Situs inversus totalis (SIT) is a rare anatomical condition, in which all the thoracic and abdominal viscera appear in the reverse position. In case of gastric cancer patient with situs inversus, surgical procedures are technically demanding because most surgeons are not familiar with the transposed anatomy. In particular, the transposition of the vascular structures causes considerable confusion throughout the operation, because gastric cancer surgery includes lymphadenectomies around named vessels.

Ever since Yamaguchi et al. (1) first reported laparoscopy-assisted distal gastrectomy (LADG) for a gastric cancer patient with SIT in 2003, several surgeons have performed laparoscopic surgeries in patients with SIT. Although minimally invasive surgery (MIS) has evolved in the last two decades to achieve totally laparoscopic distal gastrectomy and totally laparoscopic total gastrectomy for gastric cancer in patients with SIT (2, 3), it is still difficult to accomplish lymph node dissection (LND) in such a transposed anatomical condition.

One significant issue in performing laparoscopic surgery in a patient with SIT is how to position the surgeons (including the operator, assistants, and scopist) and monitors in the operation room. Owing to the unfamiliarity with the SIT condition, surgeries performed using both right- and left-sided approaches cause considerable discomfort during lymphadenectomy (3). Several solutions have been introduced to manage this issue. Kigasawa et al. (4) used a two-monitor method, in which one monitor showed direct intra-abdominal images and the other showed mirrored images during LADG in a patient with SIT; however, they described that there still were difficulties in LND. Another remarkable solution was the introduction of a robotic surgical system. Kim et al. (5) described that the technical difficulties in patients with SIT were somewhat resolved with the aid of a robotic surgical system; the surgeon could perform the surgery using both right- and left-sided approaches freely, as the positions of the instruments could be freely changed. Furthermore, the operator feels it is less awkward to switch between the dominant and non-dominant hands in the transposed anatomies, since the right- or left-handedness is considerably filtered during robotic surgery.

However, we contemplated that the robotic surgical system is not appropriate in dealing with unexpected situations, including massive bleeding or unintended organ injury in unfamiliar anatomical conditions; therefore, we adopted the laparoscopic approach in MIS for patients with SIT.

Recently, we performed a single-port laparoscopic total gastrectomy in a patient with gastric cancer and SIT. In this case report, we describe the technical details of the surgical procedure and postoperative outcomes.

A 79-year-old woman was referred to our hospital after a clinical diagnosis of gastric cancer. The patient presented without any symptoms. Gastrofiberscopy showed an elevated mucosal lesion with the longest diameter of approximately 4 cm, located in the posterior wall of the gastric high body. Although high-grade dysplasia was diagnosed on pathological examination, the gastroenterologist who performed the gastrofiberscopy described the impression as early gastric cancer; the preoperative gastrofiberscopic findings, including the fusion and retraction of the gastric folds, corresponded to the features of submucosal invasion in patients with gastric cancer. Computed tomography revealed SIT; however, it did not indicate any distant metastases or peritoneal carcinomatosis. Her body mass index was 20.5 kg/m². The patient had no history of abdominal surgery.

We planned a single-port laparoscopic surgery for this patient. Total gastrectomy, rather than proximal gastrectomy, was considered because the tumor showed an ambiguous border and had a wide shape. The details of our procedure were as follows.

Laparoscopic surgery for gastric cancer is difficult to perform in patients with SIT. The first problem surgeons encounter is determining how to establish a camera and working ports in the patient’s abdomen. Regardless of the position preferred by the operator during laparoscopic gastrectomy, all procedures need to be performed using different approaches in patients with SIT. If surgeons choose the same position that they usually adopt for gastric cancer surgery (right-sided approach), they will have to deal with the abdominal organs in different locations. If surgeons try to accomplish the same procedures on the side opposite to the position they are familiar with (left-side approach), they will need to change the role of each hand. Therefore, regardless of the approach selected, the surgeon will be unfamiliar with the surgical procedure to be performed in patients with SIT (3).

In this patient with SIT, we performed a single-port laparoscopic gastrectomy (SPLG) to overcome unfamiliarity due to the transposed anatomy. Although SPLG involves technically demanding procedures, several strategies associated with the single-port laparoscopic approach for patients with SIT are available.

Moreover, we could alleviate the unfamiliarity caused by the right- or left-sided approach in patients with SIT. In the original SPLG procedure, the surgeon stood between the patient’s legs. Likewise, in the current case, the operator was positioned between the patient’s legs. We expected that this position might provide the operator with a similar vector toward the organs as when performing SPLG in patients with normal anatomy. In addition, for patients in whom all organs were inverted, it might induce less confusion (than right- or left-sided approach) to manipulate the organs in the median position. In this patient with SIT, “median positioned” approach causes a few unique situations. First, during omentectomy toward the left gastroepiploic vessels, the left-handed grasper could not raise the stomach (the cephalad traction of the omentum and stomach is performed using a left-handed instrument in patients with the normal anatomy). Therefore, gauzes had to be inserted to acquire adequate space between the omentectomy line and the stomach ( Figure 1A ). Second, during lymphadenectomy of LN station No. 6, there was less collision between the instruments than during SPLG in patients with normal anatomy. Generally, the duodenum is retracted upwards using a left hand-controlled grasper, while the right hand-controlled energy device is used for LND. In this patient, the grasper and energy device rarely needed to intercross intracorporeally, since the duodenum was located on the left side. Third, during the dissection of LN station No. 8a, we had to pay special attention to apprehend the inverted anatomy, including the named arteries arising from the celiac trunk ( Figure 1E ).

