Arabin cerclage pessary in the management of cervical insufficience
Objective: To evaluate the use of Arabin cerclage pessary in the management of cervical insufficiency.
Methods: The pregnancy outcome of 20 women carrying singleton pregnancy referred for suspected cervical insufficiency and chose Arabin cerclage pessary for treatment from 2009–2011 were reviewed. Pregnancy outcome were analysed according to presence of risk factors, amniotic fluid sludge, cervical length and gestation at pessary insertion. Results: At presentation, mean cervical length was 1.17 cm (range 0–2.33 cm), mean gestation at pessary insertion and delivery was 20.6 (12.9–26.1) weeks and 32.1 (14.7–40.1) weeks, respectively, and mean prolongation of pregnancy was 11.5 (0.5–25.2) weeks. Overall, 5 (25%) had fetal loss between 14.7–23.1 weeks, while 3 (15%) and 12 (60%) delivered before and after 34 weeks gestation, respectively with no perinatal mortality. Compared with women with cervical length <1.5 cm, all those with cervical length ≥1.5 cm had pregnancy prolonged for ≥49 days (100vs. 54% p= 0.032) and 86% delivered beyond 34 weeks (86 vs. 46% p= 0.085).
Conclusions: Arabin cerclage pessary appears to be optimal for treating women at high risk of cervical insufficiency with a cervical length of 1.5–2.5 cm, while it is an acceptable option for high risk women with cervical length <1.5 cm.
Introduction:
Cervical insufficiency or incompetence is one of the major causes for second trimester miscarriage and extreme preterm birth. Management of this condition is often fraught with difficulty, as there is neither accurate diagnostic method nor proven effective treatment. Traditionally, the diagnosis of cervical insufficiency is made upon a history of second trimester fetal loss or extreme preterm birth with painless cervical dilatation in the absence of uterine contractions. However, a diagnosis based on history is unreliable and has resulted in unnecessary surgical intervention by cervical cerclage on many occasions, as illustrated by the MRC trial which showed that 25 elective cerclages had to be done to save one pregnancy [1]. In recent years, studies on transvaginal ultrasound measurement of cervical length have shown correlation between short cervix and the risk of preterm delivery [2–4].
Thereafter, transvaginal ultrasound assessment of cervix is often used as an objective parameter to guide treatment in patients with history suggestive of cervical insufficiency [5].
Surgical cervical cerclage has been the conventional treatment for cervical insufficiency, but unfortunately, randomized controlled trials failed to prove its efficacy, particularly when the diagnosis is uncertain [1,6]. Moreover, this is an invasive procedure which can be associated with significant maternal and fetal risks. At the same time, different kinds of vaginal pessaries have been proffered as a non-invasive alternative to treat cervical insufficiency since 1959, but it is only in recent years that the awareness and popularity of cerclage pessaries have risen enough to be offered as an alternative to surgical cerclage [7,8]. Amongst the available pessaries, the Arabin cerclage pessary is the most widely reported to be effective [9–11]. Therefore, Arabin cerclage pessary was introduced as an alternative treatment for cervical insufficiency in our department since 2009. In order to evaluate its efficacy, we have analysed the patients managed with this treatment for the period 2009–2011, and to elucidate the clinical characteristics of the women who had benefited most from this non-invasive treatment.
Methods:
A Cerclage Pessary Clinic was set up in 2009 to manage pregnant women referred for suspected cervical insufficiency, and this review included all women referred from 2009 to 2011. In a standard protocol, all women underwent a detailed history review which included the risk factors for cervical insufficiency and the cervical length was measured by transvaginal ultrasonography. If the cervical length was <2.5 cm, they were allowed to choose either Arabin cerclage pessary insertion or surgical cervical cerclage after counselling. They were followed up 4 weeks to report any discomfort, to have high vaginal swab for bacterial culture and transvaginal scan for cervical length measurement. Cerclage pessary was removed at 37 weeks of gestation or at onset of labour. Information on demographic data, reasons for referral, risk factors for cervical insufficiency, cervical length, presence of amniotic fluid sludge on ultrasonography, presence of any discomfort and organisms isolated from vagina after pessary insertion, and various pregnancy outcome parameters (delivery at or beyond 34 weeks, delivery between 24 and 33.9 weeks, second trimester fetal loss before 24 weeks, and prolongation of pregnancy for at least 49 days) were reviewed. Amongst the above information obtained, four clinical characteristics were chosen for further analysis. These four characteristics were: (i) presence or absence of risk factor for cervical insufficiency; (ii) cervical length at pessary insertion being <1.5 cm or ≥1.5 cm; (iii) presence or absence of amniotic fluid sludge and (iv) gestation at cerclage pessary insertion <20 weeks or ≥20 weeks. For each of these four characteristics, patients were segregated into two groups and the pregnancy outcome of the two groups was compared. The results are expressed as the mean (range). Statistical analysis was performed with one-way ANOVA and chisquare test using a commercial statistical package (SPSS version 17.0). A pvalue of <0.05 is regarded as statistically significant.
