Renal tumor is a common disease of the urinary system, and surgery is the most effective method to treat renal tumor. The first laparoscopic nephrectomy reported by Clayman in 1991 marked the advent of minimally invasive kidney surgery. In recent years, more and more minimally invasive urological surgeries have been performed in China, and almost all surgeries in the abdominopelvic cavity can be handled using laparoscopy. The number of partial nephrectomies has exceeded that of radical nephrectomies every year in recent years. The following is a discussion of the common problems, difficulties and countermeasures of such surgery.
I. Choice of radical nephrectomy and partial nephrectomy for kidney cancer
Radical nephrectomy can completely remove the kidney and the mass, but the defect is that more kidney units are lost. If the patient has high-risk factors, such as diabetes, hypertension, proteinuria, recurrent kidney stones, blood creatinine close to the high limit of normal, there is a greater possibility of postoperative renal insufficiency. It is generally believed that partial nephrectomy for kidney cancer less than 100px can achieve the same purpose of radical resection to treat the tumor. Radical resection may be overtreatment, but for CT stage III scan without fast-in and fast-out tumor, attention should be paid to identify renal papillary-like renal carcinoma type II, sarcoma, medullary carcinoma and invasive uroepithelial carcinoma, etc., and do puncture biopsy when it is difficult to identify them. Although the proportion of these tumors is low, the malignancy is high.
Partial nephrectomy can maximize the preservation of effective renal units, and its indications include absolute indications (anatomic/functional isolated renal carcinoma, bilateral renal carcinoma), relative indications (presence of benign disease in the contralateral kidney, such as stones, chronic pyelonephritis, hypertensive nephropathy, diabetic nephropathy, renal artery stenosis, etc.) and optional indications (peripheral small renal carcinoma, diameter <100px). The size of tumor is the deciding factor for partial nephrectomy, while the location of tumor is more important. For example, if central type renal carcinoma with no obvious elevation on the kidney surface, partial nephrectomy should be performed under ultrasound positioning during surgery, and it is better to have a clinically experienced ultrasound surgeon on the stage; in addition, both Trocar under the rib cage are used 10mm, which is helpful to locate the tumor from different angles. Hilar tumor refers to those whose tumor edge is less than 12.5px from renal vessels. The key point of resecting this type of tumor is to firstly separate the renal vessels around the tumor, and the direction of needle when suture is passed from hilar to outward. In recent years, there are many reports of partial nephrectomy for tumors larger than 4cm in diameter, and good results have been obtained.
II. Renal vascular variation and renal vascular management
For surgery, bleeding is a common risk. Preoperative renal enhancement CT+CTU+CTA should be performed to clarify the site of tumor and the number of branches of renal vessels. About 80% of renal arteries are one main artery, which originates from the abdominal aorta below the superior mesenteric artery, but about 20% of patients have multiple renal arteries or renal veins. If the main renal artery is found to be thin intraoperatively (the diameter of renal artery is mostly around 20px, if the renal artery is found to be only 0.3~100px, we should be alert to the presence of the second artery) or the distal end of the main renal vein fills rapidly after Hem-o-lok clamping. Consider the possibility of branching when there is a larger tumor that may also come from the collateral circulation.
During surgery, the perinephric fat capsule can be freed, and the surrounding tissues can be cut off in small bundles by ultrasonic knife at the middle dorsal pulsation of the kidney to reveal the renal artery. The renal artery should be separated close to the psoas major muscle and near the beginning of the renal artery, so that the artery does not split into multiple branches near the renal hilum. If multiple renal arteries are found, blocking forceps can be used to clamp each branch when performing partial nephrectomy, and Hem-o-lok clamps can be used to clamp the renal artery when performing radical nephrectomy, and it is best to have the tip of a Hem-o-lok clamp visible at the proximal end so that there is no surrounding tissue at the locking site and to avoid Hem-o-lok clamp slippage; generally multiple renal arteries will combine with multiple renal veins, and care should be taken to find and separate them.
