Obstetrics & Gynecology:
Management of Cervical Insufficiency and Bulging Fetal Membranes
Daskalakis, George MD, PhD1; Papantoniou, Nikolaos MD, PhD1; Mesogitis, Spiros MD, PhD1; Antsaklis, Aris MD, PhD1
From the 1First Department of Obstetrics and Gynecology, University of Athens, “Alexandra” Hospital, Athens,Greece.
See related editorial on page 219.
Corresponding author: George Daskalakis, 5 Katsarou Street, 12351-Athens, Greece; e-mail: firstname.lastname@example.org.
OBJECTIVE: To evaluate the efficacy of emergency cerclage in cases with dilated cervix and protruding fetal membranes in a group of women considered at low risk for preterm delivery by their obstetric histories.
METHODS: All cases of cervical dilatation and bulging membranes were detected through a transvaginal ultrasonographic screening for preterm delivery between 18 and 26 weeks during a 6-year study period. Twenty-nine women underwent an emergency cervical cerclage and composed the cerclage group, whereas 17 others refused and formed the bed rest group. All patients were given antibiotics and prophylactic tocolysis.
RESULTS: The mean prolongation of pregnancy (8.8 weeks) and the mean birth weight (2,101 g) after cerclage placement differed significantly from those of the bed rest group (3.1weeks and 739 g, respectively). Twenty-five of the 29 pregnancies in the cerclage group ended in live birth, compared with 7 of the 17 pregnancies in the bed rest group (P = .001) (relative risk [RR] 0.33, 95% confidence interval [CI] 0.11–0.98). Neonatal survival was 96% in the cerclage group and 57.1% in the bed rest group (P = .025) (RR 0.09, 95% CI 0.01–0.76). The preterm delivery rate less than 32 weeks was 31% and 94.1% in the cerclage and the bed rest groups, respectively (P < .001) (RR 0.33, 95% CI 0.19–0.57), whereas the admission to neonatal intensive care unit was 28% and 85.7% in the 2 groups, respectively, (P = .01) (RR 0.33, 95% CI 0.16–0.66).
CONCLUSION: Emergency cervical cerclage can be accomplished safely in women with dilated cervix and bulging membranes. It can reduce preterm delivery before 32 weeks and improve neonatal survival compared with bed rest.
LEVEL OF EVIDENCE: II-1
Preterm delivery is the leading cause of neonatal mortality and morbidity.1,2 Moreover, the need for intensive neonatal care and for continuing support after discharge from the hospital, and often during childhood, is associated with an increased cost to the health care system.3 Women with a short cervix due to low cervical resistance are considered to be at a much greater risk of preterm delivery.4 Although the incidence of cervical insufficiency cannot be determined readily due to the lack of clear criteria for the diagnosis, it seems that it is responsible for approximately 10–25% of second-trimester pregnancy losses.5,6 Management of these women usually involves the placement of a cervical suture to support the cervix, which is considered insufficient. Shirodkar7 first described cervical cerclage, and McDonald later simplified the technique.8 Although several observational studies claimed high rates of successful pregnancy outcome,9,10 there is still considerable controversy regarding its effectiveness. There have been only 6 randomized trials of cervical cerclage. Two of them relied on past obstetric history or cervical assessment score, but failed to demonstrate any improvement for those treated with cerclage.11,12 The third relied mainly on the obstetrician uncertainty for the diagnosis and showed a possible reduction of preterm delivery only in patients with a history of 3 or more second-trimester miscarriages or preterm deliveries.13 However, it claimed that the operation was associated with increased medical intervention and puerperal pyrexia. Three recent studies were performed to assess the benefits of cerclage in patients with cervical changes identified with transvaginal ultrasonographic assessment of the cervix. Although 1 of these showed a reduction in the preterm delivery rate in the cerclage group,14 the other 2 failed to demonstrate a significant improvement regarding preterm delivery or any other perinatal outcome.15,16
One of the major biases of the studies reporting on cervical cerclage is patient selection. There are many differences among studies concerning the method of patients selection (obstetric history, vaginal ultrasound), the type of cervical changes detected for inclusion in the study (short cervical length, internal os dilatation), the cutoff of cervical length for cerclage placement, gestational age at enrollment, preoperative management, and suture material. Women at high risk for preterm delivery are those presenting at mid trimester with cervical dilation and membrane prolapse. In these women an attempt can be made to perform an emergency cervical cerclage aiming at prolonging the pregnancy and improving the perinatal outcome. This report describes our treatment protocol for the management of such cases and presents our experience with emergency cerclage.
