Arabin cervical pessary in women at high risk of preterm birth: a magnetic resonance imaging observational follow-up study.

Cannie MM, Dobrescu O, Gucciardo L, Strizek B, Ziane S, Sakkas E, Schoonjans F, Divano L, Jani JC.

Abstract

 

OBJECTIVE:

To help elucidate the mechanism of action of the Arabin cervical pessary in pregnancies at high risk for preterm delivery.

METHODS:

We evaluated cervical length and uterocervical angle in relation to gestational age in 198 pregnancies. They were not at high risk for preterm birth that underwent clinical fetal magnetic resonance imaging (MRI). Additionally, in 73 singleton pregnancies at high risk for preterm birth, we placed an Arabin cervical pessary at 14-33 weeks’ gestation. We performed MRI of the cervix immediately before and after placement. At monthly follow-up until removal of the pessary. In a subgroup of 54 pregnancies with a short cervix and pessary placement at 17-31 weeks’ gestation, we compared the uterocervical angle and cervical length at follow-up with the preplacement values.

RESULTS:

In pregnancies not at high risk for preterm birth, the uterocervical angle did not vary. Cervical length showed a significant decrease with gestational age (r = -0.15, P < 0.05). Among the high-risk patients, we placed the cervical pessary successfully at first attempt in 60 (82.2%) and by the second attempt in 66 (90.4%), remaining well positioned until removal. In five patients we failed to place the pessary after two attempts. Also, in one patient the pessary dislodged during follow-up. In one case the pessary was partly placed in the external cervical canal and triggered labor the next day. Among the subgroup of 54 patients, the median uterocervical angle immediately after pessary placement was significantly more acute than that prior to placement in the 46 (85.2%) who delivered after 34 weeks (132° vs 146°, P < 0.01). There was no change in the eight patients who delivered before 34 weeks (143° vs 152°, P > 0.05).

CONCLUSION:

In patients at high risk for preterm delivery, we should check the correct placement of the Arabin cervical pessary immediately. This can be performed quickly and easily using MRI. This study provides some evidence that, in singleton pregnancies with a short cervix, a cervical pessary delays birth through a mechanical effect on the uterocervical angle.

Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.