Abnormal uterine bleeding

21st February, 2023 • 16 min read

Abnormal uterine bleeding can be worrying, whether it’s a little spotting after sex, bleeding between periods or really excessive vaginal bleeding when you’re not expecting it. There can be lots of causes – most aren’t serious, and there’s lots you can do to sort it out.

What is abnormal uterine bleeding?

Most of the time, abnormal uterine bleeding is nothing to worry about. Normal hormone changes at menopause or during pregnancy are common causes. So is hormonal contraception – like the combined Pill and the IUD – especially when you first start using it. But abnormal bleeding can sometimes be a sign of something that needs to be treated.

Put simply, it’s any bleeding that’s different to your usual menstrual bleeding. This could be:

  • bleeding between periods – this can include spotting, which is very light bleeding
  • bleeding after sex
  • heavy bleeding during your period, even if your period comes at the usual time
  • menstrual cycles that are longer than 35 days or shorter than 21 days
  • a cycle length that varies by more than 7-9 days (irregular periods)
  • any bleeding after menopause (you’ve been through menopause when you’ve gone 1 year without a period. This usually occurs when you are over 45 years old but can be diagnosed in younger people if no other cause is found

So, it can be bleeding between periods but it could also involve a change in your period or bleeding after your periods have stopped.

How often does it happen?

How often you bleed can vary. Abnormal uterine bleeding can be what doctors call ‘chronic’, meaning it happens regularly over a period of 6 months. Or it can be a one-off.

How does it make you feel?

Emotionally, any kind of unusual vaginal bleeding can feel concerning, and often inconvenient and embarrassing if you’re caught out without sanitary protection. “If it happens regularly, it can get in the way of everything from exercise to your sex life, and if it’s heavy, it may even result in anemia, which can make you feel tired and drained,” says Healthily expert Dr Ann Nainan.

“It’s that constant fear you might have a stain on the back of your skirt”

“You’ve reached the point where you think you know how to manage a female body, and suddenly it starts to wrongfoot you,” says Helen Clare, a biology teacher turned menopause educator, speaking about perimenopausal bleeding in The Guardian newspaper.

Who gets unusual bleeding?

“It’s really common to have changes in your usual bleeds or unusual patterns,” says Dr Ann.

  • you’re most likely to have abnormal bleeding in puberty and in perimenopause, when hormone levels are shifting
  • worldwide, it’s thought up to 30% of women experience it at some stage. But since most research has focused on heavy menstrual bleeding rather than irregular bleeding, the true numbers may be higher

What does abnormal uterine bleeding look and feel like?

“This can vary a lot,” says Dr Ann “Remember – anything outside your usual period pattern counts as abnormal bleeding.”

  • we could be talking some mild spotting, which may be pink or brown – you may only notice it when you go to the bathroom and you probably don’t need anything more than a pantyliner to deal with it
  • it still counts as bleeding even if it’s just brown discharge
  • or you may have full-on heavy bleeding with clots and pain, going through a tampon or pad in less than an hour
  • it may feel like your usual period but go on longer

What causes it?

“Abnormal uterine bleeding isn’t a diagnosis in itself, it’s a term that describes a symptom, not the cause,” says Dr Ann. There can be lots of different reasons behind it, including hormone changes, sexually transmitted infections, and conditions including endometriosis and PCOS, and, less commonly, conditions such as cervical, uterine or ovarian cancer.

When the bleeding happens can often give important clues about what might be causing it.

Bleeding after menopause

It’s pretty normal to have irregular bleeding during perimenopause – the time leading up to your final period, when your hormones are changing. But once you’ve been through menopause – usually when you’re over 45 and you’ve gone at least 1 year without a period – bleeding is less common.

  • it may be caused by things that aren’t serious, including inflammation and thinning of your womb due to low estrogen
  • polyps (usually non-cancerous growths) of the cervix or womb
  • sometimes, HRT can cause breakthrough bleeding, especially when you first start using it
  • in rare cases, it can be a sign of ovarian cancer or womb cancer

Check any bleeding after menopause with your healthcare professional, even if it’s a one-off.

Bleeding during or after sex

There can be a lot of different causes for bleeding after or during sex (you may not notice the blood until afterwards), but it should be investigated by a medical professional. It may happen during any kind of vaginal penetration, not just penis-in-vagina sex. Some possible causes are:

  • things that are uncomfortable but not dangerous, like friction, vaginal dryness and lack of lubrication
  • things that need treatment, like pelvic inflammatory disease or sexually transmitted diseases such as chlamydia
  • Issues with your cervix, like polyps (usually non-cancerous growths) or cervical ectropian
  • in rare cases, more serious causes such as cervical or uterine cancer

Bleeding during pregnancy

Seeing blood when you’re pregnant is always alarming. But in fact, it’s common in early pregnancy, happening in up to 1 in 4 pregnancies, and doesn’t always mean there’s a problem with the pregnancy. It can happen simply because more blood vessels have developed in your cervix, so it bleeds more easily. You may notice this after sex, for example.