MATERIALS AND METHODS
During the period 1999–2005 all pregnant women who had a second trimester scan anomaly between 18 and 23 weeks of gestation at the Fetal Medicine Unit of Alexandra University Hospital, Athens, Greece, were offered the option of having preterm delivery screening. The study received the approval of the Ethics Committee of the hospital. In all cases written consent was given before the screening, which involved transvaginal ultrasonographic cervical assessment. Patient characteristics, including demographic data and previous obstetric and medical history, were obtained from the women and entered into a computer database. The women were asked to empty their bladders and were placed in the dorsal lithotomy position. Cervical length was measured with a transvaginal transducer of 7.0 MHz. The probe was inserted in the anterior vaginal fornix, and a sagittal view of the cervix was obtained by putting the calipers at the internal and the external cervical os. Three measurements were taken and the shortest 1 was recorded. The gestational age was determined by the last menstrual period or, when there was a discrepancy of more than a week, by a first-trimester scan. Women with a previous spontaneous preterm delivery, previous mid trimester spontaneous abortion or termination of pregnancy, multiple gestation, oligohydramnios or hydramnios, placenta previa, fetuses with congenital or chromosomal abnormalities, known congenital uterine malformation, cervical insufficiency, or a cervical cerclage were excluded from the study. A detailed ultrasound scan was always performed to confirm gestational age and exclude fetal malformations.
Women with a short cervix (< 15 mm) were offered the option to have either a cervical cerclage, or weekly transvaginal ultrasonographic scanning with the intention of treatment when further cervical changes were observed. Moreover, speculum examination was performed to assess possible dilation of the cervix and membranes prolapse. When a woman was found to have cervical dilation with membranes at or beyond a dilated external cervical os at any time of screening before 26 weeks of gestation, she was offered the option of having an emergency cervical cerclage and entered the study protocol. All the women with cervical dilation were asymptomatic at the time of diagnosis. Women who underwent an emergency cerclage composed the cerclage group and those who declined operation the bed rest group. Entry criteria for the study were 1) live intrauterine singleton pregnancy with no obvious fetal malformations, 2) gestational age between 18 and 26 weeks, 3) cervical dilation more than 2 cm and membrane prolapse, 4) intact membranes, 5) absence of uterine contractions, 6) absence of clinical evidence of chorioamnionitis, and 7) absence of significant vaginal bleeding. Patients with premature rupture of membranes, vaginal bleeding, or persisting contractions were excluded from the study. Before treatment, the potential risks and benefits were explained to the patients and an informed consent was obtained. All patients were observed for 8–24 hours to exclude preterm labor as the cause of the cervical dilation. Uterine activity was assessed with patient perception of contractions as well as abdominal palpation. Infection was excluded clinically by absence of pyrexia, uterine tenderness, and maternal or fetal tachycardia. Moreover, a white blood count of less than 14,000/mL and a negative C-reactive protein test were necessary. All women had a high vaginal and cervical swab as well as blood culture taken. Cervical dilation was established by transvaginal sonographic assessment and confirmed by speculum or digital examination. The patients who entered the study underwent emergency McDonald cerclage placement under general anesthesia. The women were placed in lithotomy position with steep Trendelenburg tilt, the vulva was prepared with the usual manner, and the situation was assessed by direct visualization using a Sim’s speculum. The vaginal walls and fornices were carefully prepared with antiseptic solution. Then 4 sponge-holding forceps grasped the edges of the cervix gently. A moist swab on sponge-holding forceps was used to push the membranes back into the uterine cavity, which was also facilitated by traction of the forceps attached to the edges of the cervix. Then a 5-mm polyester cerclage tape (Cervix-Set, Aesculap AG, Tuttlingen, Germany) with a large needle was placed, while the membranes were protected from accidental perforation by being held away with a smaller moist swab. The knot was tied anteriorly and a long tail of the tape was left to ease removal before vaginal delivery.
All patients were given cefuroxime and metronidazole intravenously in the operating room and continued for 48 hours. In addition, they received erythromycin 1.5 g orally daily for 10 days after the operation. After the procedure they were given prophylactic tocolysis using 100 mg indomethacin rectally twice a day for 2 days and 5 mg ritodrine orally every 6 hours for 2 weeks. All women were restricted to bed in the hospital for 7 days. They were then discharged home with instruction for strict bed rest until 32 weeks. During the bed rest period all women received daily low-molecular-weight heparin for thrombosis prophylaxis. Follow-up included antenatal clinic assessment at 2-week intervals. Ultrasound examination of the cervix was performed 48 hours postoperatively to confirm correct placement of the stitch.
