New surgical technologies inevitably require scrutiny. With the increasing introduction of transoral endoscopic thyroidectomy via vestibular access (TOETVA), it is imperative to also define the procedure for the parathyroid glands to ensure the clinically safe introduction and use of the transoral endoscopic parathyroidectomy vestibular approach (TOEPVA). This study aimed to evaluate this technique in preoperatively localized solitary parathyroid adenomas, which seem to be appropriate targets for transoral surgery due to their small size and the expected simplicity of removal via transoral access within the European Transoral Endoscopic Para‑/Thyroidectomy Vestibular Approach Study Group.
Methods
This study included patients who underwent TOEPVA between February 2016 and February 2023 at seven European high-volume tertiary referral centers. Patients with sporadic primary hyperparathyroidism, with positive preoperative localization, and without previous neck surgery or radiation were included. The data were analyzed regarding the use of preoperative localization procedures, success rates, duration of surgery, complications, and type of specimen collection.
Results
Overall, 29 (90.6%) patients underwent pure TOEPVA. In 3 (9.4%) patients, TOEPVA was combined with hemithyroidectomy. Cervical ultrasound (US) was performed for all 32 patients and yielded a positive result. Tc99m sestamibi scintigraphy with single-positron-emission computed tomography (SPECT) was performed for 30 (93.8%) patients. Choline positron-emission tomography (PET)/computed tomography (CT) was performed for 4 (12.5%) patients with positive results. The mean operative time was 102 ± 46.9 (range 40–260) min. The success rate was 100% on the first postoperative day. One (3.1%) patient had recurrent laryngeal nerve palsy. Conversion to open surgery, revision surgery, or local infection did not occur. At discharge, 2 (6.3%) patients had local swelling, 3 (9.4%) had discoloration in the chin area, and 1 (3.1%) patient had local sensory disturbance but no motor deficit.
Conclusion
This is the first European report on TOEPVA presented by the European TOETVA/TOEPVA Study Group. In accordance with the results of other study groups, our results show that TOEPVA performed by experienced endocrine surgeons is a safe alternative to conventional surgery, with results, complication rates, and success rates comparable with and equal to focused conventional parathyroid surgery in localized primary hyperparathyroidism. However, further experience and studies are needed to confirm the clinical benefit of this technique.
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Introduction
For many decades, surgery for primary hyperparathyroidism (pHPT) has been safely performed via an anterior neck incision. A better understanding of pHPT as an almost always benign disease as well as evolving and improving localization procedures has led to more focused surgical approaches instead of bilateral cervical exploration (BCE) and intraoperative visualization of all parathyroid glands [1]. Focused approaches are currently considered the new gold standard for treating localized pHPT [2]. Remote-access techniques with the aim of optimizing cosmetic results by preventing scarring in the visible area of the neck have emerged [3].
Although wound healing mostly occurs without any problems after a skin incision of less than 2 cm—especially in white patients—a worldwide consideration of potential wound healing problems may lead to a more differentiated appraisal. For example, the incidence of keloid development after skin incision is up to 15% in African and African American patients, and in some countries, a scar on the neck is related to negative social standing [4, 5].
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The transoral endoscopic thyroid and parathyroid endoscopic surgery vestibular approaches (TOETVA and TOEPVA) represent the newest and most promising remote access techniques. Because of the small size of the parathyroid adenoma, transoral surgery seems to be ideal to achieve a perfect result by completely avoiding a skin incision. Meanwhile, the transoral surgery vestibular approach to the thyroid has been well evaluated by many study groups around the world and the published data are promising.
Currently, only a few reports have focused on the use of the TOEPVA [6‐9].
One reason might be that parathyroid surgery requires excellent knowledge regarding embryologic origin and development as well as detailed anatomic skills of the thyroid region also in preoperatively localized enlarged parathyroid glands independent of the surgical technique [31, 32].
