A vaginal pessary that encircles and theoretically compresses the cervix, alters the inclination of the cervical canal, and relieves direct pressure on the internal cervical os has been proposed as an alternative to cerclage. One of the most popular is the silicone Arabin pessary. In a study of its use in women with a short cervix between 18 and 22 weeks' gestation, a subgroup analysis of 23 women with twins showed a signiicant reduction in the delivery rate before 32 weeks compared with the rate in 23 control pregnancies (Arabin, 2003). In another randomized trial, women treated with a cervical pessary had signiicantly fewer births before 34 weeks (Goya, 2016).
Other studies have been less favorable. In the randomized Pessaries in Multiple Pregnancy as a Prevention of Preterm Birth (ProTWIN) trial, 813 un selected women with twins received either the Arabin pessary between 12 and 20 weeks or no treatment (Liem, 2013). The pessary failed to reduce preterm birth overall but did decrease delivery rates before 32 weeks-29 versus 14 percent-in a subset of women with a cervical length <38 mm. Similar results were reported from a randomized multicenter trial with a total of 11r80 twin pregnancies (Nicolaides, 2016). A smaller randomized study using a Bioteque cup pessay showed no diference in outcomes (Berghella, 2017). At this time, pessary use is not recommended by the merican College of Obstetricians and Gynecologists (2016). As noted above, results from the ongoing PROSPECT trial are anticipated to provide more data.
• Treatment of Preterm Labor
Although many advocate their use, therapy with tocolytic agents to forestall preterm labor in multifetal pregnancy does not result in measurably improved neonatal outcomes (Chauhan, 2010; Gyetvai, 1999). Another caveat is that tocolytic therapy in women with a multifetal pregnancy entails higher risks than in singleton pregnancy. This stems in part from augmented pregnancy-induced hypervolemia, which raises cardiac demands and increases the susceptibility to iatrogenic pulmonary edema (Chap. 47, p. 917). Gabriel and colleagues (1994) compared outcomes of 26 twin and six triplet pregnancies with those of 51 singletons-all treated with a beta-mimetic drug for preterm labor. Women with a multifetal gestation had significantly more cardiovascular complications-43 versus 4 percent-including three gravidas with pulmonary edema. In a retrospective analysis, Derbent and coworkers (2011) evaluated nifedipine tocolysis in 58 singleton and 32 twin pregnancies. hese authors reported higher incidences of side efects such as maternal tachycardia in women with twins-19 versus 9 percent.