PURPOSE: To assess the implications of spontaneous changes in the leng
th and configuration of the gravid cervix during a single ultrasound (
US) examination and to correlate specific cervical dimensions with pre
gnancy outcome. MATERIALS AND METHODS: Sonograms in 27 pregnant patien
ts with a spontaneously changing cervix were studied prospectively. Th
e length and width of cervical funneling and the length of intact cerv
ix caudal to the funneling were measured when the cervical dimensions
were most normal and most abnormal. Sonographic measurements were corr
elated with clinical and delivery data. RESULTS: Twenty patients deliv
ered preterm, although only six delivered within a week of the US exam
ination. Wider funneling of the internal os and a shorter segment of i
ntact cervix caudal Co the funneling both correlated with an increased
likelihood of preterm delivery. CONCLUSION: Most patients with a spon
taneously changing cervix deliver preterm. Measurements obtained when
the cervix appears most abnormal are most predictive of early delivery
.