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Page 1: Emergent Cervical Cerclage: Predictors of Success or Failure

The Journal of Maternal-Fetal Medicine 5:22-27 (1 996)

Emergent Cervical Cerclage: Predictors of Success or Failure

Richard A. Latta, MD, and Brian McKenna, MD

Abington Memorial Hospital, Abington Pennsylvania (R. A. L.); State University of New York at Stony Brook (B.McK.)

Abstract Emergent cervical cerclage is a procedure not commonly performed in general clinical practice. The outcome of pregnancies requiring emergent cerclage is based on limited information. The factors that predict success are not well known. Previous studies have suggested that advanced cervical dilation, significant cervical effacement, and the presence of prolapsed membranes are correlated with cerclage failure. We present a retrospective review of maternal characteristics predictive of perinatal survival. Analysis showed the presence of membrane prolapse to be the strongest predictor of poor outcome. Analysis also reveals a significant association between initial white blood cell count and perinatal outcome. This information may he helpful in decision making regarding adjunctive procedures such as amniocentesis and counseling patients regarding the likely outcome. o 1996 WiIey-Liss. Inc.

Key Words: Cervical cerclage, Emergent, Perinatal survival

INTRODUCTION Rational decision analysis as well as ethical counseling

of patients who present in the second trimester with an incompetent cervix is difficult because of the lack ofpub- lished material on this subject. This situation occurs on a regular basis on a busy referral service but is uncommon in general clinical practice. The physician’s decision making is often affected by a single successful case or by one painful adverse outcome. Published studies are limited and very few examine maternal characteristics associated with success or failure. Published studies may also represent optimal outcome. We attempted to delin- eate for our population the factors associated with peri- natal survival. This could then be used to counsel future patients as to the likelihood of perinatal survival should they elect to undergo emergent cervical cerclage.

A recent randomized controlled trial of prophylactic cerclage for patients at risk of cervical incompetence appears to support cerclage use in select populations [ 11. Emergent cerclage is less thoroughly studied. Sev- eral previous studies have shown that the degree of cervical dilation at the time of presentation was corree lated with outcome [2-61. A scoring system was devel- oped by Kokia and colleagues [5] that can be helpful in

counseling patients regarding the likelihood of success. The major appeal of their approach is the simplicity of the scoring system, the cervical incompetence score (CIS), which assigns increasing point values for increas- ing amounts of effacement, dilation, and degree of membrane prolapse. All the information used in the scoring system is readily available at presentation. The authors demonstrated increased survival and prolonga- tion of pregnancy with low cervical incompetence scores. The three factors are most likely highly corre- lated but may not be independent predictors of out- come. There may also be additional patient characteris- tics that may impact on outcome. W e attempted to evaluate for our study population the factors associated with cerclage success.

MATERIALS AND METHODS A retrospective chart review of all patients pres-

enting to our institution over a 6-year-period who un-

Received October 7, 1994; revised August 29, 1995; accepted No-

Address reprint requests to Dr. Richard A. Latta, Abington Memorial vember 9, 1995.

Hospital, Suite 119, Abington, PA 19001.

0 1996 Wiiey-Liss, Inc.

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Page 2: Emergent Cervical Cerclage: Predictors of Success or Failure

EMERGENT CERCLAGE 23

derwent nonelective cervical cerclage placement was undertaken. The patient population was limited to sin- gleton pregnancies with the cerclage placed on an emer- gent basis. Excluded were pregnancies presenting with bleeding and/or contractions. Maternal demographic characteristics were recorded. Prior obstetrical history, presenting symptoms, and physical examination find- ings including vital signs, fundal height, and cervical examination findings (dilation, effacement, and the extent of membrane prolapse) were recorded for all patients. The criteria for establishing gestational age and the gestational age at presentation were also re- corded. Laboratory evaluation on admission included a complete blood count and sedimentation rate. Opera- tive reports, postoperative management, delivery rec- ords, and neonatal charts were reviewed. Intraoperative and postoperative management was reviewed. Out- come was evaluated based on survival, gestational age at delivery, and the interval from diagnosis to delivery. Nonparametric statistical analysis of the data was per- formed using SYSTAT software (Systat, Inc., Version 5). Results were recorded as mean 2 SD for all continuous variables. Comparisons of continuous variables be- tween groups and subgroups were analyzed using the Mann-Whitney test. A difference was considered sig- nificant at P < 0.05. Categorical variables were ana- lyzed using the chi-square test; the Fisher exact test was used for variables with low frequency.