Results:
There were 20 pregnant women with singleton pregnancy referred to the Cerclage Pessary Clinic during this 3-year period. Twelve (60%) women were referred with history of one or more previous second trimester miscarriage, 1 (5%) for previous extreme preterm delivery, 2 (10%) for previous conization or LEEP and 5 (25%) for extremely short cervix (cervical length <1 cm). All of them had cervical length <2.5 cm at the time of presentation and the mean cervical length was 1.17 cm (range 0–2.33 cm). All women preferred Arabin Cerclage Pessary. The mean gestation at insertion was 20.6 (12.9–26.1) weeks. Four (20%) required extra hospital admission prior to delivery, two because of suspected leaking which was not confirmed, and two because of vaginal bleeding which subsided spontaneously. None required treatment for premature uterine contraction. The mean gestation at delivery was 32.1 (14.7–40.1) weeks. Five (25%) women had fetal loss between 14.7–23.1 weeks. In the remaining 15 women, 12 (60%) delivered after 34 (34.6–40.1) weeks, and 3 (15%) delivered before 34 (24–30.3) weeks, all without perinatal mortality. The mean prolongation of pregnancy was 11.5 (0.5–25.2) weeks. Fourteen (70%) women had their pregnancy prolonged for ≥49 days. The demographic characteristics and pregnancy outcome for the whole group is presented in Table I. Amongst the five women who had fetal loss before 24 weeks, the mean cervical length was 0.8 (0–1.46) cm. Three of them had premature prelabour rupture of membranes and ended in termination of pregnancy, one had abruptio placentae, and one had intrauterine fetal death. The mean cervical length for those who delivered live birth before or after 34 weeks was 1.13 (0–2.03) cm and 1.33 (0–2.33) cm, respectively. There is no statistically significant difference in the mean cervical length for these three groups by one-way ANOVA (F= 0.842, p= 0.448).The pregnancy outcome according to each of the four chosen clinical characteristics is shown in Table II. Cervical length at pessary insertion turned out to be the only factor that had impact on pregnancy outcome. All (100%) of those with cervical length ≥1.5 cm had their pregnancies prolonged for ≥49 days (7 weeks) compared with 54% of those whose cervix was <1.5 cm (p= 0.032). Furthermore, there was an almost significant difference in the incidences of second trimester (<24 weeks) loss (0 vs. 39% p= 0.058) and delivery at ≥34 weeks (86 vs. 46% p= 0.085). Within this group, 71% delivered after 37 weeks. On the other hand, the pregnancy outcome was similar irrespective whether there was presence of risk factors, amniotic fluid sludge, or pessary insertion before or at/after 20 weeks. Nine (45%) women reported discomfort after cerclage pessary insertion, 8 (89%) of them complained of vaginal discharge and one complained of dragging sensation in the perineum. Amongst these symptomatic women, only one had positive vaginal culture yielding E. coli. For the whole group, the high vaginal swab yielded pathological organism on culture in only 3 (6%) women (two with E. coliand one with Group B Streptococcus), and only one woman harbouring E. colicomplained of vaginal discharge. None required removal of pessary.
