Are Blood hCG Tests More Accurate than Urine Pregnancy Tests?

Renee writes, “On March 15, i had my period and on the 17 it went off. My period usually stay on for four days, April the 13 my period came back on and stayed on for two days.and havent came on yet for the month of May. I have been feeling nauseous, my back has been hurting and, i have been really tired. My boyfriend have been vomiting and very sleepy. I have taken two home pregnancy test and both came back negative. Could it be a possibility that i am pregnant? Am im taking the test to early to tell? and Should i go to the dr so they can take my blood so it can be determined that way?”

Renee,

Thank you for your question. Without knowing all the details (i.e. whether you had protected sex or are on regular birth control), my guess is that, most likely, you are not pregnant. You’ve had your period for March and April, and mid May is yet to come. As you know from experience, periods can vary in duration. If you’ve recently changed your birth control medicine, have been sick, significantly changed your diet, have started a new exercise routine, or have been under significant stress, these factors can also affect the duration and regularity of your menstrual cycle. I would guess that you’ll probably have your period the middle of May.

Now, having said that, some women do experience what is called implantation bleeding. Implantation bleeding consists of pink or brownish colored blood. It is considerably lighter than menstrual bleeding and may occur around 5 to 12 days after ovulation. If you experience noticeable implantation bleeding (true for 20-30% of women), you’ll see it a week to a few days before the time when your regular period would begin. One of these days I’ll go into more detail regarding how implantation bleeding takes place.

Most periods start off with a light flow (which would be similar to the spotty discharge experienced with implantation bleeding), but then, with most periods, the light flow becomes heavy. This can help distinguish implantation bleeding from your regular period.

Admittedly, it does become very confusing trying to figure out if it’s just a regular period or the implantation bleeding, and that’s why we’ve got inexpensive yet quite accurate home pregnancy tests so we can put our worries on the shelf (or, for those who are trying to get pregnant, get your hopes up). Though there is much debate about this (just read the tiny print info sheets inside each HPT package), a standard urine based home pregnancy test really can’t be guaranteed to detect whether you are pregnant or not until right after you’ve missed your first period. Even then, you’re pushing it and shouldn’t assume that a negative HPT is failproof. HPTs detect the level of the pregnancy hormone in your urine, and that hormone is only produced once the fertilized egg is implanted. Since the time of ovulation during your cycle will vary from woman to woman and since the time of implantation will also vary, the pregnancy hormone (hCG) will occur in varying amounts at the beginning of the time when you should be experiencing your regular period.

So, your safest bet is to take an HPT after your regular period would have ended and then take a follow up HPT (assuming the first one was negative) a week to two following that.

In your case, going to the doctor for a blood pregnancy test (and, keep in mind that these are also “looking” for the pregnancy  hormone – hCG), may or may not be more sensitive than your home pregnancy tests. There are two different kinds of blood pregnancy tests: (1) the quantitative hCG tests measure the exact level of the hCG hormone in your blood (and, thus, are very accurate); (2) the qualitative hCG tests just check your blood to see if the pregnancy hormone is present or not (and these have about the same accuracy as your over the counter urine home pregnancy test). So, if you do spend the money (and time) going to the docs for a blood test, be sure to find out what kind of hCG test they’ll be giving you.

And, as always, if you do ever get a positive result on your HPT, by all means, start those regular doctor appointments right away! While we all just love those visits, they’ll be the best thing for your future son or daughter (and yourself).

Ta ta for now,

Hannah