Laparoscopic renal surgery

Authors: Drs Marshall Stoller (university of California SF) and Aaron Berger (Chicago) 2009-03-06

Laparoscopic renal (kidney) surgery

What is Laparoscopy?

Laparoscopy is the term used to describe abdominal surgery performed with a camera (laparoscope) and small, thin instruments placed through several small incisions. Laparoscopy is used for a wide variety of operations and results in decreased post-operative pain, decreased recovery time, and improved cosmetic results as the incisions are much smaller than traditional open surgery.

Relevant Anatomy

The urinary tract has several main components including the kidneys which form the urine, the ureters which transport the urine to the bladder, which then stores the urine until it passes out of the body through the urethra (see figure).

The kidneys are paired, bean shaped organs located in the back just below the ribs. They serve multiple functions in the body, but primarily the kidneys filter the blood to clear toxins and extra water from the body by producing urine. There are two main parts of the kidney: the cortex/medulla where the specialized filters and tubules are located that filter the blood and then adjust the concentration of the urine; and the collecting system which is where the urine empties before passing down the ureters, which are the long thin tubes (usually 25-30cm) that channel the urine into the bladder. The collecting system is comprised of a branched network of structures called calyces which empty into the renal pelvis, which then funnels the urine into the ureters. The ureters empty into the bladder where the urine is stored until the urine is eliminated from the body through the urethra.

The peritoneum is basically a large membrane which encases many of the abdominal organs including the stomach, liver, gallbladder, spleen, part of the pancreas, the transverse colon, and most of the small intestine.

The kidneys and ureters are located in what is known as the retroperitoneum which means behind the peritoneum. Most renal (kidney) surgery has traditionally been performed through a flank incision either just below the ribs or between the lowermost ribs, which allows for easy access to the kidney and ureter and avoids entering the peritoneal cavity with all its organs. Flank incisions, however, require incising several muscle layers and, so, are painful incisions that often require a long recovery time (weeks to months) and may be cosmetically unappealing. Partly in response to these concerns, laparoscopy was first used for renal surgery in the early 1990’s and has since become widespread and used for a variety of operations. When renal procedures are done using similar techniques in the retroperitoneum, they should be referred to as retroperitoneoscopic surgery, but many minimally invasive urologists prefer the laparoscopic approach through the abdomen as it provides a larger working space.

Technique and Instrumentation

Laparoscopic procedures begin with patient positioning. Most often patients are placed in a semi-lateral position (on the side) with the left side up for left sided operations and right side up for procedures on the right kidney. Supports and padding are used to ensure that no pressure points are in contact with a hard surface which can result in temporary or permanent nerve injury. Also, care is taken not to hyperextend any joints as this may lead to nerve injury as well. Typically, a catheter is placed into the bladder during the operation and sequential compression devices are placed on the legs to prevent blood clots during the operation. Additionally, a tube is placed into the stomach to decompress it to prevent inadvertent injury.

Once the patient is properly positioned, the procedure is initiated by blowing carbon dioxide into the abdomen (insufflation), which expands the working space inside the belly. There are two main methods of initially insufflating the abdomen. One is called the Veress needle technique and this involves placing a small needle directly into the abdomen using anatomic landmarks to guide needle location. The position of the needle is verified by aspirating the syringe to ensure the needle is not in the intestine or a blood vessel and then a small amount of saline is placed into the needle. If the saline drops into the abdomen quickly, the needle is likely in the correct position and is then connected to the gas and the abdomen is inflated. An alternative method is called the Hassan open technique; this involves making a small incision and then dissecting under the skin to directly visualize the peritoneum. Once the peritoneum is identified, a small opening is made and a plastic port called a trocar is placed under direct vision into the peritoneal cavity followed by insufflation. There are advantages and disadvantages to both techniques but if performed correctly, both are safe and effective.

Once the abdomen is insufflated, which is referred to as pneumoperitoneum, the laparoscope is placed through the trocar into the abdominal cavity. Once the abdominal contents are visualized, the surgeon will typically place two or three additional trocars into the abdomen depending on the type or procedure being performed and surgeon preference. In addition, some urologists may elect to use a hand port which is a small device that allows the surgeon to place a hand into the operative field without losing the insufflation of the abdomen and this is known as hand-assisted laparoscopy.

