Let's talk about this "HPT accuracy chart"

[graysweater]

Ok, I have a question. What about testing with something other than FMU. How does that play into all this? Especially if it is early like 10, 11, 12 DPO. 

[getzystark]

Jan 23, 2015 15:50:28 GMT -5 graysweater said:

Ok, I have a question. What about testing with something other than FMU. How does that play into all this? Especially if it is early like 10, 11, 12 DPO. 

So those stats would only involve FMU because that's what the box tells you to do, and I'm assuming the study they are using to back it up, used FMU.

Diluted urine or SMU is likely to be less concentrated in HCG, so it could make the difference between an early squinter and a negative.

[mugster]

According to WebMD, 4 hours of held urine is an adequate substitute for FMU, but not a perfect substitute. All of this has to do with concentrations of hormone in the urine, so it is pretty easy to throw off that percentage if your urine is too diluted.

[cateyes]

Jan 23, 2015 15:50:28 GMT -5 graysweater said:

Ok, I have a question. What about testing with something other than FMU. How does that play into all this? Especially if it is early like 10, 11, 12 DPO. 

It makes it even less likely you will get a positive, especially earlier on. FMU has the most concentration so the probability of getting a positive on days 10 or 11 would be much lower if you used SMU or tested later in the day. 

[anonymouseliza]

Jan 23, 2015 15:50:28 GMT -5 graysweater said:

Ok, I have a question. What about testing with something other than FMU. How does that play into all this? Especially if it is early like 10, 11, 12 DPO. 

Well, that's an interesting question and you'd have to read individual studies to know for sure.

Holding your urine for 3-4 hours without diluting it with beverages is the same as FMU, and for early testing, probably better . . . because it's a few more hours for hcg to reach traceable amounts in your body.

With my first planned pregnancy, I had a maybe faint positive at 9 dpo, a distinct but light line at 10 dpo with FMU and a clearly, no question about it pink line at 10 dpo 9:00 pm with a 3 hour hold. 

How that may or may not be accounted for in the number is unclear though.

[graysweater]

Jan 23, 2015 15:53:55 GMT -5 getzystark said:

Jan 23, 2015 15:50:28 GMT -5 graysweater said:

Ok, I have a question. What about testing with something other than FMU. How does that play into all this? Especially if it is early like 10, 11, 12 DPO. 

So those stats would only involve FMU because that's what the box tells you to do, and I'm assuming the study they are using to back it up, used FMU.

Diluted urine or SMU is likely to be less concentrated in HCG, so it could make the difference between an early squinter and a negative.

Thank you! Thats what I was thinking. I am glad you started this post. It has really put somethings into a different perspective for me. 

[graysweater]

Jan 23, 2015 15:56:19 GMT -5 anonymouseliza said:

Jan 23, 2015 15:50:28 GMT -5 graysweater said:

Ok, I have a question. What about testing with something other than FMU. How does that play into all this? Especially if it is early like 10, 11, 12 DPO. 

Well, that's an interesting question and you'd have to read individual studies to know for sure.

Holding your urine for 3-4 hours without diluting it with beverages is the same as FMU, and for early testing, probably better . . . because it's a few more hours for hcg to reach traceable amounts in your body.

With my first planned pregnancy, I had a maybe faint positive at 9 dpo, a distinct but light line at 10 dpo with FMU and a clearly, no question about it pink line at 10 dpo 9:00 pm with a 3 hour hold. 

How that may or may not be accounted for in the number is unclear though.

The only time I have ever seen a BFP was with my son and it was totally unplanned. I tested at night because I cant read directions and I was too antsy to wait. I also was not temping or anything so I had no idea how far past a missed period I was. 

[kcones88]

Jan 23, 2015 15:31:50 GMT -5 anonymouseliza said:

Jan 23, 2015 15:23:01 GMT -5 kcones88 said:

Good info to know. I average an 11 or 12 day LP, so I should definitely NOT be testing before my period is due. At least, that's what I took away from this discussion, LOL.

