Cervical pessary may prevent preterm birth in women with short cervix
The use of a cervical pessary may reduce the risk of preterm birth in women with singleton pregnancies and short cervical length, according to a single-centre study from Italy.
The use of a pessary to prevent preterm birth has been garnering interest due to its noninvasive nature, ease of use, and nonrequirement of anaesthesia for insertion and removal, said the researchers.
“[In this study], use of a cervical pessary, compared with no pessary use, resulted in a lower rate of spontaneous preterm birth at less than 34 weeks of gestation,” they said.
Women with asymptomatic singleton pregnancies, no history of spontaneous preterm birth, and a cervical length of ≤25 mm (identified through transvaginal ultrasound) between 18 and 23 weeks and 6 days of gestation (mean age 29 years, mean gestational age 22 weeks, mean cervical length ±12 mm) were randomized to receive a cervical pessary or not (n=150 in each group). The pessary was removed during the 37th week of gestation or earlier if necessary, such as in the case of active vaginal bleeding or preterm labour.
Women with a cervical length of ≤20 mm were also given progesterone (200 mg daily vaginal suppositories) until 36 weeks of gestation (88.7 and 83.3 percent in the pessary and control groups, respectively).
Women who used the cervical pessary were less likely to experience spontaneous preterm birth at <34 weeks gestation compared with women who didn’t use the pessary (7.3 percent vs 15.3 percent; relative risk [RR], 0.48, 95 percent confidence interval [CI], 0.24–0.95; p=0.04). [JAMA 2017;318:2317-2324]
Use of the cervical pessary was also linked to a longer gestational age at delivery (mean, 37.6 vs 36.2 weeks; p=0.001), higher birth weight (mean, 2889.9 vs 2644.6 g; p=0.006), lower rate of neonatal intensive care admission (RR, 0.54; p=0.04), and lower incidence of adverse perinatal outcomes (RR, 0.46; p=0.01) compared with non-use.
However, there was a higher incidence of vaginal discharge among women who used the cervical pessary (86.7 percent vs 46.0 percent; RR, 1.88, 95 percent CI, 1.57–2.27; p<0.001).
“The leading hypotheses for [the] mechanism of action [of the pessary] are that [it] helps keep the cervix closed and changes the inclination of the cervical canal so that the pregnancy weight is not directly above the internal os. Another proposed mechanism is that the pessary could strengthen the immunological barrier between the chorioamnion-extraovular space and the vaginal microbiological flora, as cerclage has been postulated to do,” said the researchers, remarking that the actual mechanism has yet to be established and advocating for extension of this study to a multicentre setting.
Use restricted to very short cervical length?
“[C]linicians may contemplate recommending pessaries for all women with a short cervix identified on antenatal sonogram,” said editorialists Drs Robert Silver and David Branch from the University of Utah Health Sciences Center and Women and Newborns Clinical Program of Intermountain Healthcare, Salt Lake City, Utah, US, respectively. However, they recommended caution against “universal adoption” of this method as previous research on its use has yielded conflicting findings. [JAMA 2017;318:2299-2300; N Engl J Med 2016;374:1044-1052]
One potential reason for the discordant findings is that participants in this trial had a much shorter mean cervical length compared with that of the previous trial (12 vs 20 mm), said Silver and Branch.
“The shorter the cervix, the higher the risk of preterm birth … thus, the results may not be generalizable to women with relatively less short cervical lengths [eg, 20–25 mm],” they said.
“[I]t is crucial that physicians accept that these interventions have not solved the problem of preterm birth … The way forward is to determine for which subsets of pregnancies each of the treatments … is effective … [and] to assess how different treatments interact with each other and whether they are synergistic, redundant, or perhaps less effective when used in combination,” they concluded.