To add to data regarding transoral parathyroid surgery, this study focused on TOEPVA surgeries performed in seven highly specialized endocrine centers, and overall, highly specialized endocrine surgeons from nine centers were involved. The aim was to provide additional data regarding the technical details, results, potential procedure-related complications, and need for and differences in preoperative localization procedures.
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Methods
Within this retrospective multicenter cohort study, data pertaining to TOEPVA procedures were evaluated from February 2016 to February 2023. TOEPVA was performed at five European endocrine centers, which are all members of the European TOETVA/TOEPVA Study Group. The data were collected by each institution. Centers using the EUROCRINE platform documented their data within the EUROCRINE TOETVA module. The selection of patients differed slightly from center to center; similar perioperative outcomes were identified among the patients.
This study was approved by the Ethics Committee of the Medical University of Vienna (EK 2493/2020).
All patients provided written informed consent for all diagnostic and therapeutic procedures. After approval, the data were pooled and analyzed retrospectively. In all patients, a diagnosis of pHPT was confirmed by blood tests, including parathyroid hormone (PTH) and serum calcium (Ca) tests.
Preoperative cervical ultrasound (US) and Tc99m sestamibi scintigraphy with SPECT as well as conventional CT scan and magnetic resonance imaging (MRI) was available in all centers. Choline positron-emission tomography (PET)/computed tomography (CT) was available in only two centers.
Inclusion and exclusion criteria
Inclusion criteria
We analyzed the following pHPT patients who underwent surgery with TOEPVA: (a) patients with a confirmed diagnosis of pHPT and a positive localization result from at least one localization procedure, (b) patients with informed consent, (c) patients of at least 18 years old, and (d) patients for whom none of the exclusion criteria were applicable.
Exclusion criteria
The following patients were excluded: (a) patients with incomplete data or incomplete follow-up, (b) patients with repeat operations, (c) patients lacking or with inconclusive parathyroid adenoma localization, (d) patients with recurrent or persistent pHPT, (e) patients with suspected multigland disease, (f) patients with secondary or tertiary HPT, (g) patients with a family history of multiple endocrine neoplasia (MEN), (h) patients with suspected parathyroid carcinoma, and (i) patients with previous neck radiotherapy.
TOEPVA
The surgical technique has already been described in previous publications [6, 10].
Transoral surgery was performed with either three 5‑mm trocars to reduce tissue trauma or one 10–12-mm midline trocar and two lateral 5‑mm trocars.
TOEPVA was performed by placing the patient in the supine position with slight neck extension under orotracheal intubation. Amoxicillin-sulbactam acid (3 g) was administered at least 30 min before the incision. The laparoscopic ports were inserted straight under the lower lip at the lateral oral vestibular area between the canine and first premolar teeth (Fig. 1). A 5‑ or 10-mm 30° rigid optical device was used via the central trocar. The working space was created down to the sternal notch and laterally up to the sternocleidomastoid muscles, and strap muscles were separated in the midline and retracted laterally by a transcutaneous suture (2.0 PDS) to widen the working space together with low-pressure (6–8 mm Hg) CO2 gas insufflation. In contrast to those used in transoral thyroid surgery, the thyroid isthmus was not routinely divided. Next, the thyroid lobe on the suspected side was mobilized, and the para- and retrothyroidal space was scanned precisely to detect the enlarged parathyroid gland (Fig. 2). The suspected parathyroid gland was mobilized (Fig. 3), and the vessels were sealed and dissected using a sealing device. After resection, the specimen was placed in an extraction bag and retrieved through the central incision.
Fig. 1
Trocar placement in the oral vestibule
Fig. 2
Mobilization of the right thyroid lobe. Arrow: recurrent laryngeal nerve (RLN) crossing the inferior thyroid artery (ATI). PG Patahtyroid galnd
Fig. 3
Right lower parathyroid adenoma, recurrent laryngeal nerve (RLN), and inferior thyroid artery (ATI)
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The landmark used was the position of the parathyroid glands relative to the recurrent laryngeal nerve (RLN). The upper parathyroid glands typically lie dorsal to the plane of the RLN, while the lower parathyroid glands lie ventral to the plane of the RLN. Intraoperative parathyroid monitoring was used in all patients. Intraoperative neuromonitoring was performed at all the institutions. Furthermore, in two centers, near-infrared fluorescent (NIRAF) imaging was used as an adjunctive tool for localization of parathyroid glands.
