Families First of Loudoun

Beyond the Bishop Score

Since the 1960′s, the Bishop Score has been a frequently used predictor in assessing feasibility of induction of labor. This scoring system attempts to predict the success of induction by assessing five factors: position of the cervix in relation to the vagina, cervical consistency, dilation, effacement and station of the presenting part. The higher the score, the higher rate of success of the induction. A score less than five indicates an unfavorable cervix for induction. Some texts also reference the Burnett Scale* which assesses approximately the same factors.

In an effort to find a more accurate predictor of successful induction, two relatively new methods are now being used: transvaginal sonography of the cervix and comparative levels of fetal fibronectin.

The length of the cervix can be measured by transvaginal sonography. In expectant mothers with an unfavorable Bishop score (typically less than 7), a cervical length of less than 26 mm is associated with a lower risk of cesarean section and a shorter duration of labor. In several independent studies, when the Bishop score has been as low as 3 and the cervical length was 28 mm, successful induction has been achieved.

To measure the cervical length, an expectant mother goes to an office or radiology department of the hospital. It is an outpatient procedure, where the mother’s bladder is empty and she wears a hospital gown. A transducer (roughly the size of a tampon) is used to transmit ultrasound/ sound waves, which bounce back to produce an image that can be recorded. The transducer is inserted into the vagina and the image is noted on the monitor or it can be printed. This information is reported back to the physician for evaluation.

Fetal fibronectin is a protein that can be found in fetal membranes and amniotic fluid. When present in cervical and vaginal secretions, fetal fibronectin can be useful in determining a woman’s risk for preterm labor and may be predictive in estimating when the mother is ready for labor.

The test for fetal fibronectin is simple and painless, involving only the swabbing of the vaginal and cervical area for a sample of secretions.

It is important to note that expectant mothers showing signs of preterm labor should be tested at 24 to 25 weeks’ gestation, while high-risk women without symptoms can be tested as early as 22 weeks’ gestation and continually tested as appropriate.

Is there, then, a relationship between cervical length, fetal fibronectin and the increase of oxytocin receptor sites on the uterus? We will be anxiously awaiting research on this!

From Birthsource.com