Version May 2024
INTRODUCTION — Cervical insufficiency refers to painless cervical dilation that leads to second-trimester fetal expulsion (miscarriage or preterm birth). Although the diagnosis may be suspected in the first pregnancy in which it occurs, the diagnosis is confirmed when it recurs in consecutive pregnancies. The American College of Obstetricians and Gynecologists' definition of cervical insufficiency is "the inability of the uterine cervix to retain a pregnancy in the second trimester in the absence of clinical contractions, labor, or both" [1].
This topic will review issues related to diagnosis and management of patients with cervical insufficiency. Cerclage procedures for treatment of cervical insufficiency are discussed separately. (See "Transvaginal cervical cerclage" and "Transabdominal and laparoscopic cervicoisthmic cerclage".)
PATHOGENESIS — Structural cervical weakness is the likely cause of cervical insufficiency. The weakness may be secondary to (see 'Risk factors' below):
●Prior cervical trauma (eg, rapid mechanical cervical dilation, childbirth)
●Decidual inflammation/infection, bleeding at the interface of the decidua and placenta, or uterine overdistension, which initiates biochemical changes that lead to premature cervical shortening. This pathway likely results in a single rather than recurrent second-trimester miscarriage or preterm birth.
●A congenital cervical abnormality (rare)
CLINICAL FINDINGS
Past history — The classic obstetric history of patients with cervical insufficiency is characterized by all of the following:
●Recurrent (ie, more than one) second-trimester pregnancy losses or extremely preterm live births (often before 24 weeks of gestation)
●No or minimal, mild symptoms (see 'Symptoms' below)
●Cervical dilation and effacement on physical examination inconsistent with the absence or minimal degree of uterine activity
In addition, the duration of time from recognition of symptoms/physical findings to delivery may have been extremely short, and successive pregnancies may have been associated with progressively earlier gestational age at loss or live birth.
Risk factors — Cervical abnormalities are a risk factor for structural cervical weakness and, in turn, recurrent cervical insufficiency.
●Cervical trauma – Cervical trauma is probably the most common risk factor for cervical insufficiency. It may result from the process of labor or birth (spontaneous, forceps- or vacuum-assisted, cesarean) [2], mechanical cervical dilation before a gynecologic procedure, or treatment of cervical intraepithelial neoplasia. (See "Overview of pregnancy termination", section on 'Future pregnancies' and "Reproductive effects of cervical excisional and ablative procedures".)
●Congenital cervical abnormality – Congenital abnormalities can be associated with structural cervical weakness, but this is rare. These abnormalities include structural uterine anomalies, genetic disorders affecting collagen (eg, Ehlers-Danlos syndrome) [3-5], and in utero diethylstilbestrol exposure. Biologic variation of the cervix may also account for some cases of cervical insufficiency. (See "Congenital uterine anomalies: Clinical manifestations and diagnosis" and "Outcome and follow-up of diethylstilbestrol (DES) exposed individuals", section on 'Pregnancy loss and preterm birth'.)
●History of short cervical length – In contemporary obstetrics, where transvaginal ultrasound (TVU) cervical length (CL) screening is often performed, patients may describe a past pregnancy or pregnancies in which a short CL was detected on ultrasound and was associated with subsequent second-trimester loss/birth. The finding of an asymptomatic short second-trimester CL on TVU examination alone is not a strong risk factor for cervical insufficiency as many patients with a short CL deliver at term, even without intervention. CL screening is reviewed separately. (See "Short cervix before 24 weeks: Screening and management in singleton pregnancies".)
Symptoms — Patients with cervical insufficiency in the current pregnancy may be asymptomatic or may present with mild symptoms, such as:
●Pelvic pressure
●Braxton-Hicks-like contractions
●Premenstrual-like cramping and/or backache
●Change in vaginal discharge. Discharge volume may increase; the color may change from clear, white, or light yellow to pink, tan, or red spotting; and the consistency may become thinner.
Symptoms, if present, typically begin between 14 and 20 weeks of gestation and may be present for several days or weeks before the diagnosis of cervical insufficiency is made.
