The myth of "Evap lines"

awesome, and also very hopeful and inspiring!

for those that wont, dont or cant click on links, here is the (rather long but VERY interesting post.

Roy Hopodopodopolis
Roy Hopodopodopolis

28/01/2013 at 01:53
PM


Hello everyone I get really annoyed when I read all these articles and comments about 'evaporation lines' on home pregnancy tests, and especially, when such comments or articles are said to be written by so-called 'experts' or 'clinicians', and which seem to leave a large number of women with all sorts of doubts and anxieties about test-results. So I thought I would sit and write a few facts about various similar tests. I am a clinician and I also have much experience using various tests within laboratories or clinical settings. I have also been trained in the medical micro-biology (lab-testing).

The home pregnancy tests are 'assay' tests which rely on specific reactions between chemicals, to produce coloured lines. The 'control' lines of the home pregnancy tests are assayed areas which are designed to react with specific chemicals commonly found in urine, and which, when detected, react with the chemicals in the control-line assays (strips/areas) and turn them a certain colour (pink or blue depending on the test used). However, the 'pregnancy' assay (test -area/strip) is designed to change colour only if it comes into contact with the HCG hormone – the 'pregnancy' hormone. HCG is only produced when an egg has been fertilised. So then, if no conception has occurred, then no HCG will be produced by the body, and therefore, no HCG will ever be found in the urine.

Moving on... sometimes fertilisation occurs and HCG is produced for a while, but for some reason, the body detects that the pregnancy will not be successful (not 'viable') and the fertilised egg ceases to continue to divide and develop. So the pregnancy stops. However, until the pregnancy stops, the woman will still be producing HCG, and may well have some of the other 'usual' symptoms of pregnancy (though some women have absolutely no symptoms for a considerable period of time), and; although the pregnancy may have stopped almost as soon as it began; it may still take a couple weeks or so for all the HCG in the body to be disposed-of via the urinary system. Also, it may still take a couple weeks or so for the 'symptoms of pregnancy' to stop altogether. This process of fertilisation, followed by a very early termination is known as a 'chemical pregnancy', and many women can have these, whereby the woman is sure she is pregnant, but then she later has a period – even though a home pregnancy test might have shown a faint or clear line in the first couple weeks or so – and hence is why some women are left wondering why their period returned.

So for those women whereby, unfortunately, fertilisation has occurred, but the pregnancy was not viable, they were pregnant, but the pregnancy stopped. However, for those women whose egg(s) is fertilised, and for whom the pregnancy continues, then they will continue to produce HCG from the moment of fertilisation, and, those levels of HCG will rise over the coming weeks, and will, at some stage, be readily detectable either by home pregnancy tests, or by blood tests via their local Doctor or Clinic.

So then, back to home pregnancy tests ….. I have already said that the control lines react to molecules found within normal urine, and, when those molecules pass over those control-line areas (control 'assay' areas) then the molecules come into contact with other molecules within the control assay and they bind together. Indeed, they are attracted to each other by a process known as 'chemotaxis'. And on contact, two different molecules form a 'complex' which changes both it's shape and it's colour – hence the coloured control lines you see in the test areas. However, if the right molecules are not present in the urine, then no other molecules can bind to the control molecules – and no colouration will occur – so the test will be 'void' – and another test should be done.

However, in the event of carrying out a test – and the control lines change colour as they should, then the woman or couple is anxiously waiting (if they wish to have a baby that is) for the 'positive' or 'pregnancy' line to change colour too! And here is where we need to get onto the subject of the 'faint' lines and the 'evaporation' lines that people keep talking about. Going back to the test-strip; the 'pregnancy' line contains different molecules to the molecules of the 'control' lines; and the molecules in the pregnancy line/strip (the pregnancy test-assay) will only react – and change colour – in the presence of one other molecule; and that is the HCG hormone. No other molecule or hormone will cause it to change colour.