Several points need to be noted in the process of dealing with the vessels.
①Renal arteries are often surrounded by abundant lymphatic vessels, which can be gradually cut off by ultrasonic knife in slow gear to prevent postoperative lymphatic leakage;
② Pay attention to the separation along the longitudinal direction of the artery, lateral separation can cause damage to the surrounding tissues or tear the vessel, cut the arterial sheath with the ultrasonic knife and free the renal artery by 1.5~50px, then clip the artery with Hem-o-lok (2 at the proximal end and 1 at the distal end) and cut the artery, make sure to see the tip of Hem-o-lok to completely wrap the renal artery to confirm complete clamping; if using a linear If a straight line cutter is used to handle the renal artery also ensure that the cross line at its front end crosses the renal artery;
③The renal vein has a thin wall and more branches, so the separation process with curved forceps and ultrasonic knife must be seen clearly and along the longitudinal axis of the vein, otherwise it is easy to tear the vein. Again, it is necessary to free the renal vein by 1.5~50px, and then use Hem-o-lok or linear cutter to deal with it. When cutting the right renal vein it is important to distinguish whether it is a renal vein or a vena cava. When we separate the right renal vein, we routinely divide it to the upper and lower corners of the confluence of the renal vein and the inferior vena cava. The gonadal vein, the central adrenal vein and the lumbar vein that converge into the left renal vein are closed with Hem-o-lok clamps or with titanium clamps if necessary and then cut with scissors, or they can be cut directly with the ultrasonic knife in slow gear, while the rest of the branches are usually cut directly with the ultrasonic knife in slow gear. The ultrasonic knife slow file is first clamped about 5mm on both sides of the place to be cut, and the ultrasonic knife slow file is used respectively until the vessel is white, and then cut in the middle, so that two places of each vessel stump are coagulated;
④Hem-o-lok plastic clips and sizers require relatively less operating space due to their smaller size than linear cutters, which can avoid complications that may be brought about by linear cutter treatment of the renal tip, such as cutting the surrounding vessels with the tip of the cutter, and the overall cost is relatively lower than linear cutters, so we generally choose to use Hem-o-lok clips;
⑤ The presence of tissue between the clasps is one of the main reasons for Hem-o-lok slippage, and it is important to ensure that the vessels are adequately free. If Hem-o-lok slippage is found intraoperatively, the renal vessels should be free again, and if the right renal vein is too short, a linear cutter can be used instead of Hem-o-lok to deal with it;
(6) In partial nephrectomy, the renal artery is blocked with blocking forceps, and the renal vein does not need to be blocked.
The time of thermal ischemia during partial nephrectomy is obviously related to the postoperative renal function, and it is generally believed that the time of blocking renal artery should be less than 30 min. intraoperatively, the renal vessels can be searched and freed first, and then the kidney can be freed to clarify the tumor site and resection range before blocking renal artery. Suturing is performed immediately after removal of the tumor. Generally, one can choose to suture without knotting (i.e. clip a Hem-o-lok fixation after every 1 stitch is stretched tightly) or use a suture with barbed thread, which can omit the step of knotting to shorten the blocking time. It is also possible to choose to reduce the renal temperature (using methods such as ice crumb coverage, renal artery perfusion or retrograde ureteral perfusion) to reduce renal blood flow and metabolism.
III. Treatment of tumor resection scope and positive cut edge
For radical nephrectomy, if the tumor is close to the upper pole of the kidney or invades the ipsilateral adrenal gland, the adrenal gland can be considered to be removed together. For partial nephrectomy, the extent of tumor resection and the management of positive margins should be considered. Previous studies suggested that the resection margin should be 5-10 mm away from the mass, but the greater the distance, the more kidney units will be removed and the risk of complications such as damage to the collecting system and bleeding increases. Currently, it is considered ideal that the tumor is 5 mm away from the incisional margin, but a distance of 1~2 mm is sufficient to meet the negative rate of the incisional margin. When performing partial nephrectomy, cold knife resection is used as much as possible, with clear levels and easy to identify the boundary between normal kidney tissue and tumor.
