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Preterm Birth: Part 2 – What can we do?

Pregnancy Dr Minke Burke Director
Being at risk of preterm birth is stressful. There are ways to prolong your precious pregnancy, helping your little baby grow and mature in your belly as long as possible….

In Part 1 of our blog we learnt about what Preterm Birth is, the risk factors and detection.  In Part 2 we will explore treatment options for you should you find yourself at risk of preterm birth.

Treatment options 

Treatment options for preterm birth (PTB) are individual and based on your previous pregnancy history and medical history.  In general, two groups of women can be identified:

  1. Women with a previous history of pregnancy loss or PTB;
  2. Women without a previous history of pregnancy loss or PTB.

Treatment options include insertion of a cervical suture (cerclage), vaginal progesterone, or cervical surveillance with repeated ultrasound scans.

10% of women have a cervix less than 25 mm at the time of morphology scan, 5% have a length of 20 mm and only 2% have a length of 15 mm or less.  If you haven’t had a previous PTB, the risk of PTB with a cervical length of 25 mm or less is around 30%. This means that 70% of women with a short cervix on ultrasound deliver at term without any intervention. However, 3 out of 10 women deliver before 34 weeks gestation and their babies have a significant risk of death, severe infections, and breathing difficulties. Treatment with progesterone will reduce the risk of PTB in this group by a further 44%, and a cervical cerclage reduces the risk by 35-40% in this group of women.

The risk of PTB with a cervical length of 25 mm or less with a history of a previous PTB increases the risk to 60%. Treatment with a cerclage or progesterone is recommended for all women in this group.

Cervical Cerclage:  This is a surgical procedure that aims to close the cervix with a stitch and to keep it closed until term or as close to term as possible.  A piece of synthetic tape or suture is placed around or through the cervix, increasing its strength. The procedure may be performed vaginally, laparoscopically or abdominally and this will depend on the length of the cervix and whether it is an elective or an emergency procedure.  The two most common types of cerclage are called Shirodkar or McDonald, named after the doctors who performed them first.

A Shirodkar suture can be placed prior to pregnancy. This is recommended if women have had 3 or more midterm pregnancy losses. It can also be placed in the early second trimester after the first trimester screening scan.

With a Shirodkar suture, a vaginal approach is used and an incision is made in the front and at the back of the cervix. The bladder is pushed back and a tape or a tube is placed around the cervix, as close to the top as possible.  The skin is then closed over the tape or tube. A caesarean delivery is usually recommended and the tape may remain in place for future pregnancies.

With the McDonald cerclage, the stitch is placed through the main body of the cervix without pushing back the bladder or bowel and is the more commonly performed suture when the cervix is very short or the membranes and sac may be seen coming through the cervix. This is called an emergency stitch.

Other cerclage procedures are termed Cervico-Isthmic and refer to the location at the junction of the cervix and uterus where the stitch is placed. These are performed abdominally, laparoscopically or vaginally. This type of stitch may be recommended if you have had previous second trimester losses or after the failure of the cerclages listed above.

For any cerclage, the procedure needs to be performed in hospital under a general anaesthetic so that you are maximally relaxed.  After you are asleep, your legs are placed in stirrups so that the cervix may be clearly and easily seen.  The top of the cervix is identified and the stitch is placed according to the methods described above.  If the stitch is being placed as an emergency, you will be placed in a head down position, particularly if the membranes and fluid sac is coming through the cervix as this is a high-risk suture and the membranes may be damaged.

Other risks include infection of the cervix or possibly in the sac around the pregnancy (called chorioamnionitis – see below), bleeding, trauma to the cervix or surrounding tissues such as the bladder or bowel. It is important to note that this is a high-risk procedure and may result in miscarriage.

Infection inside the uterus (chorioamnionitis) may be an important cause of cervical shortening, rather than always being a result of a procedure to close the cervix. If you are having a cerclage procedure, your Alana doctor will perform vaginal swabs and blood tests to look for any sign of infection and to determine which bacteria or other microbe is responsible for the infection. You will be commenced on antibiotics and it is essential that you continue on these for as long as directed.

If there are symptoms or signs of severe infection, then it may in fact be dangerous to place a stitch.  If a stitch is placed in the cervix and your waters break (rupture of membranes) after its placement then it must be removed, owing to the high risk of infection. In this event your Alana doctor will discuss future treatment options with you.

Studies have shown that the placement of cervical sutures may reduce the risk of premature delivery (before 34 weeks) by 35%.  This is an approximate figure only and is dependent on whether is stitch is placed electively or as an emergency, as well as your individual circumstances. After a stitch is placed, you will require individualised and frequent follow-up that will be discussed with you.

Vaginal Progesterone:  A second option for treatment of a short cervix is by using the hormonal treatment progesterone. For women who are recommended to have this treatment option, a vaginal pessary containing 200 mg of progesterone is inserted each night before bed.  It is common to have a vaginal discharge when using this medication owing to the outer coating of the pessary. There may also be mild vaginal irritation.  It is also possible to use the suppositories rectally if this occurs.

Long-term use of progesterone in pregnancy is considered very safe and there are no increased major birth defects for babies born to women using progesterone in this manner. For male babies born to women using progesterone, there is a mild increase in a condition called hypospadias where the urethra doesn’t end in the centre of the penis.

Cervical surveillance:   As 70% of women with a short cervix detected at morphology ultrasound (and without any other risk factors) will deliver at term, there is an option to ‘wait and see’.  You can have a cervical assessment on a weekly or two weekly basis depending on your cervical length and gestation. If you have had a cervical cerclage or if you are on progesterone treatment, cervical surveillance is of benefit if the cervix is indeed very short.  There is an option to receive corticosteroids from 24 weeks gestation. Two injections are given to you 24 hours apart to help your baby’s lungs mature, and it has also been show to be of benefit for your baby’s gut and decreases the risk of bleeding in the baby’s brain. Steroids will be effective for about 7-10 days. A repeat steroid dose (“rescue dose”) can be given at a later gestation when still premature.

We’re here to help

At Alana, we will guide you through the decision-making process for what is the best and most appropriate treatment for your unique circumstances.  We recognise that this is a very difficult and anxiety-provoking time for you and your family and will stand by you providing information, skills and compassion to help you through this difficult time.  Please contact our friendly staff if you wish to arrange to discuss your individual circumstances at a consultation with one of our specialists.

For more information about our services please visit our Obstetrics, Gynaecology, or Fertility main page.  Alana Healthcare for Women – Illuminating women’s health.