RESULTS The review included 20 patients. The overall success

rate (liveborn subsequently discharged from the hospi- tal) of the emergent cervical cerclage procedures was 55% (1 1/20). The mean maternal age was 28.1 * 4.9 years, gravida 3.8 ? 1.4, parity 0.5 * 0.6, and mean gestational age at presentation was 19.5 -+ 3.9 weeks. Seventy percent of patients received their care from private physicians, while 30% were from the residents’ service. Seventeen different attending physicians were involved in their care.

The successful procedures were compared to the unsuccessful procedures with regard to maternal demo- graphic characteristics. The data are presented in Table 1. Parity was found to show a statistically significant difference. Sixty-four percent (7/11) of patients with a successful procedures had a prior term delivery, com- pared to 11% (1/9) of patients with unsuccessful proce- dures. Thirty-five percent (7/20) of patients in this study had a history of at least one prior midtrimester

termination of pregnancy. There was no statistically significant difference in outcome between groups with or without a history of prior midtrimester termination of pregnancy.

A review of presenting symptoms revealed that eight patients complained of pelvic pressure, three patients presented complaining of vaginal discharge, and five patients presented complaining of concordant vaginal discharge and pelvic pressure. No patients presented with complaints of contractions or bleeding. Four pa- tients, following a “routine” pelvic examination, dem- onstrated cervical dilation. There was no statistically significant association of perinatal outcome with the patient’s presenting symptoms.

Patients were compared with respect to their initial examination findings. No patient had a cerclage placed if there was any evidence of clinical chorioamnionitis, defined by fever (temperature L 100.4”F) and/or uter- ine/abdominal tenderness. All fundal height assess- ments were appropriate for dates. All patients were evaluated for rupture of membranes by ferning and nitrazine tests and were negative. The maximum in- itial temperature at the time of presentation was 993°F (group mean 98.5” +- 0.8”F). There was a strik- ing and statistically significant difference with respect to the initial temperature when successful cerclages (98.1 +- 0.5”F) were compared with the failures (98.9” * 0.6”F, P < 0.007).

The cervical status on admission was evaluated. Cer- vical dilation was recorded as an integer with the con- vention of rounding to the lowest whole number (i.e., “fingertip dilated” was interpreted as 0). The efface- ment was recorded as an integer of 0-100%. Membrane prolapse was defined on the basis of a sterile speculum examination. The membranes were recorded as pro- lapsed (membranes visualized extending beyond the external 0s) or not prolapsed (not fulfilling the criteria for prolapse). Overall, the mean cervical dilation on admission was 1.9 * 1.0 cm, the mean effacement 71.5% f 23.7%, and 50% of the patients had prolapsed membranes. The successful procedures were then com- pared to the unsuccessful procedures (Table 2). Mean cervical dilation on admission was not statistically dif- ferent in the group of patients with successful cerclages, as compared with the unsuccessful cerclages (P = 0.055,95% confidence interval 0.246-1.73). The mean effacement was not statistically different between groups. Eight of the nine unsuccessful cerclage patients versus 2/11 successful cerclage patients had prolapsed

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Page 3: Emergent Cervical Cerclage: Predictors of Success or Failure

24 LATTA AND McKENNA

TABLE 1. Result of Emergency Cerclage Placement: Maternal Demographics and Obstetrical History

Successful Unsuccessful (N = 11) (N = 9) P

Age (v) 28.9 t 5.2 27.1 t 4.6 NS Gestational age at presentation (wk) 19.1 t 4.3 20.0 t 3.6 NS Gravida 4.0 ? 1.3 3.4 2 1.6 NS Para 0.7 t 0.6 0.1 2 0.3 <0.02 Prior mid-trimester termination 3 (27%) 4 (44%) NS

TABLE 2. Cervical Examination Prior to Emergency Cerclage

Successful Unsuccessful (N = 11) (N = 9) P

Dilation (cm) 1.5 t 0.9 2.3 2 0.9 NS Effacement (%) 71.4 2 19.2 71.7 ? 21.6 NS Bulging membranes 2 8 <0.006

TABLE 3. Laboratory Evaluation Prior to Cerclage Placement

Successful Unsuccessful (N = 11) (N = 9) P

White blood cell count 9.8 +- 1.6 13.1 ? 2.8 <0.02

Erythrocyte sedimentation rate (ESR) 20.3 t 16.3 34.6 t 10.9 NS (WBC) (cellsimm’)

TABLE 4. Postoperative Therapy

Successful Unsuccessful (N= 11) (N = 9) P

Prophylactic antibiotics 36% (4111) 89% (819) <0.03 Tocolysia 36% (4111) 56% (519) NS

membranes (P < 0.006). Three successful cerclages were placed with a cervical dilation score of 0 (< 1 cm dilated) , apparently based only on cervical effacement or cervical change. Excluding these three patients does not result in a change in significance with respect to effacement or the presence of membrane prolapse.

