Ultrasound can be a helpful diagnostic for many conditions of a mother, fetus, or neonate. These include placenta previa, abruption, incomplete abortion, causes of bleeding, multiple gestations, ectopic pregnancies, and many others. Compact ultrasound units have gained interest for low-resource settings due to their portability and lower price.
Mechanism of Action
Ultrasound devices transmit sound waves at 2-18 MHz (hundreds of times greater than the limit of human hearing) and create an image based on the reflected waves received by the same handheld transducer. The strength of the reflected wave depends principally on the difference in density between adjacent structures inside the body. The more dissimilar the tissues, the more reflective their boundary will be. Images are typically 2D “slices” but more recent devices present 3D images and animations. Doppler ultrasound can also be used to measure blood flow. Devices require a coupling gel on the surface of the body, and most come with probes of different shapes suited to imaging different anatomy.
Current Use in High-Resource Settings
Universal coverage is common in many developed countries, although substantial debate persists on the utility of routine screening. A Cochrane review of eight studies randomizing 27,024 women found that routine ultrasound after 24 weeks gestation does not improve outcomes of pregnancy. Selective screening of high risk mothers, on the other hand, is generally agreed to save lives. In all settings, clinical relevance is highly dependent on the operator’s skill and timing of the screening.
Application in Low-Resource Settings
Ultrasound use is less common in the developing world, but available in urban centers. The use of ultrasound for fetal sexing (leading to selective abortion) is a serious issue in several emerging markets, including India, where fetal sexing by ultrasound is illegal, and punishable with prison time.
Associated technologies in Development
GE India Mobile Ultrasound, ITW Ultrasound, Mobisante Mobile Ultrasound, UWASH Ultrasound