Surgical treatment for renal tumor with VTT is technically demanding and challenging. However, radical nephrectomy with thrombectomy could provide a good prognosis and is the main treatment option for renal tumor and VTT.
With the development of minimally invasive technique, laparoscopic surgery has gradually been used in the treatment of renal diseases, including complex renal tumor [8, 9]. It is reported that laparoscopic surgery could reach outcomes equal to open surgery . Moreover, laparoscopic surgery has some advantages over open surgery, including smaller incision, less blood loss, less pain, shorter hospitalisation, and shorter recovery time. In 2006 Romero et al first described pure LRN and thrombectomy for RCC with level II VTT . Then, an increasing number of studies have established the efficacy and safety of LRN and thrombectomy for the treatment of RCC patients with level II-III VTT [12, 13]. In this study, we introduce our modification in the treatment of LRN and thrombectomy for renal tumor and level II-III VTT and present our preliminary results.
Both retroperitoneal and transperitoneal approaches have been reported to be used in LRN and thrombectomy [14–17]; thus, it is the preference of surgeon that decides the selection of surgical approach. In our centre, we performed LRN and thrombectomy using the retroperitoneal approach, because we have extensive experience in retroperitoneal laparoscopic surgery. The retroperitoneal approach could provide more direct and quicker access to the renal artery and lumbar veins . The early occlusion of the renal artery could result in less intraoperative bleeding and lower risk of tumor embolism. The retroperitoneal approach does not disturb intraabdominal organs, and provides good exposure to the retroperitoneal vessels. Moreover, the retroperitoneal approach is not affected by the history of abdominal surgery and abdominal adhesion .
Compared with routine LRN and thrombectomy for renal tumor with level II-III VTT, the essential difference of our pioneering technique is that the proximal end of the IVC is not clamped. During the surgery, the surgeon can elevate the pressure of the pneumoperitoneum to achieve the occlusion of the proximal end of the IVC. The pressure of the pneumoperitoneum is usually maintained at 15 to 25 mmHg. The lumen of the IVC maintains blood filling and not outflowing. If there is outflowing of blood, the pressure is elevated and often raised to 21 to 25 mmHg. During this procedure, the suction apparatus remains closed as much as possible to avoid interfering with the pressure of the pneumoperitoneum. After excision of the VVT, a bulldog clamp is put on the proximal end of the IVC to prevent bleeding. Not all patients with renal tumor and VVT can be treated using the DOPI technique. The DOPI technique applies only to patients whose retrohepatic and subhepatic segments of IVC wall are not invaded by tumor. We use CT and MRI to confirm the extent of VTT before surgery. Further, intraoperative ultrasound, typically used to assess the exact extent of VTT, is not necessary. With our DOPI technique, the dissociation of the liver is unnecessary. We do not need to disconnect the round, right and left triangular coronary and falciform ligaments. And the dissociation of the first port and suprahepatic IVC is unnecessary. Thus, the incidence of hepatic injury and bleeding volume decrease. The estimated blood loss in our study is less, and the mean estimated blood loss is 466.7 ± 245.5 ml. In addition, no tumor embolism or air embolism occurred in our patients.
Based on our initial experience, there are some important steps that should be taken into consideration in this procedure. First, after mobilisation of the kidney, we incise the peritoneum near the paracolic sulci and put the kidney into the peritoneal cavity through the incision. Thus, the space of the retroperitoneal cavity becomes larger, and the IVC and contralateral renal vein can be better exposed. A larger retroperitoneal cavity is conducive to the surgery. Second, short hepatic veins and lumbar veins are electrocoagulated to tawniness using bipolar electrocoagulation at the proximal and distal ends of veins before severed, which helps to avoiding bleeding caused by Hemolok clips that might fall off during surgery. For lumbar veins, they should be severed about 2 mm from the IVC with ultrasonic scalpel. If there is bleeding at the proximal end of veins, it was sutured with 4 − 0 Prolene vascular suture. Third, the vessel loop is not used to clamp the IVC and contralateral renal vein during surgery. We cut the smallest segment of the transfusion set, and use it to block the IVC and contralateral renal vein. The transfusion set is cheaper than vessel loop, and helps to reduce the cost of hospitalisation. Furthermore, the transfusion set is harder than vessel loop, and it is easier to be manipulated. Fourth, our longitudinal waist incision could reduce damage to peripheral nerves and muscle fibres, and thus, decrease the incidence of incisional hernia and the degree of lower abdominal pain. In our study, no abdominal hernia occurred in the patients, and any discomfort in the lower abdomen was not serious.
We acknowledge some limitations in our study. First, the sample size of this study is small. A larger series of patients is required to verify the efficacy and safety of our DOPI technique. Second, our median follow-up time of 21 months is short, and we cannot evaluate the long-term oncologic outcomes. Third, the IVC occluded time is important in the LRN and thrombectomy, but our related data are absent. In a word, further studies with longer follow-up time and larger sample size are needed to assess this technique.