Kidney transplantation is a major surgical procedure that involves both vascular and ureteric anastomoses, and it is usually performed by a dedicated transplant surgeon, although in the past it was performed predominantly by urologists or vascular surgeons. Most recipients are already established on dialysis, although some may avoid dialysis by having the transplant preemptively, and many consider this the gold standard treatment. Preemptive transplantation confers a modest benefit over transplantation after the start of dialysis, but not if the duration of dialysis is less than a year. There are concerns about equity of access to preemptive transplants, as it tends to disadvantage individuals who are less educated and from lower socioeconomic groups. In addition there is a suggestion that patients transplanted preemptively may have lower adherence to immunosuppression. Preemptive transplantation is particularly advantageous in children. Renal transplant recipients are frequently elderly, with other comorbidity (e.g., diabetes, cardiovascular disease, obesity), which increases the surgical and anesthetic challenges. In addition most have impaired platelet function through a combination of uremia and antiplatelet therapy (aspirin or clopidogrel), and some will be on warfarin for previous thromboembolic disease or prosthetic heart valves. Thus this group of patients carries a relatively high operative risk.
Preparation of Recipient
The general preparation and selection of recipients for transplantation is discussed in Chapter 4 . Potential kidney transplant recipients are carefully assessed before being placed on the waiting list. Medical and surgical risk factors will have been identified and evaluated, and periodically reassessed while waiting. On admission for transplantation, a further careful history and physical examination are required to ensure that there is no immediate contraindication to major surgery. For example, have there been changes since the patient was last assessed? Particular attention should be paid to the patient’s fluid and electrolyte status. In addition a history of recent sensitizing events should be elicited (blood transfusions, immunosuppression withdrawal in someone awaiting a retransplant). These should be brought to the attention of the histocompatibility laboratory. The patient may require dialysis before going to surgery because of fluid overload or a high serum potassium concentration; this will depend on the nature of dialysis and when this was last carried out. Potassium often rises as a consequence of anesthesia, blood transfusion, and reperfusion of the kidney; it is essential to ensure that the patient has a normal serum potassium pretransplant. It is much easier and safer to dialyze a patient before transplant than immediately posttransplant.
The potential risks of a renal transplantation should be discussed with patients at the time of listing and must include general risks of surgery and specific risks of the procedure. These risks include technical complications such as arterial or venous thrombosis, bleeding or urinary complications, risk of delayed graft function (which can occur in up to 50% deceased donor kidney transplants), and of acute rejection. Careful explanation of the possible requirement for biopsy should be given. The need for immunosuppression, with its attendant drug-specific and immunosuppression-associated side effects, should also be discussed at the time of listing. Any recipient choices as to the nature of donors considered acceptable or not acceptable should be recorded (e.g., donors with a history of cancer or high risk behavior for hepatitis or HIV). At the time of admission for transplant, specific risks pertaining to the donor should be discussed with the patient where appropriate. Informed consent to proceed can then be obtained.
Immunosuppression may be commenced before the patient goes to surgery. Although there is no hard evidence that preoperative immunosuppression is necessary, many centers prefer a loading dose of a calcineurin inhibitor or antimetabolite to ensure a better blood level in the first hours posttransplant. Induction agents (most typically basiliximab) are also started preoperatively. Where the recipient is receiving an antibody-incompatible graft (typically from a living donor), he or she will usually have received several days of preoperative immunosuppression in addition to undergoing antibody removal.
Prophylaxis against deep vein thrombosis and pulmonary embolus should be undertaken with low dose molecular weight heparin according to hospital protocol, thromboembolic deterrent (TED) stockings, and perioperative intermittent calf compression.
Although the transplant operation is a clean one, the patient will be immunosuppressed and is at high risk for wound infection. In addition it is possible for the deceased donor kidney to be contaminated during retrieval or for there to be a urinary tract infection as a consequence of the donor having a urethral catheter while on the intensive care unit before death. Infection in the vicinity of the vascular anastomosis may result in secondary hemorrhage, which is an uncommon but catastrophic complication, resulting in loss of the kidney, compromise of distal circulation, and significant mortality. Prophylactic antimicrobial therapy, with a spectrum to cover common skin organisms as well as possible urinary tract contaminants, has been shown to reduce the risk of developing sepsis with bacteremia and for developing bactiuria ; a single dose may be sufficient. Antimicrobial cover may also be required if the donor was known to be infected, such as donors dying from meningococcal meningitis; the advice of a specialist in microbiology is valuable in these situations.
