INTRODUCTION:

The cervix plays a critical role in a successful pregnancy. Broadly speaking the cervix helps contain the pregnancy within the uterus until the end of gestation. Thereafter it must undergo significant changes that allow the safe delivery of the baby during labour. The inability to perform the first function can result in a late miscarriage or Preterm birth^(14).

PTB, defined as delivery of a fetus before 37 weeks of pregnancy, occurs in 9.6% pregnancies according to the World Health Organisation’sreport. The importance of Preterm birthis that it contributes to up to 14.1% of perinatal mortality worldwide. Those premature babies that survive are at risk of developing spastic cerebral palsy, cognitive, behavioural, attention and socialisation defects, chronic lung disease, vision disturbance and hearing loss.Such impediments result in multiple hospital visits and admissions with significant psychosocial and emotional consequences that impact the individual and their families.

Such consequences have both short and long-term health service cost implications^(15).

Preterm birthmay either be spontaneous or iatrogenic when a woman is electively delivered. Spontaneous Preterm birthcan be as a result of maternal or fetal causes or a combination of them both. However, in the majority of spontaneous cases the cause is unknown or idiopathic. Maternal conditions that may lead to Preterm birthinclude hypertensive disorders, autoimmune conditions like systemic lupus, diabetes mellitus, smoking, as well as maternal infections such as malaria, urinary tract infections, or intrauterine infections. Furthermore, uterine anomalies, cervical incompetence, polyhydraminos, immunological factors may also play a role while fetal anomalies itself can play a role in preterm labour and birth^(16).

Cervical Insufficiency:

The term cervical incompetence was first described as early as 1865 in the Lancet. However, it was only in the 1955 when Shirodkar described the interval repair of anatomical cervical defects associated with the obstetric history of recurrent spontaneous mid-trimester births that the concept was widely accepted^(17).

Cervical incompetence is a clinical diagnosis, and is mostly made retrospectively. Its definition varies but there are two widely accepted definitions. The first one defines cervical incompetence as the inability of the uterus to retain a pregnancy in the absence of signs and symptoms of clinical contractions or labour or both in the second trimester of pregnancy⁽¹⁸⁾.

The second definition involves both clinical and physical components, namely “the painless dilatation of the cervix resulting in rupture of membranes and midtrimester miscarriage (12 - 24 weeks) and the passage without resistance, of size 9 Hegar dilators (9mm), through the cervix in the non-pregnant state⁽¹⁹⁾.

The latter finding is no longer regarded as reliable. Although an ultrasound finding of a short cervical length in the second trimester of pregnancy can be used as a tool to aid in the diagnosis of cervical incompetence in some cases, this is not an acceptable sole criterion for the definition. Therefore, the diagnosis of cervical incompetence comprises a historical component, namely the history of a painless cervical dilatation with preterm mid-trimester loss or preterm delivery, and/or the combination of physical findings of cervical shortening and dilatation during digital cervical examinations, and/or findings of a short cervix during midtrimestersonography in women with the relevant history of spontaneous Preterm birthor a combination of all three. There are two main theories that identify the pathophysiology of cervical incompetence in preterm labour. The first theory is that cervical incompetence results in the loss or compromise of the mucus plug resulting in the ascending of vaginal infection that can result in Preterm birth⁽²⁰⁾.

The second proposed model suggests that cervical incompetence is a continuum that is a consequence of premature cervical ripening (in absence of clinical labour) caused by one or more underlying factors including infection, local inflammation, hormonal effects, or genetic predisposition. These factors may be superimposed on a cervix with compromised mechanical integrity, and by means of the inflammatory cascade may also present as part of the preterm labour syndrome. The incidence differs in different countries and even in different hospitals within the same country due to population and ethnic differences, variable diagnostic criteria, and reporting bias⁽²¹⁾.

