In light of these data, Ob/Gyns should individualize the management of patients with preterm PROM and a preexisting cerclage, weighing the risk of infection against those of precipitating an extremely premature delivery with cerclage removal.
In my own practice, I have changed from being a staunch advocate of cerclage removal to a supporter of either approach, depending on individual practice style (my style remaining one of removal in the setting of preterm PROM, provided that such removal can be easily accomplished).
It is unlikely that a patient with a short cervix and no history of adverse pregnancy outcome would benefit from cerclage.
Again, we are hampered in decision-making by a paucity of data to support or refute either approach. I would emphasize the importance of dialogue, making sure the patient is aware of her options before a course of action is decided upon.
Controversy 6
Should a cerclage be placed in a woman with a short cervix?
In recent years, a number of screening tests have been introduced to identify women at increased risk of preterm delivery: biochemical tests such as fetal fibronectin,7,8 hormonal tests such as salivary estriol,9 and serial cervical ultrasound examinations to assess cervical length and the presence or absence of membrane funneling.10,11 Real-time sonographic evaluation of the cervix has demonstrated a strong inverse correlation between cervical length and preterm delivery.10,11 If the cervical length is below the 10th percentile for gestational age, the pregnancy is at a 6-fold increased risk of delivery prior to 35 weeks.10 A cervical length of 15 mm or less at 23 weeks occurs in less than 2% of low-risk women, but is predictive of delivery prior to 28 weeks and 32 weeks in 60% and 90% of cases, respectively.10
Several retrospective studies suggest that placement of a cervical cerclage in asymptomatic women with short cervical length may improve perinatal outcome.12-15 One study reported a 10-fold reduction in the incidence of delivery prior to 32 weeks’ gestation in women treated with cerclage, with pretermdelivery rates of 52% and 5% for women in the control and cerclage groups, respectively.13 These women were identified via endovaginal ultrasound as having a reduced cervical length prior to 24 weeks’ gestation.
According to more recent data, however, cerclage is not indicated in women with evidence of cervical shortening.16,17 Indeed, 1 study showed a higher rate of preterm PROM in women undergoing cerclage, compared with those without cerclage (65.2% versus 36.5%; P<.05>17 Further studies are needed.
In essence, clinicians must tabulate all of the risks for preterm birth before selecting a course of action, with the final decision residing in a risk-benefit analysis that involves the patient. For example, it is unlikely that a patient with a short cervix (found incidentally on ultrasound) and no history of adverse pregnancy outcome would benefit from cerclage. She may, however, benefit from other screening modalities, such as ultrasound surveillance of cervical length until 24 weeks, and possibly fetal fibronectin determinations to better assess her absence of risk for preterm delivery.
On the other hand, a patient with a history of prior idiopathic preterm delivery who is found via ultrasound to have a shortened cervix may benefit from early cerclage placement.
Controversy 7
Should all DES-exposed women be offered prophylactic cerclage?
In utero exposure to DES alters the structure of the cervix in up to 69% of women.18 For example, the endocervical canal is narrower, and the demarcation between it and the lower uterine segment is less clear than in unexposed women. In addition, the cervix does not protrude as far into the vagina as in unexposed women. These and other changes can resemble alterations associated with an incompetent cervix.
Women exposed to DES are 2.6 to 6.7 times more likely than unexposed women to experience premature delivery.18 Even so, most experts have concluded that prophylactic cerclage is not indicated in patients with a history of in utero exposure to DES unless those women have experienced a previous pregnancy loss or have clear evidence of cervical shortening. One reason is the fact that the DES-exposed cervix responds differently to surgery. Further studies are required to clarify this issue.
Controversy 8
What is the role of cervical cerclage in multiple gestations?
Although multiple gestations face an increased risk of preterm delivery, there is no reliable evidence that prophylactic cerclage is helpful in uncomplicated twin pregnancies.19-22 In fact, a randomized trial of the issue failed to reveal any advantage,20 as did 2 randomized trials involving women at high risk of preterm delivery that included patients with twins.21,22 (Women with a classic history of cervical incompetence were excluded from the latter trial.)22