Kidney Transplantation: The Operation
The donor kidney
Renal anatomy and an malies
Most kidneys have a single artery and vein, although the incidence of multiple vessels is significant (10–20%). Multiple arteries usually arise close to each other, although a lower pole artery sometimes arises from the iliac artery instead of the aorta; others may take origin anywhere along the abdominal aorta, although most arise at or just below the origin of the superior mesenteric artery. Multiple veins may also occur, more commonly on the right than the left; when they do occur on the left the caudal vein sometimes passes behind the aorta; the left renal vein invariably passes in front.
Double ureters may also occur, although in the vast majority of cases only a single ureter is present.
Preparation of the donor kidney
When a deceased donor kidney is removed it is generally removed with a wide margin of surrounding tissue, including peri-renal fat and fascia, to preserve any possible anomalous vessels. This is not the case with live donor kidneys, where the vascular anatomy is usually known before nephrectomy and it is undesirable to remove too much extra tissue. Before implantation the deceased donor kidney is inspected for damage, either caused during retrieval or as a consequence of the catecholamine storm in the donor. Typical injuries are tears in the intima (the lining) of the artery, a conse- quence of either traction on the artery or donor hypertension when coning occurs.
Finally, the inferior vena cava (IVC) and aorta around the origins of both renal vein and artery are trimmed to produce Carrel patches to facilitate implantation.
In order to monitor fluid status post operatively a central venous catheter is usually placed at the time of transplantation, in addition to the other peri-operative monitoring.
A urinary catheter is also placed, and connected to a bag of normal saline containing a blue dye (e.g. methylene blue) or antibiotic or both. This allows the bladder to be inflated so it can be easily located during surgery, and the blue dye permits confirmation by the surgeon that it is the bladder that he/she has opened and not the peritoneum or a loop of bowel.
The donor kidney is implanted in one or other iliac fossa, with the right side being generally preferred to the left since the iliac vessels are nearer to the surface. Dissection extends through the muscles but remains outside the peritoneal cavity. By keeping extraperitoneal and away from the intestine, the patient can resume eating and drinking soon after surgery. Extraperitoneal placement also has advantages later when it comes to taking a biopsy of the kidney, since any bleeding that may follow is relatively contained, rather than filling the entire peritoneal cavity.
The peritoneum is displaced medially to expose the external iliac artery and vein, the blood vessels that take blood to and from the leg. They are surrounded by lymphatic tissue and this is dissected free; it is this process that may predispose to lymphocoele formation post-operatively.
Most deceased donor kidneys are implanted with the renal artery anastomosed to the recipient’s external iliac artery, and renal vein to the external iliac vein. This technique was first devel- oped in Paris in the early 1950s, and was the placement copied by Murray when he performed his first transplant in 1954. The lower pole of the kidney now lies in proximity to the bladder, facilitating the ureteric anastomosis. The ureter is anastomosed to the dome of the bladder and, in most transplant units, a double J stent, a small plastic tube, is inserted to splint the anastomosis; this is removed cystoscopically 6 weeks later.
Where there is no Carrel patch on the artery, such as with kidneys from live donors, the renal artery may be joined end-to- end to the internal iliac artery. Multiple renal arteries may be joined to the divisions of the recipient’s own internal iliac artery on the back table before implantation.
Multiple arteries and veins
There is a network of veins within the kidney, so in general the smaller of two veins can be tied off. This is not the case for the arterial supply, which is end-artery and needs to be preserved. Where possible the multiple arteries are brought close together onto a single patch to make implantation easier; cut polar vessels are implanted into the side of the main artery or, if large, implanted separately.
Transplanting kidneys into small children is done at a few special- ist centres. Generally live donor or young adult deceased donor kidneys are used. For small children, implantation is on to the aorta and IVC, usually intra-peritoneal, rather than to the external iliac vessels, which would be too small.
Paediatric kidney transplantation has implications regarding fluid balance – the blood volume of an adult kidney may be half the circulating volume of a small child, so careful and experienced anaesthetic support is essential.
Some patients have a non-functioning bladder or have previously undergone a cystectomy. In order to provide a urinary reservoir a short segment of ileum is isolated and one end brought to the surface as a stoma. This urostomy (or ileal conduit) acts as a bladder; the transplant ureter is implanted at its base. A stoma appliance is placed over the urostomy to collect the urine.
Renal transplantation significantly improves patient survival compared with dialysis. Current UK 1-year, 5-year and 10-year patient and graft survival following a first kidney transplant are summarised below.