Reference data representative of normal findings at three-dimensional power Doppler ultrasound examination of the cervix from 17 to 41 gestational weeks.

OBJECTIVES: To develop normal reference ranges for cervical volume and vascular indices using three-dimensional (3D) power Doppler ultrasonography from 17 to 41 gestational weeks. METHODS: This was a cross-sectional study of 352 nulliparous and 291 parous women who delivered at term and underwent transvaginal 3D power Doppler ultrasound examination of the cervix once at 17 to 41 weeks' gestation. We examined approximately 25 women in each gestational week. Cervical volume, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated. RESULTS: There was no change in cervical volume between 17 and 40 weeks' gestation. At 41 weeks cervical volume was slightly smaller than it was at 17-40 weeks (P=0.03 for nulliparous women and P=0.08 for parous women). The cervical volume was larger in parous than it was in nulliparous women (median 38 cm3 vs. 32 cm3 at 17-40 weeks, P<0.0001; median 31 cm3 vs. 22 cm3 at 41 gestational weeks, P=0.288). FI did not differ between nulliparous and parous women and remained unchanged between 17 and 41 weeks' gestation (median 30.6, range 21.2-55.2). VI and VFI did not change consistently from 17 to 41 weeks, but the values were higher in parous than they were in nulliparous women at 17-30 weeks (median VI 5.3% vs. 3.1%, P<0.0001; median VFI 1.6 vs. 0.9, P<0.0001). At 31-41 gestational weeks the median VI for all women irrespective of parity was 4.9% and the median VFI was 1.4. CONCLUSION: Reference values for cervical volume and blood flow indices as assessed by 3D power Doppler ultrasonography have been established for the second half of pregnancy. These lay the basis for studies of pathological conditions.

Three-dimensional ultrasound assessment of the cervix for predicting time to spontaneous onset of labor and time to delivery in prolonged pregnancy.

OBJECTIVES: To determine whether three-dimensional (3D) ultrasound including power Doppler examination of the cervix is useful for predicting time to spontaneous onset of labor or time to delivery in prolonged pregnancy. METHODS: A prospective study was conducted in 60 women who went into spontaneous labor. All underwent transvaginal 3D power Doppler ultrasound examination of the cervix immediately before a prolonged-pregnancy check-up at > or = 41 + 5 gestational weeks. Univariate and multivariate logistic regression analysis was used to determine which of the following variables predicted spontaneous onset of labor > 24 h and > 48 h and vaginal delivery > 48 h and > 60 h: length, anteroposterior (AP) diameter and width of the cervix and of any cervical funneling; cervical volume (cm3); vascularization index (VI); flow index (FI); vascularization flow index (VFI); parity; and Bishop score. Multivariate logistic regression analysis was carried out both with and without Bishop score as a predictive variable. Receiver-operating characteristics (ROC) curves were used to describe the diagnostic performance of the tests. RESULTS: The areas under the ROC curves for Bishop score, cervical length, and logistic regression models did not differ significantly (areas ranging from 0.72 to 0.82). If Bishop score was not included in the logistic regression model, cervical length, VI and FI independently predicted delivery > 48 h, the likelihood increasing with increasing cervical length, decreasing VI and increasing FI. CONCLUSIONS: In prolonged pregnancy cervical vascularization as estimated by 3D power Doppler ultrasound is related to time to delivery > 48 h, but the likelihood of delivery > 48 h can be predicted equally well using Bishop score alone or sonographic cervical length alone.

Bishop score and ultrasound assessment of the cervix for prediction of time to onset of labor and time to delivery in prolonged pregnancy.