Unless you are comfortable knowing that you are testing before implantation may have occurred.  Basically - test whenever the hell you want.  If you're not pregnant, it doesn't matter when you test, and if you are pregnant, your test won't be positive until a couple of days after implantation occurs.  If you test - at 10dpo, you aren't out unless you are looking at a multitude of other signs suggesting it (though implantation could theoretically be happening as you test).

Makes perfect sense

[teraiin]

Wow thanks for breaking that down! I'm not going to lie, I stink at understanding logical statistic things like this but you wrote it in a way that made sense.

[anonymouseliza]

Jan 23, 2015 16:37:43 GMT -5 b said:

What tests are you using that give you positives at concentrations less than 25? I'd like to see the sources that confirm this.

Almost everything I've read over the past 4 years states implantation can occur anywhere between 6 and 12DPO - the accuracy chart in the OP essentially states that 96% of people implant by 9DPO and I'm really curious what scientific literature you have to back that up. Especially since it indicates only 1% of people ovulate at 10DPO or later, despite most scientific literature stating 10-12DPO implantation still falls within the curve of averages.

*** www.ncbi.nlm.nih.gov/pubmed/10362823 *** This study is 15 years old, but is pretty comprehensive regarding the pregnancy rates of over 200 women (a study needs at least 20 results). Of those that were still pregnant after 6 weeks, 84% of them "had implantation on day 8, 9, or 10" after ovulation.

Not OP but I had +'s on internet cassettes, FRER, Target Up & Up blue line with beta test coming back at 20.  FWIW, since urine and blood concentrations are not exactly the same.  Granted, these were faint, but they were clear.  This was also 3-5 years ago.

[anonymouseliza]

Jan 23, 2015 16:45:04 GMT -5 b said:

Jan 23, 2015 15:34:47 GMT -5 anonymouseliza said:

I mean. . . I've said this at least 5x in the tww thread . . . there is science and there is superstition. I know all the stuff posted above, but I always test around 9/10 dpo, because my successful pregnancies (beyond first tri) were positive then, and the unsuccessful pregnancies weren't.

Obviously, a successful pregnancy could implant at 10 dpo and yield a positive at 12 dpo and be fine, but . . . superstition.

So even with all of that, you're gonna do what you're gonna do, you know? Just be aware of it so you don't look like as asshat.

The same study I linked above also has statistics on the day of implantation vs. the rate of loss in the study, and it seems to back up what your anecdotal experience was.  

"The risk of early pregnancy loss increased with later implantation (P<0.001). Among the 102 conceptuses that implanted by the ninth day, 13 percent ended in early loss. This proportion rose to 26 percent with implantation on day 10, to 52 percent on day 11, and to 82 percent after day 11."

The really stark one was the cervical ectopic.  No positive until 12 dpo, and it came with spotting and then a full period, and eventually turned out to be a cervical ectopic.  That is a stupidly rare type of pregnancy, even among ectopics.  They have next to no data about it or even retrospective studies because of the rarity with which it occurs.  But the OB I saw later theorized (and it makes sense) that the zygote traveled too far and ended up implanting in the cervix because the lining was already breaking down at the end of my lp.

[getzystark]

Jan 23, 2015 16:37:43 GMT -5 b said:

What tests are you using that give you positives at concentrations less than 25? I'd like to see the sources that confirm this.

Almost everything I've read over the past 4 years states implantation can occur anywhere between 6 and 12DPO - the accuracy chart in the OP essentially states that 96% of people implant by 9DPO and I'm really curious what scientific literature you have to back that up. Especially since it indicates only 1% of people ovulate at 10DPO or later, despite most scientific literature stating 10-12DPO implantation still falls within the curve of averages.

*** www.ncbi.nlm.nih.gov/pubmed/10362823 *** This study is 15 years old, but is pretty comprehensive regarding the pregnancy rates of over 200 women (a study needs at least 20 results). Of those that were still pregnant after 6 weeks, 84% of them "had implantation on day 8, 9, or 10" after ovulation.

