Pregnancy Outcome of Cervical Incompetence in Twin Versus Singleton Pregnancies

Nam, Soo Hyun; Lee, Ji Eun; Choi, Suk Joo; Oh, Soo Young; Kim, Jong Hwa; Roh, Cheong Rae

Abstract

OBJECTIVE
The aim of this study was to compare the incidence and clinical features of cervical incompetence between singleton and twin pregnancies in women with newly diagnosed cervical incompetence.
METHODS
We retrospectively reviewed the medical records of 64 women who were diagnosed with cervical incompetence for the first time during pregnancy and delivered between 1994 and 2004. Cervical incompetence was defined by the presence of painless cervical dilatation during mid-trimester with either bulging amniotic membranes through the external cervical os or shortened cervical length (<2 cm) with funneling on transvaginal ultrasound.
RESULTS
The incidence of cervical incompetence which was diagnosed for the first time during pregnancy was 0.16% (54/33, 176) in singleton pregnancies and 1.23% (10/813) in twin pregnancies. Multiparity or a history of preterm delivery was more common in the singleton compared to the twin pregnancies. The median gestational age at diagnosis was similar in the two groups. In the patients who had undergone emergent cerclage, twin pregnancies had more advanced cervical dilatation [median (range); 3.0 (2.0~5.0) vs. 2.0 (1.0~4.0) cm, p<0.05] and effacement [median (range); 75 (50~100) vs. 50 (10~100) %, p<0.05] compared to the singleton pregnancies. After emergent cerclage, gestational age at delivery was earlier in the twin pregnancies [median (range); 24.8 (23.1~30.6) vs. 35.3 (16.4~41.1) weeks, p<0.05] than in the singleton pregnancies.
CONCLUSION
The incidence of cervical incompetence in twin pregnancies was seven times greater than in singleton pregnancies. Although the onset of cervical incompetence was not different in the groups, prolongation of pregnancy, after emergent cerclage, was less likely in the twin pregnancies compared to singleton pregnancies, due to a more advanced cervical change at the time of diagnosis.