Cervical insufficiency (weak cervix): signs, monitoring and cervical stitch

Tommy's explains that sometimes the cervix shortens and opens too soon in pregnancy, which can lead to a baby being born prematurely. You may hear weak cervix, cervical incompetence or cervical insufficiency. Tommy's notes these are just medical terms but that some women do not like them and prefer preterm cervical shortening. It quotes a woman who lost her first baby at 20 weeks and says nobody is to blame and that this is a medical condition.

The RCOG leaflet on cervical stitch states that a stitch may be recommended when there is a chance that the cervix may shorten and open too soon, which can lead to premature birth or late miscarriage.

Tommy's says the cervix can shorten and open without any pain or other symptoms. Some people have smelly or yellow or green discharge, bleeding, or a feeling of pressure in the lower tummy or vagina, and should tell their maternity team. Because it can be silent, it is usually diagnosed only when someone has had one or more late miscarriages or premature babies and other causes have been ruled out.

Tommy's lists possible causes: a cervix born prone to shortening, a differently shaped womb, collagen conditions such as Ehlers-Danlos syndrome, and injury to the cervix from procedures such as LLETZ or cone biopsy for abnormal cervical screening results, or from a previous labour, including an emergency caesarean when fully dilated. The RCOG lists the same kinds of history among reasons for early specialist referral.

The RCOG says you should be referred to a specialist early in pregnancy if you have had a miscarriage after 16 weeks, a birth before 34 weeks, waters breaking before 34 weeks in a previous pregnancy, treatment to your cervix such as LLETZ or cone biopsy, scarring of the womb lining or an unusually shaped uterus, a previous caesarean at full dilatation (10 cm), or a cervical stitch in a previous pregnancy. Tommy's adds that your midwife will assess at your booking appointment whether you would benefit from extra monitoring.

Depending on the situation, the RCOG says the team may recommend a planned stitch based on your history, or offer vaginal ultrasound scans to measure the cervix between 16 and 22 weeks. Tommy's gives 16 to 24 weeks. If the cervix is found to be short (less than 25 mm), options in the RCOG leaflet are a scan-indicated stitch, daily progesterone pessaries until 34 weeks, or close monitoring if you prefer neither. Tommy's says that if you have a short cervix on scan but are pregnant with one baby and have no other risk factors for preterm birth, a stitch is not recommended. These pathways differ between hospitals and UK nations.

The RCOG says a stitch is usually done between 11 and 24 weeks, most often vaginally, in an operating theatre with a spinal or general anaesthetic. The operation takes less than an hour, you may have antibiotics and a catheter, and you can usually go home the same day or the next day. You may have some bleeding or brown discharge for a day or two and are usually advised to rest for the first 2 days; bed rest is not routinely recommended. The RCOG says a stitch does not affect the baby's growth, and you can have sex when comfortable.

Other types: a transabdominal stitch (put in through the abdomen or by keyhole surgery, usually before pregnancy or in early pregnancy) which is not removed and means birth by caesarean; and an emergency stitch placed after the cervix has already begun to open, which the RCOG and Tommy's both say has higher risks and is less likely to work. Tommy's gives 16 to 28 weeks for the emergency stitch.

Tommy's describes vaginal progesterone as a pessary shaped like a small tampon that most people find easy to insert, used usually until 34 weeks. It says progesterone is a hormone that helps support pregnancy, including keeping the womb relaxed, but it does not always work. Tommy's says there is no evidence that a stitch or progesterone is better than the other, so preferences matter. For multiple pregnancy the RCOG says there is no evidence a stitch will prevent early labour and care is individualised; the NHS says a woman with twins who has a short cervix on a scan at 16 to 20 weeks may be offered progesterone tablets to take daily until 34 weeks. Decisions on any medicine are made by your clinician.

The RCOG says a stitch may not be advised if you have signs of infection, vaginal bleeding, contractions or waters that have already broken, or if the cervix is too short or too far open to place it.

Surgical risks listed by the RCOG are bleeding, infection, injury to the bladder or cervix, and waters breaking early; the stitch may not always work. It is removed in hospital, usually at 36 to 37 weeks, without anaesthetic in most cases, taking a few minutes. If labour starts with the stitch in place, contact your maternity unit straight away so it can be removed to prevent cervical damage; if waters break early but you are not in labour the stitch will usually be removed because of infection risk.

Contact your healthcare team without delay, the RCOG says, for contractions or cramping, abdominal pain, continued or heavy vaginal bleeding, waters breaking, or smelly or green vaginal discharge. If you cannot reach them or you feel very unwell, call 999. Tommy's adds that it is normal to feel guilt, fear and sadness and encourages telling your team how you feel.