Consideration must be given at this stage to the cold ischemia time, which should be minimized. Prolonged cold ischemia is associated with increased rates of delayed graft function and worse long-term outcomes, particularly in transplants from donors after circulatory death. Logistical factors such as preoperative dialysis and the need for a prospective crossmatch, contribute significantly to cold ischemic times.
After induction of anesthesia, a central venous catheter (CVC) may be inserted into the internal jugular vein (preferably under ultrasound guidance) to allow central venous pressure monitoring to ensure optimal fluid replacement and postoperative dialysis, although in some centers, the use of CVC may be reserved for those patients who will receive antithymocyte globulin (ATG) induction. In patients without hemodialysis access the selected catheter should enable postoperative hemodialysis if required. Subclavian vein cannulation should be avoided if possible because of the risk of causing subclavian venous stenosis, which would prejudice future upper-limb vascular access when the kidney has failed. Other aspects of the induction of anesthesia and monitoring during the operative procedure are discussed in Chapter 13 .
Once the patient is anesthetized, a urinary balloon catheter is inserted aseptically into the recipient’s bladder (see later). The skin should be prepared carefully in the operating room; body hair is removed and the skin of the abdominal wall prepared with an antimicrobial agent, typically chlorhexidine gluconate in alcohol. It is wise to prepare the entire abdomen from nipples to midthighs, especially in a recipient with vascular disease, because occasionally the original incision may need to be extended or abandoned and the opposite iliac fossa opened, or saphenous vein harvested to manage a vascular problem.
Immediately before surgery, the World Health Organization (WHO) surgical safety check should be undertaken, giving additional consideration to checking blood group compatibility of donor and recipient and confirming the HLA crossmatch status. It is also important to ensure that the correct donor kidney is in the operating room.
Preparation of Kidney
The preparation of the deceased donor kidney should be done in advance of the transplant procedure in case some anomaly (for example, a previously unrecognized tumor) is present that would preclude transplantation, or damage is found that requires repair. Good preparation will ensure an adequate length of vessels with good hemostasis at the time of reperfusion, both in living and deceased donor kidneys. A varying degree of dissection of the kidney is required when the kidney is removed from cold storage. In the case of a deceased donor kidney removed as part of an en bloc procedure, considerable dissection needs to be performed, and this should be done carefully and with a good light on a back table with the kidney in a bowl of ice slush.
The kidney should be oriented as it is in the body. The renal vein should be picked up and dissected toward the kidney, dividing small tributaries, and ligating and dividing the gonadal and adrenal veins. Dissection should not continue close to the renal pelvis. If there is more than one renal vein, smaller veins can be ligated, assuming that there is one large renal vein. If two renal veins are of equal size and are not arising from a single caval patch, there is a risk of subsequent venous infarction if one vein is ligated; it is preferable to implant both veins separately or to join the veins to form a common trunk for a single anastomosis. A short right renal vein can be extended with donor inferior vena cava or external iliac vein.
Once the venous preparation is complete, the renal vein may then be folded over the kidney and the artery dissected out from adherent fat. Care must be taken to define the arterial anatomy, ensuring that no polar arteries are damaged in the process. In particular, the right renal artery typically gives a branch to the adrenal which may occasionally pass on to supply the upper pole of the kidney. The ureter can now be dissected free, with care not to divide the tissue between the ureter and lower pole of kidney (the so-called golden triangle, see Chapter 29 ) and to retain a small amount of tissue around the ureter to preserve its blood supply.
Once the kidney has been prepared, the perinephric fat can be removed. The kidney may then be flushed with 100 to 200 ml of kidney perfusion fluid, as this may remove products of metabolism and allows detection of defects in the artery or vein, which should be repaired at this stage.