Types of cervical insufficiency:

1. Congenital (hereditary) cervical insufficiency with congenital uterine malformations.

2. Aquiredcervical insufficiency occur after over curettage and dilatation, cone biopsy, cauterization⁽²¹⁾.

Diagnosis of cervical insufficiency:

There is no diagnostic test for cervical insufficiency. Although many tests have been reported or are used (assessment of the cervical canal width by hysterosalpingogram, assessment of the case of insertion of cervical dilators (size q Hegar) without resistance, the force required to withdraw an inflated foley catheter through the internal os, the force required to stretch the cervix using an intracervical balloon, none of these meet the criteria required for adiagnostic test, part of the diagnosis is based upon the exclusion of other causes of preterm delivery or mid-trimester pregnancy loss, In recent practice, transvaginal ultrasonography has been increasingly used as ademonstrably valid and reproducible method of cervical assessment, and cervical shortening correlates with the risk of preterm delivery⁽²¹⁾.

This process is based upon the identification and recognition of key risk factors in the woman’s history and in the index pregnancy⁽²¹⁾.

Ahistory of prior cervical surgery e.g. Loop electrosurgical excision procedure (LEEP), may also present arisk for cervical insufficiency, In such patient there may also be arole for cervical length assessment by ultrasound. In patient who have had aprior LEEP, a 30mm cervical length has appositive predictive value, for preterm birth of 54% , but anegative predictive value of 95% . other forms of cervical trauma, for example cervical tears⁽²¹⁾.

The Key finding in the current pregnancy is the identification of cervical shortening, cervical length assessment by ultrasound is an established means of assessing the risk for preterm labor And delivery (cervical length 25mm)⁽²¹⁾.

Patient may also be found to have cervical dilatation rather than just shortening, or they may present with preterm membrane rupture. Identification of cervical dilatation in absence of maternal history of contractions, with or without membrane rupture is considered tantamount to adiagnosis of cervical insufficiency⁽²¹⁾.

Evidence for Cervical Cerclage:

The mainstay of treatment for cervical incompetence is a surgical procedure, namely cervical cerclage. This entails the placement of a surgical suture around the cervix as close as possible to the level of the internal cervical os. Theprocedure is performed at a gestational age of 14 - 24 weeks gestational age (GA) via either a transvaginal or transabdominal route. The ideal timing varies according to the specific type of procedure and in some cases, is even considered prenatally. It is believed that the cervical cerclage helps to prevent the loss of the cervical mucus plug, which prevents the ascension of microorganisms in the cervical canal in addition to providing mechanical support. The suture is usually removed at 37 weeks of gestation in the absence of contraindications. However, in some cases it is left in-situ when a caesarean delivery is performed and the cerclage (typically of the transabdominal type) is retained for the next pregnancy⁾²²⁽.

The original method described in 1955 by Shirodkar was an interval repair of anatomical cervical defects associated with the obstetric history of recurrent spontaneous mid-trimester birth that was a particularly invasive vaginal procedure. Another widely accepted and less invasive procedure was described by McDonald in 1957. These two procedures have not been compared directly and because the latter procedure is less invasive and vaginal delivery more easily accomplished, it is currently the more favoured method⁽²³⁾.

There is improvement in pregnancy outcome after cervical cerclage for cervical insufficiency in current study which is same that found in IkimaloJl, et al⁽²³⁾.

Main Indications of Cervical Cerclage:

1. Ultrasound indicated cerclage (UI cerclage):

Cervical screening using transvaginal ultrasound for the prediction of preterm labour in women with a positive history has become a safe gold standard. This accolade presupposes that it is performed correctly⁽²⁶⁾.Evidence to support the use of transvaginal ultrasound to predict preterm labour risk in these women was provided in the blinded observational study by Owen et al., in 2001This study found that women with a previous spontaneous Preterm birth<32 weeks, with cervical lengths <25mm in the current singleton pregnancy had a relative risk of spontaneous Preterm birth before 35 weeks of 4.5%. This threshold of <25 mm had a sensitivity of 69%, specificity of 80% and positive predictive value of PTB of 55%⁽²⁷⁾.

It is now widely accepted that cervical length assessment in this group of women can be used as a surrogate of cervical incompetence at appropriate gestations. On the other hand, in low risk women without a prior history of Preterm birth where an incidental finding of a short cervix (<25mm) at 16 - 23 week scan was noted only 17% ended up with a Preterm birth<32 weeks.