OBJECTIVES: To determine the ability of Bishop score and sonographic cervical length to predict time to spontaneous onset of labor and time to delivery in prolonged pregnancy. METHODS: Ninety-seven women underwent transvaginal ultrasound examination and palpation of the cervix at 291-296 days' gestation according to ultrasound fetometry at 12-20 weeks' gestation. Sonographic cervical length and Bishop score were recorded. Multivariate logistic regression analysis was used to determine which variables were independent predictors of the onset of labor/delivery < or = 24 h, < or = 48 h, and < or = 96 h. Receiver-operating characteristics (ROC) curves were drawn to assess diagnostic performance. RESULTS: In nulliparous women (n = 45), both Bishop score and sonographic cervical length predicted the onset of labor/delivery < or = 24 h and < or = 48 h (area under ROC curve for the onset of labor < or = 24 h 0.79 vs. 0.80, P = 0.94; for delivery < or = 24 h 0.81 vs. 0.85, P = 0.64; for the onset of labor < or = 48 h 0.73 vs. 0.74, P = 0.90; for delivery < or = 48 h 0.77 vs. 0.71, P = 0.50). Only Bishop score discriminated between nulliparous women who went into labor/delivered < or = 96 h or > 96 h. A logistic regression model including Bishop score and cervical length was superior to Bishop score alone in predicting delivery < or = 24 h (area under ROC curve 0.93 vs. 0.81, P = 0.03) and superior to Bishop score alone and cervical length alone in predicting the onset of labor < or = 24 h (area under ROC curve 0.90 vs. 0.79, P = 0.06; and 0.90 vs. 0.80, P = 0.06). In parous women (n = 52), Bishop score and sonographic cervical length predicted the onset of labor/delivery < or = 24 h (area under ROC curve for the onset of labor 0.75 vs. 0.69, P = 0.49; for delivery 0.74 vs. 0.70, P = 0.62), but only Bishop score discriminated between women who went into labor/delivered < or = 48 h and > 48 h. Three parous women had not gone into labor and six had not given birth at 96 h. In parous women logistic regression models including both Bishop score and cervical length did not substantially improve prediction of the time to onset of labor/delivery. CONCLUSIONS: In prolonged pregnancy Bishop score and sonographic cervical length have a similar ability to predict the time to the onset of labor and delivery. In nulliparous women the use of logistic regression models including Bishop score and cervical length is likely to offer better prediction of the onset of labor/delivery < or = 24 h than the use of the Bishop score alone.

Assessment of changes in endometrial and subendometrial volume and vascularity during the normal menstrual cycle using three-dimensional power Doppler ultrasound.

OBJECTIVES: To describe changes in endometrial and subendometrial volume and vascularity during the normal menstrual cycle using three-dimensional (3D) power Doppler ultrasonography. METHODS: Fourteen healthy volunteers, 24-44 years old with regular menstrual cycles, underwent serial transvaginal 3D power Doppler ultrasound examinations of the uterus on cycle day 2, 3 or 4, then daily from cycle day 9 until follicular rupture and 1, 2, 5, 7 and 12 days after follicular rupture. Endometrial and subendometrial volume (cm3), vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated using the VOCAL (Virtual Organ Computer-aided AnaLysis) software. RESULTS: Endometrial and subendometrial vascularity indices increased throughout the follicular phase, decreased to a nadir 2 days after follicular rupture and then increased again during the luteal phase. Endometrial and subendometrial volume increased rapidly during the follicular phase and then remained almost unchanged during the luteal phase. CONCLUSIONS: Substantial changes occur in endometrial volume and vascularization during the normal menstrual cycle. There is the potential for 3D power Doppler ultrasonography to become a useful tool for assessing pathological changes associated with female subfertility and abnormal uterine bleeding.

Reference data representative of normal findings at two-dimensional and three-dimensional gray-scale ultrasound examination of the cervix from 17 to 41 weeks' gestation.

