By means of a program in a rural health system in Zanzibar, 62% of antenatal providers of varied medical backgrounds were trained to provide screening ultrasound exams on pregnant patients. Trainees were able to perform all tasks recommended by the WHO in limited-resource developing world settings [30]. To reflect regional practice realities, the majority of clinician-trainees were neither medical officers (general practice physicians) nor consultants (obstetrics/gynecology specialists). These findings extend the utility of this type of training which has been successfully applied in previous studies of physician providers to environments where non-physician providers are used for primary care and basic evaluations [12, 14, 22]. Six of the eight trainees who successfully completed the course were non-physicians. Thus by including non-physician providers, we increased the number of ultrasound-trained practitioners and provided one regional hospital with professionals with ultrasound skills on site. All 13 trainees significantly improved their ultrasound skills from their baseline pre-training test.
Recommendations for universal performance of an antenatal ultrasound evaluation are based on the clinically important information that it provides [5, 29]. In addition to facilitating recognition of fetal growth restriction, a major cause of perinatal morbidity and mortality, ultrasound allows improved decision-making about the level of obstetrical care that will be needed at delivery. In rural and low-resource settings, this determines the need for and timing of transfer of patients to facilities with more advanced resources. This decision is consequential first because failure to recognize a serious condition requiring transfer (e.g., placenta previa) places both mother and child at risk of death or life-long morbidity, and second because unnecessary or untimely transfers burden an already-overloaded referral system and may lead to financial and logistical burdens in an environment where many patients live far from roads and vehicular transport is limited.
While defined standards are needed for any diagnostic test one of the essential characteristics of PoCUS and CPUS is that it is a focused and limited exam. Because PoCUS is performed by providers with many other clinical duties and responsibilities, a common determinant of the focus and limitations of the exam is its complexity. In general, PoCUS applications tend to be more easily incorporated into practice if they are simple to perform and interpret. With respect to image acquisition, this involves sonographically accessible anatomy, easily identifiable structures, readily obtainable imaging planes, and key findings that are subject to binary (“yes/no”) interpretation (with “I don’t know” always being a third option). In our study, we found that measurement of femur length was challenging to many learners. This is most likely because accurate femur acquisition relies on an accessible fetal position, can require more difficult imaging planes, and can be confused as the humerus bone [31]. Accordingly, we did not include it as a requirement for successful completion of the ultrasound program. This will result in a minor limitation in the estimation of fetal age for trainees of this course since in the third trimester methods that combine several measurements are slightly more accurate than those that use one only [28, 29, 32]. However, all methods of estimating due date are most accurate in the first trimester with declining accuracy thereafter and a margin of error of 3 weeks in the third trimester [32,33,34,35]. This limitation would not affect the utility of the exam to determine multiple gestations, fetal lie, placenta previa, and oligo- or polyhydramnios, typically in the third trimester.
CPUS provides valuable diagnostic information from equipment that is increasingly compact, robust, and user-friendly. Capital costs and infrastructure needs are moderate in comparison to those of other modalities of diagnostic imaging and can be used to inform clinical decisions in real-time at the point of care. A challenge is the level of educational investment that is required for the training of sonologist-clinicians. Users of CPUS must master a range of skills that include cognitive mastery of ultrasound theory, technical mastery of the ultrasound machine, anatomical knowledge, ability to conceptualize anatomy in “3-D”, psychomotor skills to manipulate an ultrasound probe with one hand while operating a machine with the other, and the ability to integrate the information obtained by ultrasound into clinical practice [36, 37]. The “muscle memory” to simultaneously operate the ultrasound machine with one hand and the transducer with the other requires extensive repetition. In addition, identification of fetal anatomy that has no uniform location or axis (in contrast, for example, to an adult heart) and normal variations in maternal habitus require complex spatial reasoning. The psychomotor processing that occurs during ultrasound scanning is summarized in Fig. 3. The importance and difficulty of acquiring these skill sets is reflected by the extensive practice requirements of most CPUS training programs. In the current study, the 6 months of on-site proctoring was deemed necessary for the relatively large group practicing in geographically disparate sites with ongoing clinical responsibilities that prevented them from using a shorter period dedicated exclusively to ultrasound training.