Physical examination — Early in the course of cervical insufficiency, the cervix may be soft and closed, with minimal effacement [6]. Tocodynamometry typically reveals no or infrequent contractions at irregular intervals that are not perceptible or barely perceptible to the patient. Provocative maneuvers such as suprapubic or fundal pressure by the clinician or having the patient make a forced expiratory effort against a closed glottis (Valsalva maneuver) may reveal fetal membranes in the endocervical canal or vagina, which is always an abnormal finding. In some cases, membranes may be prolapsed without provocation or may be ruptured.
Imaging — On TVU, CL is typically short (≤25 mm) and debris (sludge [fetal squames, vernix, leukocytes, bacteria] or biofilm) may be seen in the amniotic fluid. If serial ultrasound examinations are performed, CL may decrease over time [7].
Laboratory — Uncomplicated cervical insufficiency is not associated with laboratory abnormalities.
DIAGNOSIS — The diagnosis of cervical insufficiency is usually limited to singleton gestations because the pathogenesis of second-trimester pregnancy loss or extremely preterm birth in multiple gestations is usually unrelated to anatomic weakness of the cervix.
Diagnostic categories
Obstetric history-based diagnosis of cervical insufficiency — We make an obstetric history-based diagnosis of cervical insufficiency in patients with a classic history of ≥2 consecutive prior second-trimester pregnancy losses or extremely preterm births (<28 weeks) associated with no or minimal mild symptoms. The presence of risk factors for structural cervical weakness supports the diagnosis. Most of these cases are pregnancy losses before 24 weeks. (See 'Past history' above.)
Challenges to making this diagnosis are that the relevant findings in the prior pregnancy are often not well-documented in medical records and the patient's recounting of events may not provide adequate information; thus, the process that led to the second trimester loss or extremely preterm birth is often a subjective assessment.
Ultrasound-based diagnosis of cervical insufficiency — We make an ultrasound-based diagnosis of cervical insufficiency in patients with both an obstetric history of second-trimester loss or extremely preterm live birth (<28 weeks) plus a short cervix on transvaginal ultrasound (TVU) examination (CL ≤25 mm before 24 weeks) in the current pregnancy, after exclusion of relevant other diagnoses (eg, labor, infection, bleeding related to placental abruption or placenta previa) (see 'Diagnoses to exclude before making the diagnosis' below). The presence of risk factors for structural cervical weakness supports the diagnosis. (See 'Past history' above.)
To identify these individuals, we perform serial TVU examinations in patients with a past history of preterm birth and those in whom a history-based diagnosis is uncertain, as shown in the algorithm (algorithm 1). TVU screening is discontinued at 24 weeks of gestation, as cerclage is rarely performed after this gestational age [8].
If a patient in this population develops symptoms of cervical insufficiency (see 'Symptoms' above) between cervical screening examinations, an ultrasound examination for CL should be performed promptly because a normal physical examination cannot reliably exclude the diagnosis of cervical insufficiency. Most cervixes that are 10 to 25 mm in length by second-trimester TVU feel long and closed on physical examination; effacement and dilation are usually not detected until the transvaginal CL is ≤10 mm. In one study, less than one-third of patients with CL <11 mm had cervical dilation ≥1 cm on physical examination [9].
Physical examination-based diagnosis of cervical insufficiency — We make a diagnosis of physical examination-based cervical insufficiency in patients at 14 to 27 weeks of gestation with a dilated (≥1 cm) and effaced cervix on physical examination and no contractions or mild irregular contractions that appear inadequate to explain the cervical dilation and effacement. The membranes may be prolapsed or ruptured. Labor, infection, and bleeding related to placental abruption or placenta previa should be excluded. (See 'Diagnoses to exclude before making the diagnosis' below.)
Diagnoses to exclude before making the diagnosis
Labor — Labor should be excluded by tocodynamometry. Labor is characterized by increasing regularity, frequency, and strength of uterine contractions over time. (See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment".)
Abruption, previa — Bleeding from placental abruption or placenta previa should be excluded by history and physical and ultrasound examination as these disorders could account for biochemically mediated cervical ripening leading to second-trimester pregnancy loss or extremely preterm delivery independent of structural cervical weakness [10]. (See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment" and "Acute placental abruption: Pathophysiology, clinical features, diagnosis, and consequences" and "Placenta previa: Epidemiology, clinical features, diagnosis, morbidity and mortality".)
