Nephrectomy

The genitourinary system is derived from the intermediate mesoderm and shows three stages of development:

At the terminal end of the mesonephric duct, an outgrowth called the ureteric bud appears and ascends along the pathway by which the mesonephric duct had descended. The ureteric bud penetrates the metanephros (condensation of mesoderm), which forms the metanephric cap. The distal end of the ureteric bud subsequently dilates, forming the primitive pelvis. Simultaneously, the primitive pelvis splits into cranial and caudal portions that divide and further subdivide to give rise to major and minor calyces. At the blind end of the minor calyces, collecting ducts are formed. At the distal end of the collecting ducts there is a metanephric tissue cap that under the influence of the tubule moves laterally to form renal vesicles. At the medial end, the vesicle becomes associated with the collecting tubule and breaks into it. The lateral end is invaginated by a small capillary loop, thus forming Bowman’s capsule. The rest of the vesicle forms the proximal and distal convoluted tubules and the loop of Henle, thus resulting in a functioning kidney. The metanephros, which is initially located in the kidney, later ascends to a more cranial position—the ascent of the kidney. This migration is thought to occur due to diminution of the body curvature and the increased growth in the lumbar and the sacral regions. The metanephros derives its blood supply from the common iliac artery and subsequently directly from the aorta as the kidney ascends. The lower vessels degenerate, although they may persist as supernumerary renal arteries. Initially, the renal hilum is directed ventrally, but as the kidney ascends it rotates medially and the hilum points anteromedially.

ANATOMY

Both kidneys are retroperitoneal organs that lie on the posterior abdominal wall. The kidney and the associated structures are outlined in fig 1. Each kidney lies obliquely, with the upper pole being nearer to the midline than the lower pole. Because of the presence of the liver on the right side, the right kidney is located slightly lower than the left. On the medial aspect of each kidney is the hilum, which is located approximately at the level of the transpyloric plane. Present at the hilum are the following structures, starting from the most superficial: the renal vein, the renal artery, and the ureter. The kidney has its own fibrous capsule but lies surrounded by perinephric fat that has an outer layer of perinephric fascia, known as Gerota’s fascia. Gerota’s fascia is a continuation of the transversalis fascia and separates the kidney from the adrenal glands that are located on the superior pole. The renal bed is composed of the diaphragm, the costal diaphragmatic recess of pleura, and the 11th and 12th ribs. The inferior aspect of the renal bed is formed by the psoas, quadratus lumborum, and transversus abdominis muscles. The three nerves that lie posteriorly to the kidney are the subcostal, iliohypogastric, and ilioinguinal nerves. Each renal artery arising from the aorta divides into several branches and supplies the kidney. The renal veins drain into the inferior vena cava, the right renal vein being much shorter than the left. The other veins that drain directly into the left renal vein include the left gonadal, left adrenal, and renolumbar veins. The lymphatic drainage is into the para-aortic nodes along the origin of renal arteries.

Fig 1: Anatomy of the kidney and the associated structures

PREOPERATIVE PREPARATION

A thorough assessment of the patient’s cardiovascular and respiratory condition is performed. To evaluate contralateral renal function, baseline serum creatinine and, if necessary, a nuclear renal scan are obtained. Renal tumors are now commonly detected as an incidental finding on computed tomography of the abdomen. If nephrectomy is being performed for renal malignancy, the computed tomography scan or magnetic resonance image is carefully examined for the presence of renal vein or inferior vena cava tumor thrombus that would require special intraoperative approaches. If the patient is noted to have an elevated serum creatinine after contrast studies, intravenous fluid administration is indicated along with mannitol. If there is possibility of en bloc bowel resection, standard bowel preparation is necessary.

Operative Procedure

The approach to the kidney depends on the indication for nephrectomy. A simple nephrectomy for benign processes can be approached through the flank, whereas a radical nephrectomy for renal malignancy should be performed via a transabdominal approach.

Simple Nephrectomy

POSITION

The patient is placed in a lateral position with the flexion of the operating table in line with the anterior superior iliac spine of the pelvis. The lower leg is flexed to 90 degrees at the knee to prevent the body from rolling from side to side, whereas the upper leg is kept straight to maintain tension in the flank region. An axillary roll is placed under the lower dependent arm to prevent pressure on the axillary neurovascular bundle. The upper arm is placed on a special rest and secured. The lateral position of the patient is maintained by applying wide adhesive tape extending from the operating table and across the iliac crest. Another tape is placed at the level of the shoulder in a similar fashion to prevent the upper body from tilting forward. Next, the kidney rest is elevated and the operating table flexed, thus allowing the flank region to be under tension. All regions of the patient’s body are carefully inspected, with particular attention to areas of pressure that must be relieved by placement of pillows. A nasogastric tube and Foley catheter are placed. The operative area is prepped and draped in the usual sterile fashion.

