Renal Autotransplantation



Renal Autotransplantation


VENKATESH KRISHNAMURTHI

DAVID A. GOLDFARB



Having been first performed by Ullman over 110 years ago, renal autotransplantation is now considered a last resort in the spectrum of surgical treatment for upper urinary tract disorders (1). Renal autotransplantation serves to maintain urinary tract integrity in cases of extensive ureteral tissue loss. This operation is also valuable for any disease where intervention on the kidney would expose it to prolonged warm ischemia resulting in permanent renal damage, such as is the case for complex distal renal arterial disease and large kidney tumors where renal preservation is imperative. The basic techniques have evolved as a consequence of developments in the field of renal allotransplantation, particularly an improved understanding of renal preservation. The advantages of back-table reconstruction include optimal exposure, use of optical magnification (loupes), a bloodless surgical field, and incorporation of renal preservation techniques (intracellular flush solutions and hypothermia) (2).





INDICATIONS FOR SURGERY

Autotransplantation of the kidney is an acceptable treatment option for patients with impassable proximal ureteral obstruction and extensive ureteral loss (3). Complex renal vascular lesions requiring ex vivo repair can also be successfully managed with renal autotransplantation (2). Lastly, complex intrarenal or central renal tumors may be successfully treated with ex vivo resection and autotransplantation.

Urinary tract disorders that necessitate consideration for autotransplantation include proximal ureteral obstruction that cannot be managed with bladder-based methods of repair (Boari flap, with or without psoas hitch). These bladder-based repairs require the presence of a large capacity bladder and, notwithstanding this prerequisite, these repairs can rarely extend beyond the pelvic ureter. Moreover, even if bladder-based flaps can reach beyond the area of obstruction, successful reconstitution of the urinary tract may be compromised by excessive tension at the site of reconstruction.

Common etiologies of proximal ureteral obstruction include multiple failed repairs of ureteropelvic junction (UPJ) obstruction (failed pyeloplasty or endoscopic repair), desmoid tumor (with or without Gardner syndrome) obstructing the proximal ureter, and extensive ureteral stricture. Prior to pursuing autotransplantation, these patients have generally been managed with indwelling ureteral stents and/or percutaneous nephrostomy tubes. They are completely stentdependent and often have developed recurrent episodes of pyelonephritis.

An uncommon condition that is amenable to autotransplant would be the loin-pain hematuria syndrome (4). This is characterized by flank pain with gross or microscopic hematuria for which exhaustive diagnostic testing has failed to disclose a specific etiology. Aggressive treatment is driven by the chronic pain that accompanies the syndrome.

Finally, some centers have used ex vivo back-table excision, reconstruction, and autotransplantation for large renal cancers that are not felt to be amenable to in situ repair (5,6).


ALTERNATIVE THERAPY

An alternative to renal autotransplantation in patients with proximal ureteral obstruction is ileal ureteral substitution; however, ileal substitution may not be possible in patients with a history of extensive intestinal surgery, such as those patients with the Gardner syndrome who have undergone total proctocolectomy with ileostomy or ileal pouch creation. Additionally, the long-term consequences of intestinal interposition within the urinary tract are not completely known and must be considered when utilized in younger patients. Therefore, for patients in whom an ileal substitution does not seem favorable, autotransplantation may be the only option.

Complex renal vascular disorders are also an indication for renal autotransplantation. These are most often arterial disorders such as stenoses or aneurysms involving the segmental renal arteries and are difficult to treat with in situ methods. As an extension of the techniques routinely applied in renal allotransplantation, the renal hilum can be readily accessed while the kidney is on the “back table.” Revascularization to branch vessels or excision of aneurysms deep in the hilum is much easier on the back table and thus can be accomplished satisfactorily prior to autotransplantation.


TECHNIQUE OF RENAL AUTOTRANSPLANTATION


Surgical Instrumentation

Autotransplantation of the kidney combines the techniques of living donor nephrectomy and standard renal transplantation within the same patient. Successful performance of these operations requires instrumentation to facilitate fine vascular repairs. Although the specific instrumentation is a matter of individual preference, instrumentation for vascular surgical procedures should include (a) noncrushing vascular clamps designed for blood vessel occlusion, (b) forceps with fine tips designed for handling both small suture needles and the walls of small blood vessels in an atraumatic manner, (c) needle holders with fine tips to grasp small needles yet prevent unwanted needle movement, and (d) an assortment of silastic vessel loops and umbilical tapes for atraumatic vessel manipulation.

Given the variety of sizes and shapes of vascular clamps, appropriate selection depends on the size of the vessel to be occluded and the desired direction of vessel wall occlusion (longitudinal, transverse, or oblique). The jaws of vascular clamps should have rows of interdigitating teeth that allow vessel wall apposition without endothelial damage. Vascular clamps should be applied by compressing the jaws only to the point necessary for blood flow cessation. Excessive or forceful application can result in endothelial damage and subsequent vessel dissection.

For small, delicate blood vessels or relatively inaccessible areas, spring-loaded (bulldog) clamps are useful devices for vascular occlusion. Bulldog clamps also come in a variety of sizes, strengths, and shapes. Additionally, plastic varieties with soft padded jaws may be useful for extremely delicate vessels.

Vascular forceps must have tines that are in direct apposition, and the tips should be precise enough to grasp the vascular adventitia as well as a suture needle. Forceps with
rows of interdigitating teeth serve to accomplish both of these purposes. Alternatively, forceps designed for stable needle grasp, such as diamond jaw forceps, do not allow for reliable manipulation of tissue.