The use of cervical cerclage in this group had no effect on the reduction of Preterm birth. It has been shown that a short cervix <15mm does predict a high risk of Preterm birthbut it means screening over 100 women to find 1 case in a low risk population⁽²⁸⁾.

Therefore, in low risk groups, transvaginal cervical ultrasound assessment is still not regarded as an effective screening tool. In addition, funnelling of the cervix does not predict or add to the prediction of Preterm birth⁽²⁹⁾.

There also a decrease in previablePreterm birth<24 weeks and perinatal mortality^(
30).

Cervical cerclage placement did not decrease the rate of Preterm birth^)31(.

In addition, in women with other risk factors for PTB, such as cone biopsy, Diethylstilbestrol exposure, dilation and curettage, who were randomised to cerclage, no cerclage after cervical screening and findings of cervical length of <25 mm,cerclage placement did not show a decrease in PTB.Therefore, ultrasound indicated cerclage is reserved for cases with a cervical measurement of <25mm, with or without funnelling, before a gestational age of 24 weeks in women who are undergoing cervical length screening due to a prior history of spontaneous Preterm birthbetween 16 - 24 weeks gestation. This group may also be a target for progesterone therapy which will be briefly discussed later⁽³²⁾.

Recently, the American college of obstetricians and Gynecologistis (ACOG) guideline regarding indication for history indicatedcerclage was changed from 3or more previous second trimester fetal losses to one or more⁽³²⁾.

2. Clinically indicated emergency(rescue) cerclage:

Clinically or physical examination indicated cerclage is the placement of cervical cerclage in women in the second trimester who present with cervical dilatation in absence of labour⁽³³⁾.

Although controversial, when inserted in correctly selected cases the overviews show greater benefit than harm. There has been a recent systematic review and meta-analysis of CI cerclage that included ten studies (one small randomised control trial, two prospective cohorts and seven retrospective groups). This analysis studied women between 14 - 27 weeks’ gestation with a minimum cervical dilatation of 0.5cm. It included a total of 757 women. The primary outcome of neonatal survival was higher in the cerclage group vs control group. There was a significant prolongation of pregnancy (mean difference 34 days), and a greater gestational age at delivery (mean difference 32 days), with reduced Preterm birth between 24 - 28 weeks (8% compared to 37%) and PTB less than 34 weeks of gestation (50% compared to 82%). However, there was no difference in Preterm birth under 24 weeks. It must be appreciated that the studies included in this systematic review were limited in size and had variable quality and study design. Overall there is weak positive evidence that CI cerclage is effective in reduction of Preterm birth⁽³³⁾.

About elective cervical cerclage, indication has been done to prevent spontaneous preterm birth befor 34 weeks gestation indication of a rescue cervical suture may be inserted when the patient present with a cervix that is already dilated with the membranes bulging in to the vagina but no signs of Labor, infection or heavy vaginal discharge⁽³³⁾.

Elective and ultrasound indicated cervical cerclage appear to have low complication, rates and high live-birth rates. It is difficult to predict those who may require rescue cervical cerclage, although multiple pregnancies are at risk rescue cerclage has a very high complication rate and is associated with a high loss rate.⁽⁶³⁾

Role of cervical cerclage in treatment of patient with placenta previa, cervical cerclage was undertaken to prevent sever bleeding while prolonging pregnancy between the 24^th and the 30^th weeks of gestation, according to the MCDonaled technique we performed cesarean section delivery in all cases.

The medium prolongation of the pregnancy was of 8.2 weeks and the foetus weighed from 1.820 to 3.360g,no complication due to fetal respiratory distress were observed. No patients needed transfusions postpartum and the puerperium were regular

These results support the use of cervical cerclage for the treatment of patients with symptomatic placenta previa early in gestation.

In the analysis by Ehsanipoor et al., several risk factors were identified that influenced the outcome of CI cervical cerclage, namely cervical dilatation, membrane prolapse, obstetric history, evidence of infection^(34).