Our findings are consistent with previous data demonstrating that trainees can master the cognitive portion of ultrasound training [7,8,9, 11, 13,14,15, 17, 18]. Our finding that the more successful students in the OSCE were those who performed the most scans (112 compared to an average of 76.6 for those who did not pass) is open to two very different interpretations. On the one hand, it might be taken to indicate that the number of scans performed predicts successful test performance. This hypothesis would suggest that future training programs should consider a target number of required scans of 100 or more, rather than 75. However, we favor the alternative hypothesis that trainees with greater innate aptitude find it easier to learn the skills of ultrasound, and therefore perform more scans (which thereby creates a “virtuous cycle” in which they learn more from doing more scans, leading to ultrasound becoming more clinically useful to them, thereby creating a further incentive to perform more scans). This hypothesis is consistent with the common observation among those involved in ultrasound education that learners have a broad spectrum of aptitudes to the complex cognitive, visual, and psychomotor skills required to perform ultrasound [32, 33]. Based on these considerations, our finding would argue that future training programs should strive for a more tailored approach in which earlier and more frequent OSCEs would identify the trainees with natural aptitude earlier thereby allowing them to be recognized as competent for independent practice sooner, and with less scans. This would result in ultrasound’s benefits being conferred on the patients of the trainees with “high aptitude” while freeing up trainers to focus their time on those who need the most help. Unfortunately in the current training program, we lacked the manpower to perform more frequent OSCEs in this scattered group of learners in a geographically remote and inaccessible area.
The selection of trainees for this ultrasound course was made by the MOH with our recommended emphasis on trainees’ interest, and need for proficiency in English. Ideally, assessment of potential trainees would focus not only on interest and English proficiency, but also computer and touch-screen competency, psychomotor skills, and visuospatial intelligence. This might lead to increased successful completion of the training program, in addition to allowing for a more tailored approach to training and competency certification, as discussed above. It is also possible that teaching in learners’ native language (Swahili in this case) might accelerate learning, even among conversationally fluent English speakers.
All trainees had the same opportunities to perform proctored scans and instruction was offered outside of scheduled duty hours but many participants did not make use of this option. Conversely, trainees who successfully completed the course had higher attendance at scheduled training sessions and, if unable to attend, were more likely to schedule a make-up session. It is possible that despite these arrangements, competing personal or professional responsibilities interfered with some trainees’ ability to attend. Anecdotally we noticed that practitioners who lived far from the training sites and those with heavy clinical loads did less proctored scanning. For future training programs, it would be ideal if participants’ clinical sites could offer trainees protected time during duty hours to ensure attendance at supervised scanning sessions. Given the human and financial resource limitations in many developing-world rural areas, this will continue to be an issue when planning future courses.
An unexpected challenge for our learners, all of whom use cell phones extensively, was lack of familiarity with common components of lap-top technology such as trackballs, track-pads, keyboards, and touch screens. Before we could begin teaching image acquisition and interpretation, a significant amount of time was needed for some trainees to familiarize themselves with this interface. This slowed the learning curve that had been anticipated during the initial 10-day training course. Therefore, in future initiatives of this type, it would be useful to make a pre-course assessment of baseline familiarity with the required technology.
Our group was made up of providers with three levels of medical training. At the first level, nurse-midwives receive 2 years of tertiary (beyond secondary school) education. Clinical officers who are widely used in health systems throughout Africa receive 3 years of medical education. They work clinically by performing medical histories, physical exams, and basic treatment in health centers [38]. Further training can qualify clinical officers to perform some surgical and obstetric operations such as exploratory laparotomy and cesarean sections. Tanzanian physicians (also referred to as “medical officers” if they have not received any specialty training) have attended a 5-year medical school program followed by a mandatory 1-year general internship [38, 39]. All physicians are trained to perform routine obstetric operations. A notable finding in our study was that trainees with higher levels of education also performed better on the written and OSCE exams. These findings suggest that more extensive study of preclinical sciences (especially basic physics and general anatomy) is advantageous in developing the psychomotor skills needed in real-time ultrasound scanning. It was also noted that those with more training had better proficiency in English which may have improved communication and learning with our English-speaking group of instructors. To address these issues, we would suggest the following modifications. First, the initial pre-test should de-emphasize ultrasound knowledge (which is minimal) and try instead to identify trainees’ knowledge of anatomy, clinical management, and English proficiency. Second, basic lectures should be tailored to address knowledge gaps identified in the pre-test. Finally, time allowances should be made to teach this material in the introductory classroom course.
This study sheds new light on the challenges of ultrasound training in developing world settings, in addition to confirming some previous observations. In 2014, Swanson et al. reported on a training program for 14 midwives in rural clinics in Uganda. They successfully trained the entire group in a curriculum that was more limited than ours (cardiac activity, fetal presentation, fetal number, placental position, and first trimester identification of intrauterine pregnancy), with the stated goal of ensuring a scanning time of 5 min or less. A key element of their program was a continuous 6-week proctored course in a single location during which time trainees were relieved of all clinical responsibilities, which were taken over by temporary replacement providers. In another report of a training program for midwives, Vinayak et al. trained a group of 3 providers using a pre-training e-learning module followed by 4 weeks of dedicated training that included direct bedside proctoring and 2 h of lectures daily. This training period was supported by funding for trainees’ salaries, travel to a distant training location, lodging, and replacement providers to cover their clinical duties while away. The training period was followed by a period in which the scans of 271 patients were transmitted digitally for teleradiology review, with almost 100% confirmation of the midwife sonologist findings. Sonologists were able to reduce scan time from 20 to 10 min with increasing experience and confidence.