Intraoperative parathyroid hormone (IOPTH) levels were initially checked after the induction of anesthesia. The IOPTH levels were then re-checked after surgical removal of the parathyroid gland. A > 50% drop or a drop into the normal range in IOPTH levels after removal was used to confirm successful removal of the abnormal gland. The timepoint of post-removal IOPTH measurement was different at all centers.
In the case of simultaneous hemithyroidectomy, first, the thyroid isthmus was divided, and the lobe was mobilized. Afterwards, the upper pole vessels were sealed and dissected with a sealing device. The not-enlarged parathyroid was preserved, while the enlarged parathyroid was removed together with the thyroid lobe in an extraction bag. No drain was placed, and no pressure dressing was placed around the chin or upper neck.
Definitions
Primary HPT was diagnosed by the presence of hypercalcemia and a concomitant elevated or inappropriately normal serum parathyroid hormone (PTH) level—specifically, PTH >65 pg/ml with a serum Ca level >2.6 mmol/L. The diagnosis of asymptomatic pHPT was based on the absence of typical symptoms or signs associated with hypercalcemia; the diagnosis was made incidentally upon serum Ca level testing or neck ultrasound (US). The laboratory test results included serum Ca levels (reference range 2.20–2.60 mmol/L), serum phosphate levels (0.60–1.60 mmol/L), fasting blood glucose levels (FBS; 3.7–6.0 mmol/L), alkaline phosphatase levels (AKP; 50–135 U/L), serum creatinine levels (sCr; 58–133 µmol/L), PTH levels (15–65 pg/mL), and 25-hydroxyvitamin D levels (25(OH) D; ≥ 30 ng/mL). Patients were followed up by their surgeon, referring endocrinologist, or radiologist.
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Variables and outcomes
In addition, age and sex (male, female); type of preoperative localization procedure and outcome; intraoperative data, including duration of procedure (min), type of procedure, i.e., TOEPVA with or without additional retroauricular sampling incision; histology; intraoperative complications; conversion to open surgery; revision (defined as reoperation due to complications; reasons for conversion and/or revision were documented); postoperative complications such as temporary and permanent laryngeal nerve palsy (RLNP), hypoparathyroidism, infections, hemorrhage, seroma, scarring, skin discoloration, sensory disturbances, motor disturbances; and length of hospital stay were recorded. No recovery for more than 6 months was defined as permanent hypoparathyroidism. Complications related to the transoral approach were defined and assessed as perioral, mandibular rim, or cervical disorders, like discoloration of the skin or skin burn in the chin area, motor or sensibility disorders due to injury to the mental nerve (drooping corner of the mouth unilaterally or bilaterally), or impaired motor function of the neck.
Statistics
Data analysis was performed using SPSS version 23.0 (IBM Corp., Armonk, NY, USA USA). A p-value <0.05 was considered to indicate statistical significance. The metric parameters are described by the means, corresponding standard deviations, and minimums and maximums. The ordinal and nominal parameters are presented as absolute and relative numbers, respectively.
Results
Population
This study included 32 patients (all female) who had undergone TOEPVA. The preoperative data are summarized in Table 1. The diagnosis of pHPT was confirmed in all patients, and all patients were highly motivated to undergo transoral surgery.
Table 1
Demographic and preoperative data
Parameter
Mean ± SD (range)/n (%)
Age (years)
46.53 ± 12.79 (20–67)
Calcium (mmol/l)
2.89 ± 0.22 (2.5–3.5)
PTH (ng/dl)
196.13 ± 83.7 (98–453)
Sex: female
32 (100)
US
32 (100)
Tc99m sestamibi scintigraphy
30 (93.8)
Choline PET-CT
4 (12.5)
SD Standard deviation, PTH Parathyroid Hormone, US Ultrasound
The numbers of performed TOEPVAs in each center are shown in Table 2.
