Obstetrical Ultrasound Technique Improves Care in Resource-poor Areas
Monday, Nov. 30, 2015
An easy-to-learn volumetric imaging technique has the potential to widen the reach of obstetric ultrasound and reduce infant mortality in resource-poor regions of the world, according to research presented Sunday.
Women in medically underserved communities throughout the world often have no access to basic obstetrical imaging during their pregnancies due to a lack of resources and trained personnel. Without ultrasound, potentially dangerous complications of pregnancy can go undetected, resulting in increased maternal, infant and neonatal mortality.
Study author Kristen K. DeStigter, M.D., from the University of Vermont College of Medicine, saw firsthand the value of ultrasound in resource-poor communities while working in Africa in the 1990s. In 2007, she partnered with Brian Garra, M.D., an expert in ultrasound volume scans, which replace each still ultrasound image with a series of images gathered by sweeping the transducer across the organ or body area of interest. Through their foundation, Imaging the World, Drs. DeStigter and Garra developed a protocol for capturing these volume scans—also known as "cine loops" or ultrasound sweeps—and sending them across the Internet to an obstetrical expert for evaluation.
The technology is highly portable, relatively inexpensive, and previous research has shown that the scanning portion can be taught in a just few hours to people with no experience.
"At first we were compressing and transmitting the sweeps for quality assurance purposes, but when we saw that the images were quite good we started to wonder whether it was possible to use the sweeps for primary interpretation to identify complications early in pregnancy," Dr. DeStigter said. "If so, then this method could be a game changer for rural areas where skilled human resources are scarce."
Dr. DeStigter and colleagues taught individuals to generate anatomically guided sweeps by making three passes with the transducer over the abdomen of pregnant patients both horizontally and longitudinally. They then asked two obstetricians and one radiologist to review the anatomy on those sweeps. Results for 91 patients were compared to those from routine obstetric ultrasound exams performed on the same day on the same patients.
The sweeps were effective at identifying basic findings of pregnancy, such as multiple pregnancies and breech presentations.
In a result that Dr. DeStigter described as both surprising and encouraging, scans from more than 73 percent of the minimally trained individuals were useful for estimating gestational age through measurements of the biparietal diameter (BPD), a skull measurement commonly used to measure fetal size.
The sweeps were accurate to within seven days of the gold standard, suggesting they could be used to evaluate for intrauterine growth restriction (IUGR), a condition in which the fetus is smaller than it should be at a particular point in gestation. IUGR, which can lead to serious health problems for the baby, is closely linked with the health of the mother.
Accurate ultrasound dating also is important in cases of preeclampsia, a hypertensive disorder of pregnancy that is a common health problem in Africa. Women often present at a rural health clinic in critical condition with preeclampsia, and decisions about management, such as emergent delivery versus treatment with steroids to delay delivery, must be based on accurate ultrasound dating to improve fetal outcomes and decrease maternal morbidity.
"It's important to know the gestational age and, if necessary, get the mother to a higher level of care," Dr. DeStigter said. "If the mother has a condition like diabetes or high blood pressure, we can treat her condition and improve the chances of a successful pregnancy."
The technology has potential applications outside of the obstetrics realm, Dr. DeStigter added, such as imaging pediatric patients for abdominal emergencies, looking for evidence of heart disease in pregnant women and evaluating breast lumps. Ultrasound sweeps also show great potential for emergency imaging in the aftermath of natural disasters, Dr. DeStigter said.