When you have vaginal bleeding after having sex it is known as post-coital bleeding. If you have vaginal bleeding and it is not due to your period, see your doctor. Normally it is nothing to worry about but, in some cases it could be a sign of something more serious.
What is post-coital bleeding?
Post-coital bleeding is vaginal bleeding that occurs within 24 hours after sexual intercourse.
Normally you should only have vaginal bleeding when you have a period, but if you have irregular periods, you may not be sure if the bleeding is normal or not. If you are not sure if your bleeding is part of a period, see your GP to discuss this.
Heavy bleeding immediately after sex is not normal – seek urgent medical help.
Where does post-coital bleeding come from?
A woman's reproductive system can be divided into upper and lower parts:
The upper part includes the body of your uterus, your fallopian tubes and your ovaries. Bleeding during your period occurs when the lining of your uterus breaks down as part of a normal monthly cycle.
The lower part of a woman’s reproductive system is the neck of your womb (cervix), your vagina, and your vulva and labia, which are on the outside of your body.
It is the lower parts that are usually involved in post-coital bleeding.
What are the causes of post-coital bleeding?
The most common causes of post-coital bleeding include the following:
Cervical polyps – small growths caused when cells multiply abnormally. In rare situations these can develop into cancer. They can easily be removed at the time of a smear test.
Cervical ectropion – when cervical cells grow outside your cervix, where they can be damaged during sex.
Vaginal thrush – a common yeast infection that can occasionally cause bleeding along with other common symptoms such as pain, itching and vaginal discharge.
The contraceptive pill or injection – contraceptives can affect the lining of your cervix and make it extra sensitive, especially when you first start on them.
Having sex – occasionally, sex can cause bleeding from your vagina or vulva, especially if you have a condition called atrophic vaginitis where the lining of your vagina becomes thinner.
Less common but more serious causes include the following:
Cervical cancer – this a serious condition but if it is treated early it can be cured completely. This cancer can be identified before it becomes a serious threat through a smear test. Remember that no test is perfect, so even if you have had a recent smear test, you should still see your GP if you have post-coital bleeding.
Cervical infections – such as chlamydia and gonorrhoea. These infections can cause serious problems and need to be treated.
Pregnancy – bleeding in early pregnancy is common, but needs to be checked out by a doctor. Early pregnancy bleeding can occur with an ectopic pregnancy, which occurs when the pregnancy is growing in a fallopian tube. This is potentially very dangerous.
In girls who have not started having periods, any vaginal bleeding is not normal. See your doctor for a check-up and advice.
To find out the cause of the bleeding, your GP will need to ask you some personal questions about your sexual activity. These questions can be a bit embarrassing but your GP talks about this kind of thing all the time. The more information you can give the easier it will be for them to find out what's going on.
Your GP will also need to find out about:
what contraception you are using
any other medications you are on
when you last had a cervical smear.
If you are not seeing your regular GP it can be really helpful if you take along your medications such as 'the pill' if you are using it.
Tests and procedures
There are some common tests and procedures that your doctor may also ask for, such as the following:
A urine sample to check for pregnancy or urine infection.
A vaginal examination to look for causes of bleeding in your vagina or cervix. This examination is the same as having a smear test.
A smear test might be repeated and tests for infection can be done at the same time.
Occasionally your GP may also do a test called a pipelle. This is done at the same time as a smear test, but using a very thin plastic tube to collect a sample of the lining of the uterus. The GP will want to know whether you are pregnant before this test.
An ultrasound scan, especially if your pregnancy test is positive, the examination suggests there is a problem with your uterus or ovaries, you are over 45 years old or if there is a family history of certain types of cancer.
What is the treatment for post-coital bleeding?
Treatment for post-coital bleeding will depend on what the cause is. Your doctor will advise you on the best course of action once a diagnosis has been made.