Table 2
Number of performed transoral endoscopic parathyroidectomy procedures
Institution
n
Ege University Hospital, Izmir, Turkey
10
Maria Hilf Hospital, Alexianer GmbH, Krefeld, Germany
8
Medical University of Vienna, Vienna, Austria
6
University of Milan, Milan, Italy
6
RoMed Hospital, Bad Aibling, Germany
2
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The mean follow-up period was 20.4 ± 19.2 (0.5–62) months.
Preoperative laboratory tests
Preoperative Ca and PTH levels were 2.89 ± 0.22 (2.5–3.5) mmol/l and 196.13 ± 83.7 (98–453) pg/ml, respectively. These test results, together with all performed blood testing results, confirmed the diagnosis of pHPT and excluded other reasons for hypercalcemia.
Preoperative localization imaging
Preoperative cervical ultrasound (US) was performed for all patients, which revealed a suspected parathyroid adenoma. In addition, 30 (93.8%) patients underwent Tc99m sestamibi scintigraphy with SPECT. In 28 (93.3%) patients, the presence of single suspected parathyroid adenoma was consistent with the US results. However, in 2 (6.7%) patients, the localization was not clear. Choline positron-emission tomography (PET)/computed tomography (CT) was performed for 4 (12.5%) patients and showed a definite localization. In one patient (3.1%) for whom Tc99m sestamibi scintigraphy was inconclusive, PET/CT showed the correct localization. In the other patient (3.1%), no further preoperative imaging was performed. MRI scans or other noninvasive or invasive localization procedures were not performed.
In three (9.4%) patients, an additional hemithyroidectomy was performed on the same side as the localized parathyroid adenoma. In all patients, the specimen was taken via the vestibular approach. The mean operative time was 102 ± 46.9 (40–260) min. Intermittent intraoperative neuromonitoring was performed in 29 (90.6%) patients.
Intraoperative parathyroid monitoring (ioPTH) was used in 22 (68.8%) patients, and intraoperative autofluorescence imaging was used in 6 (18.8%) patients. One (3.1%) patient experienced recurrent laryngeal nerve palsy.
Pathology
The location of the resected parathyroid adenoma was the upper left in 2 (6.3%) patients, the lower left in 19 (59.4%), the upper right in 2 (6.3%), and the lower right in 9 (28.1%) patients. The three (9.4%) combined parathyroid and thyroid operations lasted 175 ± 80.47 (range 100–260) min.
The median weight of the parathyroid adenomas removed was 0.8 g ± 0.3 (range 0.5–1.2 g). All glands were removed intact and within an endobag to avoid parathyroid cell spillage and rupture of the capsule.
Outcomes
Neither revision nor conversion was necessary. No burns of the skin in the chin area were noted. In addition, no transient hypoparathyroidism occurred, and the success rate, i.e., the achievement of normal postoperative Ca and PTH levels with mean values of 2.23 ± 0.15 (1.8–2.5) mmol/l and 28.21 ± 12.79 (11.16–60) ng/dl, respectively, was 100%, and no recurrent pHPT occurred in patients with a follow-up of more than 6 months. Postoperative pain immediately after surgery was 4/10 on the visual analog scale (VAS), where 10 is the maximum pain intensity; however, data regarding the VAS score were not available from all centers. No motor disturbances were observed. At discharge, swelling occurred in 2 (6.3%) patients, and mild hematoma in the chin area occurred in 3 (9.4%) patients; this swelling completely resolved within 2 weeks after surgery without intervention. Sensitivity disturbance, also in the chin area, was documented in 1 (3.1%) patient; no sensitivity disturbances were noted on the lower lip. No signs of infection were observed (Table 3).