Infection — Infection should be excluded by appropriate testing, such as urinalysis/urine culture and possibly amniocentesis for laboratory examination of amniotic fluid. Amniocentesis is not routinely performed in patients with an ultrasound-based diagnosis, as most do not have significant cervical dilation, prolapsed membranes, or abnormal-appearing amniotic fluid, which are high-risk factors for subclinical infections. By comparison, amniocentesis is often indicated in patients with a physical examination-based diagnosis since many have significant cervical dilation, prolapsed membranes, or abnormal-appearing amniotic fluid and thus at high risk for subclinical infection.
Candidates for amniocentesis — We perform amniocentesis to look for subclinical infection:
●Routinely, when the cervix is ≥2 cm dilated on digital or speculum examination, as the incidence of intraamniotic infection in these patients is approximately 20 to 50 percent [11]
●On a case-by-case basis, when:
•Ultrasound findings are consistent with inflammation (eg, debris in the amniotic fluid [sludge or biofilm] (image 1))
•Membranes are visible and exposed at the external os, but the cervix is <2 cm dilated.
In these settings, the incidence of intraamniotic infection is probably no more than 5 to 10 percent.
Management of patients with subclinical infection on amniocentesis — We do not perform cerclage if we find evidence of infection after testing amniotic fluid, as these pregnancies are at increased risk of preterm birth and other pregnancy complications [12-15]. We do not give antibiotics in an attempt at expectant management and continuation of pregnancy; we recommend induction.
The safety and effectiveness of antibiotic treatment in these patients have not been evaluated extensively. In the largest study, which included 22 patients with painless cervical dilation >1 cm between 16.0 and 27.9 weeks, intact membranes, no uterine contractions, and evidence of intraamniotic inflammation (19/22) or infection (3/22) on amniocentesis, administration of triple antibiotic treatment (ceftriaxone, clarithromycin, and metronidazole) was associated with delivery more than one week after amniocentesis in 16 patients (73 percent), and no cases of serious maternal morbidity were reported [16]. Twelve patients received a cerclage. Importantly, 9 of the 12 patients who underwent repeat amniocentesis had objective evidence of resolution of intraamniotic infection/inflammation. Of the three with intraamniotic infection on initial amniocentesis, two had positive amniotic fluid cultures and delivered within a week, whereas the third only had a positive polymerase chain reaction (PCR) for Ureaplasma species. This patient had a negative PCR at repeat amniocentesis three weeks later, despite membrane rupture a week after the initial amniocentesis. She was induced at 34 weeks with good neonatal outcome. Given that the pathogenicity of Ureaplasma in amniotic fluid is unclear and no patients with a positive amniotic fluid culture gained more than a week despite antibiotics, the safety and effectiveness of expectant management with antibiotic therapy remain unproven and not recommended. (See "Clinical chorioamnionitis", section on 'When to perform amniocentesis to test amniotic fluid'.)
Can cervical insufficiency be diagnosed before pregnancy? — The diagnosis of cervical insufficiency cannot be made or excluded by any test in nonpregnant patients. Evaluation of cervical function with dilators, balloons, or hysteroscopy is not helpful. Ultrasound, magnetic resonance imaging, or hysterosalpingography may reveal a uterine anomaly, which is a risk factor for cervical insufficiency, but not diagnostic. (See "Congenital uterine anomalies: Clinical manifestations and diagnosis".)
CERCLAGE PLACEMENT AND USE OF PROGESTERONE SUPPLEMENTATION — The following approach to management applies to patients with singleton pregnancies. Pretreatment evaluation was reviewed above. (See 'Diagnoses to exclude before making the diagnosis' above.)
Obstetric history-based cervical insufficiency
●Cerclage – We suggest placing a history-indicated cerclage at 12 to 14 weeks of gestation in patients with recurrent (more than one) second-trimester pregnancy losses or extremely preterm births (<28 weeks) preceded by painless cervical dilatation. Structural weakness of the cervix can be treated effectively with structural support from a cerclage. Anatomical, biochemical, and clinical evidence from observational studies and randomized trials consistently support this approach [17-20].