Dr Jeremy Tuohy is an Obstetrician and Gynaecologist with a special interest in Maternal and Fetal Medicine. Jeremy has been a lecturer at the University of Otago, Clinical leader of Ultrasound and Maternal and Fetal Medicine at Capital and Coast DHB, and has practiced as a private obstetrician. He is currently completing his PhD in Obstetric Medicine at the Liggins Institute, University of Auckland.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Jeremy Tuohy, Obstetrician & Researcher, University of Auckland
Last reviewed: 28 Feb 2020
Common causes of post-coital bleeding
Polyps occur when some cells in an area grow too much. They can occur in many parts of your body and are usually not serious. Because a polyp is made of cells that have grown abnormally, they can occasionally develop into a cancer. This is how many bowel cancers are thought to start.
Cervical polyps often occur in women with polyps inside your uterus. If the polyps grow too much they can bulge out of the opening of your cervix into your vagina. The cells on polyps are not tough like skin, so if they are rubbed during intercourse they will bleed.
Rarely, cervical polyps develop into cancer of the lining of the womb, called endometrial cancer. Endometrial cancer is not usually detected on a cervical smear but does usually cause irregular vaginal bleeding before it is very advanced, so there is a good chance of a cure. Read more about cervical polyps.
This condition is not serious but is one of the more common causes of post-coital bleeding. Sometimes female hormones cause the cells inside your cervix to grow outward into the part of your cervix that your doctor and nurse can see when they take a cervical smear. This is why sometimes you may have some bleeding after a smear.
Cervical ectropion is similar to cervical polyps except that the cells have not grown too much and are not abnormal, they are just in the wrong place on the outside part of your cervix, where they can be damaged during sex. Read more about cervical ectropion.
Occasionally a bad case of thrush can cause bleeding. Usually, there will be a lot of discharge and discomfort as well. You can buy treatment for thrush over the counter at a pharmacy. If you treat thrush but the bleeding doesn’t go away or if you get thrush often, see your GP for a check-up. Recurrent thrush can be a sign of diabetes. Read more about thrush.
Bleeding due to the contraceptive pill or injection
When you first start taking 'the pill' or 'the injection' you can have some irregular bleeding for 2–3 months. Irregular bleeding when on the injection is quite common and is one of the main reasons women stop using this form of contraception.
If you are sexually active and are not planning to become pregnant, there are many effective different types of contraception. Go to Family Planning or your GP to discuss the choices and find a method of contraception that works for you.
Bleeding caused by sex
Occasionally, sex can cause bleeding from your vagina or vulva. This may occur sometimes the first time you have sex but it should not be heavier than a period or last more than a couple of days.
Although sexual activity does not usually cause damage to your vagina, a rip or tear in your vagina can sometimes occur. Your vagina has a lot of blood vessels just under the surface, so the bleeding can be very heavy and requires management in a hospital.
Bleeding from your vagina after sex is more common if you have gone through menopause and stopped having periods.
This is often associated with a condition called atrophic vaginitis where the lining of your vagina becomes thinner and more susceptible to infection.
Women on medications for breast cancer (such as tamoxifen) may also have this condition due to low hormone levels.
Using a water-based lubricant during sex can help prevent bleeding if this is the cause.
Infection of your cervix is usually a sexually transmitted infection (STI). Some STIs, such as chlamydia and gonorrhoea, are serious and need to be treated. The infection can spread from your cervix to your uterus and fallopian tubes and cause problems getting pregnant. Because they are sexually transmitted, your sexual partner/s will also need to be checked for infection.
Condoms are a very effective protection against infections such as chlamydia and gonorrhoea. They also protect against pregnancy and serious conditions such as HIV.
Bleeding in early pregnancy is common. Most women will know they are pregnant soon after missing a period, but many others won't realise they are pregnant for a couple of months. If early pregnancy bleeding occurs around the time you are expecting a period, it is easy to mistake this for a period.
There are several important reasons to find out whether you are pregnant:
If you are pregnant and plan to continue the pregnancy you may need to change lifestyle behaviours, such as smoking or drinking alcohol, to make sure your baby gets the best possible start in life.
The treatment of bleeding in early pregnancy is very different to treatment of post-coital bleeding
Your GP may not want to prescribe some medications if you are pregnant.
Early pregnancy bleeding can occur with an ectopic pregnancy, which occurs when the pregnancy is growing in a fallopian tube. This is potentially very dangerous.