Changing the subject slightly, if we take a pure white tissue and add one drop of water onto it, the area of the tissue containing the water will now have turned slightly 'grey' – because it's wet. But it wont turn pink or blue. So if we carry out a home pregnancy test and the control lines are pink or blue (depending on the test you use), but the 'pregnancy' strip remains white or slightly grey – even hours after the test – then there has been no HCG detected in the urine, to mix with the pregnancy-strip molecules and to make them change colour (which is what you will be hoping for). So if the strip remains white or slightly grey – no matter how many hours or days after you did the test - then the strip is simply wet from the urine, but it does not contain any HCG. So, either you are not pregnant, or, if your period has stopped, then you may still be pregnant but your HCG is so low that it cannot yet be detected by the test.

However, if you do a test and you get the faintest coloured line in the 'pregnancy' test-strip/assay area on the test, then HCG has definitely been detected. If it's faint, then HCG is present in very low concentration, and if it is a dark coloured line, then the concentration of HCG is higher. But whatever the concentrations, provided you get a colour in he 'pregnancy' area, then you are pregnant at the time of testing.

And now for the famous 'evaporation lines' that so many people – and 'experts' talk about. To start-with, no evaporation line will be coloured (pink or blue etc. depending on the test you used). Only the HCG can combine with the pregnancy-assay molecules and bring about a colour-change. So if the line is coloured – no matter how faint the line is – then HCG made the line change colour – nothing else! However, just like the wet tissue-paper we talked about earlier, if the area is simply wet with urine, the pregnancy strip may possibly turn a little 'grey' – like a 'shadowy' colour; but if there is no pink or blue colour, then no HCG has been detected. However, remember that the area of the test-stick that you 'wee' on is made of a very dense material, and urine will be absorbed by this dense material and will travel along the test-stick by 'passive-diffusion'.

And liquids like to move from an area of their high concentration – to an area of their low concentration, so, because the test-stick is sealed and dry, the urine will travel along it – to it's other end – and may 'drip-out' inside the sealed area of the stick (the bit after the test and control areas that you cannot see). So the urine will keep moving until the end that you 'wee'd' on has no more urine to offer! Then the 'concentration gradient' ceases and the 'diffusion' will stop. And in most cases, test-sticks – especially those with caps on – can stay wet for days! So if you go back to the stick an hour, or two, or three or four hours etc after the test; and the 'pregnancy' strip has changed colour (pink or blue depending on the test etc), then, whilst the urine has spent several hours travelling up the stick from one end to it's other – and 'dripping out at the other end – the urine has been passing over the 'pregnancy' area all the while.

Therefore, even if the HCG levels are virtually undetectable (but present in minute quantities), as the urine travels over the pregnancy-assay, the HCG will still be attracted-to (remember the 'chemotaxis' we talked about earlier) and will bind with the molecules in the pregnancy-assay – hence a positive coloured line showing up to several hours after the test was done. Like I said, no other molecule or hormone will make the pregnancy-assay change colour – except HCG. So, if after an hour, or several hours, you have a coloured line in any way, then HCG has been detected – and HCG can only be found in your urine if an egg has been fertilised.

So let's not have any more if this 'evaporation line' confusion. If it's slightly grey or remains white – however long after the test you look - then no HCG is present. But if it 's coloured – then HCG is present – in whatever concentration – because only HCG can bring about the colouration of pink/blue, depending on the test you are using. And finally, some tests don't dry out for days – sometimes many days (especially those that you put the caps back on) - so the water-content of the urea has not even evaporated – yet people still go on about 'evaporation lines' – which, in my opinion, is nonsense. And for the record, my Wife's test had a coloured line several hours after we did the test – and I knew she was pregnant – despite the articles I read on the internet about evaporation lines.

And indeed, the next tests proved that she was. I am critically aware of the intense emotions involved when people are hoping or trying to become pregnant - and I hate to think of the emotional heartache and anxieties that these mixed or uncertain test-results can cause - hence the reason for taking the time to write this short article. I hope it helps, and feedback - whether positive or otherwise - is always useful. Take care - and lots of baby-dust - to all prospective Mums-n-Dads

credit to Roy Hopodopodopolis from the post on the link in the o/p

I bloody well knew my chemical pregnancy wasn't an evap line! Thank you!