Table 3
Postoperative data
Parameter
Mean ± SD (range)/n (%)
Operative time
102 ± 46.9 (40–260) min
Calcium (mmol/l)a
2.23 ± 0.15 (1.8–2.5)
PTH (ng/dl)b
28.21 ± 12.79 (11.16–60)
Adenoma weight (g)
0.8 g ± 0.3 (0.4–1.2)
TOEPVA
29 (90)
TOEPVA + hemithyroidectomy
3 (10)
Success rate
32 (100)
RLN palsy
1 (3)
Conversion to open
0
Local swelling at discharge
2 (6)
Infection
0
SD Standard deviation, PTH Parathyroid Hormone
aNormal range calcium: 2.2–2.7 mmol/l
bNormal range PTH: 11–65 ng/dl
Discussion
After substantial experimental and preclinical investigations regarding the potential to reach the thyroid region transorally by different study groups since 2006 [11‐13] and the worldwide first transoral parathyroid resection in 2010 [13], clinical proof of concept for transoral surgery via the vestibular approach was given by Anuwong, who published the first 60 transoral operations in patients who underwent scarless thyroidectomy via the lower vestibule of the mouth with excellent outcomes [14]. Sasanakietkul et al. published the first series of transoral transvestibular parathyroid operations (TOEPVAs) with promising results [6]. Moreover, several reports regarding the use of the TOEPVA have been published, and the results have been good. However, the number of cases is still limited [6‐9, 15, 30].
Our data are in line with other reports confirming that TOEPVA can be performed in selected patients with localized primary hyperparathyroidism [6‐9, 15, 30]. Results, complication rates, and success rates are comparable with and equal to focused conventional parathyroid surgery. Like in focused open and other remote-access techniques, definite preoperative diagnosis of pHPT, assurance of single-gland disease, and exclusion of contraindications, in addition to reliable localization of the suspected parathyroid adenoma, are of utmost importance.
In addition to a thorough diagnosis of pHPT and definite localization of the suspected solitary gland, selection of the “right” patient is of utmost importance.
Localization procedures
Ideally, ultrasound is the first-line imaging procedure, performed using a 12–15-MHz linear probe with a specificity of more than 90% for detecting a single adenoma. However, the sensitivity is between 27% and 95% due to the investigator dependence [16].
Surgeon-directed US should always be the preferred practice for visualizing the gland and evaluating its position in relation to the surrounding anatomic structures. In addition, thyroid pathologies can be detected, evaluated, or excluded. Once a suspected parathyroid adenoma is detected by US, as in open minimally invasive parathyroid surgery, to increase safety regarding the correct localization of the suspected gland, additional preoperative imaging can be performed. In our series, patients only underwent TOEPVA with positive US imaging, and only 2 patients underwent US alone to avoid unsuccessful transoral exploration and possible conversion to open surgery because all patients clearly expressed their wish to avoid a visible scar on the neck. However, given the experience over the past decade regarding success rates in other focused approaches, no further localization procedures are necessary if a suspected gland is detected by US and if the family history is inconspicuous regarding Multiple Endocrine Neoplasia (MEN) or familial primary HPT. Like other groups, the authors emphasize that surgeon-directed US should be iterated once anesthesia has been induced and the patient has finally been positioned in the operating room [17].
If further localization is necessary, technetium99m sestamibi scintigraphy should be performed in combination with SPECT, which helps to increase the accuracy of localization, with a sensitivity of approximately 70% and a positive predictive value of 78% to 100% [18]. Notably, the accuracy of nuclear imaging is diminished in patients suffering from multinodular goiter or an intrathyroidal parathyroid adenoma.
In conventional minimally invasive video-assisted parathyroid surgery, discordant preoperative localization or non-visualization of the gland on nuclear imaging does not necessarily lead to BCE if US reveals a suspected gland, because bilateral exploration of the neck can also be performed by video-assisted surgery and enlargement of the skin incision can easily be performed. However, the authors suggest that in cases of discordant preoperative localization and patients still interested in TOEPVA, additional imaging is inevitable, although it is also technically possible to perform bilateral exploration transorally.
