Laparoscopic surgery requires special skills and an increasingly specialized training. Human cadavers have recently begun to be used for laparoscopy training since they provide an anatomic model that resembles a real patient (1, 2). Fresh-frozen cadavers have been proposed as a useful model, but they can have increased costs since they must be kept in a large freezer and can present risk of infectious transmission (3). Furthermore, within three hours of de-freezing, the tissue begins to deteriorate, tissue quality decays and, consequently, they can only be used for a limited time. In the search for other embalming methods that achieved a better preservation, Thiel developed a formula that importantly reduced smell (when compared to fresh-frozen or formalin) and optimally preserved tissue, color consistency and transparency (5, 6). This embalming method is based on water and contains glycol, several salts and conservatives with low levels of formalin (0.8% in the immersion liquid). With the Thiel method, tissue decay is significantly slower, allowing the use of the cadaver for a longer period and repetition of the training sessions if necessary (7, 8).
The main reported disadvantage with this embalming method, if compared with animal models, is the lack of blood flow (7). In our course, 88% of our trainees and 70.6% of faculty thought that the Thiel-embalmed cadaver was an unreralistic model due to the lack of bleeding. In addition, 29.4% of the faculty and 44% of the trainees felt that the visceral tissue was less consistent/solid than an in vivo model. However, these cons are even more outstanding in any other cadaver models. Animal models can be considered an alternative for cadaveric simulation based on the realistic texture and appearance of the tissues, but the anatomical lay-out of the different structures presents significant differences. The logistics and necessary facilities plus the animal wellbeing policies can weigh against these training models.
Another characteristic of the Thiel method is that it provides exceptional desinfection qualities with a minimal exposure to the noxious chemical products, although the expenses for embalming can be relatively high and the fixation process may take as long as six months. The use of conventional formalin embalming is limited by the resulting tissue rigidity, consistency, and texture, by the strong smell and the impossibility of creating a pneumoperitoneum for laparoscopic training. (5, 8, 9)
Despite the Thiel cadaver model creates good conditions for laparoscopic surgery skill practice and excellent tissue preservation, it is not widely spread, and has only been used in 10% of the world’s Anatomy laboratories (10, 11). In the present study only one teacher and one trainee had used a Thiel cadaver for anatomic dissections and only 11.1% of the trainees had done any practice or laparoscopic procedures with a Thiel cadaver.
Nevertheless, even though Thiel cadavers provide a very appropriate model for surgical training, they have also some limitations that affect their usefulness as a surgical training medium. Firstly, the availability of cadavers is limited by the number of voluntary donations, the high cost of the embalment procedures and the requirement for specific facilities dedicated to cadaver storage, conservation, and dissection. (2, 12, 13). Secondly, their useful life is restricted, meaning that they must be used within a certain period and only a limited number of surgical procedures can be performed in each cadaver. The quality of cadaver tissue can vary widely depending on the time from death to preservation and the period in storage (1).
Cadaver models with this embalming method have proven to be anatomically superior to pigs in training procedures involving colorrectal surgery (9, 10). In our course, 94.1% of the faculty and 88% of the trainees considered the Thiel model to be superior to pigs or other animal models for laparoscopic surgery training sessions. Yiasemidou et al described that among surgeons the satisfaction level with currently used simulation models was low (65.4% of the participants in their study were dissatisfied with previous simulation models). However, the participants in their study found Thiel cadavers suitable for surgical simulation, realistic, and have reduced odour. They even concluded that the use of Thiel cadavers can be even more cost-effective that other simulation models14. A recently published study conducted on pelvic floor procedures simulation also confirmed our results. The participants recognized that Thiel cadavers present more similarities to patients than other simulation methods. The Thiel cadaveric method was considered by most responders to be the best for the simulation of surgical procedures on the pelvic floor and perineum. Most of the surgeons surveyed recommended conducting these courses with Thiel cadavers for different colleagues in other specialties as a reliable simulation method for training for difficult surgical procedures15.
Consequently, whenever possible, cadaveric models should be of choice for postgraduate training in surgical skills, allowing for a better real-life scenario visualization and providing the best opportunity to learn diverse surgical techniques in the human anatomy (3).
Given the high degree of satisfaction of the participating residents and staff in these workshops (100% of the faculty and 80% of the trainees considered it excellent), a standardized plan for similar courses should be explored to be included in the National Training Programs (12, 14). Thiel cadaver courses can be a great tool as a training model to teach, reinforce and improve technical skills in surgical practice. They can also be helpful to evaluate performance of specific procedures and could become part of the skills considered in the end-of training evaluation of surgical residents (8).
Costs associated with the use of a Thiel-embalmed cadaver for medical education are 10–20% greater than those of a formalin-preserved cadaver, but, as it can be reutilized and preserved without decaying or need for constant refrigeration, the long-term exploitation of a Thiel-embalmed cadaver could potentially be less costly.
Certainly, low incidence or high-risk procedures continue to be a concern in some medical training programs (9, 10). Many surgical residents have not been exposed to or performed these uncommon procedures on a patient during their clinical training. This issue has led to the need for alternative training methods that can compensate this lack of clinical exposure and allow the trainees to acquire the necessary skills and practical experience to master different techniques. Possibilities for this include employing simulation or animal and cadaveric models. The Thiel-embalmed cadaver can be a reasonable option to complement the surgical trainee’s clinical experience in environments in which not enough of these high-risk or low-frequency procedures are performed. In our course, 82.4% of the faculty and 72% of the trainees believed that training with a Thiel cadaver ought to be compulsory during residency training in preparation to performing live colorrectal surgery. This could also allow standarization of surgical procedures and a more precise evaluation of surgical capacities across the surgical training system, something that is essential to guarantee that the surgeons-to-be can perform these procedures safely, precisely, and efficiently (1, 13, 14).