●Supplemental progesterone – At 16 weeks of gestation, the author of this topic also begins daily vaginal progesterone supplementation for all patients with a history-indicated cerclage and continues it until 36+6 weeks of gestation. A meta-analysis of comparative studies in high-risk patients (cervical length <25 mm or previous preterm birth) found that the combination of vaginal progesterone plus cervical cerclage (history-indicated, ultrasound-indicated, or cervical length <10 mm) was associated with a lower risk of preterm birth <37 weeks than cerclage alone (11 versus 24 percent; RR 0.45, 95% CI 0.29-0.71) or progesterone alone (36 versus 42 percent; RR 0.75, 95% CI 0.58-0.96) [21]. Compared with cerclage only, combined therapy was also associated with reductions in preterm birth <34 weeks, <32 weeks, <28 weeks, and neonatal mortality. Limitations to interpretation include that several studies were of low quality with significant risk of bias and the mixed risk characteristics of the patient population. Use of progesterone in these patients is controversial. These data are discussed separately. (See "Progesterone supplementation to reduce the risk of spontaneous preterm labor and birth", section on 'Singleton pregnancy with prior preterm birth'.)
Ultrasound-based cervical insufficiency
●Cerclage – We suggest placing an ultrasound-indicated cerclage in patients with one or more prior spontaneous preterm births and TVU CL ≤25 mm before 24 weeks in the current pregnancy.
In meta-analyses of randomized trials, placement of a cerclage upon identification of a short cervix on ultrasound was effective in reducing preterm birth [22], resulted in pregnancy outcomes comparable to history-indicated cerclage [23], and avoided cerclage in approximately 60 percent of patients in whom the diagnosis of cervical insufficiency was uncertain early in pregnancy [23].
•In a meta-analysis of randomized trials, placement of an ultrasound-indicated cerclage reduced preterm birth <24, 28, 32, 35, and 37 weeks compared with no cerclage (eg, relative risk for birth <35 weeks: 0.70, 95% CI 0.55-0.89) [22].
The only evidence that vaginal progesterone alone may be as effective as cerclage alone in this setting is an indirect meta-analysis of randomized trials in which the two groups were not similar for several risk factors for preterm birth and the cerclage group was at higher risk for preterm birth than the vaginal progesterone group [24].
•In a meta-analysis of randomized trials comparing CL screening with cerclage placement in those with a short CL versus placement of an obstetric history-indicated cerclage in patients with prior preterm birth [23]:
-Both groups had similar rates of preterm birth before 37 weeks (31 versus 32 percent, relative risk [RR] 0.97, 95% CI 0.73-1.29), preterm birth before 34 weeks (17 versus 23 percent, RR 0.76, 95% CI 0.48-1.20), and perinatal mortality (5 versus 3 percent, RR 1.77, 95% CI 0.58-5.35).
-In the ultrasound screening group, only 42 percent of patients developed a short CL and received cerclage whereas, in the history-indicated group, 100 percent of patients received a history-indicated cerclage. Therefore, TVU CL screening can be considered for most patients with a prior spontaneous preterm birth, instead of routine history-indicated cerclage [23].
●Supplemental progesterone – For patients with a prior spontaneous preterm birth, the author prescribes vaginal progesterone 200 mg every evening beginning at 16 (optimal) to 20 weeks of gestation (which may be before or after cerclage placement) and continues it through 36+6 weeks. Although trials of vaginal progesterone for preventing spontaneous preterm birth in patients with singletons and a previous such birth have yielded mixed results [25], heterogeneity among these patients and the assumption that this history is representative of a singular disease process may account for negative studies [26].
The author continues progesterone after cerclage placement because, as described above, a meta-analysis of comparative studies in high-risk patients (cervical length <25 mm or previous preterm birth) found that the combination of vaginal progesterone plus cervical cerclage (ultrasound-indicated, history-indicated, or cervical length <10 mm) was associated with a lower risk of preterm birth <37 weeks than cerclage alone (11 versus 24 percent; RR 0.45, 95% CI 0.29-0.71) or progesterone alone (36 versus 42 percent; RR 0.75, 95% CI 0.58-0.96) [21]. Compared with cerclage only, combined therapy was also associated with reductions in preterm birth <34 weeks, <32 weeks, <28 weeks, and neonatal mortality. Limitations to interpretation include that several studies were of low quality with significant risk of bias and the mixed risk characteristics of the patient population.
