Ultrasonic assessment of cervix in "at risk" patients.

One hundred seventy patients were considered to be at risk of cervical incompetence from their previous history. They were scanned serially from the first trimester to 36 weeks gestation. Of the 170, 105 patients (61.8%) were found to have defective cervix (the length of cervix, width of the cervix, and cervical canal at the level of the internal cervical os, and herniation of amniotic membrane with or without fetal parts into the cervical canal). Of the 105 patients diagnosed to have defective cervix (possible cervical incompetence), 22 patients (21%) aborted, 48 patients (45.7%) had to have cervical cerclage, 26 patients (24.8%) had preterm delivery and the remaining 9 patients (8.5%) had no problems during pregnancy. The remaining 65 patients (38.2%) did not have ultrasonic evidence of cervical incompetence and 3 aborted and only 2 patients delivered between 35 and 37 weeks gestation while 60 patients delivered between 37 and 42 weeks gestation. These 65 patients would have had cervical cerclage on the basis of the clinical history alone, but in only 6, cervical cerclage was inserted.