OBJECTIVES: To create reference values representative of normal findings on two-dimensional (2D) and three-dimensional (3D) transvaginal ultrasound (TVS) examination of the cervix from 17 to 41 weeks' gestation and to determine the agreement between cervical measurements taken by 2D and 3D TVS. METHODS: Cross-sectional study covering 17 to 41 weeks in 419 nulliparous and 360 parous women who delivered at term and who underwent 2D and 3D TVS examination of the uterine cervix. We examined approximately 25 women in each gestational week. The length, anteroposterior (AP) diameter and width of the cervix (and of any cervical funnel) and AP diameter of the cervical canal were measured. Results were plotted against gestational age. The agreement between 2D and 3D ultrasound results was expressed as the mean (+/- 2 SDs) difference between the results of the two methods and as the interclass correlation coefficient (inter-CC). RESULTS: There was excellent agreement between measurements taken by 2D and 3D ultrasound (inter-CC values, 0.80-0.98) but measurements of cervical length taken using 3D ultrasound were greater than measurements taken by 2D ultrasound (mean difference, -0.04 +/- 0.36 cm). Cervical length did not change substantially between 17 and 32 gestational weeks but decreased progressively thereafter. Cervical length was similar in nulliparous and parous women at 17-32 weeks, but from 33 weeks the cervix tended to be longer in parous women. In nulliparae, cervical length decreased from a median of 3.8 (range, 0.7-6.1) cm at 17-32 weeks to 2.3 (range, 0.4-6.0) cm at 33-40 weeks and to 0.7 (range, 0.2-1.5) cm at 41 weeks. In parous women, the corresponding figures were 3.9 (range, 1.0-6.1) cm, 3.0 (range, 0.4-5.7) cm and 0.8 (range, 0.4-3.4) cm (results obtained by 3D ultrasound). Cervical AP diameter and width did not differ between nulliparous and parous women. Median AP diameter increased from 3.0 (range, 2.0-4.6) cm at 17-30 weeks to 3.5 (range, 1.8-5.5) cm at 31-40 weeks and to 4.0 (range, 2.8-5.9) cm at 41 weeks. Cervical width was 3.7 (range, 2.3-6.0) cm at 17-30 weeks and 4.5 (range, 2.3-6.1) cm at 31-41 weeks. The percentage of women with funneling increased from 4% (3/84) at 17-18 weeks to 63% (12/19) at 41 weeks and the percentage of women with an open cervical canal increased from 19% (15/84) to 72% (13/19). Funneling and opening of the cervical canal were equally common in nulliparous and parous women. CONCLUSIONS: Reference data provide the basis for studies of pathological conditions. Common reference values for nulliparous and parous women can be used for cervical AP diameter and width from 17 to 41 weeks and for cervical length from 17 to 32 weeks. Separate reference values for cervical length for nulliparous and parous women should be used from 33 to 41 weeks.

Intraobserver and interobserver reproducibility of three-dimensional gray-scale and power Doppler ultrasound examinations of the cervix in pregnant women.

OBJECTIVES: To determine intraobserver and interobserver reproducibility of three-dimensional (3D) gray-scale and power Doppler ultrasound examinations of the cervix in pregnant women. METHODS: Thirty-two pregnant women underwent transvaginal 3D gray-scale and power Doppler ultrasound examination of the cervix by two examiners. Each observer acquired two volumes, and they each analyzed their volumes twice using the commercially available software Virtual Organ Computer-aided AnaLysis (VOCAL). The variables analyzed were cervical volume (cm3), vascularization index (VI), flow index (FI) and vascularization flow index (VFI). Intraobserver repeatability was expressed as the difference between two measurement results (mean difference +/- 2 SD, i.e. limits of agreement) and as intraclass correlation coefficient (intra-CC). Interobserver agreement was expressed as the difference between the results of the two observers (limits of agreement) and as interclass correlation coefficient (inter-CC). The contribution of various factors (examiner, acquisition, analysis of acquired volume) to intrasubject variance was estimated using different analysis of variance models. All statistical analyses were performed using log-transformed data. The results presented are those obtained after antilogarithmic transformation, i.e. the results are presented as ratios between two results of the same observer, or as ratios between the results of Observer 1 and Observer 2. RESULTS: All intraobserver and interobserver log-transformed differences were normally distributed. There was no systematic bias between the two observers. Both intra- and inter-CC values were high (0.93-0.98) for all variables except FI (0.63-0.88), despite the limits of agreement being wide, especially for VI (widest range 0.4-2.4) and VFI (widest range 0.3-2.6). Acquisition explained most of the intrasubject variance of the flow indices, the contribution of examiner and analysis being unimportant. CONCLUSIONS: Given the wide range between the lower and upper limits of agreement, it would probably not be possible to detect anything but large differences or changes in cervical volume or cervical flow indices using current 3D ultrasound techniques. Because acquisition explained most of the intrasubject variance, the average of several repeated acquisitions should be used to enhance reproducibility. However, it is not worth doing more than one analysis of an acquired volume, because the effect of analysis on measurement results is small.