Brilliant post isn't it - so what do you make of this? Can you see the line?

Looks like a line to me

Looks like grey line to me.

That looks like a line to me, looks very pink on my screen.

Looks like a pinkish line to me but hard to tell on the screen

Not even a vague line. Very clear on phone screen! Congrats

Pink line. Definitely. Congratulations!

Thanks for posting the article and congrats x

Definitely a line - congrats!!

bumping this for anyone who is interested!

Wow, that's really interesting!

Hi i have missed a period and i have taken 4 test my first 2 had very faint lines but no colour so i threw them thinking it was more than likley evap line i did another yesterday it was negative i took this one on the photo this morning it now has a blue second line does anyone think i am possibly pregnant?

Sorry, I don't believe this.... I have had false faint lines and definately not been pregnant. I've also had chemical pregnancies.

I think it does make a lot of sense and hopefully helps people understand more!

Hi, I took a test and it’s confused me. Am I imagining a line? Thanks

Thank you! This post has put my mind at eAse been getting very faint but BLUE lines on Tesco tests for a couple of days, but doubting myself. Fingers crossed they progress x

I know this post is a bit old but i took 2 tests, nothing within the 10min window but a few hours later I have 2 posistive tests. What makes me doubt they are posistive is that the vertical line is very thin, but still blue.?

How do you add photos to this thread?

On any blue dye test, I would always get a faint blue 'positive' line. This happened perhaps 10 seperate times (different months) and I was never pregnant at any point in those cycles.

3 DC down the line I know now to avoid blue dye tests when initially testing for a pregnancy. Blue dye tests still do read sufficiently positive in a genuine pregnancy, but the squinting and anxiety when first testing was made worse for me by using them.

I've been saying this about evaps for years. They simply are not as common as mumsnet would have you believe. There's nothing wrong with blue dye tests either other than a grey 'wet' line may look bluer than it does pink, thus making people unsure if it's actually a bfp.

I had a very faint line within the 10 minute time frame and as time went on within half hour of doing the test I had a very strong line. Would you say this is positive? I have blood tests to see tomorrow to see.

Sorry, but that’s a load of crap.

Certain tests are notorious for giving out false lines .

Take the clear blue for example, countless women have suffered with their bullshit faint lines yet have absolutely zero line on any other test.
That isn’t because the clear blue is oh-so-wonderful at picking up the minute HCG but because they are absolutely crap tests.

Take the Superdrug test, it used to be very reliable, a popular test for this reason. Then they “improved” it and it started giving lines out all over the place for many women yet they were getting stark negatives on all other tests (same urine!) that isn’t because the Sd test is good, it’s because it’s shite.

Yes Chemical Pregnancies occur, that’s an absolute fact.

And no, perhaps Evaps aren’t real (I’ve no idea)

But it IS possible for a coloured line to come up on a test and it NOT be because it’s picking up minute HCG from a C.pregnancy but purely because the test is unreliable and shit.

I also don’t like the tone at the very begninning of the thread pointing out that it was written by a man. So? Does that make it more credible? Absolutely not.

And yes I know this a 3 year old Zombie Thread, but it’s still bullshit.

And I love the “I am a clinician.”

Please! As is that has any weight. And so what he’s spent time in a labatory. He is one man, with one persons experience in one labatory. Statistically speaking that counts for precisely fuck all.

content://media/external/file/24222
What about this?

Totally agree with @JustVent I have had coloured evaps even with a FRER. It's totally unhelpful to convince women that they must have been pregnant because they have a pink line on a test that's been cracked open and sitting out for 24 hours. Total bollocks.

Hello!
I’m new to the site and have been TTC for 3 months. My cycle has decided to go from an almost regular 26 days to a 32 almost immediately when we began TTC 😩 which has made it hard and frustrating to track. I’m currently on CD 31 and have had very different cramps the past 4 days so I took a test. I thought I saw a very faint line but my BF couldn’t see anything. After 2 hours there was a very clear blue line. I know Sainsbury’s tests are notorious for evap lines but thought I’d ask for some advice.