Potential additional imaging procedures differ between hospitals and centers.
Even though not used in our series, one option is a so-called 4D CT scan.
Multiphase CT images were acquired in three phases (precontrast, arterial, and venous) along with the fourth phase, which represents the change in perfusion over time. Four-dimensional CT has a sensitivity of 85%, provides optimal anatomical detail in the neck, and may help in detecting multigland disease, while the increase in external radiation is small [19, 20].
Instead of CT or MRI, 18F-fluorocholine PET was used in 4 patients, all of whom had positive results. 18F-fluorocholine PET is rarely available and expensive (Fig. 4). The FSD indicates the functional status of the suspected gland in combination with its localization, with a high sensitivity of up to 94% and an overall accuracy of 95% [21‐25].
Fig. 4
a, b18F‑choline positron-emission tomography scan of a left lower parathyroid adenoma in a 65-year-old female with primary hyperparathyroidism. PT Parathyroid adenoma
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If two noninvasive imaging modalities are concordant, the positive predictive value in identifying the suspected gland is up to 99% [26].
In principle, if US clearly reveals a parathyroid adenoma, no other localization procedure is necessary in open and minimally invasive parathyroid surgery. Data currently available regarding TOEPVA do not ultimately show that TOPEVA can also be safely performed with only one localization procedure. However, in the case of non-detection of the suspected gland on one side, it is also possible to perform bilateral exploration transorally before conversion to open surgery.
Like in TOETVA, “correct” patients should also be highly motivated toward a “scarless” approach, and patients must be informed that cosmesis is the only veritable advantage of transoral surgery.
However, in most patients, especially in dedicated white individuals, wound healing occurs without any problems and is negligible after a skin incision of less than 2 cm is made [5, 15].
A small incision with potentially excellent long-term outcomes does not prevent a definite discrepancy in the perception of scars between surgeons and these patients, which leads to serious patient considerations regarding scar revision years after surgery in up to 10% of patients [5, 26, 27].
This finding is in line with reports that emphasize the significant negative effect of a cervical incision on health-related quality of life (HRQOL). The impact of a cervical incision on HRQOL was found to be similar to the impact of vitiligo, psoriasis, or severe atopic dermatitis [5, 27].
The presence of a scar in the visible area of the neck impairs patients’ ability to maintain healthcare privacy. In this context, Liao et al. demonstrated attentional bias toward the neck instead of the face or eyes during a conversation due to the presence of a scar after open thyroid/parathyroid surgery [28].
Furthermore, worldwide consideration of potential wound healing problems may lead to a more differentiated appraisal. In African countries, for example, the incidence of keloid development after skin incision is up to 15%, and in some countries, a scar on the neck is historically related to a negative social standing [4].
Various remote-access approaches to the thyroid have been proposed to prevent scarring. Remote-access surgery includes areolar, axillary, or combined areolar/axillary (ABBA) incisions as well as the retroauricular approach, which can effectively minimize the cosmetic burden in some patients. On the one hand, improved cosmesis but unfamiliar dissection planes, longer routes to the central neck, and novel complications have led to further investigations focusing on so-called natural-orifice approaches. The use of TOETVA as popularized by Anuwong has gained acceptance because it is safe and has a short learning curve [29]. He also proposed the transoral endoscopic parathyroidectomy vestibular approach (TOEPVA), which is like TOETVA.
As in other series, the success and complication rates of the current study are comparable to those of the conventional minimally invasive and open techniques [6‐9, 15, 30].
Surgeons interested in performing transoral parathyroid surgery should be well experienced in parathyroid surgery and familiar with embryological and anatomical characteristics, as in conventional parathyroid surgery [30‐32]. In addition, experience with laparoscopic instrumentation is beneficial. The transoral technique should be trained in cadaveric courses and should be frequently offered in specialized centers. Subsequent first transoral operations in the clinical setting should ideally be performed with the assistance of an experienced transoral surgeon.