Use of progesterone in these patients is controversial. The evidence is discussed in more detail separately. (See "Progesterone supplementation to reduce the risk of spontaneous preterm labor and birth", section on 'Singleton pregnancy with prior preterm birth'.)
Physical examination-based cervical insufficiency
●Cerclage – For patients with physical examination-based cervical insufficiency before 24 weeks of gestation, we consider physical examination-based cerclage placement a reasonable option (this was formerly called rescue or emergency cerclage).
•In a meta-analysis evaluating transvaginal physical examination-indicated cerclage because of premature cervical dilation ≥2 cm and/or exposure of fetal membranes at or beyond the external os before 28 weeks of gestation, cerclage was associated with improved overall survival compared with expectant management in singleton pregnancies (73 versus 36 percent; RR 1.6, 95% CI 1.2-2.1) and increased the mean gestational age at birth from 25.4 weeks to 30.5 weeks, independent of dilation and gestational age at diagnosis [27]. It was also associated with improved overall survival in twin pregnancies (44.1 versus 2.6 percent; RR 16.8, 95% CI 2.4-120.3) and increased mean gestational age at birth from 22 to 26 weeks, but fewer pregnancies were available for this analysis.
The effects of individual patient characteristics were not analyzed. Although these observational data are low-quality evidence, the analysis is the best available evidence to inform decision-making in this setting. In the only randomized trial of physical examination-based cerclage, cerclage reduced the rate of preterm birth before 34 weeks compared with bed rest (7 out of 13 births [54 percent] versus 10 out of 10 births [100 percent]), but included only 23 patients [28].
Most clinicians avoid placing a cerclage after approximately 24 weeks of gestation since the vast majority of the data on its efficacy are from pregnancies <24 weeks and the procedure may cause accidental rupture of the fetal membranes leading to early preterm delivery of a viable infant, with its attendant high risk of neonatal morbidity and mortality. However, each case must be individualized, weighing the risks of the procedure against the likely outcome with expectant management. (See "Periviable birth (limit of viability)".)
●Progesterone supplementation – The author's practice is to continue vaginal progesterone supplementation post-physical examination-based cerclage in patients who had been on the drug pre-cerclage because of a previous preterm birth or short cervix. For patients with no history of previous preterm birth or short cervix, the author begins vaginal progesterone post-cerclage. As described above, combined therapy appears to improve outcomes compared with cerclage alone [21]. Use of progesterone in these patients is controversial. These data are available separately. (See 'Obstetric history-based cervical insufficiency' above and "Progesterone supplementation to reduce the risk of spontaneous preterm labor and birth", section on 'Singleton pregnancy with prior preterm birth'.)
Cerclage procedures — Cerclage procedures, potential complications, post-operative care and follow-up, and outcome are described separately. (See "Transvaginal cervical cerclage" and "Transabdominal and laparoscopic cervicoisthmic cerclage".)
MANAGEMENT OF SPECIAL POPULATIONS
Patients with no prior second-trimester pregnancy loss or extremely preterm birth, but risk factors for cervical insufficiency — Although a minority of these patients develop cervical insufficiency, most do not; therefore, we believe the current pregnancy course and outcome need to be evaluated before making the diagnosis of cervical insufficiency. The author performs a single transvaginal cervical length (CL) measurement at 18 to 24 weeks of gestation (usually at approximately 20 weeks, with the anatomic survey ultrasound) in this population, and treats those with a short cervix in the same way as other patients without a history of preterm birth who develop a short cervix. (See "Short cervix before 24 weeks: Screening and management in singleton pregnancies", section on 'Patients with NO prior spontaneous preterm birth'.)
Patients with no prior preterm birth but a short cervix — Patients with singleton pregnancies and no history of preterm birth who develop a short cervix are treated with vaginal progesterone. Placement of a cerclage may be helpful in those with transvaginal ultrasound (TVU) CL <10 mm. These data and approaches to this population are reviewed separately. (See "Short cervix before 24 weeks: Screening and management in singleton pregnancies", section on 'Patients with NO prior spontaneous preterm birth'.)