After 32 weeks, women were allowed mobilization with plenty of rest. The suture was removed at 37 weeks of gestation or whenever labor was established. The primary efficacy variable was pregnancy prolongation. A power analysis revealed that, with this sample size, the study had 99% power to detect a significant increase of pregnancy prolongation from the bed rest to the cerclage group.
For the statistical analysis the variables were first tested for normality. When the normality assumption was satisfied, Student t tests were used for the comparison of means of continuous variables between the 2 groups of women, and the Mann–Whitney test was used when the distribution was not normal. For the comparison of proportions of categorical variables Fisher exact or χ2 tests were used. Risk ratios and their 95% confidence intervals were calculated to present the association of preterm delivery, neonatal survival, and other factors with cervical cerclage.
During the study period 1.1% of all the women who fulfilled the entry criteria for the study had a cervical length less than 15 mm. During the follow-up scans 46 of them were found to have cervical dilation with membranes at or beyond a dilated external cervical os, and they were offered the option of having an emergency cervical cerclage. Twenty-nine of them accepted cerclage, whereas 17 others refused and served as the bed rest group. The details of both groups are shown in Table 1. Cerclage was technically successful in all cases. Membrane rupture did not occur at the time of cerclage placement in any patient, and there were no operative or anesthetic complications. None of the procedures had more than 50 mL of blood loss, nor in any case was it necessary to repeat the cerclage during the pregnancy. In all cases the cervix remained closed 48 hours postoperatively, and the cervical length ranged from 4–23 mm.
The perinatal outcome of both groups is summarized in Table 2. The mean prolongation of pregnancy after cerclage placement was 8.8 weeks (range 0–17 weeks) and differed significantly (P < .001) from the mean prolongation of pregnancy in the bed rest group, which was 3.1 weeks (range 0–11weeks). Of the 29 women, 4 aborted, whereas 25 pregnancies ended in live births. Only 7 of the 17 pregnancies of the bed rest group ended in live births (risk ratio [RR] 0.33, 95% confidence interval [CI] 0.11–0.98). Twenty-four of the 25 liveborn infants survived in the cerclage group, compared with 4 of the 7 liveborn infants in the bed rest group (RR = 0.09, 95% CI 0.01–0.76). Seven of the 25 liveborn infants were admitted to the neonatal intensive care unit in the cerclage group and 6 of the 7 in the bed rest group (RR 0.33, 95% CI 0.16–0.66). The mean birth weight was 2,101 g (range 410–3,340 g), whereas the median birth weight was 2,280 g for the cerclage group, and these were significantly greater (P < .001) than the mean and median birth weight in the bed rest group, which was 739 g (range 345–2,130 g) and 530 g, respectively. Nine of the 29 women in the cerclage group and 16 of the 17 women in the bed rest group had a preterm delivery less than 32 weeks (RR 0.33, 95% CI 0.19–0.57
The suture was removed in 3 patients. In 2 of them this was due to preterm rupture of membranes, 3 and 12 days after the procedure, respectively, and in the third due to strong persistent contractions 2 weeks after the cerclage placement. All 3 had histologic evidence of placental and chorioamnionic infection. None of the 3 extremely preterm neonates survived. Caesarean delivery rate was 24.1% in the cerclage group, compared with 11.8% in the bed rest group. In 3 cases a cervical laceration was found at delivery in the cerclage group. Moreover, cervical dystocia due to scar tissue which prevented cervical dilation was observed in another.
The main difference between our study and others is the initial selection of potential candidates. All trials included patients with risk factors of preterm delivery. However, a short cervix in these women does not necessarily mean cervical insufficiency. It may also be the endpoint of different pathophysiologic process, most commonly infection or abruptio placentae. This study has focused exclusively on women with no clinical risk factors who were found to have cervical dilation and membrane prolapse at the time of a scheduled mid trimester ultrasonographic assessment. This progressive asymptomatic cervical dilation indicates that these women were at increased risk of preterm delivery due to cervical insufficiency. All cases of cervical dilation were detected through a transvaginal ultrasonographic cervical screening for preterm delivery and confirmed by speculum examination. Our findings suggest that emergency cervical cerclage in this group of women, between 18 and 26 weeks of gestation, can prolong pregnancy and can lead to the delivery of a viable infant. It can promote a 3-fold reduction in preterm delivery rate before 32 weeks, which in its turn results in a 3.5-fold increase in neonatal survival rate. Moreover, the vast majority of infants of the study group did not require admission to a special care unit, in comparison with almost all infants of the control group. These results are in accordance with that of previous studies that reported fetal survival rates up to 89%.17–24 Direct comparisons among studies cannot be made, mainly due to the small number of patients included and the observational nature of most of them. Moreover, there are major disparities among studies concerning inclusion criteria, cerclage technique, gestational age at enrollment and preoperative and postoperative management. There was only 1 prospective randomized trial reporting on emergency cervical cerclage.25 This trial, which included women at high risk of cervical insufficiency, showed that preterm delivery rate before 34 weeks, as well as the neonatal morbidity rate, were significantly lower in the emergency cerclage group, compared with the bed rest group.