However, always get checked out because it can be a sign of more worrying causes such as:

Bleeding in later pregnancy can be serious and you should always seek help urgently.

Bleeding after first-time sex

This can happen if your hymen – a thin piece of skin partially covering the entrance of your vagina – tears or stretches the first time you have sex.

  • it doesn’t always happen, though – your hymen can tear or break before that, during exercise or from using tampons, for example
  • the amount of blood may be so small you may not notice

Heavy periods

You have heavy periods if you feel bleeding has gotten heavier than usual, and/or if any of the following happen:

  • blood soaks through to your clothes or your bedsheets
  • you have to have to change your tampon or sanitary towels very regularly, such as every 1-2 hours
  • you pass large clots – the size of a quarter, or bigger
  • you have to double up on sanitary products
  • your period lasts more than 7 days
  • you have to avoid work or your hobbies because of your periods
  • you have to get up in the night to change sanitary protection

Around 1 in 3 women report heavy menstrual bleeding at some point, but that doesn’t mean it’s normal.

  • it can be caused by conditions including endometriosis, where womb tissue grows outside your womb, pelvic inflammatory disease, fibroids or polyps
  • if you don’t release an egg (ovulate) regularly, womb lining can get thicker and build up, which can result in heavy bleeding when the womb lining sheds. It’s more common around puberty and perimenopause, and can happen in women with PCOS or an underactive thyroid
  • problems with your blood that stops it from clotting, such as liver disease or inherited clotting disorders, can make you bleed more
  • some medicines, like blood thinners and aspirin, can cause heavy bleeding in some women
  • heavy periods can also be associated with diabetes and kidney problems
  • the IUD can cause it, especially in the first year you start using it
  • what seems like a heavy period could be a miscarriage or ectopic pregnancy (you may not have known you were pregnant)
  • and, less commonly, it can be a sign of cervical cancer or endometrial cancer, although endometrial cancer tends to affect women after the menopause and in their 60s

Random vaginal bleeding

Bleeding between periods can range from light to heavy, happen once or regularly, and it can have a number of different causes, but should always be checked out. These can include:

  • starting on hormonal contraception like the combined pill, progesterone-only pill, patch, implant, injection or IUS – these can all cause irregular bleeding in the first few months
  • HRT may also sometimes cause unpredictable bleeding or spotting, especially when you first start on it
  • missing a contraceptive pill, or being sick soon after taking one, so you haven’t absorbed the hormones
  • taking emergency contraception or ‘the morning after pill’
  • hormone changes due to perimenopause or PCOS
  • a recent miscarriage or abortion
  • STIs like chlamydia
  • fibroids
  • harmless changes in your cervix, or vaginal dryness
  • cervical or womb polyps
  • less common, serious causes like vaginal, vulval, cervical or uterine cancer

Bleeding for a month straight

Everyone’s periods are different, but if you have one that goes on for more than 7 days, it could be a sign of a problem and should be investigated. Some women may bleed for up to a month. Again, there can be a lot of potential reasons, including:

  • conditions such as fibroids, uterine polyps (small benign growths in your womb), endometriosis and adenomyosis (where bits of the womb lining get into your womb’s muscle layers)
  • hormonal imbalances like hypothyroidism
  • bleeding disorders
  • hormone changes in perimenopause can also cause longer, irregular periods
  • more rarely, conditions like cervical or uterine cancer

Is abnormal uterine bleeding ever serious?

Usually, it’s nothing to worry about, or is caused by something like an infection, which often can easily be treated. But there can be more serious causes and complications:

  • it may be a sign of miscarriage or ectopic pregnancy
  • if you lose a lot of blood, whatever the underlying cause, you may become anemic or even go into shock
  • rarely, it could be a symptom of a type of cancer that affects your reproductive organs, such as vaginal, cervical, uterine or ovarian cancer
  • that’s why it’s always important to seek emergency help for very heavy bleeding
  • if you have unusual bleeding and pain, or if the bleeding is less heavy and irregular, to be checked by a doctor, even if you don’t think there’s anything to worry about. They can rule out serious causes

“Always get unusual bleeding and other symptoms checked”

Sally was diagnosed with cervical cancer after having unusual vaginal bleeding. “I was having some unusual bleeding between periods and after sex, as well as a few urine infections. I’ve always attended smear tests and wasn’t due another until the following year,” she says on the Jo’s Cervical Cancer Trust website. After treatment, Sally is now free of cancer, but says: “If you’re experiencing bleeding, like I was, then a smear test isn’t what you need. In fact, it will just slow everything down! I wanted to share my story to urge others to get any unusual symptoms, like bleeding, checked.”

When to see a doctor

Most of the time, abnormal uterine bleeding isn’t serious but you should always speak to your doctor about it. It might be something that needs some simple treatment to make it stop. And it’s worth finding out what’s going on, because it can be uncomfortable and inconvenient – you don’t have to put up with it.