The effectiveness of emergency cerclage for women who present with adilated cervix in the second trimester and use term (rescue stitch) which is same that found in current studies done by PubMed and Cochrane 2012⁽³⁴⁾.

3.Cerclage under special circumstances:

3.1. Transabdominalcerclage:

This cerclage is placed in women with poor obstetric history where transvaginalcerclage has failed, the cervix is very short (e.g. after recurrent cone biopsies) or has significant damage such as deep tears. Transabdominal cerclage involves the insertion of the cerclage internally at the upper level of the cervical canal. The procedure may be performed openly or laparoscopically. The timing in open surgery is usually restricted to a gestation window from 12-14 weeks (thereby allowing for spontaneous first trimester miscarriage) but laparoscopic procedures are often performed prior to pregnancy (is apermanent procedure hence the delivery has to happen through C-Section). The success rates in reported case series are very high (85 - 90%)⁽³⁵⁾.

Whiletransvaginalcerclage may be placed anytime within the 12^th week onwards. The transvaginalcerclage is removed around the 37^th week so that there are chances of normal delivery after cervical cerclage⁽³⁵⁾.

But in Transvaginalcervico- isthmic cerclage. Can be removed for vaginal delivery or can be left if is a c-section⁽³⁵⁾.

3.2. Cerclage in multiple gestations:

Twin gestations have a higher risk of PTB compared to singleton pregnancy. However, unlike singleton pregnancy the use of cervical cerclage in an asymptomatic twin pregnancy with a short cervix < 25mm before 24 weeks does not prevent Preterm birthand may increase the risk for harm. This position is supported by the recent Cochrane review and another large meta-analysis. These reviews showed associated worse neonatal outcomes with delivery up to four weeks earlier compared to controls. However, these outcomes were not adjusted for confounders of demographic characteristics, risk factors and indication for cervical cerclage. This prompted a recent meta-analysis where the outcomes were adjusted for such confounding variables and results were reported using a random effects model⁽³⁶⁾.

These results showed no benefit or harm from cervical cerclage compared to controls, with the rate of very low birth weight and respiratory distress syndrome being higher in the cerclage group compared to the control group with borderline significance⁽³⁷⁾.

In conclusion, there is currently no role in the use of cervical cerclage in asymptomatic twins with short cervix <25 mm on transvaginal ultrasound, in current studies done by Rakael TV in 2014 (main finding) are when cerclage was compared with no cerclage in women with multiple gestation, there was no difference in perinatal death or neonatal ill health⁽³⁷⁾.

Cerclage and PPROM:

Insertion of cervical cerclage with preterm prelabour rupture of membranes (PPROM) is not recommended. Additionally, there is insufficient evidence for the removal of cervical cerclage upon immediate diagnosis of PPROM or even within 24 hours after administration of steroids. Although it has been shown that retention of cervical cerclage for more than 24 hours after PPROM has been shown to prolong pregnancy there is also an increased risk of infection for both the mother and neonate⁽³⁸⁾.

In current study the rates of preterm premature rupture of membranes (PPROM) were 7% and 8% the rates of PPROM at 32 weeks 2.1% and 3.4%⁽³⁸⁾.

Indication of Removal of cervical cerclage.

· The pregnant woman has vaginal bleeding.

· The pregnant woman is having sever uterine contraction.

Techniques of Cerclage:

McDonald’s Cerclage:

The McDonald’s cerclage is performed using a permanent non-absorbable (silk or nylon) suture. It was originally described as follows: the bladder having been emptied, the cervix is exposed and grasped by Allis’ or Babcock forceps. A purse string suture of No. 4 Mersilk on a Mayo needle is inserted around the exo-cervix as high as possible to approximate to the level of the internal os. This is at the junction of the vagina and smooth cervix. Five or six bites with the needle are made, with special attention to the stitches behind the cervix. These are difficult to insert and must be deep. The stitch is pulled tight enough to close the internal os, the knot being made in front of the cervix and the end left long enough to facilitate subsequent division. The ends are cut long to allow identification at term and facilitate removal%⁽³⁹⁾.

