Cervical Insufficiency and Preterm Labour

Cervical insufficiency, which is considered as one of the causes of preterm births, occurs in 1-5% of pregnant women.

It is characterized by painless opening of the cervix in the second trimester of pregnancy (between 14-24 weeks).


Diagnosis of cervical insufficiency

Typically, painless cervix opening and sagging amniotic membrane are the main diagnostic criteria in the second trimester of pregnancy.

Diagnosis during pregnancy is made by history, vaginal examination and ultrasonography.

Apart from pregnancy, vaginal examination is performed with a history, hegar spark plug, balloon (foley) test and medicated uterine film (hysterosalpingography).

The most important in diagnosis are the woman’s previous pregnancy stories. If painless cervical opening and / or sagging of amniotic membranes occurred between 14-24 weeks in the past, this means cervical insufficiency. Some schools seek the criterion for this situation to be experienced twice. However, if the story is clear, a loss is sufficient for diagnosis. In these cases, the woman usually opens the water sac without pain, then the baby is born and the placenta will be born from behind. Here, the diagnosis is made by retrospective inquiry based on the story.

A progressive opening in the cervix in the clinical examination of the patient who presents with bleeding and / or pain or opening the early water bladder may also be diagnostic for cervical insufficiency.

In women who have no complaints, measuring the length of the cervix with vaginal ultrasonography and evaluating its patency are among the most important criteria in diagnosis. In case of pain or other complaints, the cervix should be evaluated by vaginal ultrasonography. If the cervix length is below 25 mm before the 24th week, the risk of preterm delivery will increase even if the woman has not previously lost. Here, it is evaluated whether the cervix is ​​T, Y, V and U shaped. As the evaluation of the cervix became widespread with ultrasonography, the number of early diagnosed cases increased. This can provide the opportunity to plan the treatment at the right time.

Pain-free loss between 14-24 weeks mostly indicates cervical insufficiency and painful loss after 26th week preterm delivery. In both cases, it is sometimes difficult to decide on differential diagnosis and diagnosis, and there will be differences in treatment approaches.

The shortening of the cervix: increases the likelihood of preterm labour below 32 weeks compared to the shortening rate.

If it is <30 mm,  1%

If it is <15mm, 50%

If it is <5mm, 80% preterm birth is observed.


The causes of cervical incompetence

Can be innate:

  • Connective tissue diseases
  • Uterine abnormalities
  • Being exposed to DES(diethylstilbestrole)

Can be acquired:

  • Traumatic birth and abortion history
  • Previous cervical surgery
  • Ripening in the cervix: Infection
  • Increased enzyme activity (collagen breakdown and increased nitric acid synthesis


The treatment of cervical incompetence

If the conditions are appropriate when the diagnosis is made, the treatment is cerclage (surgical stitching in the cervix).

If diagnosed based on the story, prophylactic (protective) cerclage is performed.

If the diagnosis is made by ultrasonography, therapeutic (therapeutic) cerclage is applied.

If diagnosed by examination, emergency cerclage is required.

Prophylactic (protective) cerclage is applied at weeks 13-16 of pregnancy. It is applied between weeks. The CIPRACT study concluded that prophylactic cerclage was not significant (2002). The MRC / RCOG study published in 1993 states that it is significant only in those with a history of more than 3 second trimester loss or more than 3 premature births.

It is stated that preventive cerclage performed based on the patient’s medical history is not significant in multiple pregnancies (Dor et al. 1982, Rebarber et al. 2005). There are even publications suggesting that protective cerclage increases the likelihood of premature birth in multiple pregnancies. Here, evaluation of the cervix with vaginal ultrasonography at regular intervals allows us to determine whether cerclage is necessary and, if necessary, the right time.

In congenital anomalies of the uterus, cerclage is not necessary if the woman has uterus septus (the ligament extending downwards from the upper part of the uterus), didelfis and bicornis, if there is no premature birth or loss in the history. However, in 30% of uterine anomalies, cervical insufficiency can be seen and the possibility of preterm delivery and second trimester loss increases in this group. Considering this rate, the woman should be evaluated in her own condition by history, examination and ultrasonography and if necessary, cerclage should be applied.

Ultrasonographic indication (for therapeutic purposes) is used in case of serial cervical ultrasonographic measurements in case of cervical shortness and funneling. In two different studies, in cases where the cervix length was below 25 mm, Rust and his colleagues did not find any difference in preterm labour in 2001 and Berghella et al. found a significant difference in their article published in 2004. CIPRACT study (2002) also revealed that preterm delivery rate decreased in cases determined by ultrasonography follow-up in high-risk cases.

In this group, if the cervix length is below 15 mm, therapeutic cerclage application reduces the risk of preterm labour.

In cases where the cervical shortening is below 25 mm, if there is a second trimester loss or preterm birth history, the cervix should not be expected to be shortened further. In this group, cerclage application reduces the possibility of preterm birth.

If the cervix is open under 28 weeks of emergency cessation or if the amniotic membrane is prolapsed, cerclage may be considered. In 2003, in the study of Althusius, a much more day gain was achieved in the sequencing group. In the study of Stupin et al. In 2008, the rate of live birth increased from 25% to 72% by emergency cerclage.

Before emergency cerclage, it should be ensured that there is no anomaly in the fetus, the placenta is not displaced, there is no infection and early water intake. In case of pain or bleeding from the uterus, cerclage is not appropriate. Of course prophylactic (protective) cerclage and cerclage with ultrasonography indication; It is more successful and less complicated than emergency cerclage.


Cerclage techniques

The most common technique is Mc Donald technique. Less often Shirodkar is used. Both are administered vaginally. The success rates of both techniques are close to each other.

It is a procedure that takes 5-10 minutes under general anesthesia and general anesthesia is not harmful to the baby. Using special sewing materials, the cervix is sewn all around the area of the cervix closest to the uterus and shrinks like a pouch. It is natural to have a small amount of bleeding after the procedure. There is no difference between single or double stitches.

Hospitalization after the procedure is not always necessary. The decision is made according to the patient’s condition. Generally, progesterone preparations are recommended from the anus, vaginally or orally, and antibiotics if necessary. In the presence of contraction, medication can be administered through the vascular access in the hospital.

The fact that the cervix is very battered with previous surgeries makes it difficult to find enough space to sew from time to time. In addition, there may be a history of unsuccessful cerclage attempt vaginally. In this case, cerclage can be performed from the abdomen by operation. However, this route, which requires twice surgery for two stitches and removal and requires a longer anesthesia period and is more economically costly, more invasive and bleeding should not be preferred.


Cerclage complications

  • Infection: less in urgent and therapeutic cerclage in preventive cerclage)
  • Opening the water bladder (more often in emergency cerclage)
  • Risks related to anesthesia
  • Stitch cutting the tissue
  • Tearing in the cervix
  • Bleeding
  • Urinary tract complications can occur.