  • You should see a doctor urgently if you have any of the following:
  • you have bleeding or spotting in between your periods or any bleeding after the menopause
  • you have any vaginal discharge which is new for you
  • you have new pain or bleeding during sex of after sex
  • you’ve noticed any lumps
  • you have new symptoms, such as losing weight without meaning to, more bloating, more tiredness, changes in your bowel habits or urinary habits (such as an urge to pee more than usual) ,or blood in your urine

You should go to the emergency room if you have any of the following:

  • you have new vaginal bleeding and other symptoms like feeling faint, breathless, bruising, or you have other bleeding, like nose bleeds
  • you have fever, new tummy pain or pain at the tip of your shoulder
  • you’re pregnant with new bleeding
  • you have very heavy bleeding

How is it diagnosed?

  • you’ll probably be seen by an ob-gyn and they’ll start by asking about symptoms and your personal medical history, including any medications you take, and whether you’ve been pregnant before
  • if there’s a chance you may be pregnant, they’ll carry out a pregnancy test
  • it’s also likely you’ll have some tests for STIs – these are usually simple urine tests or swabs
  • you may need some blood tests to check for other conditions like anaemia or to checkhow your thyroid is working
  • your ob-gyn will do a general physical exam and they’ll probably want to carry out an internal pelvic exam, which shouldn’t be too uncomfortable
  • you may not need further tests – for example, if your ob-gyn can see there’s an obvious reason for the irregular bleeding, like menopause. But depending on things like your age, other symptoms, and what tests show so far, they may also want to carry out some further examinations to look more closely at your womb. These could include:
  • an ultrasound exam, which uses sound waves to make a picture of your pelvic organs
  • a hysteroscopy, using a thin scope inside your vagina and through the opening or your cervix to look at your womb
  • endometrial biopsy, where a sample of your womb lining is taken out and looked at under a microscope
  • sonohysterography, a procedure where fluid is flowed into your uterus through a thin tube while ultrasound images are made
  • magnetic resonance imaging (MRI), a test that uses powerful magnets tomake images of your pelvic organs
  • computed tomography (CT), a type of X-ray that looks at a cross-section view of your pelvis

How is abnormal uterine bleeding treated?

You may not always need treatment, or you may decide not to have any. For example, if bleeding during pregnancy doesn’t have a serious cause, your doctor or midwife will probably just monitor you. And if you have irregular bleeding because you’re going through the menopause, you may decide to live with it until it settles.

What you can do yourself

If you know you have a condition like endometriosis, PCOS, or fibroids, or you’re experiencing heavy periods or symptoms of perimenopause, visit those pages to get our self-care tips. Otherwise, while unexpected bleeding is usually a reason to visit your doctor’s office, there are a few things you can do to help yourself:

  • keep a note of bleeding and any other symptoms while you wait for your appointment. This can give your ob-gyn some important information and may help with your diagnosis. Details such as how often the bleeding happens and how heavy it is can be helpful
  • look after yourself while you’re figuring out what’s going on, especially if you’re bleeding heavily or having more frequent periods – getting sleep, managing stress and eating a balanced diet are all important steps for your overall wellbeing
  • while bleeding can be a worry, try not to stress yourself too much. If you’re talking to your doctor, you’re doing the right things to work out the cause and get the right treatment, if you need it

What your doctor can do

If you need treatment for abnormal uterine bleeding, what your doctor recommends will depends on the cause and may include:

  • a medicine called tranexamic acid, which treats heavy bleeding and might be given at the time to help ease it, or regularly at the start of your period to lighten it
  • non-steroidal anti-inflammatories (NSAIDs) such as ibuprofen, to help control bleeding and ease cramping
  • hormonal birth control, such as the combined pill, patch, IUD or injection, which may help control heavy bleeding in women of childbearing age. These are only suitable if you’re not trying to get pregnant. Bear in mind that some types of contraception can actually cause heavy bleeding – if you’re already on birth control and your ob-gyn thinks it may be the problem, they’ll discuss alternatives with you
  • antibiotics, if an STI has caused the bleeding
  • HRT to control menopausal bleeding, once other causes have been ruled out, especially if you have other symptoms of menopause that are getting in the way of life
  • medicines called gonadotropin-releasing hormone (GnRH) agonists if fibroids are the cause of your bleeding. You can take them for up to 6 months to stop your cycle and temporarily reduce the size of fibroids
  • surgery may sometimes be recommended. This may include:
    • surgical treatment to remove fibroids, if those are the cause
    • endometrial ablation, which destroys the lining of your womb but isn’t suitable if you want to get pregnant one day
    • hysterectomy to remove your womb, as long as you don’t want to get pregnant

For some of these treatments you may need to be referred to a specialist.

Your health questions answered

Can stress cause abnormal uterine bleeding?

“Yes, stress can be a cause. Don’t assume that’s the reason for abnormal uterine bleeding, though – always see your doctor to rule out other things. Once you’ve been checked out, if you and your doctor agree stress may be an underlying issue, it’s important to take steps to deal with it.”
Dr Ann Nainan

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.