Once all of the trocars are in place, the initial steps to access the kidney involve freeing up the overlying colon and allowing gravity to pull it down and expose the kidney below. To perform the surgical dissection, there are a wide variety of instruments available to the urologist including basic scissors and graspers, suction/irrigators, monopolar and bipolar electrocautery, Harmonic Scalpel® (Ethicon Endo-Surger, Cincinnati, OH) which utilizes high frequency vibration to cut and cauterize tissue, and the Ligasure™ device (ValleyLab, Boulder, CO) which fuses tissue and blood vessels. Laparoscopic renal surgery can also be performed with the robotic daVinci® Surgical System (Intuitive Surgical, Sunnyvale, CA). The robotic system utilizes a robotic tower with three or four arms which are attached or docked to special trocars placed into the abdomen. There are multiple instruments which can be attached to the working arms and one controls the camera. The surgeon operates the robot from a separate console in conjunction with an assistant at the bedside. The robotic instruments have a greater range of motion than most traditional laparoscopic instruments and may help facilitate some procedures.

Laparoscopic Nephrectomy

The first laparoscopic kidney operation performed, and currently the most common, is the laparoscopic nephrectomy which means removing the entire kidney from the patient. This can be performed for a variety of reasons but the most common indications are for a tumor in the kidney, if the kidney is non-functional due to obstruction and causing pain and/or infections, or for donation to someone else in need of a kidney transplant. Typically, a computed tomography (CT) scan or magnetic resonance imaging (MRI) of the abdomen and pelvis is performed pre-operatively to help the surgeon understand the patient’s anatomy as well as the location and number of blood vessels going to the kidney (normally one artery and one vein). As mentioned previously, once in the abdomen, the colon must be released from its normal position overlying the kidney. Once this is done, the ureter is identified, typically lateral to the gonadal vein, and transected near the lower portion of the kidney.

The remaining steps depend on which kidney is being removed. On the right side, the upper portion of the kidney must be released from the liver and the medial aspect of the kidney must be released from the inferior vena cava and the duodenum (part of small intestine) which will expose the renal vein and artery, collectively known as the renal hilum. Once the hilum is exposed, the vessels are dissected out and then typically first the artery and then the vein are transected. This may be accomplished with surgical clips, sutures, or stapling devices depending on surgeon preference. Once the blood vessels are ligated (tied off), the remaining attachments are divided and the kidney is completely released. Laparoscopic nephrectomy on the left is similar except the upper portion of the kidney must be released from the spleen and care must be taken not to injure the pancreas which courses medial (close) to the renal hilum. In addition, the left renal vein has more branches than the right so more care must be taken in dissecting out the renal vein to avoid the adrenal, lumbar, and gonadal veins. During a nephrectomy for a large tumor or a tumor in the upper portion of the kidney, the adrenal gland may be removed along with the kidney. Typically, for kidneys with tumors, infections, or poor function, the kidney and all of its surrounding fat (perinephric fat) is removed.

Once the kidney is released, there are several options for specimen extraction. If the surgeon has utilized a hand port, the kidney may be removed from this location. Alternatively, a small incision, similar to a Caesarian section incision, known as a Pfannenstiel incision, may be made in the lower portion of the abdomen to remove the kidney in its entirety. This extraction incision does not cut through any muscle layers so is much less painful and is in a much more concealable location than the flank incisions used for open renal surgery. Similarly, a small vertical midline incision in the lower abdomen may be used. In women, a small incision may be made through vagina to remove the kidney which is referred to as natural orifice extraction. An alternative to removing the kidney whole is to perform what is called morcellation. This is where the kidney is placed into a sac and then broken up into small pieces which can then be removed from one of the trocar sites. This allows the specimen to be removed through a very small incision, but it potentially may have an impact on the pathologist’s ability to accurately stage a kidney cancer. Laparoscopic nephrectomy for donors is similar except that more care is taken to get as much length as possible on the renal vessels as they will be needed to connect the kidney to the blood supply of the recipient. Also, unlike nephrectomies for cancer or non-functional kidneys where the kidney and all the surrounding fat are removed, donor kidneys have most of the fat removed to allow for a smaller and easier extraction.

