Self-made transvaginal ultrasound simulator: new training equipment in ultrasound evaluation of controlled ovarian stimulation and oocyte retrieval

The process of teaching and learning clinical and surgical procedures during medical practitioners’ residencies or postgraduate training is complex and filled with ethical issues^(1–3). Future specialists traditionally acquire their new skills while assisting actual patients, under the direct supervision of a more experienced professional. However, this form of training may increase the patients’ risks to injuries and it is associated with varied levels of treatment success; real-life training also requires a long period of mentoring, resulting in a slow learning curve and high training costs^(4–6).

Simulation is a training method used in different areas of knowledge, including medicine, where it is known as “medical simulation” or “healthcare simulation”^(7,8). Using simulators to train future specialists in medical procedures offers the opportunity to acquire and practice technical skills in a safe, controlled, and reproducible environment without the risk of harming the patient⁽⁷⁾. Other benefits of using simulators in medical education include a reproducible curriculum for all students, immediate learning feedback, improvement of psychomotor skills, accuracy in clinical decision-making, and learning to work in a multidisciplinary team⁽⁹⁾. The earliest simulators in medical history were the obstetrical manikins introduced around 1700. Nowadays, simulators are frequently used to train doctors, nurses, and laypersons in such procedures as cardiopulmonary resuscitation^(7,8).

Several medical societies currently recommend that training in a simulated environment should be part of the curriculum for resident physicians in several specialties. Computer technology advancements have made it possible to design virtual simulators that teach clinical and surgical skills with unlimited scenarios, simulation environments, and virtual patients^(10–14).

Modern virtual simulators are widely used as an aid in the training of invasive and non-invasive ultrasound skills; however, the cost of acquiring and maintaining such equipment is still a limiting factor for many medical teaching centers, especially in developing countries^(4,5,15,16). Several training programs in ultrasound use self-made simulators that stand out for the realism of obtained images and low cost of production^(17–21). These simulators, also known as “phantoms,” are created from synthetic products, as well as other components of animal and plant origin, to simulate the anatomical relationships and echogenicity of different body organs and tissues. Their small size, ease of assembly, and durability, especially in ultrasound phantoms using “‘meat models,” are important characteristics for an ideal self-made simulator^(22,23).

Practitioners involved in assisted reproduction technology and infertility fellowship programs must become proficient in ultrasound control for patients undergoing controlled ovulation stimulation and oocyte retrieval⁽¹¹⁾. The number of oocyte retrieval procedures performed under supervision to acquire proficiency may vary among trainees, but it is estimated that half of the trainees in a typical fellowship program need at least 13 procedures. On the other hand, proficiency in transvaginal ultrasound for monitoring controlled ovulation stimulation is quite variable^(11,24).

Soave et al.⁽²⁴⁾ observed that using a virtual oocyte retrieval training simulator improved the procedure’s efficiency, speed, and accuracy both in a group of experienced practitioners and in another group of novice physicians. In another study, involving 46 residents from several French hospitals, Corroenne et al.⁽¹⁵⁾ showed that a virtual oocyte retrieval simulator was a simple and efficient training method. Unfortunately, the cost of equipment and its delivery hinders access to the majority of commercially available virtual oocyte retrieval simulators.

This study aims to describe the creation of a self-made ultrasound simulation model for training practitioners in ultrasound control of ovulation induction and oocyte retrieval.

Training in antral follicle count and controlled ovarian stimulation The phantom can be used for 24 hours (conservation time of biological material) for training in antral follicle count and to count and measure follicles in the simulation of controlled ovarian stimulation. A transvaginal ultrasound probe at a frequency of 8–13 MHz was used to capture images (Fig. 3). The ultrasound probe should be covered with a condom for protection. During training with the phantom, the ultrasound technique is the same as that used in vivo: performing longitudinal and/or transverse scanning of each ovary and calculating the average diameter of each follicle based on the measurement of two axes. The superior opening of the 3D pelvis allows the repositioning of the ovaries in different locations, changing the degree of difficulty of the training (Fig. 3).

Fig. 3.

Feedback questionnaire

Figure 4 summarizes the answers provided by 14 physicians after the training sessions with the phantom. A review of the responses to the questionnaire showed that the phantom had a good appearance and design, is was realistic, helped to improve motor coordination, and could be a useful tool in the training of specialists in assisted reproduction.

