An external tocodynamometer belted around the abdomen and connected to an electronic waist recorder allows a woman to ambulate while uterine activity is recorded. Results are transmitted via telephone daily. Women are educated concerning signs and symptoms of preterm labor, and clinicians are kept apprised of their progress. The 1985 approval of this monitor by the Food and Drug Administration (FDA) prompted its widespread clinical use. Subsequently, it was proven that the use of this expensive and time-consuming system does not reduce preterm birth rates (Collaborative Home Uterine Monitoring Study Group, 1995; lams, 2002; Urquhart, 2017). Despite improvements in technology with the internet and cellular telephones, use of such monitoring is discouraged (merican College of Obstetricians and Gynecologists, 20 16c).
his glycoprotein is produced in 20 diferent molecular forms by various cell types, including hepatocytes, fibroblasts, endothelial cells, and fetal amnion cells. Present in high concentrations in maternal blood and amnionic luid, fFN is thought to function in intercellular adhesion during implantation and in maintenance of placental adherence to uterine decidua (Leeson, 1996). Detected in cervicovaginal secretions in women who have normal pregnancies with intact membranes at term, fFN appears to reflect stromal remodeling of the cervix before labor.
Lockwood (1991) reported that FN detection in cervicovaginal secretions before membrane rupture was a possible marker for impending preterm labor. Qualitative and quantitative FN levels are measured using enzyme-linked immunosorbent assays, and values exceeding 50 ng/mL are considered positive. Sample contamination by amnionic luid and maternal blood should be avoided. Interventional studies based on the use of FN screening in asymptomatic women have not demonstrated improved perinatal outcomes (Andrews, 2003; Esplin, 2017; Grobman, 2004). The American College of Obstetricians and Gynecologists (2016c) does not recommend screening with FN tests. Its use in conjunction with cervical length measurement is discussed next.
are associated with increased rates of preterm birth (lams, 1996). he technique to measure cervical length with sonog raphy is described in Chapter 10 (p. 189). When performed by trained operators, cervical length analysis using transvagi nal sonography is safe, highly reproducible, and more sensitive lege of Obstetricians and Gynecologists, 20 16c). The Society for the performance of proper cervical length measurement.
obtain speciic training in the acquisition and interpretation of cervical length imaging through accreditation programs.
Transvaginal cervical sonography is not afected by maternal obesity, cervix position, or shadowing from the fetal presenting part. Because of the inability to easily distinguish the lower uterine segment from the cervix in early gestation, transvaginal cervical length assessment is typically performed ater 16 weeks' gestation.
Such interrogation is currently limited to singleton gestations and not recommended for multifetal gestations outside of research tri als (American College of Obstetricians and Gynecologists, 2016c).
Indications for cervical length measurement are somewhat controversial. For those women with a history of prior spontaneous preterm birth, the Society for Maternal-Fetal Medicine (20 16b) recommends transvaginal cervical length screening. But, the American College of Obstetricians and Gynecologists (2016c) only recommends consideration of screening for this indication. In women with singleton pregnancies but without a history of prior preterm birth, the Society for Maternal-Fetal Medicine (20 16b) views cervical length screening as reasonable yet acknowledges that this remains an area of debate.