How do you know if you have ruptured your memebranes?

What is amniotic fluid and how do you know if your have ruptured your membranes?

Amniotic fluid is the liquid that surrounds the fetus whilst it is in the uterus. It has many functions that all relate to the development of the fetus.

What is amniotic fluid

About 12 days into a pregnancy, an amniotic sac forms around the growing fetus. Amniotic fluid fills the sac and has several functions, including:

  • Offering protection and cushioning the fetus
  • Keeping the fetus at the correct temperature
  • Allowing the fetus to breathe in the fluid while the lungs develop
  • Assist the fetus’s digestive system to develop as they swallow the amniotic fluid
  • Assist the muscle and bone development of the fetus as they move around the uterus in the fluid
  • Protects the umbilical cord which carries oxygen supply and nutrients from the placenta to the fetus

The quantity of the fluid within the amniotic sac will steadily increase in volume until late in the third trimester when it starts to decrease in volume.

The fetus and fluid are contained within the amniotic sac. The sac will often break before or during the time that a woman is in labour.

Leaking amniotic fluid may feel like a gush of warm fluid or a slow trickle from the vagina. It is usually clear in color and often has a distinct odour. It may also contain traces of blood or mucous.

Many women fear that their membranes have ruptured but this may not always be the case. The bladder is compressed by the uterus so it is not uncommon for women to leak urine.

It is also not uncommon to experience an increase in vaginal discharge during pregnancy. Normal discharge tends to have a mild smell and looks milky in appearance.

When to contact labour ward or your doctor?

If you are concerned that you may have ruptured your membranes you should put a pad on and wait. If the fluid coming away is amniotic fluid it will not stop leaking and your pad will be damp and become heavy quite quickly.

If your pad remains dry then the loss is usually a result of a urine leak or a gush of vaginal discharge.

If you think you have definitely ruptured your membranes or are concerned and not sure what to do, you should contact one of the midwives in my office during office hours. After hours you should contact labour ward at the Epworth Freemasons. The midwives will advise you what to do and whether you should come into the office or labour ward to be checked.

If you think you have ruptured your membranes you should not insert a tampon, have intercourse or do anything else that may introduce bacteria into the vagina.

Your doctor will examine you by the use of an Amnicator which is a sterile swab impregnated with a sensitive pH indicator. Using a speculum, the Amnicator is introduced into the vagina and any fluid coming away or fluid pooled in the vagina is sampled. By a simple pH color change, we can accurately detect the presence of amniotic fluid. Sometimes we get an equivocal result so we then use an Amnisure which is a more accurate predictor.

You should also contact the midwives if you have:

  • Foul-smelling, brown or green discharge from the vagina
  • Have a temperature/fever
  • Your uterus feels tender
  • You feel generally unwell

Management of rupture of the membranes

Management will vary and depend upon:

  • Gestation of the pregnancy
  • The length of time the membranes have been ruptured
  • The presence or absence of infection


Dr Len Kliman is one of Melbourne’s most experienced and respected obstetricians and gynaecologists.

With more than three decades of experience, Dr Kliman has delivered over 20,000 babies and still counting!

In 2017, Dr Kliman was awarded an Order of Australia for his services to obstetrics and gynaecology.