Fig. 4.

During their training, specialists in reproductive medicine should acquire, among others, ultrasonographic skills of antral follicle counting, evaluating the number and size of ovarian follicles during controlled ovarian stimulation, and guiding oocyte retrieval procedure. To achieve this end, the European Society of Human Reproduction Embryology (ESHRE) recommends that the curriculum structure provide simulation training for future specialists¹¹. However, the reduced number of simulator models and the high cost of their acquisition and maintenance are limiting factors for implementing the recommended practice in residency and graduate programs.

Derr et al.⁽⁶⁾ observed that emergency physicians needed at least 25 exams in point-of-care ultrasound training to acquire proficiency in adequate preparation and insertion of the endovaginal transducer, identification of the bladder and uterus, and anatomic relationships of pelvic organs. However, the authors found that emergency physicians still had difficulty identifying the ovaries after this initial training, suggesting that a learning curve persisted after 25 exams⁽⁶⁾. Several authors have highlighted the importance of simulator training to improve ultrasound skills in obstetrics and gynecology. Chao et al.⁽²⁵⁾ observed that virtual simulator training considerably improved the skills of performing transvaginal ultrasound among first-year gynecology and obstetrics residents. Byford et al.⁽²⁶⁾ found that incorporating virtual simulator training into an obstetrics and gynecology residency program improved confidence and ability to perform transvaginal ultrasounds. There are no clear guidelines on the minimum number of oocyte retrievals needed under the supervision of an expert to acquire competence in this procedure. ESHRE suggests that competency in oocyte retrieval is achieved with at least 30 procedures, and that a minimum of 50 oocyte pick-up (OPU) procedures would be required to achieve adequate qualifications⁽¹¹⁾.

Proficiency in oocyte retrieval should be evaluated not only by performing the procedure but by the results obtained, using the following variables: absolute number and rate of oocytes collected (number of oocytes collected/number of follicles), number of ovarian punctures, procedure duration, and number of short- and long-term complications⁽¹¹⁾. ESHRE suggests that, where possible, simulators should form part of the structured training for beginners wishing to perform OPU. Simulators make it possible to monitor basic skills and reach a predefined level of performance in a safe and controlled environment before performing the procedure on actual patients⁽¹¹⁾.

Our literature review did not find any mention of other self-made simulators being used in reproductive medicine to train practitioners in ultrasound skills. The strong points of our phantom include its low cost, ease of assembly, reproducibility, and the possibility of training many times by beginners. Practice with the phantom can help trainees in reproductive medicine to acquire basic ultrasonographic skills such as image construction, orientation in the sagittal and coronal planes, identification of the uterus and ovaries, counting and measuring ovarian follicles, and invasive procedures such as oocyte retrieval. Another strength of the phantom is the possibility of additional training for professionals who are already qualified but do not perform a sufficient annual number of OPUs to maintain their skills or need to refresh their existing ones.

The durability of the simulator and the lack of possibility to evaluate the rate of recovered eggs ‒ an essential criterion in competence evaluation – were the main limitations associated with this self-made simulator. The same simulator allows multiple assessments of ovarian follicles, but only a single OPU. Another downside of the phantom is the absence of structures that simulate the pelvic vessels, intestine, and rectum, which is relevant, as injuries to these organs are responsible for the rare complications observed in OPU.

The feedback questionnaire shows that the self-made ultrasound simulator produces ultrasound images that correspond to those obtained from an actual patient, especially of the uterus and ovaries with follicles of different sizes. The use of the ultrasound simulator allows the practices of counting, measuring, and follicular aspiration. However, an intervention study is needed to assess the impact of phantom-based training on the acquisition of ultrasound skills by OPU beginners.

In conclusion, the phantom described above has been designed for the purposes of instruction and practice in ultrasound-guided oocyte retrieval and evaluation of ovarian follicles in a supervised training environment. In addition, its realism and portability allow students to use it as a stand-alone repetitive practice station at their own pace and convenience. Thus, this self-made simulator is proposed as a training tool that could be included in the curricular structure of residency and postgraduate programs in reproductive medicine.