The WHO recommends that all pregnant women should receive at least one ultrasound scan before 24 weeks’ gestation to estimate gestational age, improve detection of fetal anomalies and multiple pregnancies, reduce induction of labour for post-term pregnancy, and improve a woman’s pregnancy experience.1 An ultrasound scan for gestational age estimation is most accurate when it is performed in the first trimester of pregnancy.2 Several antenatal interventions recommended by WHO confer benefit when used at specific gestational ages—such as antenatal corticosteroids for women at risk of preterm birth prior to 34 weeks’ gestation,3 aspirin for women at increased risk of pre-eclampsia prior to 20 weeks’ gestation4 and induction of labour for post-term pregnancy5—and hence the safe and appropriate use of these interventions can be affected by accuracy of gestational age estimation. WHO’s antenatal care recommendations emphasise the need for effective and reliable antenatal ultrasound services to be available to all pregnant women, in order to optimise maternal and newborn health outcomes.6 However, in many low-/middle-income countries (LMICs), women’s access to reliable antenatal ultrasound is often limited or only available in certain contexts, such as tertiary hospitals or in private health services.7 8 Resource constraints and limited infrastructure in rural health facilities further impact the ability to implement traditional or conventional ultrasound machines in these settings.
Recent years have seen the development of portable, wireless, compact or mobile-based ultrasound systems for obstetric use.9 If such portable ultrasound devices are as accurate as conventional, cart-based ultrasound systems—as well as being easy to use, affordable and acceptable to women and their healthcare providers—they could help improve pregnant women’s access to antenatal ultrasound, and thus increase coverage. A 2016 systematic review explored available research on the use of portable ultrasound devices in the triage, diagnosis and management of adult patients in LMICs, and found 36 studies describing their use in cardiac screening, abdominal assessment, obstetric dating, and in rapid triage in rural areas or emergency settings.9 While that review identified only three studies related to portable ultrasound use in pregnancy, a number of new portable ultrasound models have become commercially available since that review was conducted, including several models intended specifically for pregnant women.
We therefore aimed to conduct a scoping review to identify all available studies assessing the use of portable ultrasound devices for pregnant women, as well as aiming to identify what portable ultrasound models are currently commercially available. We did this review to help identify which (if any) devices would be useful for improving access to antenatal ultrasound for women in LMICs.