Multiple gestations — The body of evidence does not support the efficacy of routine cerclage in multiple gestations, but it may be useful in patients with a classical history of cervical insufficiency or a short cervix. These data are reviewed separately. (See "Twin pregnancy: Management of pregnancy complications", section on 'Patient selection for cerclage' and "Triplet pregnancy", section on 'Unproven interventions'.)
ADJUNCTIVE BEHAVIORAL COUNSELING — Lifestyle interventions (cessation of work and exercise, abstinence from coitus, bedrest/limited activity) have not been adequately evaluated by well-designed studies. Clinicians should consider the available evidence and the patient's individual circumstances when making lifestyle recommendations as there are social, psychological, financial, and medical side effects associated with these interventions.
●Obstetric history-based diagnosis of cervical insufficiency – We advise these patients to continue their normal daily activities, with no restrictions other than those given to healthy pregnant patients.
●Ultrasound-based or physical examination-based diagnosis of cervical insufficiency – We advise these patients to continue their normal daily activities, with no restrictions other than those given to healthy pregnant patients. Activity restriction in patients with a short transvaginal ultrasound (TVU) CL has been associated with an increase in preterm birth compared with no activity restriction [29].
Although coitus does not promote the onset of labor in patients at term who are scheduled for induction [30], minimal data are available on the safety of coitus in patients at risk for preterm birth because of previous preterm birth or preterm cervical ripening [31]. We discuss this uncertainty with patients and the option of avoiding or limiting sexual activity.
INEFFECTIVE AND UNPROVEN INTERVENTIONS
Pessary — We do not prescribe pessaries for patients with a short cervix. In meta-analyses of randomized trials comparing use of a cervical pessary with standard care (no pessary, +/- vaginal progesterone) in asymptomatic patients at high risk for preterm birth (eg, cervical length (CL) ≤25 mm), pessary use did not result in a statistically significant reduction in spontaneous preterm birth <28, 34, or 37 weeks or improve perinatal outcome; however, the trials had many limitations and there was uncertainty around the effect estimates [32-34]. In a subsequent well-designed trial in which 544 patients were randomly assigned to Arabin pessary placement at 16 to 23 weeks of gestation or usual care, the rate of preterm birth or fetal death <37 weeks was the same for both groups (45.5 versus 45.6 percent; RR 1.00, 95% CI, 0.83-1.20). Fetal or neonatal/infant death occurred more often in the pessary group (13.3 versus 6.8 percent; RR 1.94; 95% C, 1.13-3.32) [35]. Whether the excess perinatal deaths in the pessary group were due to pessary use or a confounding factor was not clear. Strengths of this trial included a very high-risk population (short cervical length was defined as <20 mm), exclusion of individuals with a history of preterm birth, and routine use of progesterone supplementation in both groups.
The theory behind use of vaginal pessaries is that they alter the axis of the cervical canal and displace the weight of the uterine contents away from the cervix. By changing the angle of the cervix in relation to the uterus, the pessary also obstructs the internal os and thus may provide protection against ascending infection.
MANAGEMENT OF FUTURE PREGNANCIES FOLLOWING CERCLAGE IN INDEX PREGNANCY
Successful outcome after cerclage
●Successful obstetric history-indicated cerclage – We usually suggest repeat history-indicated cerclage for these patients. If the indication for the initial prior history-indicated cerclage was not evidence based, patients can be counseled that the alternative of serial cervical length (CL) screening can be safe and effective as well [36].
●Successful ultrasound-indicated cerclage – We suggest transvaginal ultrasound (TVU) CL screening in future pregnancies for patients who received an ultrasound-indicated cerclage in a prior pregnancy and had a successful outcome (delivery at or after 34 weeks). The absolute risk of preterm birth in future pregnancies does not warrant routine placement of a cerclage [37], but if ultrasound surveillance shows a short cervix in a subsequent pregnancy, then we place another cerclage. In one study, approximately 50 percent of patients with a history of an ultrasound-indicated cerclage required another ultrasound-indicated cerclage in the subsequent pregnancy, and their outcomes were similar to those who underwent planned cerclage in the subsequent pregnancy [38].