I done one with just water and there was no blue line. Trying to post a pic but not sure how lol.

I need help understanding a pregnancy test, i spotted 3 days around the 7/8 of may usually don’t get a period until 15th or the 24th of each month.. I used 2 different test when I tested and they didn’t show right away the lines appeared in the testing area but they were colored not just grey tested in the past and never used to see a line at all Obgyn nurse said when they sit they get faint lines but never knew the faint lines to be colored in the past

I took a test yesterday and this is what I saw. I'm afraid to take another one because I do not know what I will see. I don't know what this means!!

[IMG]http://i67.tinypic.com/p7mzb.jpg[/IMG]

i67.tinypic.com/p7mzb.jpg

Hi sorry to jump on your post but hat do you guys think? Evap line or faint positive?

What do you guys think?

Looks like a positive to me! Were you pregnant in the end?

I have two positive looking test Faint lines and one negative I took the first two one on a Wednesday night and the other Thursday morning around 10:30 am the one that came out negative looking I took Thursday around 3pm and I had tinkled about 5 times by that point so I am wondering if it is just super early I would only be a couple weeks. I have pictures I do not know how to add them

I need some advice, I don’t want to offend anyone but I am not looking to get pregnant, I was a bit silly and didn’t use anything over the course of two weekends, I went to a local clinic and had the morning after pill, I still haven’t come on, I am now 3 days late, yesterday morning I took a clear blue test and it showed a positive, through out the day I tried different brands some with blue dye and some pink, this morning I tested with a cup of urine, I used Asda, Morrison and first response pink dye test and a Sainsbury’s blue one. Pink ones show negative (I hope is true) and the blue again looks like it’s showing a positive, I would post a picture but unsure how to.

Can someone tell me how to upload a picture so I can ask opinions on it?

Ive got a very faint positive line although its obviously blue im still confused my tubes have been tied 5 years can this be real?? Helpcontent://media/external/file/7621

What brand is the test? Clear blue and Tesco's own almost always have a faint blue line when negative.

Is this test positive

Okay, I was really confused! I’m 10 days late and I’m having all the symptoms my test came back positive but with a blue faint plus sign.

Hello i know this thread is quite old but im hoping someone sees this and replys.. what do you think?

I have the same problem did you turn up pregnant?

Hello yes i was pregnant but ended up miscarrying at 10weeks xx

How do I post pictures of my tests that I need advise on

IMG_0585.JPG
Came back 20 minute to this after it said 10 minutes... true or no?? Happened with another one really faint

I tried to upload a photo I don’t know why it’s not working

I took a pregnancy test one morning. It said negative. When I got off work my bf saw it in the trash and showed me it. It said positive. The line is thin but pink. I'm not sure if it's really positive. I've taken 3 other tests and none have done the line even hours later. What should I do?

I know this is an old post but if it’s true what he is saying then my picture has detected hcg, I had a 2 day period that started 10 days ago and this is only just showing..., I have lots of pregnancy signs...... does this just mean I have to wait a little longer to test or I had a chemical pregnancy? Thanks

It’s a bit clearer on this side

@babydustneededplease your situation sounds exactly like mine! Following to see if we get any answers

@Prettyplease202 I’m starting to think I aren’t, I’ve got a huge problem with looking to much into it and start shining under the light etc...... I’m thinking I maybe had a chemical pregnancy because still giving negative and my symptoms are starting to calm down a lot gutted but keep trying. Good luck hope it’s a better situation for you xx

@Babydustneeded please. I thought that I had a chemical too. Went to the doctors and the were very dismissive said as the bleeding stopped I was probably okay. Tested again today (should be 5 weeks) and got a very faint line, was expecting a neg. I too read into it it just drives you mad!!

