This study was approved by the Institutional Review Board of Korea University Hospital (approval number: 2017AN0077). A 35-year-old female patient with a BMI of 21.33 kg/m² was found to have a 0.9-cm-sized nodule in her left thyroid lobe on ultrasound. Fine needle aspiration biopsy showed papillary carcinoma (Bethesda category VI). Since the patient did not want to have a surgical scar on her neck, after counseling on the various approaches for thyroid surgery, she underwent TORT using the da Vinci Xi surgical system (Sunnyvale, CA, USA).

The patient was transorally intubated with an electromyogram tube (Medtronic, Minneapolis, MN, USA), and the tube was fixed to the right angle of the mouth (Supplementary video clip 1). Intraoperative neuromonitoring is routinely performed in our procedure to identify the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve, in order to prevent nerve injury during the operation. The patient was positioned supine with slight extension of her neck. After draping, the patient's oral cavity was irrigated with a solution of chlorhexidine and povidone-iodine. A diluted epinephrine-saline solution (1:200,000) was injected into the lower lip down to the chin for hydro-dissection. Then, we made an inverted U-shaped midline incision at 2 cm above the frenulum labii inferioris, measuring 1 cm in length. Subcutaneous tissue of the chin was dissected through the midline incision with Mosquito and Kelly clamps. Next, we injected the epinephrine-saline solution into the subplatysmal space with a Veress needle (Medtronic) for hydro-dissection of the subplatysmal plane. Then, blunt dissection with an 8-mm-tipped vascular surgical tunneler was performed to separate the platysma from the strap muscles. After flap formation, an 8-mm midline trocar was inserted and carbon dioxide insufflation was maintained at the maximal pressure of 5–7 mmHg. Subsequently, we made 0.5-cm lateral incisions near both angles of the mouth, and a similar blunt dissection was performed through the incisions to insert the 8-mm trocars. Next, an ultrasonic energy device (HARMONIC ACE+, Ethicon Endo-Surgery, Cincinnati, OH, USA) and a suction-irrigator electrocautery through the lateral ports were used to elevate the platysma for working space creation from the level of the mandible to the sternum vertically and to both the sternocleidomastoid muscles horizontally. An additional 8-mm trocar was inserted through a right axillary incision for countertraction of the strap muscles or perineural tissue, and for later insertion of the closed suction drain.

After the creation of the working space, a da Vinci Xi Surgical System was docked laterally from the left with the patient laid in the supine position. Then, the robotic arms were docked to the ports, and the robotic instruments were inserted; A Maryland bipolar forceps to the left port, the harmonic scalpel to the right port, and 8-mm Prograsp bipolar forceps or a Maryland bipolar forceps to the right axillary port.

First, the midline raphe was dissected using a monopolar hook cautery, and the isthmus was divided in the midline with an ultrasonic energy device. After detaching the isthmus from the trachea, the strap muscles were dissected from the thyroid gland (Fig. 1). Then, the superior pole was addressed. The sternothyroid muscle was retracted laterally with the Maryland bipolar forceps through the left intraoral port, and the thyroid gland was lifted up with the Maryland bipolar forceps through the axillary port. Then, careful dissection of the superior lobe was performed ligating one vessel at a time using an ultrasonic energy device or metal clips. Subsequently, the superior parathyroid gland was identified and dissected, and the ligament of Berry was dissected to identify the RLN with the ultrasonic energy device through the left intraoral port and Maryland bipolar forceps through the right intraoral port. The dissection was then performed inferiorly while tracing the RLN and preserving the lower parathyroid gland. Then, a prophylactic ipsilateral central compartment dissection was performed. The specimen was removed using an endoplastic bag through the axillary port, and a Jackson-Pratt drain was inserted.

The total operative time and the console time was 195 minutes and 110 minutes, respectively. There were no postoperative complications, and the patient was discharged on postoperative day 2 after removal of the Jackson-Pratt drain. The final pathology demonstrated papillary carcinoma 0.9 cm in size, and metastasis in 1 out of 9 regional lymph nodes, with a final staging of pT1aN1aM0 (American Joint Committee on Cancer 8th edition).