The indications for cervical cerclage vary widely. In a meta-analysis of randomized trials, it was found that a prophylactic cervical stitch in women at risk of preterm delivery or second-trimester pregnancy loss, has no clear benefit on perinatal outcome.26 To eliminate the use of unnecessary cervical cerclages, many investigators supported transvaginal ultrasonographic cervical assessment, for an optimal patient selection. However, the results of 3 randomized trials are contradictory.14–16 The main problem of studies reporting on cervical cerclage is that cervical insufficiency is extremely difficult to establish objectively. The policy to delay an elective cerclage until the appearance of cervical changes at ultrasound scan may increase the percentage of women with a dilated cervix and threatened abortion in the mid trimester. When we undertook this study, we chose this group of women as candidates for cervical cerclage. Although cervical dilation does not indicate impending labor,27,28 the finding of a dilated cervix with bulging membranes indicates that imminent delivery is likely. To strengthen this even more, the preterm delivery rate before 32 weeks in the group of women who remained untreated in our study was 94.1%. We considered 26 weeks the upper limit for study inclusion, because before 26 weeks of gestation fetal survival is invariably low, making any intervention to prolong the pregnancy justifiable.
We chose to use the McDonald technique because it is technically easier, has less intraoperative blood loss, and requires less operating time compared with the Shirodkar procedure. Various authors have proposed both techniques, but there is no evidence that there is an advantage of one over the other.17–19,29 Harger17 and Hordnes et al22 reported rupture of the membranes at the time of the procedure in 30% and 6.3% of cases, respectively. However, in our study as in many others, membrane rupture did not occur in any of our patients. It is of paramount importance for a successful outcome after emergency cerclage placement to exclude both women with placental abruption and women in labor as candidates for the procedure. Therefore, an observation period before the cerclage is mandatory. The main difficulty is to exclude infection before insertion of the suture, because this is the most likely cause of complications after cerclage. Most patients with histologic evidence of infection show no clinical signs that make the detection of intrauterine infection difficult. In 3 cases in which we removed the stitch due to preterm premature rupture of membranes or preterm contractions there was histologic evidence of infection. It is not known whether infection is the cause of cervical dilation or its result.
Unfortunately, there is no effective noninvasive method to detect subclinical infection. Microbiological assessment with high vaginal swab, as well as C-reactive protein and white blood cell count estimation are suboptimal, and because of this, of limited value in deciding whether to apply a cerclage. Even amniocentesis could not detect infection in cases where it was undoubtedly present.20 Although there is no proof that antibiotics may prevent infection after emergency cerclage,30 we advocate the use of broad spectrum antibiotics perioperatively to diminish the number of microorganisms already present and reduce the risk of subsequent infection.
Whether the prophylactic use of uterine relaxants is of value remains a subject of controversy.19,31,32 We used the prostaglandin synthetase inhibitor indomethacin because any inflammatory disruption of membranes from the decidua stimulates prostaglandin production. Moreover, prostaglandin production is augmented in patients undergoing cervical cerclage, especially those with advanced cervical changes.32,33 In addition, prostaglandins may be released by the local use of various genital tract microorganisms on the bulging membranes in patients with a dilated cervix.34 We also continued prophylactic tocolysis with β-mimetics for 2 weeks, because in most patients the uterus will remain irritable after cerclage.
The results of the present study as those of others suggest that emergency cervical cerclage in women with a dilated cervix and bulging membranes can be safely accomplished, converting in most cases an almost inevitable abortion into the delivery of a viable infant. We believe that in cases in which cervical dilatation is mainly related to mechanical failure, emergency cerclage should be considered the first option procedure. The stitch holds the cervix closed so that the fetal membranes are protected from direct exposure to vaginal bacteria. In contrast, when cervical changes are related to various aspects of infection, emergency cerclage placement is contraindicated. We acknowledge that safe conclusions regarding effectiveness of such techniques can only be drawn after prospective randomized trials. However, this is not practical without using multicenter collected data. Finally, we believe that due to the rarity of this condition, single-center experience is of value and should be appropriately reported.
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© 2006 The American College of Obstetricians and Gynecologists
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