Although traditionally the right iliac fossa was used for implantation of the kidney, in reality there is little to choose between sides. It has been suggested that the left kidney is best placed in the right iliac fossa and the right kidney in the left iliac fossa, an approach that places the pelvis and ureter medially to facilitate future ureteric reconstruction, should it be required. In contrast, placing the deceased donor kidney on the ipsilateral side with anastomoses to the external iliac vessels avoids crossing the renal artery and vein, and may be facilitated by the use of a subrectus pouch (see later); similarly, live donor kidneys implanted using the internal iliac artery may be placed contralaterally to avoid vessels crossing. In general, however, it is reasonable to use either iliac fossa for placement of the kidney.
Other factors which may dictate the optimal site of placement include the existence of previous abdominal incisions, particularly if placement of a transplant incision would result in devitalizing an area of abdominal wall. Previous venous thrombosis in one leg is an indication to use the opposite side lest the thrombus has obliterated the ipsilateral iliac veins. A history of femoral vein cannulation is also a relative contraindication to use that side for fear of iliac venous thrombosis or partial thrombosis.
If a colostomy or ileostomy were emerging from one side of the abdomen, the contralateral side would usually be chosen, although it would be preferable to use the same side as an ileal conduit (urostomy) to facilitate ureteric implantation. The presence of large polycystic kidneys may dictate which side is chosen, as there may only be room to implant a kidney on one side. Occasionally the polycystic kidneys are too large to permit placement of a transplant. Such a situation should be picked up as part of the assessment process and one or both polycystic kidneys should be removed before the patient is activated on the transplant list. Polycystic nephrectomy is best done either laparoscopically or through a midline incision; a transverse incision is contraindicated to avoid later concerns regarding skin viability when performing the transplant incision.
In children, in whom the vascular anastomoses of the renal vessels may be to the aorta and vena cava because of the size of the kidney, the right side is preferred because the kidney is placed behind the cecum and ascending colon. Where combined pancreas and kidney transplantation is performed via a vertical midline transperitoneal approach, the pancreas is usually placed in the right iliac fossa and the kidney in the left iliac fossa. To prevent torsion of the renal pedicle, the kidney is best placed in the retroperitoneal space, which is accessed by inserting an index finger into the prevesical space just lateral to the midline and developing the plane laterally.
There are two common incisions used to expose the external iliac vessels and bladder. The oblique Rutherford Morison or curvilinear incision is made in the right or left lower quadrant of the abdomen beginning almost in the midline 2 cm above the pubic tubercle and curving upward and 2 cm parallel to the inguinal ligament and ending just above the anterior superior iliac spine of the iliac crest. Caution is taken to avoid the lateral cutaneous nerve of the thigh, which emerges through external oblique 1 cm medial to the anterior superior iliac spine. In a child or small adult, this incision can be carried up to the costal margin to increase exposure. The external oblique muscle and fascia are divided in the line of the incision and split to the lateral extent of the wound. This incision is carried medially on to the rectus sheath to permit retraction or division of part of the rectus muscle for later exposure of the bladder. To expose the peritoneum, the internal oblique and transverse muscles are divided with cautery in the line of the incision.
The Alexandre or pararectal incision is slightly more vertical than that of Rutherford Morison. It starts 2 cm above the pubic symphysis and passes laterally and cranially along the edge of the rectus sheath, two finger breadths medial to the anterior superior iliac spine. The confluence of the oblique abdominal muscles just lateral to the rectus sheath (the Spigelian fascia) is divided to expose peritoneum beneath.
Once the peritoneum is exposed, the inferior epigastric vessels may be ligated and divided to improve access, but if there are multiple renal arteries, the inferior epigastric vessels should be preserved in the first instance in case the inferior epigastric artery is required for anastomosis to a lower polar renal artery. It may also be wise to preserve the vascular supply to the rectus muscle if the muscle has been divided in previous surgery, for example, during a subcostal incision to remove an ipsilateral kidney, gallbladder, or spleen. Although division of the spermatic cord was advocated in early descriptions of the procedure and was common practice for many years, it should not be done and is rarely required for adequate exposure. The spermatic cord may be freed laterally, which allows it to be retracted medially. In females the round ligament can be divided between ligatures.