Discussion:
The first report in English literature on the effectiveness of Arabin cerclage pessary in preventing spontaneous preterm birth in high risk patients was published in 2003 [9]. There were no spontaneous preterm births at <36 weeks in the 12 singleton pregnancies with cervical length <1.5 cm treated with Arabin cerclage pessary compared with 50% in the control group without pessary. Thereafter, two similar studies were published [10,11]. In a prospective cohort study on 29 women with cervical length <2.5 cm being given Arabin cerclage pessary, 55% delivered after 34 weeks [10]. In another 44 women with cervical length between 15–30 mm and treated similarly, 83.3% delivered after 37 weeks [11]. The result of our study is therefore consistent with that of the latter two studies.Among the risk factors evaluated, past history, amniotic fluid sludge and gestation at pessary insertion were not shown to impact on outcome. Among these factors, amniotic fluid sludge is the most unexpected to be useless, as its presence is attributed to the presence of a severe intra-amniotic infection-related inflammatory process and has been associated with spontaneous miscarriage, cervical insufficiency and spontaneous preterm delivery [12]. Moreover, presence of sludge was reported to be an independent predictor for spontaneous preterm delivery in patients at high risk for spontaneous preterm delivery, particularly in women with short cervix [13].
Since it represents an inflammatory process, a mechanical device like the Arabin cerclage pessary might not be effective in its presence, yet this was not demonstrated in our study. The only significant determinant of successful outcome in our study was the cervical length at pessary insertion, since 86% of the women with cervical length ≥1.5 cm at pessary insertion delivered at/after 34 weeks without any fetal loss. In terms of days gained, all had pregnancy prolonged by ≥49 days (7 weeks). We have chosen a pregnancy prolongation of 49 days as a treatment goal. This is because with a median gestation at cerclage pessary insertion of 20.6 weeks, pregnancy prolongation by ≥49 days would have allowed the pregnancy to reach 27–28 weeks so that the baby would have an excel-lent chance of survival with low morbidity. Thus for women with cervical length ≥1.5 cm, Arabin cerclage pessary appears to be the optimal treatment. Even for women with cervical length <1.5 cm, more than 50% had their pregnancy prolonged by ≥49 days and almost 50% could still achieve delivery at/after 34 weeks. Therefore in the latter group of women, the Arabin cerclage pessary could still be offered as alternative treatment to surgical cerclage.
The Arabin cerclage pessary is an inexpensive device that can be inserted and removed with ease in the outpatient clinic. Its side effects are also well tolerated. Arabin (9) reported about half of the women on pessary complained of increased vaginal discharge, which is consistent with our finding. Although nine of our 20 (45%) patients on pessary reported discomfort, 90% of the reported discomfort was vaginal discharge only in which no infective cause could be found in most cases. Vaginal discharge may be just a natural mechanism to protect the vaginal and cervical mucosa from abrasion caused by the pessary. Nevertheless, the resulted vaginal discharge can be copious and can easily be mistaken as leaking, as illustrated by the two cases of suspected leaking which was not confirmed in this series. Only 6% had pathogenic organism in vagina, but two of these three patients were asymptomatic. This finding was consistent with the reported 5.5% incidence of pathogenic vaginal organisms found among pessary users [14].
The limitation of our study is that ours is a small retrospective series without a randomized control group. In fact, as pointed out in the Cochrane review, most published papers are non-random-ized trials [15]. The ethical dilemma of offering no treatment to such high risk patients, as well as patient refusal to randomization, are practical issues that need to be overcome in order for a well designed randomized controlled clinical trial to be conducted to prove its efficacy. Even so, all reported series, including ours, did show the effectiveness of cerclage pessary in preventing preterm delivery. Furthermore, our study has identified that a cervical length of 1.5 cm distinguishes between patients with 100 versus 50% success rate, and this should be taken into consideration in case of designing future randomized control trials, for example, stratifying the randomization by cervical length. Several randomized controlled trials are now in progress and two have already been completed [16,17]. However, these two studies focused on low risk women with short cervix and showed conflicting results. While Goya et al reported a reduction in the risk of preterm delivery before 34 weeks from 27% in the placebo group to 6% in the pessary group [16], Hui et al found no signifi-cant difference in preterm delivery rate between the placebo group and pessary group (5.5 and 9.4%, respectively) [17]. In view of the differences in the findings between the two studies, further researches are needed to elucidate the efficacy of Arabin cerclage pessary in both low risk and high risk women.
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