A study published in 2020 by Shah et al. examined a POCUS training protocol at labor and delivery triage for 25 Ugandan practitioners (23 midwives and 2 physicians) that included a 2-week training course followed by an additional 8 weeks of hands-on training, image quality review, and 25 proctored scans. Trainees completed OSCEs and had an 89.4% first attempt pass rate. This study benefited from having dedicated local trainers which assisted in overcoming language barriers and improved contextual understanding. Interestingly, this cohort had greater accuracy measuring femur length and more difficulty with other gestation age-related biometry measurements which is the opposite of what we found.
Our program suffered from a shorter dedicated training period (during which trainees returned to their home environments for the weekends). While it is possible that medical students whose lives are entirely dedicated to study can assimilate ultrasound skills as an integrated part of coursework, it appears that those in clinical practice (including those in residency) benefit from a period of dedicated training, which seems to lead to a more rapid mastery of ultrasound skills, improved retention, and integration of ultrasound into previously established patterns of clinical practice. To compensate for these factors, our program was designed with the continual presence of an experienced sonologist to proctor scanning and continue with didactics over a 6-month period after the initial training course.
Several other challenges were encountered in the course of our program. All of our lectures and course materials were delivered in English. Despite a requirement of English proficiency during the selection process, trainees had various degrees of English competency. Since medical school training in Tanzania is in English, this was not a problem for physicians, but was increasingly prevalent among our trainees in inverse proportion to the number of years they had spent in post-secondary school education. Future courses would ideally include a local language interpreter/trainer [22, 40]. In addition to the previously noted problem of some trainees not obtaining adequate numbers of proctored scans, 3 of the 13 trainees took leaves of absence for over a month during the training course due to illness or family circumstances. Such absences are likely to both impede psychomotor progress at the same time as eroding retention of previous training [9, 13, 41].
Common infrastructural problems can also be important impediments. Reliable electricity is often an issue in sub-Saharan Africa, leading to difficulty maintaining battery charges for the ultrasound machines. Environmental conditions with extremes of heat, humidity and dust make many parts of the developing world a challenging environment for electronic equipment, even with machines designed to military specifications such as the Sonosites used in this study. There is very limited local technical support for almost any form of medical equipment in sub-Saharan Africa, so that two (of three) ultrasound machines had to be returned to the United States for repair during the training course (one with screen, the other with battery malfunction). Since the ultrasound manufacturers do not cover the shipping for repairs, transportation of machines to and from the United States had to be arranged by the program through other groups or individuals working in Africa. Fortunately, the machines were incapacitated at different times, so that the remaining two machines could be shared between sites. However, the absence of dedicated machines at each site spanned 2 months in which trainees at one of the sites could not perform ultrasounds. We attempted to mitigate these issues by including lectures on basic maintenance and troubleshooting and would suggest that future programs make contingency plans with back-up resources for almost inevitable equipment malfunction.
The time and effort of this program depended entirely on volunteerism. While there are clear personal benefits of such work, there are also intangible as well as financial costs to the donor individuals, as well as the economic loss to the health system in the volunteers’ home country, ultimately shared by the taxpayers who help to shoulder the burden of supporting medical education [42]. Both forms of cost should be considered in ensuring that the limited resources available for medical infrastructure building in the developing world are used to the maximum effect while seeking to ensure that projects cohere with the priorities and goals of the host country [40]. The current project sought to address these competing priorities with an extensive needs assessment of the host healthcare system, and consideration of the available resources of the volunteer trainers. While it is ideal to have a trainer present continually as we did during our study period, such resources will rarely be available over such extended periods. With improving connectivity and bandwidth in all parts of the globe, it is likely that remote forms of proctoring with telemonitoring technology as well as distance learning techniques will mitigate the need for such intensive on-site supervision.
Our project was subject to challenges common to ultrasound education in remote and resource-limited settings. Limitations of manpower and the need for high trainer to trainee ratios resulted in a small cohort of learners for our study. We recognize that our small sample group limits our ability to generalize our findings to other populations or settings.
Despite the relatively low course pass rate of only 8 of 13 trainees, the MOH feels that this training has resulted in improved prenatal care in the clinics in Pemba. They have invited the PURE organization to repeat the course in the southern island of Unguja and are supporting it by applying for funding for this initiative. Along similar lines, a 1-week “train-the-trainer” course was completed in February of 2018 for the successful trainees. The impact of the “train-the-trainer” course in training a second “generation” of sonologists remains to be evaluated.