ShirodkarCerclage:

Many modifications have been made, but in general, the Shirodkar technique involves dissection of the vaginal mucosa and retraction of the bladder and rectum to expose the cervix at the level of the internal os. The original technique was described as follows: (i) A strip of fascia lata 1/4 inch wide and 4 1/2 inches long, is removed from the outer side of the thigh, and each end of this strip is transfixed with a linen suture. (ii) The cervix is pulled down, a transverse incision is made above the cervix as in anterior colporrhaphy, and the bladder is pushed well up above the internal os. (iii) The cervix is then pulled forward, toward the symphysis pubis, and a vertical incision is made in the posterior vaginal wall, again at and above the internal os, going only through the vaginal wall. (iv) Through the right and left corner of the anterior incision, an aneurysm needle is passed between the cervix and the vaginal wall until its eye comes out of the posterior incision. (v) The linen attached to each end of the fascia is passed through the eye of the aneurysm needle, and the right end of the fascia is pulled retrovaginally forward into theanterior incision. The same thing is done from the left side. (vi) The two ends of the strip cross each other in front of the cervix and are tightened to close the internal os. The operator’s left index finger in the internal os will indicate how much to pull on the strips. The assistant should be holding one end of the strip with an artery forceps. (vii) The two ends are stitched together by a number of stitches that take a bite of the muscle fibers of the lowest part of the lower uterine segment, using a small curved needle and fine linen. (viii) Extra portions of the fascia are cut out, and the anterior and posterior incisions are closed with chromic catgut No. 0.⁽³⁹⁾.

Caspi et al. described a modification using a single transverse incision in the anterior fornix. A monofilament suture is passed on each side, under the mucosa at the level of the internal os, from the anterior incision to exit through the mucosa of the posterior cervix, and is then tied. The modified procedure has been compared with the original technique of Shirodkar in a randomized trial in 90 subjects who lost their pregnancies despite having undergone McDonald’s procedure or with cervical anatomy felt to be unfavorable for McDonald cerclage placement. Similar pregnancy outcomes were reported⁽⁴⁰⁾.

Benefits (advantage) of Acerclage:

Cervical cerclage helps prevent miscarriage or preterm labor caused by cervical incompetence the procedure is successful in 85% to 90% of cases. Cervical cerclage appears to be effective when true cervical insufficiency⁽⁴¹⁾.

Risks of Cervical Cerclage:

While Cervical cerclage is generally a safe procedure there are a number of potential complications, including:⁽⁴¹⁾.

Cervical laceration if labour happens befor the cerclage is removed, cervical infection and infection of amniotic sac (chorioamnionitis), vaginal bleeding and injury to the cervix or bladder, fever and some risk associated with general anesthesia or with regional include vomiting and nausea, cervical dystocia—an inability of the cervix to dilate properly when thetime comes (dilate normally in the course of labor) require c-section, cervical stenosis—permanent narrowing of the cervix and displacement of the cervix. premature breakage of the amniotic sac Premature contractions and cervical rupture (may occur if the stitch is not removed befor onset of labor⁽⁴¹⁾.

Success Rate of Cervical Cerclage in Preventing Preterm Labour:

The effectiveness of cervical cerclage in women with cervical incompetence using Mc Donald procedure increased the rate of term deliveries to 95.4%, the mean gestational age at delivery was 35 weeks⁽⁴²⁾.

7.5% of miscarriages, 18.7% of premature deliveries, 73.7% of term deliveries and 85.1% of fetal survival rate (good apgar score) were observed after cervical cerclage in patients having sonographically incompetent cervix⁽⁴³⁾.

Observational studies show that in classical cases with a severely traumatized or virtually absent cervix, neonatal survival may be up to 93% after effective cerclage as compared to 27% before the cerclage⁽⁴⁴⁾.

In current study the incidence of preterm delivery ( 32 weeks) was significantly lower in patient with one previous second-trimester pregnance loss than in those with 2 losses, in the 1 loss and 2 losses groups⁽⁴³⁾.

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Received on 04.03.2019 Modified on 23.03.2019

Research J. Pharm. and Tech 2019; 12(10):5076-5082.

DOI: 10.5958/0974-360X.2019.00880.1