Vascular needle holders should also have fine tips to stabilize small suture needles. The two common choices in vascular needle holders are a ring-handled needle holder and the spring-loaded type. Needle holder selection is a matter of individual preference; however, spring-loaded needle holders generally enable precise needle placement without large degrees of wrist rotation. Ring-handled needle holders permit a more stable needle grasp and facilitate accurate needle placement in deep structures or through densely-calcified vessels.

As with surgical instruments, the selection of vascular suture is also a matter of individual preference. The caliber of the suture should be as fine enough to minimize bleeding through suture holes but strong enough to avoid suture line disruption. In most cases, suture sizes between 2-0 and 7-0 will be applicable for vascular procedures in the abdomen and pelvis. At the level of the aorta, a 2-0 or 3-0 suture should suffice, and 4-0 is almost always suitable for the inferior vena cava. As one progresses to smaller vessels, including the common and external iliac arteries and veins, a 5-0 and 6-0 suture is suitable. Repair of small vessels, such as segmental renal arteries, may require a 7-0 or 8-0 suture.

Nonabsorbable sutures should be selected for vascular procedures. Although silk suture has favorable handling and tying characteristics, its popularity has waned with the development of synthetic, nonabsorbable sutures such as polypropylene. In comparison to silk, synthetic monofilament sutures are relatively inert in tissue, have a low coefficient of friction and thereby result in less tissue drag, and tend to retain a greater amount of tensile strength over time. Vascular sutures are swaged onto fine, one-half-circle or three-eighths-circle needles. The vascular needle should be large enough to penetrate tissue yet small enough so as not to cause hemorrhage from the needle holes. A common practice in vascular repair is to use a continuous suture with needles swaged onto both ends. This construction allows for greater flexibility in accomplishing the repair (e.g., closure from both directions). In select instances, specifically that of pediatric vascular surgery, absorbable monofilament suture with a long half-life (e.g., polydioxanone suture) can be used to allow anastomotic growth.

As with all operative procedures, an essential requirement for renal autotransplantation is optimal retraction and exposure of the operative field. We prefer to use a self-retaining, ring-based retractor system that is fixed to the table. For flank exposure, the Bookwalter retractor (Codman & Shurtleff, Inc, Raynham, Massachusetts) provides for excellent exposure of the kidney and renal hilum. We have modified the medium-sized Bookwalter oval by creating a modest angle (20 to 30 degrees) along the two ends of the ring. This enables the ring to better “fit” the patient’s flank during the operative procedure. A standard oval ring works very well in the iliac fossa. Lastly, for midline intraperitoneal abdominal incisions, we have utilized both the Bookwalter retractor system and the Thompson retractor (Thompson Surgical Instruments, Inc, Traverse City, Michigan). In our opinion, the Thompson retractor provides better exposure in more obese patients as the side bars of the retractor can be placed further from the incision. One disadvantage of this feature, however, is that the side bars tend to be closer to the operating surgeon and can be difficult to work around.


Renal Autotransplantation: Operative Approaches

The selection of the incision for renal autotransplantation depends on (a) the patient’s prior surgical history and (b) the indication for autotransplantation. When the autotransplant is being performed to treat conditions affecting the proximal ureter (as opposed to the renal vasculature), we favor placing the kidney into the contralateral iliac fossa. This enables the renal pelvis and ureter to be the most superficial structures such that if repeat procedures are required on the urinary tract, these structures can be accessed without dissecting or retracting the main renal vessels. Although the kidney can be removed and placed in either iliac fossa through a midline intraperitoneal incision, we often prefer a retroperitoneal flank approach for “donor nephrectomy,” when the kidney is being removed for conditions affecting the proximal urinary tract (7). Following completion of the flank approach for the “donor” nephrectomy, the patient is placed back in the supine position, the contralateral iliac fossa is reprepped and draped, and exposure of the iliac vessels is conducted in a standard manner. In theory, combining two separate procedures may result in a longer total operative time; however, this must be balanced against the benefit of extraperitoneal procedures and improved exposure along both the flank and iliac operative fields.

A midline intraperitoneal approach functions very suitably for renal autotransplantation. We prefer to use this technique when the autotransplant is being performed for vascular conditions, since the midline approach enables dissection of any abdominal structure. During repair of vascular disorders, arterial conduits (e.g., hypogastric artery) are often necessary for reconstruction, and these vessels can be easily exposed through a midline intraperitoneal approach. In contrast to two retroperitoneal procedures, the midline approach does require mobilization and retraction of the small bowel and colon, which may add to postoperative ileus. An upper abdominal transverse intraperitoneal approach is not recommended because it is very difficult to expose structures caudal to the aortic bifurcation, such as the iliac vessels.

Lastly, a laparoscopic approach has also been successfully utilized for the donor nephrectomy portion (8,9). In order to effectively utilize the laparoscopic approach, however, the kidney extraction incision should be made over the iliac vessels for subsequent implantation of the autograft. As mentioned previously, when autotransplantation is performed for urinary tract disorders, placement of the kidney in the ipsilateral iliac fossa puts the urinary tract structures in the most posterior location, which is suboptimal should further procedures become necessary.


Technique of Flank Donor Nephrectomy

Following satisfactory induction of general endotracheal anesthesia and placement of the necessary arterial and central venous monitoring lines, a Foley catheter is placed in the bladder. The patient is then placed on his or her side with the kidney that will be operated on facing “up.” The “down” leg is then bent and the “up” leg is maintained in a straight position. Pillows are placed between the legs, and the greater trochanter along the table surface is padded with egg crate mattresses.
The kidney rest is maximally elevated and the operating table is placed in a fully flexed position. This enables a maximum distance between the lower ribs and the iliac crest. An axillary roll is placed, and the arms are padded and secured to a double arm board. The patient is then secured to the table prior to preparation and drape of the operative field.

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Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Renal Autotransplantation

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