@Prettyplease202 sorry to hear that! It’s such a stressful thing trying for a baby and they say stay calm and don’t stress ...... ha no chance lol. It’s so hard not to look too much into it when you want it so bad, but I’m definitely going to stop it now and try be a bit more chilled out about it (I can try anyway lol) I wish you all the luck and hope it happens for you soon xx

@babydustneededplease I admire your affirmation to be more relaxed I will try to do the same! All the luck in the world to you on your baby making journey xx

Hi I had a faint positive then the next day a couple negatives. Which is right?

Hi I took 3 pregnancy test yesterday and just looked at them there & 2 of them have a blue line could this be an evap line or not. I also took a clear blue one and a line appeared but it appeared the wrong way round. I then took one from Asda and there is a very very faint red line I’m not sure how to post pics

@rachel1995 I know u posted a few years back but was ur test from Sainsburys & were you pregnant ? X

@prettyplease202 any update on your pregnancy?

@Dfg345 thanks for asking. No news yet. Waiting until next week to test again as the HCG could still be in my system

Hi can anyone help please is this a positive or a evaparation line thank u not shure if this post will be seen

@dfg345 update, was a chemical 😢

@Georginaclinton1 did you attach a photo? I can see one

Hi can anyone help me post a pic please

No hun I don’t know how to

@Georginaclinton1 it’s the little paper clip symbol at the bottom of the box. I know how crazy and alone these tests can make you feel.

Thank u so much for ur reply hun I havmt a paper clip I am very slow on these things lol I know hun you see 2 lines and think right that’s positive then there are evap lines so it confuses u so much x

@Georgiaclinton1 I am certainly no expert, from my reading around the subject, the difference seems to be the colour. If your line has any colour to it then it’s positive. Evap lines are grey or almost transparent. I know the waiting’s hard but test again in 2 days as the hormone should be stronger, producing a darker line. Good luck! 🍀

Good Day. Thank you for your informative article regarding pregnancy tests and evaporation lines, I took a test yesturday morning with first morning urine the test read negative so I put it in the trash can trash can was empty lol) but after 5 hours I took it out and I have now seen a very faint pink line on the test?? Also before putting it in the trash I put a few drops of water over the area of the test ( so I'm not sure if water mixing with the urine can activate possible hcg on a test even if it's a small amount??)

I got two lines after hours of taking the test. Looks like a marker line and a pen line.... I think that's a NEGATIVE for me😔 but I took 3 total. The first one (been sitting the longest) hasn't developed another line (evap line) like the last 2. So.....WHAT THAT MEAN??? I think I'm trippin out!!!😳

Hi not sure how to put a picture up but I done a home pregnancy strip test and it came out negative I left it in my bag an came back to it 3-4 hours later an there is a slight faint line it looks more pink that it does grey an i’m Not the only one who can see it my friend could see it on a picture an my other could also see it in person? It’s so faint that it’s not giving me much hope (TTC for 13 months) it’s 6 days before period an I may be testing early but I done another today an they were negative? Now am not sure what to think any advice would be appreciated

This is a one step pregnancy test, I've taken a few the last 2 days and all come up with faint positive but I took clear and simple early response test and they were negative with the same urine that gave me a positive on first response. Do you think it's an evap line or am I really pregnant

Hello I am new to this group and looking for some advice, I came off of the implant a few weeks ago and I have had unprotected sex I have done a few tests because my breasts were very tender and I feel like they are positive but the lines are so faint and only showed after the 10 minute mark. Please have a look and help me I’m so confused.
Thank you in advance

Hi I took a pregnancy test showed negative so I threw it in the trash when I went to get it out it had another line on it this was hours later could this be evaporation line ?’ I will post a picture on as I can’t see an option to add a picture I’m new to this forum

How do u post a pic?!

Hi sorry for barging in but I’d love to know if my test is an evaporation line or a positive. I tested yesterday and looked at it again this afternoon.

