Transabdominal cervicoisthmic cerclage during pregnancy: The strength of cerclage band and the pregnancy outcomes

Moon, Young Jin; Park, Moon Il

Abstract

BACKGROUND/OBJECTIVE: After introducing transabdominal approach of cervical cerclage since 1965, several authors have reported significant increases in fetal survival rate. However, this procedure has not been widely used because its complexity of procedure and serious complications. Furthermore, there is a dilemma on the strength of the cerclage bands knots. Yet, there is no standard guidance in this approach. The purpose of this study was to suggest degree of adequate tension on the knot when tying the cerclage band on the cervico-isthmic junction during post-conceptional transabdominal cerclage and to assess whether the strength of the band is associated with uterine blood flow or pregnancy outcomes. STUDY DESIGN: Sixty-five transabdominal cervico-isthmic cerclages during pregnancy were performed for 7 years since 1989 in patients of incompetent cervix who could not be taken transvaginal cerclage. The procedures were performed with our own technique, modified technique from original Novys procedure. The cerclage used a 5mm-Mersilene band and knot was placed on the anterior side. Pre- and post-operative uterine blood flow were evaluated with Doppler velocimetry. After cesarean section at term, cerclage bands were removed and collected for measurement of bands length if they do not want further pregnancies. The relationships between strength of cerclage, length of band and pregnancy outcomes were evaluated. The effects of the bands length on the uterine blood flow were also analyzed.
RESULTS
To date there have been 56 completed pregnancies in 50 patients. Among these, 21 cerclage bands were removed and collected for measurement of bands length. All pregnancies (27 pregnancies from 21 patients) were successful; the average gestational age at delivery was 38.4 weeks (range: 37-43) and mean birth weight was 3178gm (range:2670-4370). Average length of cerclage bands was 7.01cm(range:5.0-9.4), thus diameter of cerclage bands was calculated as 2.2cm. Statistically, significant positive correlation was found between the bands' length and birth weights (r=0.614, p=0.002). There were no differences between pre- and post-operative uterine blood flow regardless of cerclage bands length.
CONCLUSIONS
We suggest 7cm is adequate bands length when performing transabdominal cerclage during pregnancy. Uterine blood flow was not influenced by operation. It was interesting that bands length was correlated with birth weight. It seems that tightened cerclage might preclude the adequate formation of lower uterine segment during pregnancy. Recently we use the specific Mersilene bands after marking of each centimeter interval on it, and bands are tied with 7cm in length for adequate strength of the cerclage. We propose this result also could be used when performing the pre-conceptional transabdominal cerclage.