A weakened cervix, also known as cervical insufficiency, is the main cause of miscarriage in the second trimester and also one of the most frequent causes of premature birth.
A weakened cervix shortens and opens too early, so in order to prevent a miscarriage or premature labour, doctors recommend an operation to put a stitch of strong thread around the cervix to ensure it stays closed.
How common is this?
As the pregnancy advances, the cervix shortens and begins to open, preparing for birth. But for one in a 100, this happen too early, long before the pregnancy is carried to term. This can lead to miscarriage, premature rupture of membranes or premature birth.
The risk of cervical insufficiency is higher in women who:
- have undergone cervical surgery;
- have had a pregnancy terminated;
- have undergone a difficult birth;
- were born with a malformation of the uterus or cervix.
If any of these factors apply, then your doctor will monitor your cervix as the pregnancy progresses by pelvic examination and ultrasound.
When is the procedure performed?
If the doctor determines that you have a high risk of cervical insufficiency, then he or she will recommend that you have the stitch put in, so that your cervix stays closed until the pregnancy is carried to term.
The procedure can be performed between weeks 12 and 14 of pregnancy in order to prevent cervical opening and shortening. It can also be performed later during the pregnancy when the cervix is already slightly dilated and shortened. But the operation cannot be done if the membranes have broken or the cervix is dilated to more than four centimetres.
If cervical changes occur towards the end of the pregnancy, then your doctor may recommend bed rest instead of the procedure.
How is it done?
It is done under local anaesthesia and there are two ways of performing it:
- by a multiple knot tied around the cervix;
- through a pessary – a ring made of special material which is placed around the cervix.
You may be kept in hospital overnight or just for a few hours, and you may experience vaginal bleeding and cramps. Bed rest will be prescribed for a few days and sex is not allowed for at least a week.
Generally, the stitch around the cervix is removed around week 37, but it can be taken out even earlier if you go into labour.