I don’t see the attachment button to add a picture

Same here I cant figure out how to post the picture. I'm nor sure if its a positive or just evaporation line

Ok I’ve had sore nipples and breasts and other early pregnancy signs I took a test on Wednesday that was positive and then got blood work done Thursday then on on Thursday started to spot , I’m very confused because I started spotting when I was expecting my period but it was insanely light compared to what my normal day one flow is .....
Friday still a light flow and light cramps
Took 4 home tests and and at first they were negative but going back later there was a faint line on one of them .... I’m soooo confused is this common with clear blue to give faulty positive results?
Waiting on blood work but going a little nuts waiting

Hi can anyone tell me what they think of these texts, evap lines or positive ?

Hi, I’m after doing four pregnancy tests in last few days! Today Alere came with faint blue line, clear blue today not pregnant! Trying to upload pic how do I do that? Xx

I've never heard of evaporation lines before even after a couple children, however I've had a feeling I'm pregnant, after your first you seem to tell the difference I've never normally been wrong and done tests. However I'm looking to see what's peoples opinions of mine all done in last 3 days, and very very faint and hard to see but there are still lines

I cannot find how to upload pictures thou xxx

My girlfriend just took a pregnancy test and she believes its a positive, shes began telling people shes pregnant but i'm not as convinced....to me it looks like a evap line, it may just be my eyes and I hope that i'm wrong but the pregnancy line looks grey to me, what do you guys think?

Hey there. Thank you so much for this! I can't figure out how to post a pic of my tests but the point is, one of them showed a very faint line in the first five minutes but almost undetectable and the second test showed nothing until an hour later. The first one I mentioned is now a distinct blue line and the second is a faint, but blue, line. It's been about 6 hours. I am so confused about the conflicting information. Can some one tell me how to post a pic so I can get an opinion? I tried copying and pasting into the body of the post but it isn't working and I don't see a button to add a photo. Technology is not a friend of mine...

How did you post this? I can't figure out how to post a pic. Also, looks like an evap line but I am not expert.

@Raign that looks positive to me- it looks to have colour in.

@NOTaFAN2019 you need to be a member for 48 hours I think before you can post a photograph. If you have been, then there's a paper clip symbol below the text box. Click that, and you can attach a photo.

Thanks for that! I guess I will upload a pic in a couple days.

I also meant to add that I took a digital test this morning and it said not pregnant even though I am looking at two seemingly positive tests.

hi I'm new here and I was just wondering if anyone could help out i was four days late and I took a test and thought I could see a faint line, i checked it again after about 30 mins and a line had come up, it happened on two tests but the next day I started spotting, I did another test and it came up negative I went over the doctors and the nurse said that it looked positive on the test and took a blood test from me because I had started bleeding, she also told me it could have been a chemical pregnancy, I was jw if anyone could tell me if this is an evap line or a positive because I m just not sure, the blood test came back as negative and that's why she thinks it might be a chemical one I'm not sure how to add a picture thank you everyone

i took a test at 9dpo 2 days ago.. i had been meaning to come on here and ask anyone for some help to tweak or to possibly shed some light on this for me .. im debating whether to buy another test since my mIu was only at 4.04 when i took this test possibly being the reason its sooo thin but then idkk . ill be 12dpo tomorrow but i cant wait to know or have some kind of idea... help!!!
edit : the very thin line does have color, it doesnt really look like it over the camera but me looking at it with the flash on , i as well as my partner both see the purple in it being just very thin . i think it could be an vap line but the 2 tests i took before this one from the day before the evap lines were as thick as the control line but had NO color whatsoever . with the other tests before this one i was able to put the flash directly behind the test facing upward and not see anything but with this one im able to see the purple thin line with the flash behind it ... im so confused 😟😟😟!!!!!!

Hi! I know this is old but I need some help!!

Do you think this could be an evap??

I’m in the same situation. What was your outcome?

You can definitely get coloured evap on blue dye. A faint line came up after a few hours and then got a negative yesterday and my period today (4 days late) I'm convinced this is an evap as not TTC so doubtful it would be chemical. I wont trust blue lines.

Do you see a line?

I don’t know if anyone looks at this thread anymore but I’m not sure if what I’ve got is an evaporation line or just a faint positive that took a few hours to turn up. It’s blue, not grey.