SAN FRANCISCO - With its unique ability to demonstrate mid-sagittal and coronal planes in a multiplanar display, three-dimensional ultrasound may be a more effective predictor of pre-term delivery than two-dimensional sonography, according to a presentation at the American Institute of Ultrasound in Medicine conference this week.
The study compared 3-D ultrasound of the cervix with 2-D ultrasound in 20 pregnant patients at risk for pre-term delivery. Using a multifrequency probe of 5-8 MHz, cervical volumes were acquired, along with multiplanar views of the mid-sagittal, coronal, and axial planes.
"The real benefit of 3-D ultrasound data is that it can be reformatted in an infinite number of scan planes," said presenter Dr. Gjergji Bega of Thomas Jefferson University in Philadelphia. "We are trying to develop a standard technique for using 3-D ultrasound to study the pregnancy cervix in a multiplanar display. Our specific hypotheses with this study were that cervical length, funnel width, and funnel length differ between 2-D ultrasound and 3-D ultrasound."
The three parameters were measured with both 3-D and 2-D ultrasound and correlated with pre-term delivery at less than 35 weeks. Pre-term delivery occurred in five of the 20 study subjects (25%).
3-D imaging showed a shorter cervical length than 2-D in 25% of cases, with a range between 6 mm and 12 mm. Two of the patients with a shorter cervix on 3-D had a pre-term delivery. In another five patients, cervical length was longer in 3-D images, ranging from 6 mm to 15 mm, with no pre-term delivery.
In five cases, only 3-D ultrasound was able to show a flattened or slit-like funnel, Bega said. Of the two patients who had funneling on the sagittal and coronal planes of the 3-D ultrasound image, one had pre-term delivery. Two cases where funneling was found only on the 3-D ultrasound coronal planes did not result in an early birth. But the one patient who had funneling on a 3-D ultrasound sagittal image did have a pre-term delivery.
Future studies with a larger patient population will need to be done, but 3-D ultrasound imaging does improve the understanding of cervical morphology, Bega concluded.
By Shalmali Pal
AuntMinnie.com staff writer
April 6, 2000
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