Tổng số lượt xem trang

Thứ Tư, 17 tháng 4, 2019

Ultrasound in late pregnancy could reduce C-section rate.

By Kate Madden Yee, AuntMinnie.com staff writer
April 17, 2019 -- Performing ultrasound scans late in pregnancy helps women avoid undiagnosed breech presentation of their babies, translating to improved clinical outcomes, lower rates of emergency cesarean sections (C-sections), and perhaps even lower healthcare costs, according to a study published April 16 in PLOS Medicine.
The findings are good news not only for women and their babies but also for the healthcare system, wrote a team led by David Wästlund of the University of Cambridge in the U.K.
"According to our estimates, universal late pregnancy ultrasound in nulliparous women would virtually eliminate undiagnosed breech presentation, would be expected to reduce fetal mortality in breech presentation, and would be cost-effective if fetal presentation could be assessed for less than 19.80 pounds [$25.95 U.S.] per woman," the group wrote.
Fetal breech presentation increases the risk of complications for the baby and the mother, Wästlund and colleagues noted. Typically, a baby's position is assessed by palpating the woman's abdomen, but this technique's sensitivity varies by practitioner.
"Despite the relative ease with which breech presentation can be identified through ultrasound screening, the assessment of fetal presentation at term is often based on clinical examination only," the researchers wrote. "Due to limitations in this approach, many women present in labor with an undiagnosed breech presentation."
The investigators performed screening ultrasound at 36 weeks gestation in 3,879 English women having first pregnancies between January 2008 and July 2012. Of these, 179 (4.6%) were diagnosed with breech presentation. In more than half of those (54%), breech presentation had not been suspected prior to labor.
Women with babies in the breech position were offered a procedure called an external cephalic version (ECV) to try to turn the baby; for those who did not want this procedure or for whom it did not work, a C-section was scheduled.
The investigators also estimated the cost of universal late pregnancy ultrasound scans using data from the English National Health Service (NHS) to compare birth outcomes of breech pregnancies screened with and without ultrasound.
The ECV procedure was attempted in 84 (46.9%) of the women with breech babies and was successful in 12 (14.3%). Of the 179 women with breech babies, the researchers found the following:
  • 10.6% delivered vaginally (following either a planned or spontaneous version).
  • 61.5% delivered via elective C-section.
  • 27.9% delivered via emergency C-section (due to labor starting before the scheduled cesarean date).
"No woman in the cohort had a vaginal breech delivery or experienced an intrapartum cesarean for undiagnosed breech," the researchers noted.
Wästlund and colleagues estimated that routine late pregnancy ultrasound could prevent nearly 15,000 undiagnosed breech presentations, more than 4,000 emergency C-sections, and seven to eight baby deaths per year. But the effect of the intervention on healthcare costs needs more research, the group wrote: "If universal ultrasound could be provided for less than 12.90 pounds [$16.91] per scan, the policy would also be cost saving." But it's unclear if this is possible.
"If this procedure could be implemented into routine care, for example, by midwives conducting a routine [scan at 36 weeks gestation] and using a portable ultrasound system, it is likely to be cost-effective," the group concluded. "Such a program would be expected to reduce the consequences to the child of undiagnosed breech presentation, including morbidity and mortality."

Elastography can help characterize breast tumors.

By Kate Madden Yee, AuntMinnie.com staff writer
April 16, 2019 -- Breast elastography is an overlooked tool for evaluating breast cancer, especially since it shows promise for helping radiologists distinguish between benign and malignant lesions, according to a presentation delivered at the American Institute for Ultrasound in Medicine (AIUM) meeting in Orlando, FL.
Since ultrasound is convenient, easily accessible, and less expensive than some other modalities, it's a helpful tool in the breast cancer detection arsenal. And since it can help characterize breast lesions, breast elastography could have downstream effects on patient care, according to presenter Dr. Stamatia Destounis of Elizabeth Wende Breast Care in Rochester, NY.
"Identifying the relative tissue stiffness can help clinicians distinguish between benign and malignant lesions, which in turn has the potential to reduce unnecessary biopsies," she said.
Although breast elastography has been available for more than 15 years, it's not widely implemented, in part because the various methods lack consistency -- particularly in color scale interpretation, Destounis noted.
"As research continues and elastography is used in clinical practice, there's a need for standardization of the color scale," she said.
Elastography can be performed in static and dynamic modes, and consensus about which mode is better is generally lacking. Static elastography includes strain imaging, while dynamic elastography includes shear wave. Strain elastography is the most widely used technique, estimating the relative stiffness of a particular area compared with other tissue.
In strain elastography, tissue stiffness data are displayed in a color map that is superimposed on a real-time grayscale image. Cancers tend to appear larger on strain elastography than on B-mode ultrasound, and benign lesions tend to appear smaller; this size change between the modes has shown to be highly sensitive and specific for characterizing breast lesions, Destounis said.
Studies have demonstrated that strain elastography is effective for detecting breast cancer, but it does have its drawbacks.
"It can be difficult to measure the amount of force during compression, and absolute elasticity can't be calculated," she said.
As for shear-wave elastography, it offers real-time, quantitative assessment of tissue stiffness; rather than relying on external compression, it uses short acoustic pulses to identify stiffness. To characterize breast lesions, clinicians should focus on the area of highest stiffness in the lesion. But be careful, Destounis cautioned.
"Some breast cancers don't allow for adequate shear-wave generation and may appear black -- that is, no shear-wave speed calculated or with a low shear-wave speed due to noise," she explained.
So which technique should clinicians use? Destounis cited research from Chang et al that found mixed results (American Journal of Roentgenology, August 2013, Vol. 201:2, pp. W347-356). The study compared strain and shear-wave ultrasound elastography for differentiating benign from malignant breast lesions, and it showed that strain elastography is more specific than shear-wave elastography (93.7% compared with 84.8%) but less sensitive (81.7% compared with 95.8%).
It may be a matter of improving elastography technology, Destounis told AuntMinnie.com via email.
"Several vendors have different types of elastography technology, and it needs more consistency in technique and color representation," she stated.