Successful pregnancy outcome after ultrasound-indicated cerclage does not establish or exclude a diagnosis of cervical insufficiency. A substantial proportion of pregnancies with premature cervical effacement have good outcomes in the index pregnancy and future pregnancies in the absence of surgical intervention. This is particularly true in patients who, after removal of the cerclage at 36 to 37 weeks, do not go into labor in the next two weeks.
●Successful physical examination-indicated cerclage – For patients with a successful physical examination-indicated cerclage (delivery at ≥34 weeks), we suggest TVU CL screening in future pregnancies, starting at 12 to 16 weeks. We place an ultrasound-indicated cerclage if a short CL develops. (See "Short cervix before 24 weeks: Screening and management in singleton pregnancies".)
Unsuccessful outcome after cerclage
●Unsuccessful obstetric-history indicated cerclage – We offer robotic interpregnancy transabdominal cervicoisthmic cerclage to patients who fail to deliver a healthy newborn after placement of a history-indicated cerclage. (See "Transabdominal and laparoscopic cervicoisthmic cerclage".)
●Unsuccessful ultrasound-indicated cerclage – For patients with a prior ultrasound-indicated cerclage who went on to have an early spontaneous delivery (eg, <34 weeks), we generally suggest an obstetric history-indicated transvaginal cerclage at 12 to 14 weeks of gestation in the next pregnancy because these patients always develop a short CL in subsequent pregnancies [38]. If the obstetric history-indicated cerclage is also unsuccessful, then we offer transabdominal or laparoscopic cervicoisthmic cerclage in a subsequent pregnancy. (See "Transabdominal and laparoscopic cervicoisthmic cerclage".)
●Unsuccessful physical examination-indicated cerclage – We suggest a history-indicated cerclage in future pregnancies for patients with prior unsuccessful (delivery before 34 weeks) physical examination-indicated cerclage.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Cervical insufficiency (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Diagnosis – We base the diagnosis of cervical insufficiency on either a classic obstetric history or on a combination of obstetric history and transvaginal ultrasound (TVU) measurement of cervical length (CL). Physical examination alone is adequate for diagnosis of cervical insufficiency in patients with advanced cervical dilation. The diagnosis is usually limited to singleton gestations because the pathogenesis of second-trimester pregnancy loss/extremely preterm delivery (ie, <28 weeks) in multiple gestations is usually unrelated to anatomic weakness of the cervix. (See 'Diagnosis' above.)
•Obstetric history-based diagnosis of cervical insufficiency – We make an obstetric history-based diagnosis of cervical insufficiency in patients with a classic history of ≥2 consecutive prior second-trimester pregnancy losses/extremely preterm births (ie, <28 weeks) associated with no or minimal mild symptoms. The presence of risk factors for structural cervical weakness support the diagnosis. Most of these cases are pregnancy losses before 24 weeks. Using this diagnostic approach, all of these patients will be offered a history-indicated cerclage. (See 'Obstetric history-based diagnosis of cervical insufficiency' above.)
•Ultrasound-based diagnosis of cervical insufficiency – In patients with a past history of a spontaneous preterm birth and those in whom a history-based diagnosis is uncertain, we perform serial TVU examinations and make a diagnosis of cervical insufficiency when CL is ≤25 mm before 24 weeks (algorithm 1). TVU screening is discontinued at 24 weeks of gestation as cerclage efficacy has not been adequately studied after this time. The presence of risk factors for structural cervical insufficiency supports the diagnosis. Using this diagnostic approach, approximately 40 percent of these patients will be offered a cerclage. (See 'Ultrasound-based diagnosis of cervical insufficiency' above.)
•Physical examination-based cervical insufficiency – We make a diagnosis of physical examination-based cervical insufficiency in patients at 14 to 27 weeks of gestation with a dilated and effaced cervix on physical examination and no contractions or weak irregular contractions that appear inadequate to explain the cervical dilation and effacement. The membranes may be prolapsed or ruptured. Most patients <24 weeks of gestation will be offered cerclage (in the absence of contraindications such as infection, [often evaluated by amniocentesis] or rupture of membranes). After 24 weeks, each case must be individualized, weighing the risks of the procedure against the likely outcome with expectant management since the procedure may cause accidental rupture of the fetal membranes leading to early preterm delivery of a viable infant, with its attendant high risk of neonatal morbidity and mortality. (See 'Physical examination-based diagnosis of cervical insufficiency' above.)