Laparoscopic nephrectomy for chronically infected kidneys may be very challenging due to the extensive inflammatory reaction around the kidney. In many cases of infected kidneys due to stones and obstruction, also known as xanthogranulomatous pyelonephritis (XGP), it may be very difficult to find the correct surgical planes to clearly identify the ureter and renal blood vessels and great care must be taken during the dissection.

Laparoscopic Partial Nephrectomy

Laparoscopic partial nephrectomy (LPN) is where a portion of the kidney is removed, usually a mass suspicious for containing a cancer. LPN starts in a similar fashion to a laparoscopic nephrectomy however once the colon in released and the renal hilum is identified, the suspicious mass must be located. Typically, a laparoscopic ultrasound probe is used to help the urologist locate the tumor and determine the width and depth of the tumor to plan an appropriate resection (removal). Once some of the overlying fat has been removed so the tumor can be visualized, the renal artery and sometimes the renal vein are clamped to stop the blood flowing into the kidney, a condition known as warm ischemia. Once the blood flow is reduced, the suspicious mass is excised and the kidney reconstructed with sutures and/or surgical sealants to prevent bleeding and urine leakage. Once the tumor is excised and the reconstruction is completed, the clamps on the blood vessel(s) are removed and the site is observed to make sure there is not any significant persistent bleeding. In some cases, if the tumor is very exophytic – mainly growing out from the kidney and is not very deep – the tumor may be resected without clamping the renal artery, but these cases are relatively rare. It is unclear what the long-term effects on kidney function are from clamping of the renal artery, but most experts agree that 30-45 minutes of warm ischemia is safe and some data indicates that even longer times may not have any long term impact.

Once the tumor is excised, it is placed into a small sack and then removed from the patient and sent to the pathologist. At the end of the procedure, most urologists will leave a small drain adjacent to the kidney to monitor for any bleeding or urine leak for the first one to two days post-operatively. In most cases, the drain is removed prior to discharge from the hospital. Laparoscopic partial nephrectomy is a fairly complex procedure due to the kidney reconstruction that is necessary to prevent bleeding and urine leak so it is often reserved for urologists with specialized laparoscopic training.

Laparoscopic Tumor Ablation

A laparoscopic technique also may be used during ablation of kidney tumors. Ablation of a renal tumor, either with cryoablation (freezing) or radiofrequency ablation (heat), is an option to treat small (often less than 3 cm) masses without having to clamp the renal artery and subject the kidney to warm ischemia. These procedures are performed similarly to a laparoscopic partial nephrectomy but once the tumor is identified, the cryoablation or radiofrequency ablation (RFA) probe is placed in the tumor and the ablation cycle is started. Once completed, the procedure is basically completed. These ablative procedures may also be done percutaneously (through the skin of the back), but a laparoscopic approach is beneficial for tumors in the front (anterior) aspect of the kidney. The advantages of ablation are that there is less risk of bleeding or urine leakage compared to a partial nephrectomy and the kidney is not subjected to warm ischemia. The main disadvantages are that since the tumor is not excised there is no pathologic analysis available, frequent surveillance CT scans or MRI scans are necessary, and the long term efficacy data is not yet available.

Laparoscopic Pyeloplasty

An ureteropelvic junction (UPJ) obstruction may be congenital or acquired and occurs at the point where the renal pelvis joins with the ureter.

In some patients, there is a segment of the ureter that does not have normal muscle development and the urine does not get propelled down the ureter and this leads to a back up of urine and swelling of the kidney (hydronephrosis). This swelling often causes flank pain, especially with excess fluid intake or when patients drink alcohol which is a diuretic and causes further stretch of the collecting system. In other cases, an obstruction of the UPJ may be caused by a crossing blood vessel, usually going to the lower part of the kidney. UPJ obstruction also may be a result of scarring from kidney stones and/or prior surgical procedures.