For cases with intact normal kidney tissues encircling the cut margin by visual observation, intraoperative routine cryopathological examination is not necessary. If the postoperative margins are positive, close follow-up or radical nephrectomy can be considered. Some literature suggests that positive surgical margins do not seem to increase the long-term risk of local recurrence and distant metastasis, i.e., positive margins in partial nephrectomy specimens do not always mean a poor prognosis.
IV. Management of renal tumors in different locations
The factors affecting partial nephrectomy are not only related to the size of the mass, but the location of the mass is also critical. The more specific ones are hilar tumor and central type tumor.
4.1 Hilar tumor
Hilar tumor is a tumor whose edge is less than 5 mm from the hilar vessels. This type of tumor is closer to the renal blood vessels and has higher surgical risk. Up to now, the following matters should be noted for this type of surgery.
①Pre-operative perfect renal enhancement CT+CTU+CTA to understand the number of branches of renal hilar vessels, the adjacent relationship between the vessels and the tumor and the depth of the tumor;
(2) The renal hilum and surrounding area should be fully freed during surgery, and if necessary, additional puncture cannula should be used to pull the perirenal fat so that the tumor, renal vessels and collecting system can be clearly revealed to avoid injury;
(iii) The renal hilum should be freed as long as possible, and laparoscopic vascular blocking forceps should be placed away from the hilum in order to preserve sufficient operating space at the hilum;
④Attention should be paid to avoid rupture and bleeding of the tumor trophoblastic vessels during the separation of the tumor from the renal hilum;
⑤ Most of the hilar tumors are adjacent to the collecting system, so it is easy to suture the renal blood vessels and damage the collecting system during surgery. The key point of resecting such tumors is to separate the renal blood vessels around the tumor firstly, and the direction of the needle should be passed outward from the hilar when suturing;
(6) The laparoscopic ultrasound probe can be applied for intraoperative tumor localization to understand the depth of tumor and its boundary with normal renal parenchyma to avoid excision too deep and damage to blood vessels and collecting system; the suture should not be too deep when closing the trauma of renal parenchyma to avoid formation of arteriovenous fistula or suture of renal artery or ureter to form arterial stenosis or hydronephrosis.
4.2 Central tumor
Central tumor is a tumor that is completely or mostly buried in the renal parenchyma. The outline of this type of tumor cannot be seen directly during surgery, and it is difficult to find, locate and resect the tumor under lumpectomy. If too little tissue is removed, positive margins may occur; if too much tissue is removed, too many kidney units will be lost, and the collecting system and even small renal vessels may be damaged, resulting in excessive bleeding and urinary fistula. Preoperatively, CT examination should be improved to find the location of tumor according to CT reconstruction, and intraoperative ultrasound should be used to clarify the location and resection range of tumor, and ultrasound can also determine whether there are satellite foci. After the tumor location and boundary are clearly identified, the tumor is marked by electrocautery at the edge of the mass with ultrasound knife, the ultrasound probe is removed, the renal artery is blocked with laparoscopic arterial blocking forceps, and the tumor is wedge-shaped resected along the mark at 12.5px from the tumor edge.
For this type of tumor.
①Pre-operative enhancement CT examination of the kidney should be completed to have a good understanding of the relationship between the tumor and surrounding vessels and the number of vascular branches supplying the tumor;
(2) Ultrasound must be used for positioning during surgery to accurately remove the tumor and preserve the kidney unit to the maximum extent;
③The difficulty of surgical operation is related to the location of the tumor. Those relying on the dorsal side are mostly accessed through the posterior abdominal cavity, while those relying on the ventral side of the kidney can be accessed through the abdominal cavity;
④Suture in two layers, the first layer is continuously sutured with 3-0 absorbable thread, the end of the thread is knotted and a Hem-o-lok is clamped close to the knot in the direction of the needle, the thread should be tightened for each stitch, and the bleeding area is best repeated to reduce bleeding; the second layer is continuously sutured to the renal parenchyma; after releasing the arterial clamp, the head and tail of the two layers of sutures are then pulled toward the outside of the kidney to reduce intraoperative and postoperative bleeding and the formation of pseudoaneurysm;
⑤ If the tumor is close to the collecting system, the ureteral stent tube can be left in advance;
⑥The technique of such surgery is more demanding, and it is better to complete a certain number of laparoscopic partial nephrectomy before doing central tumor.
