Endometriosis UK
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Where does all the blood go!!!!

So this is another weird question and I have always wondered about it. I have Endo and polycystic ovaries. When I was younger I used to get really really heavy periods that would last for days. But over the years they have got more and more irregular and really light. But the pain has got worse over the years

They are so light now that I dont even need a tampon/sanitary pad, just a little panty liner! And they literally last 2 days max. But the pain is horrendous

So im just curious, where does all the blood go that I used to get (im sorry its a gross question)??? I guess its a good thing? Does anyone else get this? Pointless asking the Doctors, you guys know way more!! x x x

11 Replies

Its a sensible question - the menstrual blood has not gone. It simply means either that your clotting factors are great right now so when the lining of the uterus sheds away leaving little wounds they are not bleeding long before they clot shut ..or

that parts of the surface of the uterus are no longer shedding their lining each time so you have fewer tiny exposed wounds to bleed from.

So the blood hasn't got lost - it is still circulating round your body rather than escaaping from freshly opened wounds.

Periods are made up of the uterus lining cells which are darker and a set amount of lining tissue depending on how thick the lining grew before shedding away, and the fresh bleeds from the wounds they leave behind them till the next layer of menstrual tissue starts to built up.

A heavy period indicates that there is a problem clotting and these wounds unable to clot properly just carry on gushing away.

Think about when you have a nose bleed. A tiny vessel bust in a nose bleed can quickly cause a decent quantity of blood and can take quite some time to stop in some folk - sometimes it just doesn't stop and the patient has to attend hosp.

In the case of internal endo bleeds doing much the same thing - the bleeding will be just as fluid - and reluctant to stop if the clotting factors are low.

Only with no where to escape gravity will ensure that the bleeding pools in cavities and spaces where it gets stuck. The body will re-absorb that eventually in time, but by then you are fast approaching another period just to top it all up again.

In the cases of adenomyosis this pooled blood gets trapped withing muscle tissue and causes swelling and pain and a the appearance of a lumpy uterus wall - which is a tell tale sign.

Same thing with endo in bowel muscle too.

And the other locations that endo cells bleed - the blood if it cannot escape anywhere else just collects locally and irritates and puts pressure on wherever it is ending up...and hurts.

Just as a bruise does in the skin - trapped blood which eventully gets reabsorbed as the bruise changes colour and eventually fades away - and you know how long bruises take to calm down.

If an endometrioma (blood filled cyst) develops from and ovarian cyst -its quite simply becoming the reservoir of escaped blood from the endo patch it is attached to.

And seeing how quickly they can form and burst and refill up again is a petty good indicator of just how much internal bleeding is going on for some ladies.

That blood is trapped can't escape and the oxgen levels leak out leaving the blood cells to turn from fresh oxygen filled bright red in to sticky dark chocky coloured gloop. Hence they are called chocolate cysts.

If you are having light periods - that is great on the one hand.

But the pain levels indicate that perhaps there is still quite a lot of bleeding going on else where from endo which is trapped and is causing a lot of pain each month.

it might feel like it is in the uterus region - but that could be because it is within the muscle walls (adenomyosis) or falling down in the POD pocket behind the uterus or the smaller space to the front of the uterus putting pressure on those places and irritating the neighbouring tissue.

If you have not yet been checked out for adenomyosis - that is something to ask to get checked out. If it is found that you have adeno then a hysterectomy will remove those trapped bleeds in the uterus muscle wall.

hope that kind of explains things a bit better in a non-scientific way.


This is really interesting - I was diagnosed with endo ten years ago and think I understand most things about it but never really understood how periods work.

What I still don't understand is, if heavy / prolonged periods indicate that clotting factors are low, what causes us to pass blood clots?

This is probably going to sound really moronic but I had a completely different understanding of what happens - I thought that the uterine lining is basically like a sponge that fills up with blood and that blood is just released. I didn't realise that the lining basically rips away and leaves open wounds.

In October I came off the pill, and it's been the longest I've been having normal periods unaffected by treatments for about 17 years. I've noticed they're a fair bit shorter than they used to be - they're really heavy with clots etc for the first few days, then there's just three or four days of light brown blood and that's it. Before they would be up to two weeks long - so I guess either my lining isn't as thick, or my clotting factors have improved so that the wounds heal quicker?

So are the clots actually clots, or are they part of the lining? If not, do we pass the lining and what is that like?

My old pain specialist once explained that when you tricycle the pill, the blood doesn't just build up for three months - that each month it's absorbed and it starts again. I couldn't figure out how that would work.

It's amazing how little many of us understand about our own bodies and how they work - I believe I'm pretty clued up but this is something I've never understood and so have just avoided. Maybe if those chats at school were a bit more detailed about what's normal and what's not, and what actually happens, we'd all know when to see a doctor.

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ok, thats makes sense, thank you so much for explaining it:) I have not been checked for Adenomyosis, but I did have a lap to remove endo in September, so would they have checked for it then just as procedure? I did have endo removed from POD so maybe thats where the blood went! Thank you again for explaining x x


Hello Snow. Hope you enjoyed the Winter Olympics. Are you still travelling with your Snowboard?

I have adenomyosis. It is more common in older ladies and If you've had children.

My adenomyosis was first suspected on a vaginal scan. My uterus was "bulky".

An MRI scan in December 13 confirmed adenomyisis.

Symptoms of adeno are cramping pain, prolonged and heavy periods (with clots) and sometimes back pain.

GNRH drugs have little or no effect on adenomyosis.

I am trying the mirena before I look at more drastic treatment. I am 43.

Maybe your periods are light as your endometriosis is being quiet at the monent. It's a little sod though....,, it usually starts marking itself heard again eventually.

Best wishes,

Barbara x


I'm 35 and have had the mirena for 3 years it's been great for me but did take months to settle down


Hi Barbara, thanks for your message, aw and thanks for remembering about my snowboarding:) Still so sad that the olympics didnt work out for me because of the stupid endo, but LOVED watching all my friends in it. And yes, im away snowboarding now so thats the main thing. Was so worried I wouldnt be able to do it! Its a massive struggle this season with the pain, but im fighting it!!

Sounds like you have been suffering over the years too, I hope your pain levels are ok at the moment. Thank you for the info, I will look into it all when I get back to the UK

Thank you x x x


No they cant usually see adeno in an op - cos it is hidden inside the muscle. but if you have an MRI scan when you are on a period or just at the end of one this can show up as a lumpy uterus wall - it should normally be uniform thickness in a normal uterus. ]

There may be signs visible in a surgery is the lumpy bits are protruding outwardly from the uterus wall but its not something they would be rumaging for signs of.


ok thank you, maybe an MRI scan when I get back then. Thank you again for all your help x x


The other possibility is stenosis of the uterine cervix. This means that the cervix opening is very narrow or completely closed. This would obviously prevent your period from coming out.

Good luck x

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ah interesting, definitely worth looking into, thank you! Hope you are well x x x


Such an interesting read!! :-)


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