There are multiple treatments for a UPJ obstruction and these are detailed in the Knol on Urinary Tract Obstruction. The treatment of UPJ obstruction with the best long term results is a pyeloplasty where the diseased segment is incised, or excised, and then the ureter is re-attached to the renal pelvis so that there is a wide channel for urine to flow. Similar to a nephrectomy and partial nephrectomy, pyeloplasties historically were predominantly performed through a flank incision. Currently, however, many of these procedures can be performed laparoscopically. The patient positioning and preparation is similar to the procedures described above and good pre-operative imaging is important to help determine if there is a crossing blood vessel. In many cases today, CT scans can be reconstructed in 3-D to help the urologist get a detailed idea of the patient’s anatomy before initiating the procedure. In addition to CT or MRI imaging, a nuclear renal scan is routinely utilized to determine the function of the affected kidney and determine how severe the obstruction is. The pre-operative renal scan allows for comparison as a post-operative nuclear scan is also obtained to demonstrate improvement of the obstruction.

Once all the trocars are placed and the instruments are in the abdomen, the colon is again released to expose the kidney. In most cases of UPJ obstruction, the renal pelvis is dilated and is easily identified. However, patients with long standing obstruction or patients who have been managed with placement of a ureteral stent (thin plastic tube running between the kidney and bladder to bypass the obstruction) there can be significant inflammation and dissecting out the ureter and renal pelvis can be challenging. Once the renal pelvis and ureter are identified, the urologist must decide which type of procedure to perform. The most common variant is known as the Anderson-Hynes or dismembered pyeloplasty where the diseased UPJ is completely excised and the healthy proximal ureter is then re-attached to the renal pelvis. If there is a crossing vessel present, the ureter is transposed on top (anterior) of the vessel to prevent re-obstruction. Occasionally, if the renal pelvis is markedly dilated, some of the excess tissue is resected so that the newly formed UPJ has a nice funnel shape to allow the urine to flow freely and prevent stasis. Another option is to perform a Heineke-Mikulicz like or Fenger type pyeloplasty where the UPJ is incised longitudinally and then sewn back together horizontally thereby widening the opening. Several other types variations of pyeloplasty are utilized but these are the two most common and both have excellent results.

Typically, after the reconstruction of the UPJ is complete, a ureteral stent is placed to ensure that the repaired area stays open and does not scar down during the healing process.

Finally, most urologists often leave a small drain for a day or two to ensure that there is no urine leaking from the repaired UPJ, and this is normally removed prior to discharge from the hospital. The stent is typically left in place for several weeks and then is removed with a small outpatient procedure. The bladder catheter is also typically left in place for between two to seven days depending on surgeon preference to prevent any urine from refluxing up toward the reconstructed kidney. About six weeks after the stent is removed, a follow-up nuclear renal scan is usually obtained to ensure that there is good drainage across the reconstructed UPJ. Most contemporary series of laparoscopic or robotic-assisted laparoscopic pyeloplasties have greater than 90% success rates which is normally defined as improvement in patient symptoms and improvement in drainage on imaging studies.

Laparoscopic Renal Cyst Decortication

Cysts of the kidney are common as people age. They are fluid filled sacs that typically are asymptomatic. Occasionally, however, they may become quite large, greater than 8-10 cm, and may cause pain. In addition to pain, large cysts, especially of the left kidney, can compress the stomach and patients may complain of early satiety or having difficulty eating a large meal.

It is important to determine if the cyst is a simple cyst versus a cyst that is worrisome for a renal cell cancer. Typically, this determination can be made by the radiographic appearance of the cyst on either ultrasonography, CT scan, or MRI. The classification system is known as the Bosniak system. Bosniak I and II cysts are considered benign whereas Bosniak III and IV are thought to be either suspicious or highly suspicious for renal cancer and at that point should be removed by either nephrectomy or partial nephrectomy. It is also important to delineate a renal cyst versus a caliceal diverticulum which is an outpouching of one of the renal calyces and is filled with urine and not cystic fluid. In addition, some patients may have a genetic disorder known as polycystic kidney disease where the kidneys are filled with cysts, typically on both sides. Sometimes, these cysts may get to be very large in size and cause marked symptoms.

