Kathleen Kuhlman

Cervical ultrasonography compared with manual examination as a predictor of preterm delivery

OBJECTIVEnOur purpose was to compare the accuracy of ultrasonographic and manual cervical examinations for the prediction of preterm delivery.nnnSTUDY DESIGNnOne hundred two singleton pregnancies at high risk for preterm delivery were followed up prospectively from 14 to 30 weeks with both serial cervical ultrasonography measurements and manual examinations of the length of the cervix. The primary outcome studied was preterm (< 35 weeks) delivery.nnnRESULTSnExcluding six induced preterm deliveries, 96 pregnancies were analyzed. The mean cervical length measured by ultrasonography was 20.6 mm in pregnancies delivered preterm (n = 17) and 31.3 mm in pregnancies delivered at term (n = 79) (p = 0.003); the mean cervical lengths measured by manual examination were 16.1 mm and 18.6 mm in the same preterm and term pregnancies, respectively (not significant). The sixteenth- and twentieth-week ultrasonographic cervical lengths predicted preterm delivery most accurately (p < 0.0005). The 25th percentiles of ultrasonographic (25 mm) and manual (16 mm) cervical lengths showed relative risks for preterm delivery of 4.8 (95% confidence interval 2.1 to 11.1, p = 0.0004) and 2.0 (95% confidence interval 0.5 to 4.7, p = 0.1), respectively; sensitivity, specificity, and positive and negative predictive values were 59%, 85%, 45%, 91%, and 41%, 77%, 28%, and 86%, respectively.nnnCONCLUSIONnCervical length measured by ultrasonography is a better predictor of preterm delivery than is cervical length measured by manual examination. Cervical ultrasonography in patients at high risk for preterm birth seems to be most predictive of preterm delivery when it is performed between 14 and 22 weeks gestation.

Ultrasonic imaging of normal fetal response to external vibratory acoustic stimulation

Fetal facial reactions and response decrement patterns to external noise stimulation were studied to characterize normal fetal neurobehavior in the third trimester. Response decrement, or habituation, is thought to reflect higher central nervous system function. Two hundred women with uncomplicated pregnancies, who were subsequently delivered of healthy infants at term, were studied between 26 and 41 weeks gestation. After ultrasound views of the fetal face were obtained, a vibratory acoustic stimulus was applied repetitively to the maternal abdomen near the fetal head. Response decrement was defined as cessation of all components of the facial reaction, except eye blinking, over two sequential stimuli. Three response patterns were scored: (1) no startle, (2) startle without response decrement, and (3) response decrement by 12 stimuli. Whereas only 53% of fetuses between 26 and 27 weeks displayed startle reaction, all fetuses displayed startle responses by 28 weeks. As gestational age advances, an increasing number of fetuses exhibit response decrement, from no decrement at 26 to 27 weeks to 100% decrement at 40 to 41 weeks. A maturation of neurobehavioral response patterns takes place in normal third-trimester pregnancies. Response decrement testing may be a useful tool for in utero neurologic evaluation.

Three-dimensional ultrasonographic imaging in obstetrics: Present and future applications

Received September 28, 2000, from the Departments of Radiology, Division of Ultrasound (G.B., A.L.-T., A.K., B.G.), and Obstetrics and Gynecology, Division of Maternal-Fetal Medicine (K.K., R.W.), Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania. Revision requested November 7, 2000. Revised manuscript accepted for publication January 22, 2001. We thank Frederic Ross for expert assistance with preparation of the images. Address correspondence and reprint requests to Gjergji Bega, MD, Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, 834 Chestnut St, Suite 400, Philadelphia, PA. Abbreviations GSV, gestational sac volume; RVOT, right ventricular outflow tract; 3D, three dimensional; 3DUS, three-dimensional ultrasonography; 2D, two-dimensional; 2DUS, two-dimensional ultrasonography onventional two-dimensional ultrasonography (2DUS), which is routinely used in obstetrics, has proved to be a powerful tool in clinical diagnosis and management. However, the ability to obtain certain views of the fetus may be limited with 2DUS because of fetal position. With three-dimensional ultrasonography (3DUS) any desired plane through the fetus can be obtained regardless of fetal position at the time of volume acquisition, although image quality will vary among planes. As with 2DUS, certain factors such as oligohydramnios and maternal body habitus influence image quality. Using 2DUS images, the operator mentally constructs a three-dimensional (3D) concept of fetal anatomy and pathologic features. However, the ability to “think three-dimensionally” is variable among practitioners and depends on experience and innate ability. Some clinicians and patients find it difficult to gain a 3D understanding from conventional “slices” of ultrasonographic information. In addition, even experts may have difficulty interpreting 2DUS images of some complex or subtle lesions. Three-dimensional ultrasonography has recently been introduced into clinical practice. In 3DUS, a volume of ultrasonographic data, rather than a 2D slice of ultrasonographic data, is acquired and stored. The stored data can be reformatted and analyzed in numerous ways. With 3DUS, numerous arbitrary planes can be shown. By correlating the 3 perpendicular planes, which are seen in the multiplanar display, it is possible to verify that a true coronal or true midsagittal plane has been obtained. After reformatting the planes, surface rendering can be accomplished to show a lifelike 3D image. Work to date suggests that these postprocessing capabilities make 3DUS a useful tool in the visualization of normal and abnormal fetal anatomy. Furthermore, multiplanar

Application of Three-dimensional Ultrasonography in the Evaluation of the Fetal Heart

The objectives of this study were to determine whether three‐dimensional ultrasonography can provide more cardiac views than two‐dimensional ultrasonography and to develop a standard technique. Eighteen women, 16 to 26 weeks gestation, were scanned with two‐dimensional ultrasonography for 10 minutes or less to obtain fetal heart views. Three‐dimensional ultrasonography was used (< or =10 minutes) to obtain up to 4 acquisitions of the fetal heart: 4‐chamber view, left parasagittal, transverse, and longitudinal nonstandard. Views were later extracted from saved volume data, comparing the yields of two‐ and three‐dimensional ultrasonography. The 4‐chamber view was obtained in 15 (93%) of 16 cases on both two‐ and three‐dimensional ultrasonography. On two‐dimensional ultrasonography, the left outflow tract was obtained in 68% of the cases; on three‐dimensional ultrasonography, the left outflow tract was obtained in 46% from the 4‐chamber view acquisition and in 100% from the left parasagittal acquisition. On two‐dimensional ultrasonography, the right outflow tract was obtained in 68% of the cases; on three‐dimensional ultrasonography, the right outflow tract was obtained in 86% from the 4‐chamber view acquisition and in 71% from the left parasagittal acquisition. Aortic and ductal arches were obtained in 12% and 18%, respectively, on two‐dimensional ultrasonography. On three‐dimensional ultrasonography the aortic and ductal arches were obtained in 66% and 86%, respectively, from the 4‐chamber view acquisition and in 57% and 71%, respectively, from the left parasagittal acquisition. Three‐dimensional ultrasonography permitted a greater number of cardiac views to be extracted from volume data than did two‐dimensional ultrasonography.