Preparation of Operative Bed
After exposure of the transversalis fascia and peritoneum, the transversalis fascia is divided, and the peritoneum is reflected upward and medially to expose the psoas muscle and the iliac vessels. This is best done in a caudal to cranial direction. At this stage, a self-retaining retractor is inserted to provide good exposure while allowing the assistant to have both hands free to assist with the anastomosis. Dissection proceeds in the first instance to expose the external, common, and/or internal iliac arteries, depending on circumstance: the external iliac artery is the site of first preference if there is a healthy Carrel patch on the donor renal artery; the internal iliac artery may be considered if not, and the common iliac artery if it is a second transplant or if there is significant arterial disease affecting the external iliac vessels. Considerations in children are discussed later. The lymphatics that course along the vessels are preserved where possible and separated from the artery without division. It has been suggested that lymphatics should be ligated and not cauterized when being divided, because this is said to prevent the later occurrence of a lymphocele, although what evidence there is does not support that suggestion (see Chapter 28 ). The surgeon must be careful not to mistake the genitofemoral nerve for a lymph vessel. It lies on the medial edge of the psoas muscle, and a branch may cross the distal external iliac artery. If the internal iliac artery is to be used, it is important to mobilize a length of the common and external iliac arteries so that the internal iliac artery can be rotated laterally without kinking at its origin and so that the vascular clamps can be applied to the common and external iliac arteries when the internal iliac artery is short. Care is taken to inspect the origin of the internal iliac artery, if this is to be used, for any evidence of atheroma and, similarly, any atheromatous disease in the common or external iliac artery should be noted. If there are two or more renal arteries not on a Carrel patch of aorta, the dissection of the internal iliac artery is extended distally to expose the initial branches of the internal iliac artery, which may be suitable for anastomosis to individual renal arteries. This can be done either in situ, or the bifurcation of the internal iliac removed and a back table anastomosis of the two renal arteries onto the divisions of the internal iliac artery performed, before the kidney is implanted using the resected portion of recipient internal iliac as an interposition graft.
Having completed the exposure of the appropriate iliac arteries, dissection of the external iliac vein is performed ( Fig. 11.1 ). If a left kidney with a long renal vein is available, dissection of the external iliac vein alone generally allows a satisfactory anastomosis without tension. Uncommonly, if the kidney has a very short renal vein, such as with a right kidney or occasionally a left kidney whose vein has been shortened, or if the recipient is obese, the internal iliac vein and usually one or two gluteal veins can be ligated and divided. This technique allows the common and external iliac veins to be brought well up into the wound, particularly if the internal iliac artery is divided, and this facilitates the performance of a tension-free anastomosis. However, division of the internal iliac and gluteal veins is not without risk, because slippage of the ligature may result in hemorrhage that is difficult to control. Alternative means of managing short renal veins are preferred, including use of the parachute technique for venous anastomosis, a more distal placement on the external iliac vein, or use of a segment of donor inferior vena cava to lengthen the renal vein. Temporary placement of the cold kidney graft into the wound assists in the selection of the sites for anastomosis on the recipient artery and vein.
Anomalies of the renal artery or vein are common, amounting to 30% deceased donor kidneys retrieved. In living donation, whereas kidneys are selected preferentially to have a single artery, multiple arteries are common. Because the renal arterial inflow comprises end arteries with no intrarenal communication, all arteries need to be perfused, but particularly the lower-pole artery, because it is likely to give rise to the ureteric blood supply. If multiple arteries are present and separate (i.e., not on a common Carrel patch), there are several surgical techniques that can be used: The vessels can be spatulated together to form a common trunk ( Fig. 11.2 ), the internal iliac artery can be removed from the recipient and its branches used to anastomose to the renal arteries on the back table, a smaller artery may be anastomosed end-to-side to the larger main renal artery, a small accessory artery can be anastomosed to the inferior epigastric artery, or the renal arteries can be implanted separately into the external iliac artery. A small upper polar artery, if thought to be too small to anastomose safely to the major renal artery, may be ligated, provided that it supplies less than one-eighth of the kidney (this should be evident on perfusion of the kidney after removal).