●Precerclage amniocentesis (See 'Candidates for amniocentesis' above.)
•We perform amniocentesis to look for subclinical infection before cerclage when the cervix is ≥2 cm dilated on manual or speculum examination, as the incidence of intraamniotic infection in these patients is approximately 20 to 50 percent. We also perform amniocentesis on a case-by-case basis when ultrasound findings are consistent with inflammation (eg, debris in the amniotic fluid [sludge or biofilm] (image 1)) or when membranes are visible and exposed at the external os, as prolapsed membranes are associated with a poor perinatal prognosis.
•We do not perform cerclage if we find evidence of infection on amniocentesis, as these pregnancies are at increased risk of preterm delivery and other pregnancy complications and do not benefit from cerclage.
●Treatment
•Obstetric history-based diagnosis of cervical insufficiency – For patients with history-based diagnosis of cervical insufficiency, we recommend history-indicated cerclage at 12 to 14 weeks of gestation rather than ultrasound monitoring of CL (Grade 1B). The author also treats these patients with daily vaginal progesterone supplementation from 16 to 36 weeks of gestation. (See 'Obstetric history-based cervical insufficiency' above.)
•Ultrasound-based diagnosis of cervical insufficiency – For patients with an ultrasound-based diagnosis of cervical insufficiency (both prior spontaneous preterm birth and TVU CL ≤25mm before 24 weeks in the index pregnancy), we suggest ultrasound-indicated cerclage (Grade 2B). For patients with a prior spontaneous preterm birth, the author prescribes daily vaginal progesterone supplementation beginning at 16 (optimal) to 20 weeks of gestation (which is usually before cerclage placement) and continued through 36 weeks. (See 'Ultrasound-based cervical insufficiency' above.)
Pessary placement is not effective. (See 'Pessary' above.)
•Physical examination-based cervical insufficiency – For patients with a physical examination-based diagnosis of cervical insufficiency (eg, cervix dilated on speculum or manual digital examination before 24 weeks), we suggest physical examination-indicated cerclage rather than expectant management after consideration for an amniocentesis to rule out intraamniotic infection (Grade 2C). The author's practice is to also treat these patients with vaginal progesterone supplementation post-cerclage. (See 'Physical examination-based cervical insufficiency' above.)
●Multiple gestations – For patients with twin or higher-order multiple pregnancies, we suggest avoiding routine cerclage (Grade 2C). (See "Triplet pregnancy", section on 'Unproven interventions' and "Twin pregnancy: Management of pregnancy complications", section on 'Overview' and "Twin pregnancy: Management of pregnancy complications", section on 'Patient selection for cerclage'.)
●Management of subsequent pregnancies
•For patients with a successful history-indicated cerclage, we usually repeat history-indicated cervical cerclage in subsequent pregnancies. We offer robotic interpregnancy transabdominal cervicoisthmic cerclage to patients who fail to deliver a healthy newborn after placement of a history-indicated cerclage.
•For patients with a successful (delivery ≥34 weeks) ultrasound-indicated cerclage, we follow CL in subsequent pregnancies and repeat ultrasound-indicated cervical cerclage if CL is ≤25 mm before 24 weeks. If the previous ultrasound-indicated cerclage was unsuccessful (delivery <34 weeks), we perform history-indicated cerclage at 12 to 14 weeks of gestation in the subsequent pregnancy. We offer transabdominal or laparoscopic cervicoisthmic cerclage to patients who have failed to have a successful pregnancy outcome after a transvaginal history-indicated cerclage at 12 to 14 weeks of gestation.
•For patients with a successful physical examination-indicated cerclage (delivery at ≥34 weeks), we suggest TVU CL screening in future pregnancies, starting at 12 to 16 weeks and placement of an ultrasound-indicated cerclage if a short CL develops. If the physical examination-indicated cerclage was unsuccessful, we generally place a history-indicated cerclage in future pregnancies. (See 'Management of future pregnancies following cerclage in index pregnancy' above.)
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