although I still had to fight to keep my last hospital-born baby with me rather than “warmed up” in the nursery.)

      • I had a friend who was pregnant with her 7th. She did her own prenatal care and her mother delivered the babies. Her husband wasn’t hip on this method and wanted her to go see a doctor.

        At 5 months she went in and they said, “you need to pee on a stick so we can confirm pregnancy.” She said, “it’s kicking! Do you want to feel?” They said, “you must take a test!” She said, “listen to the heartbeat!”

        They insisted. She took the pregnancy test. Then they billed her for the test. She called up and said, “The baby was kicking and you made me take the test. I will not pay for it.”

        Fortunately, they had some sense and removed the charge.

        Incidentally, with my pregnancies, the doctor’s office didn’t do a pregnancy test. They said, “Did you use a home pregnancy test?” I said yes, and that was that.

    • Hmm good points. I got pregnant between my daughter and son but something was wrong from the start. I could never get a positive test but I *knew* I was pregnant anyway. If I’d gone in I’m sure I would have gotten told I was not preggo. I finally had my proof when I miscarried and nearly bled to death.

  9. I would like to know how the Midwife went on to explain her comment to the Mother. I could see where the hcg levels could be more concentrated in the urine through dehydration and not the blood. Either way (unless your on the hcg diet, but still), there’s no such thing as a false positive with pregnancy tests. A false negative, but no false positive, it can’t tell you there is a hormone present when there isn’t one. Blood or urine, if you test positive, you’re pregnant honey.

  10. Thanks to all of you. I didn’t know the answer. My question is, Why didn’t the Midwife explain this to her patient so she could fully understand?

  11. OK, I’m going to play the devil’s advocate here. Over the years I’ve had several women show up declaring they are pregnant and that day. Then we find out they are sadly not pregnant and have an obstretical psychiatric issue. Then there are the women that show up pregnant and bleeding only to find out their not pregnant and she told the boyfriend she was pregnant by him and now having a miscarriage when in fact she has started her menses. In other words it was a game to hold onto a man. Then we get those that come to us pregnant with a problem only to find out they have irregular periods and it’s not unusual for her to not bleed for 5 or so months. To the young woman that had a fetus kicking and heart tones present, you were so right not to pay that.

    • Nurse, that’s an interesting point. Certainly we don’t want more c-sections performed on women who aren’t even pregnant! Maybe it comes back to that trust relationship between a care provider and a client. If I walk in off the street saying I’m pregnant and need care for a problem with the pregnancy, I can certainly see verifying before going forward. But considering that the vast majority of women do not have these psychological, social, or menstrual-cycle problems, it’s frustrating that women who come in with a normal pregnancy just wanting prenatal care are automatically treated as if they don’t know a thing about their bodies.

      BTW, I’m curious: in the case of the manipulative girlfriend, doesn’t patient confidentiality prevent you from wising up the boyfriend anyhow, unless she’s been dense enough to bring him to the visit with her?

  12. Thoughtful,
    You’re absolutely right. The examples I posted are the exceptions and not the rule. If there is an established relationship with an OB, then I agree running test is not necessary in that case. The manipulative patient I made reference to, had indeed brought the boyfriend to the hospital because ” I’m having a miscarriage” to explain her menses. He was left in the waiting room while she came into our triage area to be assessed, tested, and ultrasounded. I asked her did she want me to bring her boyfriend back to sit with her she said no and then the story spilled outabout the game plan. Confidentiality was never breeched as much as I wanted to.

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