A deceased donor kidney usually has a renal artery or arteries arising from a single aortic patch, and this patch should be trimmed to an appropriate size and used for anastomosis to the external iliac artery. If two renal arteries are widely separated on the aortic patch, the patch may be divided to allow separate implantation into the external iliac artery, or the two separate patches joined together to form a shorter patch, or one may be implanted end-to-side to the external iliac artery and the other to the internal iliac artery, or both may be implanted to separate branches of the internal iliac artery.
Before making the arteriotomy or venotomy, the surgeon should mentally visualize the kidney in situ in its final resting place, as well as picturing the course that the renal artery and vein would take to ensure the optimal site for the anastomosis. Where the renal artery is much longer than the vein, it may either be electively anastomosed on the internal iliac artery or, more simply, the artery can be anastomosed to the external iliac artery but the kidney placed in a subrectus pouch fashioned by dissecting the peritoneum from the underside of the rectus muscle. In such a position, the longer artery tends to run a smooth course.
When the kidney has been prepared and is ready for implantation, the vessels are now ready for clamping. Heparin may be administered in a modest dose (e.g., 30–60 IU/kg), although many surgeons simply cross-clamp the recipient vessels without heparinization in patients already on dialysis. The kidney should be kept cold during the implantation phase. This may be achieved in a number of ways, such as wrapping in a surgical gauze swab filled with crushed frozen saline. Another technique uses a surgical glove to contain the kidney together with crushed ice, the vessels being brought out through a small cut in the side of the glove. This technique not only keeps the kidney cool during the anastomosis, but also facilitates handling of the kidney.
External Iliac Artery
An end-to-side anastomosis of the renal artery to the external iliac artery (or common iliac artery) usually is performed using an appropriately trimmed cuff of aorta attached to the renal artery (the Carrel patch) ( Fig. 11.3 ). Vascular clamps are applied to the external iliac artery proximally and distally if an end-to-side anastomosis is to be performed, with care taken to avoid clamping diseased segments of artery wherever possible. An arteriotomy appropriately placed is performed in the external iliac artery, and the lumen is flushed out again with heparinized saline; where the donor artery has no Carrel aortic patch, a hole punch is used to create a suitably sized hole for anastomosis.
The anastomosis is done with a continuous 5-0 or 6-0 monofilament vascular suture (see Fig. 11.2 ), although an interrupted technique may be necessary where no Carrel patch exists. In older patients and those who have been on dialysis some time, the intima may be calcified and may be easily displaced from the wall of the artery. Particular care should be taken to ensure that all the intima on the recipient artery is secured back in position during the anastomosis to prevent a dissection propagating along the distal artery on reperfusion. In very severe cases of calcification of the recipient artery, it may be necessary to carry out a formal endarterectomy of the iliac artery, with the distal intima stitched in place to prevent formation of a flap and subsequent dissection.
Internal Iliac Artery
The internal iliac artery should not be used for anastomosis if the contralateral internal iliac artery has already been used for a previous transplant or if the contralateral limb relies on collaterals from the ipsilateral internal iliac for its perfusion (for example, where the contralateral common iliac artery is occluded). If the internal iliac artery is to be used, its distal branches are ligated. A vascular clamp is applied to the internal iliac artery close to its origin (to reduce the chances of clot forming in the occluded stump) or to both the common and external iliac arteries. The internal iliac artery is then divided close to or at the bifurcation maximizing its length, and the lumen is flushed out with heparinized saline.
The internal iliac artery is anastomosed end-to-end to the renal artery with 5-0 or 6-0 monofilament vascular suture using a three-point anastomosis technique, as described by Carrel in 1902, or a two-point anastomosis ( Fig. 11.4 ) ; alternatively, the parachute technique may be used, only tying the sutures after first placing all the sutures individually.