Laboratory evaluation showed a significant differ- ence in the white blood cell counts of patients with successful cerclages from those with unsuccessful cer- clages (Table 3). The initial white blood cell counts ranged from 7,100 to 15,900 cells/mm’ (mean 11,300 5 2,720). The nonpregnant top normal range for our laboratory is ~ 1 2 , 0 0 0 cells/mm’. Limited data were available for the initial erythrocyte sedimentation rate. Fourteen values were obtained (7 successful, 7 unsuccessful). No statistically significant difference was found (P = 0.055, 95% confidence interval 2.3-30.9 cells/mm3).

Operative technique was also evaluated. Nineteen of the 20 cerclages were of the McDonald type [ 71. One Wurm procedure [8] was performed unsuccessfully. All cerclages were placed with the patient receiving general anesthesia. A wide variety of techniques of membrane replacements were used, including Trendelenburg posi- tion, filling of the urinary bladder, staykraction sutures, sterile gauze on a sponge stick, or a Foley catheter [9]. Fluid reduction amniocentesis as described by Goodlin [lo] was not used. Many of the operative reports did not specify the technique or were too vague in their description of the technique for membrane replacement to comment on it as a predictor of success.

Postoperative treatments were also evaluated (Table 4). Prophylactic antibiotic therapy was used in 60% of the cases. Ampicillin or Cefazolin was used. There was a statistically significant association of antibiotic use with cerclage failure (P < 0.03). Pharmacologic toco-

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EMERGENT CERCLAGE 25

lytic agents were given in 45% of cases. The differentia- tion between prophylactic and therapeutic tocolytic use was extremely difficult to make; analysis was therefore based only on the agents use or nonuse. Tocolysis was performed with magnesium sulfate and/or terbutaline in 38% of successful cases and 55% of unsuccesful cases. There was no association with cerclage out- come (P = 0.65).

All cerclages were successfully placed with no evi- dence of rupture of membranes at the time of the procedure. The mean days gained for unsuccessful pro- cedures was 9.9 +- 2.8 versus 118.3 ? 44.5 days for successful procedures. The most common reasons for cerclage removal in those with cerclage failure was rupture of membranes (67%), the development of clini- cal chorioamnionitis (22%), or unstoppable premature labor (1 1%). All patients with unsuccessful outcomes were treated with antibiotics during labor and in the periperium.

DISCUSSION The patient who presents to the obstetrician with a

dilated cervix, intact membranes, and live fetus repre- sents a major challenge. Emergency cervical cerclage refers to cerclage placement during a pregnancy with newly diagnosed incompetent cervix. The optimal man- agement is controversial. Traditional obstetrical teach- ing would suggest that a surgical approach, with cervical cerclage placement, is indicated. Very limited data have compared long term expectant management with cer- clage placement [ 111. The available data suggest a limited prolongation of gestation and survival, but per- haps at a large expense in neonatal morbidity [ 121. Cerclage therefore remains the treatment modality with the greatest potential.

It is difficult to counsel patients regarding outcomes in rarely performed procedures. Successful mechanical placement of a cerclage does not necessarily result in long-term improvement in outcome. High failure rates have been found with emergent cervical cerclage. A few small studies showed impressive results [ 13,141, but a recent review of the literature showed an overall success rate of 55% [6]. Limited information is available as to patient characteristics predictive of success. Kokia and colleagues [5] developed a simple scoring system that was highly predictive of success. They retrospec- tively compared the amount of cervical effacement and dilation, and the degree of prolapsed membranes with the likelihood of postoperative complications and preg-

nancy loss. The outcome was very successful (87.5% survival) if the effacement of the cervix was less than 50%, cervical dilation was less than 1.5 cm, and the membranes remained within the cervical canal. The scoring system is useful because of it’s simplicity. How- ever, additional information is available at admission that may improve the ability to predict the success or failure of the procedure.

In our study, the successful cerclage procedures- those resulting in a liveborn infant who was subse- quently discharged from the hospital-were compared with the failures. Characteristics of the groups were compared. The successes and failures were similar with respect to the maternal age, gravidity, and the gesta. tional age at cerclage placement. Patients with success- ful procedures were more likely to have had a successful pregnancy in the past. Seventy-seven percent of the women who ultimately had a successful outcome had a prior pregnancy success, but only 11% of women whose cerclage was unsuccessful had a prior successful pregnancy. Both groups had a high rate of mid-trimester termination of pregnancy (35% overall). This charac- teristic may limit the applicability of our findings to patient populations similar to ours. The national inci- dence of midtrimester termination of pregnancy is not known, but in 1990 only 11.2% of all abortions were performed 213 weeks gestation [ 151. The presenting symptoms were examined. Asymptomatic patients were no more likely have a successful outcome than were symptomatic patients.