INCISION

The 12th rib is identified, because this will be the line of incision, starting over the rib and extending anteriorly up to the lateral border of rectus abdominis muscle.

EXPOSURE AND OPERATIVE TECHNIQUE

The incision is carried down sharply through the skin and subcutaneous fat until the 12th rib is visible along the posterior aspect of the incision. The external and internal oblique muscles are incised with electrocautery (fig 2) to expose the dense lumbar dorsal fascia, which lies anteromedial to the tips of the 11th and 12th ribs. More medial to the lumbar fascia lies the transversus abdominis muscle. The lumbar dorsal fascia is opened, and two fingers are inserted beneath the transversus abdominis muscle to develop the extraperitoneal plane of dissection. As the peritoneum is reflected medially, the transversus abdominis muscle can be divided, and this dissection is continued toward the lateral margin of the rectus fascia. Posterior exposure is achieved by dividing the latissimus dorsi and serratus posterior muscles (see Fig.3). The diaphragmatic and intercostal muscle attachments to the 12th rib remain to be released. This can be achieved either by resecting the 12th rib or by carefully dividing the diaphragmatic attachments and the external and internal intercostal muscles. The wound is protected with laparotomy pads, and a self-retaining retractor is placed.

Fig 2: A, Flank incision for simple nephrectomy showing the latissimus dorsi and external oblique muscles to be divided

Fig 3 Hilar dissection showing a vessel loop elevating the renal vein to provide access to the renal artery.

Using both digital and blunt dissection with a sponge stick, Gerota’s fascia is separated medially off the psoas muscle. Gerota’s fascia is incised and extended longitudinally. With a combination of blunt and sharp dissection, the perirenal fat is freed from the surface of the kidney. The kidney is mobilized forward to provide access to the posterior aspect of the hilum where the renal vessels are secured. The renal artery is identified and carefully dissected with a right-angle Mixter clamp. The artery is ligated in continuity with 0-0 silk sutures and divided. For further security, a 2-0 silk transfixion suture ligature is placed at the proximal end. If any additional arteries are present, these are addressed in a similar fashion.

Next, the renal vein, which lies anterior to the artery, is dissected and doubly ligated in continuity. On the left side, it may be necessary to divide the gonadal, adrenal, and renolumbar veins before addressing the renal vein. The kidney is grasped and delivered into the wound. The ureter is isolated, divided, and ligated with 2-0 silk sutures. The wound is irrigated and hemostasis is achieved. The wound is filled with sterile saline solution and observed for bubbles, which may indicate that the pleural lining has been breached. If bubbles are present, either a chest tube is inserted or a small red Robinson catheter is placed through the pleural defect into the thoracic cavity; the catheter is withdrawn after completion of the wound closure, while the anesthesiologist is expanding the lung. Through a separate stab incision, a 10-mm Jackson-Pratt drain is placed into the cavity.

CLOSURE

The wound is closed in layers using 2-0 absorbable sutures. The skin is closed with staples.

Radical Nephrectomy

POSITION

The patient is placed in the supine position, and the flank can be slightly elevated by placing a log roll beneath it. The abdomen and the lower chest are prepped and draped in the usual sterile manner. A transabdominal approach is achieved through a subcostal incision based primarily on the side of the nephrectomy, which is adequate for exposure and can be extended across the midline. For a large tumor, particularly at the upper pole, a thoracoabdominal incision may be used. The muscles and fascia of the anterior abdominal wall are incised, and the peritoneal cavity is entered.

EXPOSURE AND OPERATIVE TECHNIQUE

A thorough exploration is performed with particular attention paid to excluding distant metastases and to identifying the presence of coexisting intra-abdominal pathology. A self-retaining retractor system is arranged around the wound, and the anterior abdominal wall is retracted to improve the exposure.