The study is limited by the low number of patients, the high number of centers participating, and its retrospective design.
Conclusion
In accordance with the results of other study groups, this study presenting preliminary results of the European TOETVA/TOEPVA Study Group demonstrates that TOEPVA performed by experienced endocrine surgeons is a safe alternative to conventional surgery in localized pHPT. However, more data are needed, and more operations must be performed to improve the technique and to confirm our promising results.
Members of the European TOETVA/TOEPVA Study Group
Elias Karakas (Landesklinikum Salzburg, Universitätsklinik der PMU, Müllner Hauptstraße 48, 5020 Salzburg and Philipps University Marburg, Baldingerstraße 35043 Marburg, Germany); Melisa Arikan (Division of Visceral Surgery, Department of General Surgery, Medical University of Vienna, Waehringer Guertel 18–20, 1090, Vienna, Austria); Christian Scheuba (Division of Visceral Surgery, Department of General Surgery, Medical University of Vienna, Waehringer Guertel 18–20, 1090, Vienna, Austria); Philipp Riss (Division of Visceral Surgery, Department of General Surgery, Medical University of Vienna, Waehringer Guertel 18–20, 1090, Vienna, Austria); Theocharis Nikiforos (Department of General, Abdominal and Endocrine Surgery, Maria Hilf Hospital, Alexianer GmbH, Dießemer Bruch 81, 47805, Krefeld, Germany); Stefan Schopf (Department of General, Abdominal and Endocrine Surgery, Innklinikum Mühldorf, Krankenhausstraße 1, 84453 Mühldorf a. Inn, Germany); Günther Klein (Department of General Surgery, Landesklinikum Wiener Neustadt, Corvinusring 3–5, 2700, Wiener Neustadt, Austria); Bianca Hummel (Department of General Surgery, Landesklinikum Wiener Neustadt, Corvinusring 3–5, 2700, Wiener Neustadt, Austria); Martin Schardey (Department of General, Abdominal and Vascular Surgery, Agatharied Hospital, Norbert-Kerkel-Platz, 83734, Hausham, Germany); Peter Busch (Department of General, Abdominal and Vascular Surgery, Agatharied Hospital, Norbert-Kerkel-Platz, 83734, Hausham, Germany); Michael Hermann (Department of Surgery, Klinik Landstraße, Juchgasse 25, 1030, Vienna, Austria); Thomas Grabner (Department of Surgery, Klinik Landstraße, Juchgasse 25, 1030, Vienna, Austria); Özer Makay (Department of General Surgery, Ege University Hospital, Kazımdirik, Ege University. Hst. No:9, 35100, Bornova/Izmir, Turkey); Murat Özdemir (Department of General Surgery, Ege University Hospital, Kazımdirik, Ege Univ. Hst. No:9, 35100, Bornova/Izmir, Turkey); Ziya Karimov (Department of General Surgery, Ege University Hospital, Kazımdirik, Ege University. Hst. No:9, 35100, Bornova/Izmir, Turkey); Gianlorenzo Dionigi ((A) Division of Surgery, Istituto Auxologico Italiano IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico), Milan, Italy. (B) Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy); Andrea Casaril (Endocrine Surgery Unit, Pederzoli Hospital, Peschiera del Garda, Via Monte Baldo 24, 37019, Peschiera del Garda, Verona, Italy).
Declarations
Conflict of interest
E. Karakas MD, M. Arikan MD, and the European TOETVA/TOEPVA Study Group declare that they have no competing interests.
Ethical standards
All procedures performed in studies involving human participants or on human tissue were in accordance with the ethical standards of the institutional and/or national research committee and with the 1975 Helsinki declaration and its later amendments or comparable ethical standards. This study was approved by the Ethics Committee of the Medical University of Vienna (EK 2493/2020). Informed consent was obtained from all individual participants included in the study.
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