I wasn't necessarily saying that FRER's detect anything less than 25 mIU, however there have been several ancedotes that people have claimed betas that were very low (less than 25) at 9 or 10 dpo with positive FRERs. That's the frustrating part, there's nothing that say how low they actually detect HCG or with research to back it up, that's why I was asking for more information in the OP. I also cannot find out the difference between blood concentrations of HCG and urine.

If the FRER's don't detect HCG that low, a 99% accuracy level at 12 dpo would have to be at 25 mIU, given only if you implanted at 7 dpo, or HCG doubled faster. Even if they are taking into account that you implant at 7 dpo and your normal HCG level is only 5 mIU (it could be lower than 5), doubling rules would offer a positive HPT on a 25 mIU test maybe at 12 dpo. You would think with that chart they would need to add in the possibility of implanting at later times, in order to offer that kind of accuracy, thus the possibility for the FRER to detect lower levels of HCG.

I appreciate that other article. Unfortunately I can't find the full text for it, or the article that FRER sites. The abstract isn't much help. www.ncbi.nlm.nih.gov/pubmed/19863469

[mugster]

Sometimes the tests they do to prove accuracy involve mixing HCG into non-pregnant urine at the levels that they would expect to see it at that number of days post ovulation (or pre-period?).

Per FDA rules, when they say that a pregnancy test is 99% accurate, they are comparing it to other tests, not to pregnancy.

www.fda.gov/MedicalDevices/Safety/AlertsandNotices/TipsandArticlesonDeviceSafety/ucm109396.htm

[mugster]

Jan 23, 2015 17:15:54 GMT -5 getzystark said:

<abbr>Snip:
</abbr>
I appreciate that other article. Unfortunately I can't find the full text for it, or the article that FRER sites. The abstract isn't much help. www.ncbi.nlm.nih.gov/pubmed/19863469

The full text for the other article can be found by clicking on the upper right hand corner. This link might also work: www.nejm.org/doi/full/10.1056/NEJM199906103402304#t=articleResults. I couldn't find the FRER article for free (or through any library subscriptions I have access to). It doesn't seem worth $60

[mugster]

Also, here is another article: www.clinchem.org/content/47/12/2131.full

It is also almost 15 years old, but explains why some of the accuracy claims are overly optimistic.

[anonymouseliza]

Ok, this isn't really contributory to the conversation, but from my pregnancy with my daughter, here are 10dpo fmu tests: www.fertilityfriend.com/tg/entry/7633532.html

This was my first positive at 9 dpo, pm, 3 hour urine hold. It was there, but faint enough my husband didn't really believe me or wasn't convinced. (the following morning when I handed him the clearly positive FRER, he looked - expecting a faint/evap line - and then threw it back at me yelling, "Holy fuck, that's positive!") www.fertilityfriend.com/tg/entry/7633533.html

I had my first beta 2.5 days later (12 dpo) and it was 188. Now, I had a faster doubling rate (looking back to the series it seems to have been about 38 hours), but even then, it would theoretically place my level in the 50's to 60's. Just an interesting little aside.

[juliayadda]

What I am hearing:

If you POAS before 10 dpo, you are basically peeing on a ten dollar bill (or a smaller denomination for say a dollar store HPT).

[getzystark]

Jan 23, 2015 17:54:15 GMT -5 mugster said:

Jan 23, 2015 17:15:54 GMT -5 getzystark said:

<abbr>Snip:
</abbr>
I appreciate that other article. Unfortunately I can't find the full text for it, or the article that FRER sites. The abstract isn't much help. www.ncbi.nlm.nih.gov/pubmed/19863469

The full text for the other article can be found by clicking on the upper right hand corner. This link might also work: www.nejm.org/doi/full/10.1056/NEJM199906103402304#t=articleResults. I couldn't find the FRER article for free (or through any library subscriptions I have access to). It doesn't seem worth $60

Well derp! Thank you for both of those!!