The patient preparation for a laparoscopic cyst decortication is similar to that described earlier for laparoscopic nephrectomy. Sometimes, if the cysts are very large, it may be difficult to get the initial needle or trocar into the abdomen without puncturing the cyst; therefore, in rare cases, some of the cystic fluid may need to be aspirated through a separate needle prior to starting the procedure. Once all of the trocars and instruments are in the abdomen, the cyst wall is dissected free of any surrounding structures. If at all possible, the cyst is kept intact until the surgeon is ready to puncture it as premature puncture of the cyst may make the dissection more difficult. Once the cyst wall has been completely freed, the cyst wall is punctured and the fluid is suctioned out and a sample sent for cytologic examination. The wall of the cyst is then typically resected and removed from the patient and sent for pathologic analysis. The base of the cyst is then often cauterized with a variety of instruments including electrocautery, or a device known as the argon beam coagulator. This cauterization process helps to prevent the cyst from recurring. If there are multiple cysts, the procedure is repeated for any other cysts that appear large enough to cause symptoms. Care must be taken not to enter the collecting system of the kidney during resection of the cyst wall and occasionally, a small catheter is placed from the bladder up into the kidney to allow for the injection of blue dye to ensure there are no urine leaks.

Laparoscopic Kidney Stone Extraction

Laparoscopy may be used to extract some kidney stones, especially in cases where the kidney may not be in the normal location or is malrotated. Also, stones in a caliceal diverticulum are often amenable to a laparoscopic approach and may be easier than percutaneous stone surgery (see Kidney Stone Knol). For some large stones in the renal pelvis, a laparoscopic pyelolithotomy can be performed. This procedure is similar to a laparoscopic pyeloplasty in that the renal pelvis is identified and dissected free of surrounding tissues. The pelvis is then incised and the stone(s) removed with graspers. A flexible scope can also be placed through one of the laparoscopic trocars to inspect all the calyces of the kidney to remove any smaller stones. Once the stones are removed, the renal pelvis is then sewn together using laparoscopic suturing techniques. For stones in a caliceal diverticulum, ultrasound is often used to identify the stones. Typically, caliceal diverticula are not covered by much normal kidney tissue, but it often is necessary to incise some kidney to enter the diverticulum and remove the stones. Care must therefore be taken to ensure that the incision is in the correct location to avoid excessive bleeding.

Laparoscopic Procedures for Proximal Ureteral Strictures

Similar to a laparoscopic pyeloplasty for UPJ obstruction, there are several laparoscopic procedures that may be performed for long proximal ureteral strictures which are not amenable to less invasive procedures (see Knol on Urinary Tract Obstruction). In these complex cases, one option is to replace the ureter with a segment of small intestine, which is known as an ileal ureter interposition. During this procedure, the renal pelvis and ureter are dissected free of surrounding structures and the ureter is dissected all the way down to the bladder. Next, a segment of the ileum is transected and the two free ends re-connected, often with a stapling device to restore continuity to the intestine. The free piece of ileum is then sewn between the renal pelvis and the bladder, thereby bypassing the diseased ureter. Another option for a complex stricture is to perform a laparoscopic nephrectomy and then transplant the kidney into the patient’s pelvis near the bladder (auto-transplantation). An additional procedure is known as an ureterocalycostomy where the ureter is transected just below the diseased segment. The lower pole of the kidney is then resected to expose a lower pole calyx. Once this is accomplished, the ureter is sewn directly to the lower pole calyx. These are all complex procedures and are often reserved for when less invasive attempts are repair have failed.

Conclusion

The advent of laparoscopic renal surgery has greatly decreased the post-operative pain, recovery time, and scarring compared to traditional open kidney surgery. Almost any renal surgical procedure can be performed laparoscopically and, as skill and technology continue to improve, the application of these techniques will likely become even more widespread.