Previous studies have found that the degree of dila- tion, effacement, and membrane prolapse was associ- ated with emergency cerclage success. In the present study, we were unable to show a statistically significant association with dilation or effacement. There was a statistically significant association with membrane pro- lapse. The presence of membrane prolapse was a good predictor of failure (sensitivity = 0.80). The absence of prolapse was also a good predictor of success (specificity = 0.90).

Operative technique often affects patient outcome. The technique of cerclage placement membrane re- placement was performed in a highly individualized manner. The methods were too varied to evaluate as predictors of success. The current study also did not evaluate variations in surgical technique for membrane replacement. This may be a key element of emergency cerclage success but will require a prospective eval- uation.

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Page 5: Emergent Cervical Cerclage: Predictors of Success or Failure

26 LATTA AND McKENNA

We hypothesize that a likely cause of failure of emer- gent cerclage is subclinical infection, either intra-amni- otic or decidual, that does not exhibit typical signs of chorioamnionitis-fever, uterine tenderness and leu- kocytosis. This subtle infection may be more common in patients with prolapsed membranes. The patients in our study who exhibited low-grade temperature eleva- tions and slightly elevated white blood cell count may be indicative of this subgroup. Maternal treatment for postpartum infection was used uniformly in the group with cerclage failures, making it difficult to isolate caus- ative organisms.

A review of the postoperative treatments revealed an interesting finding. Antibiotics used prophylacticly were highly associated with cerclage failure. This ap- pears counterintuitive. Two possible hypotheses are suggested to explain this finding. The selection of resis- tant organisms is well described with the use of antibi- otic prophylaxis. It is possible that host defenses are sufficient to prevent chorioamniotitis during emergency cerclage placement. The introduction of a prophylactic antibiotic may select more resistant organisms. It is also possible that the attending physicians were able, on a clinical basis, to predict those more likely to fail. There was no suggestion in the patient charts as to the reason for selecting candidates for antibiotic prophylaxis. It is possible that the reason a physician would choose to administer prophylaxis was the presence of prolapsed membranes, which is a good predictor of poor outcome. We suspect that the latter is the more likely, as organ- isms with unusual resistance patterns were not identi- fied at culture.

The cerclage failures were extensively analyzed as to the reason for the failure. Rupture ofmembranes without significant contractions was the predominant cause of cerclage failure. It is possible that more aggressive treat- ment during the perioperative period might have im- proved outcome. Evans and colleagues 1161 describe a case report using intraoperative amniocentesis and post- operative indomethacin therapy. The goal of amniocen- tesis was for initial fluid reduction and assessment of in- tra-amniotic infection [ 101. Romero et al. 1171 showed that microbial invasion of the amniotic fluid is predictive of failure. Recent reports of rapid detection tests may be useful in the operating room 1181. Amniocentesis was not performed for cerclage procedures during the cur- rent study. The patient in Evans's study was subse- quently noted to have negative amniotic fluid cultures. Indomethacin was then used both to maintain a state of

mild oligohydramnios and as a tocolytic. Indomethacin has unique properties and was not used in any of the patients included in our series.

In summary, emergency cervical cerclage is a proce- dure with the factors associated with success and failure poorly understood. We identified four characteristics of our patient population that were associated with outcome: parity, membrane prolapse status, initial white blood cell count, and initial maternal tempera- ture. Outcome was improved if the patient had deliv- ered a term liveborn in the past. Outcome was almost uniformly poor with prolapsed membranes, as pre- viously described in the literature. Analysis showed the presence of membrane prolapse was the strongest predictor of poor outcome. The development of an optimal management protocol to correct this problem may be the best method to improve success rates. The other characteristics (maternal temperature, white blood cell count, and maternal parity), are characteris- tics not amenable to modification. Although no cer- clage procedures were performed with evidence of clini- cal chorioamnionitis, mild elevations of maternal temperature and slight elevations of the maternal white blood cell counts were also associated with cerclage failure. We hypothesize that these may represent subtle signs of underlying maternal infection. If supported by further study, this information may be helpful in counseling future patients following their initial assess- ment. The role of amniocentesis in the management of these patients remains to be defined. It may be a useful adjunct both to diagnose infection and to assist in amniotic fluid volume reduction. We hope to evalu- ate this in a prospective study.

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