A Stitch in Time - The Cervical Stitch which can Prevent Miscarriage
Miscarriage and stillbirth can be caused by a number of factors, including problems with the placenta (depriving the baby of food and oxygen), birth defects, diabetes and smoking during pregnancy.Sometimes a baby miscarries as the result of alterations in the normal vaginal flora. Women prone to urinary tract infections may also be at risk of premature delivery because the way the body responds to that infection can trigger labour.
But one of the major causes of premature delivery is cervical weakness. The cervix forms the neck of the womb and its main function is to prevent the baby leaving the womb and to block bacteria from entering it. Until delivery, the cervix remains effectively closed.
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This is helped by a plug of mucus which sits in the cervix for most of the pregnancy. The cervix is an elastic structure and, although usually 4cm long, it 'shortens' to enable the baby to be delivered. The cervix supports the full weight of the foetus. If the mother has a weak cervix, it can give way and open slightly. When that happens, the womb membranes may start bulging through the cervix, which often triggers labour.
By monitoring women with cervical weakness, doctors can try to prevent problems if they suspect shortening of the cervix on a scan. The operation to put a stitch in the cervix has been used since the late Fifties, but in the past it was overused and fell out of favour because there is a theoretical risk of it causing miscarriage, because it is quite an aggressive intervention. There is also the danger of a stitch being placed which isn't up to the job.
When this happens, there may be an emergency early birth. If the stitch can't be removed in time, the mother may be left with a more damaged cervix afterwards. But these risks have to be balanced against the hope it can give women prone to repeated miscarriage.
Cervical cerclage is often referred to as a stitch. But actually the cervix is encircled with quite a thick tape about 5mm by 1mm made of a tough nylon material called Mersilene. The operation takes about 20 minutes. Doctors prefer to give the mother an epidural rather than general anaesthetic because it's safer and they try to place the stitch as high in the cervix as they can to make it as strong as possible.
Once the right position is found, the doctor takes the tape - which is threaded onto a curved needle -and tunnel it around the circumference of the cervix, rather like a belt encircling it. Then it is tied with a surgical knot.
The skin is then closed-up with one or two dissolvable stitches, the baby's heartbeat is checked and a scan makes sure everything is in order. Women will usually stay in hospital overnight and go home the next day. They should expect some spotting of blood for a few days. Some women take progesterone hormones which may help prevent premature labour.
Look here for more information about Miscarriage
December 2006 |
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