Right-sided Nephrectomy

For right-sided nephrectomy, the peritoneal reflection along the lateral border of the ascending colon and hepatic flexure is sharply divided and retracted medially to display the duodenum. The duodenum is mobilized with the Kocher maneuver to reveal the inferior vena cava. Moist laparotomy pads are placed around the medially rotated colon and duodenum to hold them in position with the retractors. The right renal vein is identified and gently dissected, and a vessel loop is placed around it. Using the vessel loop, the renal vein is carefully lifted up to allow pulsation of the renal artery to be felt beneath it. The main renal and any accessory arteries are carefully isolated and ligated in continuity with 2-0 silk, ensuring that two ligatures are placed proximally. An additional transfixion suture ligature using 3-0 silk should be placed on the proximal stump. The renal vein is not tied until all the renal arteries are dealt with. The renal vein is next ligated in continuity with 0-0 silk ligature and divided. An additional 2-0 silk transfixion suture ligature is placed on the proximal stump. If there are any lumbar veins entering the distal renal vein or the adjacent vena cava, they should also be ligated in continuity.

Once the renal pedicle has been divided, the incision is carried upward and downward anterior to the adventitia in front of the inferior vena cava, with particular care taken to hemoclip small lymph vessels. The fibroadipose and lymphatic tissues are dissected laterally; the tissue over the anterior and lateral surfaces of the inferior vena cava is included with the specimen. The ureter and the right gonadal vein are mobilized sharply to the level of the aortic bifurcation. Each of these structures is individually ligated with 0-0 silk sutures and divided. The gonadal vein is also divided and ligated at the point of its entry into the inferior vena cava.

With the medial aspect of the dissection completed, the peritoneal reflection over the lateral aspect of the kidney is divided and extended from the level of the aortic bifurcation inferiorly to just above the adrenal glands. Gerota’s fascia is mobilized off the renal bed, which consists of quadratus lumborum and psoas muscles. A variety of small and large collateral vessels will be encountered and can be either hemoclipped or ligated with 2-0 silk sutures.

After the inferior pole and the lateral aspect of the kidney have been mobilized, the entire specimen is displaced caudally, and large hemoclips are placed to control vessels and lymphatics contained within the adventitial tissue above the adrenal gland. Additional regional lymphadenectomy may be performed, which involves carefully dissecting the lymphatic tissue along the anterior surface of the aorta and vena cava; the lymphadenectomy extends from the level of the adrenal vein to the inferior mesenteric artery.

Left Radical Nephrectomy

For left radical nephrectomy, the approach involves division of the peritoneum along the line of Toldt on the lateral aspect of the descending colon. This is carried around the splenic flexure. Beneath it, the splenorenal ligament is divided to mobilize the pancreas and the spleen upward and to the right. These structures can be packed away to the right using moist laparotomy pads. The colon is lifted and reflected medially until the aorta and the anteromedial aspect of the inferior vena cava are clearly visualized. The left renal vein is located and dissected as it arches over the aorta. A vessel loop is placed around the renal vein and lifted upward to provide access to the renal artery, and its branches are ligated in continuity with 2-0 silk and divided. An additional suture ligature using 3-0 silk is placed proximally. A search should be made for accessory renal arteries, which should be dealt in a similar fashion.

Once the renal arteries have been addressed, the renal vein is ligated in continuity with 0-0 silk sutures and divided. Similar to the right-sided nephrectomy, the adventitia and lymphatic tissues are dissected off the anterior wall of the aorta and displaced toward the specimen. The left gonadal vessels and the left ureter are bluntly dissected to the level of the aortic bifurcation and ligated with 2-0 silk and divided. The lateral peritoneal reflection around the border of the kidney is divided, and Gerota’s fascia is mobilized off the renal bed. Vessels encountered during the mobilization of the kidney from its bed are hemoclipped and divided. The kidney is retracted inferiorly, and the fibroadipose tissue around the adrenal gland is secured with large hemoclips and divided.

Once the specimen has been removed, a similar limited regional lymphadenectomy along the anterior and lateral surfaces of the aorta can be performed, extending from the superior to the inferior mesenteric artery. The lymphatic tissue lying between the vena cava and the aorta is removed.

If there is preoperative or intraoperative evidence of thrombus within the renal vein, this is dealt with by placing Rummel tourniquets around the inferior vena cava above and below the entry of the renal veins. Alternatively, bleeding from the inferior vena cava can be controlled with vascular clamps. Both renal veins are similarly controlled. The inferior vena cava is lifted, and lumbar veins entering on its deep surface are carefully hemoclipped or tied with 3-0 silk ligatures. After the Rummel tourniquets are tightened, the inferior vena cava is opened longitudinally and the tumor and the cuff of the renal vein from which it is extending are removed. This segment of the inferior vena cava is flushed with heparinized saline, and the venotomy is closed with running 3-0 polypropylene monofilament sutures. The Rummel tourniquets are released, and the venotomy is inspected for leaks.

CLOSURE

The abdominal musculature is closed in layers with continuous 2-0 absorbable sutures. Skin is approximated with staples.