Another strategy for the SIT condition is the use of special instruments associated with the SPLG. At the initial period of establishing SPLG, we had used the prebent grasper (Olympus Medical Systems Corp., Tokyo, Japan) to avoid collision between the instruments and scope in the multi-channel trocar rim (10, 11). More recently, we have replaced the prebent grasper (Olympus Medical Systems Corp.) with a multi-degree of freedom (DOF) articulating instrument, ArtiSential (LivsMed, Seongnam, Korea) (12). The main mechanism for avoiding collisions during single-port surgery is to reflect the axis of the instrument. However, because we could not predict the direction toward which the instrument should be reflected in the SIT condition, we expected the multi-DOF articulating instrument might be more advantageous than the prebent grasper. ArtiSential can be freely reflected in any direction, whereas we the prebent grasper need to be re-assembled extracorporeally in order to change the direction of reflection. This feature enabled us to adapt to the transposed anatomy in the SIT patient.

Nevertheless, there remains some concerns regarding the long-term outcome, although this patient had no postoperative complications and recurrence for 2 years after the operation. In particular, the final pathology report showed that the pathologic stage was IIB (pT4aN0), which was so discrepant from the preoperative diagnosis. The preoperative endoscopic biopsy suggested that the gastric tumor was a high-grade dysplasia. Although we performed a total gastrectomy in preparation for the possibility of gastric cancer, we did not accomplish a D2 lymphadenectomy. Most of all, the first concerning point is related to the individual outcome of this patient. Despite the pathologic diagnosis of stage IIB, we cannot ignore the possibility of ‘stage migration,’ in which the stage might be underestimated due to the deficient LND. Unfortunately, this stage (IIB) was considered in the process of adopting the chemotherapeutic regimen for adjuvant therapy; we were concerned about whether S-1 monotherapy was an appropriate choice for this patient. Although there is no first-level evidence that S-1 monotherapy is inferior to the XELOX regimen, XELOX is preferred in patients with stage III gastric cancer at our institute.

Another concern correlates with the legitimacy of our surgical strategy. In this case, because we did not consider the possibility of advanced gastric cancer (AGC), D1+ lymphadenectomy was carried out. Regarding this issue, we should consider how to extend surgical radicality in patients with SIT. Although D2 lymphadenectomy has been achieved in laparoscopic surgery for AGC, it is necessary to design an upgraded strategy for future cases of SIT. Although we suggested that SPLG was a surgical solution in patients with SIT, we did not attempt D2 lymphadenectomy in a patient who had been preoperatively diagnosed with high-grade dysplasia. However, in cases of encountering patients with preoperatively-confirmed AGC, single-port laparoscopic approach might be an infeasible strategy for D2 LND in patients with SIT. Likewise, while some surgeons who perform SPLG have the expertise to perform D2 lymphadenectomy in patients with normal anatomy (13), experience is limited for patients with SIT.

Therefore, if we were to encounter patients with preoperatively-confirmed AGC in the future, the following strategies should be considered for D2 lymphadenectomy. First, we should not stick to the “unaided” type SPLG, in which a surgeon performs all the surgical procedures without any assistance (11, 14–16). In the recent days, we introduced EndoGrab™ Port-Free Endocavity Retractor (Virtual Ports, Misgav, Israel) in laparoscopic gastrectomy. With this instrument, in the left hand, the surgeon can manipulate the other tissues or organs to enhance the surgical view ( Figure 4 ) (17). However, such an instrument was not used when we performed SPLG for this patient with SIT. After performing a surgical treatment for this patient, we have been accustomed to using the EndoGrab™ Port-Free Endocavity Retractor (Virtual Ports) in single-port surgery for other patients as well. This device is expected to simulate the condition of the assistant surgeon adding counter-traction to achieve D2 lymphadenectomy during SPLG.

Second, it is not necessary to limit the length and number of incisions when performing radical surgery in patients with AGC. One reason for adopting SPLG in the patient with SIT was that the operator could be centrally positioned to avoid deviation to either side of the patient. However, if we were to encounter a patient with preoperatively-confirmed AGC and SIT, we would not limit ourselves to a single trans-umbilical incision with a length of 2.5 cm. In such cases, although we would still pursue the central position between the patient’s legs, a longer incision or additional working ports would be considered to achieve stable outcomes in the short- and long-term.

In summary, to our best knowledge, this was the first experience of performing a single-port laparoscopic total gastrectomy in a gastric cancer patient with SIT. According to our expertise regarding SPLG, single-port laparoscopic approach was adopted to overcome the unfamiliar condition due to SIT. The additional strategies should be considered to perform D2 lymphadenectomy in the future SIT cases.

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding author.

Written informed consent was obtained from the individual for the publication of any potentially identifiable images or data included in this article.

IL write the manuscript. DL collected the data and interpreted the data. CL designed the main concept of this study and verified all the contents of the study and manuscript. All authors contributed to the article and approved the submitted version.