Live Donor
Kidney Transplantation
The limited supply of deceased donor organs and an ever-increasing number
of patients waiting for kidney transplantation has led to the widespread use of
living donors. Renal transplantation has the unique advantage, compared with
other organs, that most individuals have two kidneys, and if not diseased, have
sufficient reserve of renal function to survive unimpeded with a single kidney.
The shortage of donors has also led to the use of parts of non-paired organs,
such as liver and lung lobes, the tail of pancreas and lengths of intestine
from living donors; indeed, even live donation of the heart has occurred, when
the donor has lung disease and received a combined heart-lung transplant, with
their own heart being transplanted to someone else, so called ‘domino transplantation’.
For the purposes of this chapter we will focus on live kidney donation, but
similar principles apply to other organs.
Advantages of living donor transplantation
1 Living
donation is an elective operation that takes place during standard working
hours, when there is a full complement of staff and back-up facilities
immediately available, minimising perioperative complications. This is in
contrast to deceased donor trans- plants, which often occur at night as an
emergency procedure.
2 The
donor kidney function and anatomy can be fully assessed prior to transplantation.
This ensures that the kidney, once transplanted, will provide the recipient
with an adequate glomerular filtration rate (GFR) post-transplant.
3 The
donor nephrectomy and recipient transplant operation can take place in adjacent
theatres to minimise the cold ischaemic time.
4 Unlike
deceased donor organs, there has been no agonal phase, no catecholamine storm
and no other perimortem injury to affect the function of the kidney.
5 Allograft survival. Unsurprisingly, given
the considerations listed in 1–4, allograft survival is better in living donor
kidneys compared with deceased donor kidneys. For example, in the UK, the
5-year survival of a living donor kidney is around 89% com- pared with 82% for
a deceased donor kidney (1999–2003 cohort).
Living kidney donation Assessing a living kidney donor Medical
fitness of donor
Donating a kidney involves a significant operation, lasting 1 to 3 hours.
A detailed history and careful examination should be per- formed. If the donor
has any pre-existing medical condition that would place them at high risk of
complications during an anaesthetic, e.g. previous myocardial infarction (MI)
or poor left ventricular (LV) function, then they would not be suitable for
donation. A full examination is performed, including assessment of the donor’s
body mass index (BMI). Typical donor investigations would include a full blood
count, clotting screen, renal function tests, liver function tests, an ECG and
a chest radiograph; a more detailed cardiological work-up including echocardiogram
and cardiac stress testing are performed if indicated. Tests to exclude chronic
viral infections such as hepatitis B and C, and HIV are also performed.
Psychosocial fitness
As well as physical considerations, the transplant clinicians must also
be sure that the donor is mentally and emotionally sound and understands the
implications of the procedure. They must be certain that there is no coercion
involved. Donors are also assessed by an independent third party.
Adequacy of donor renal function
Donation will involve the donor losing one kidney. Thus it is important
to ensure that the donor has sufficient renal reserve to allow this to occur
and leave adequate renal function for a healthy existence.
History: Pre-existing medical conditions, such as diabetes mellitus
or hypertension, which can lead to chronic kidney disease are a relative
contraindication to donation. A family history of renal disease should also be
sought, e.g. polycystic kidney disease, Alport’s syndrome or a familial
glomerulonephritis.
Examination: Hypertension may be previously undiagnosed and should
therefore be carefully assessed on more than one occasion.
Investigations: Initially, an ultrasound scan of the renal tract
is performed to ensure that the donor has two kidneys of normal size. The urine
is tested to ensure no microscopic haematuria or proteinuria, which may
indicate underlying renal disease. Quantification of urinary protein with a
spot urine protein–creatinine ratio, an albumin–creatinine ratio or a 24-hour
urine collection for protein is also required. Renal function is estimated by
serum creatinine, creatinine clearance and measured GFR, together with the
split function. If the renal function is sufficient to allow halving of the GFR
and some decline in renal function with age, then the donor is considered
suitable. Renal anatomy is defined by magnetic resonance (MR) or computed
tomography (CT) scan to allow choice of the most suitable kidney to remove –
preference is for the kidney with single artery and vein; if otherwise equal,
the left kidney is removed since it has a longer vein to facilitate
implantation.
Compatibility
· ABO:
The blood group of the donor must be compatible with the recipient.
Transplantation of an incompatible blood group kidney can lead to hyperacute
rejection if an individual has preformed antibodies. ABO incompatible
transplantation is possible, but the recipient must have the antibodies removed
either by antigen-specific columns or by plasma exchange; enhanced immuno-
suppression is usually required.
· HLA:
HLA matching is associated with prolonged graft survival, but even the
worst-matched live donor kidney is superior to the best-matched deceased donor
kidney. Where several donors come forward the best match is chosen. If the
prospective recipient has antibodies to HLA antigens on the donor, the recipient
may undergo antibody removal therapy. However, it tends to be more difficult to
remove HLA antibodies and results of HLA- incompatible transplantation are
inferior to those of ABO incompatible transplantation.
Donor nephrectomy technique
Donor nephrectomy was traditionally an open procedure, but is now done
laparoscopically in most centres. An open nephrectomy is performed either
through modified flank incision or a subcostal incision. Careful dissection is
required to preserve the main vessels and ureteric blood supply. The advantage
of an open approach is that it minimises potential abdominal complications
intra-operatively. However, it leaves a significant surgical scar (which can
develop herniation in the longer term) and requires a longer period of recovery
(6–8 weeks). In contrast, a laparoscopic approach is technically more
demanding, may take longer to perform, but leaves a smaller surgical scar. The
average inpatient stay is just 2–4
days, and recovery time much shorter.