If there is a disparity between the renal artery and the internal iliac artery, the renal artery being considerably smaller in diameter, the renal artery may be spatulated along one side to broaden the anastomosis. If one side of the renal artery is spatulated, care should be taken to place the spatulation of the renal artery appropriately, taking into consideration the final curve of the internal iliac artery and the renal artery to avoid kinking when the kidney is placed in its final position . If both arteries are small, the anastomosis should be performed with interrupted sutures to allow for expansion. In a child or a small adult with small arteries, the whole anastomosis should be performed with interrupted sutures.
The renal vein is anastomosed end-to-side, usually to the external iliac vein. The external iliac vein is clamped proximally and distally with vascular clamps or a Satinsky side clamp is used. The venotomy is flushed out with heparinized saline. Where possible the site of venotomy should be proximal or distal to a valve, and if a valve is present at the site of the venotomy, it should be removed carefully. The anastomosis is fashioned using a continuous 5-0 monofilament vascular suture, with the initial sutures placed at either end of the venotomy ( Fig. 11.5 ). A useful aid when doing the venous anastomosis is to place an anchor suture at the midpoint of the lateral wall, which allows the external iliac vein and the renal vein on the lateral side of the anastomosis to be drawn clear of the medial wall of the anastomosis ( Fig. 11.6 ). This technique reduces the risk of the back wall being caught up in the suture while the medial wall is being sutured. An alternative, and one suited to larger patients, is to use the parachute technique, placing several sutures at the cranial aspect of the medial suture line before parachuting the anastomosis down. This has the benefit of distributing the tension over a wider area of vein, so there is less likelihood of the suture pulling out.
The renal vein is usually anastomosed to the external iliac vein medial to the external iliac artery, although on occasion it may be lateral to the artery. Wherever the anastomosis is positioned, it is important to ensure that the renal vein is under no tension, and care should be taken that the vein is not twisted before starting the anastomosis. When a small child receives an adult kidney, it is sometimes necessary to shorten the renal vein to prevent kinking, especially when the vein is anastomosed to the inferior vena cava.
If the venous anastomosis is fashioned before the arterial anastomosis (such as when the external iliac artery is to be used), it may be desirable to remove the venous clamps to permit return of blood from the leg, so shortening the duration of venous stasis. This is best achieved by placing a separate fine bulldog clamp close to the anastomosis on the renal vein before removing the iliac vein clamps, so preventing reflux of blood into the kidney. It is important that the bulldog clamp is not traumatic to the vein, and does not slip off the vein—two clamps are often better than one to ensure the latter. This maneuver also allows any bleeding from the venous anastomosis to be managed before the kidney is revascularized.
The question of whether the arterial anastomosis or the venous anastomosis should be done first depends on the final position of the kidney and the ease with which the second anastomosis may or may not be done. If the renal artery is to be anastomosed end-to-side to the external iliac artery (usually with a Carrel patch of aorta), it is preferable to do the venous anastomosis first, then the end-to-side arterial anastomosis can be positioned correctly. If the renal artery is to be anastomosed to the internal iliac artery, the arterial anastomosis may be done first because this enables the renal vein to be positioned appropriately.
Reperfusion of The Kidney
Vascular clamps are removed sequentially, starting either with the venous clamps (proximal first then distal), or the arterial clamps (distal first then proximal), depending on surgeon preference. Once the kidney is reperfused, attention should be paid to controlling significant bleeding points on the anastomoses and ligating any tributaries that were missed during the back table preparation. The quality of reperfusion is variable. Live donor kidneys and kidneys that have been subject to machine preservation reperfuse evenly and become pink very quickly. Deceased donor kidneys, particularly those with prolonged cold ischemia or those donated after circulatory death, tend to be patchy for some time. Although this usually resolves over time, it is important to ensure the following:
All the clamps have been removed.
The artery is not twisted.
The recipient has a good blood pressure.
There is no intimal dissection of the proximal recipient artery or the donor renal artery, the latter being a consequence of traction in the donor or extreme donor hypertension during coning.
Finally, if concern still exists, the Hume test can be reassuring. When the renal vein is occluded between finger and thumb, the kidney should swell and throb. When the vein is released the kidney palpably softens as the turgor goes.