V. Prevention and treatment of surgical complications
Whether laparoscopic radical nephrectomy or laparoscopic partial nephrectomy for kidney cancer, some complications may occur. The following will be some discussion on the management of common complications.
5.1 Peritoneal injury
The most common reason for this condition is that the peritoneal gap is not large enough after balloon expansion and does not exceed the puncture point, and the placement of trocar needle in the anterior axillary line position is caused by penetration into the peritoneal cavity; the second reason is that the peritoneum is damaged when separating the kidney medially. When freeing the kidney, we must pay attention to the anatomical landmarks and separate between the lateral cone fascia and the fat capsule to avoid damaging the peritoneum. If the peritoneum is damaged, titanium clamps or Hem-o-lok clamps can be used to close it, or a pneumoperitoneum needle can be inserted under the costal margin in the peritoneal cavity to release the intra-abdominal gas; or a 5mm Trocar can be added 75px above the anterior superior iliac spine and instruments can be placed to block the peritoneum. Vascular injury: Be sure to look carefully at the CT film before surgery to understand the number and location of the branches of the renal arteries and veins. If intraoperative renal vein or vena cava tear occurs, the pneumoperitoneum can be modulated by 20 mmHg, and titanium clamps can be applied to close it or 5-0 vascular sutures can be used to stop the bleeding under lumpectomy; the confluent branches of the left renal vein often have variants, and there is often a traffic branch between the lumbar vein and the collateral vein below the main trunk of the renal vein, and this vein is often close to the renal artery, so the outer membrane of the renal artery can be opened, and the vein can be separated with curved forceps close to the renal artery to avoid damage to the vein, or with titanium clamps or Hem-o-lok clamps are used to close this vein and cut it off. When freeing the artery, if there is bleeding from a small branch of the renal artery, use ultrasonic knife coagulation or compression to stop the bleeding. It is important to remain calm while dealing with vascular injury, while taking care of volume replacement and deciding whether to transfuse blood as appropriate.
5.2 Bleeding and urinary leakage from the trauma surface
This condition is mainly seen in partial nephrectomy and depends on the closure and hemostasis of the collecting system. It is important to suture the collecting system exactly during the procedure and then suture the renal parenchyma in one layer. Our experience is to open the renal artery after the suture is completed, while lowering the pneumoperitoneum pressure to see if there is bleeding, if there is obvious bleeding, first tighten the head and tail of the second layer of sutures again, add pressure to stop bleeding for 5 min, if there is still obvious bleeding then suture the bleeding area, after tight hemostasis can be sprayed bioprotein glue on the wound surface and covered with hemostatic gauze, leave the drainage tube; the lower pole of the kidney is best without bioprotein glue, this glue can cause ureteral If ureteral stenosis occurs, dilatation with a rigid ureteroscope is sufficient. Postoperatively, the drainage should be observed, and if the drainage is high, conservative treatment is preferred; if the effect is not good, interventional embolization should be considered to stop the bleeding; if urinary leakage occurs after surgery, the drainage tube should be kept open and waiting for the healing of the collecting system.
In conclusion, laparoscopic technique has obvious advantages in the management of renal tumors with satisfactory therapeutic effects. Although technically more difficult and some complications exist, these problems will be solved with the development of technology. At present, 3D laparoscopic technology has emerged, which can give the operator 3D vision, making the operator more exact in the grasp of depth and more convenient in the process of dealing with blood vessels and suturing. It is believed that the development of surgical techniques and the improvement of surgical refinement will bring benefits to more and more patients.