Pediatric Transplantation

Pediatric GU ReviewUCSD Pediatric Urology

George Chiang MDSara Marietti MD

Outlined from The Kelalis-King-Belman Textbook of Clinical Pediatric Urology 2007

(not for reproduction, distribution, or sale without consent)

Advantages Over Dialysis

• Better growth after transplant

• More cost-effective

• Improved quality of life

Pediatric Transplantation

• Steady improvement in adult/pediatric pt survival and graft survival over last decade

• Acute rejection rates (1st 12 mo) at all time low

• Because grafts/patients survive longer, increase in long-term complications

GU Involvement in Ped Transplant

• GU causes are responsible for 25% of childhood ESRD

• MC Causes: - obstructive uropathy - aplastic/hypoplastic/dysplastic kidney - focal segmental glomerulosclerosis - reflux nephropathy - polycystic disease

GU Involvement

• High number of pediatric transplant patients require adjunctive surgical procedures prior to transplant (ex. Augment, catheterizable channel)

• More pt performing CIC than the adult population

Preparing For Transplantation

• Multidisciplinary approach – GU, neph, tx surgery, social worker, RN, dietician

• Medical Evaluation - as optimal as possible - good physical fitness and weight control - aggressive nutritional support - possibly growth hormone therapy - immunization status

Medical Eval (Cont.)

- warts - psychosocial stability - frequent/comprehensive follow up - access/compliance with immunosuppression

Goals of Urologic EvaluationConfirm adequate storage

Confirm adequate emptying

In pt with known GU problem (PUV, spina bifida) may need special void regimen, CIC or Ach prior to trasplant

If pt is fully diverted, must un-divert and cycle reservoir prior to transplant

Evaluation of Lower Urinary Tract

• Etiology of renal failure (ex valves)• History of lower urinary tract dysfunction• Voiding diary• Uroflow and PVR• VCUG• Urodynamics

• Individualized approach

Indications for Pretransplant NxStones not cleared by minimally invasive techniquesSolid renal tumorsPolycystic kidneys, symptomatic, extend below iliacs,

infectionsSignificant proteinuriaRecurrent pyelonephritisHigh grade hydronephrosisInfected stonesSevere hypertensionInfected refluxMalignancy risk (Denys-Drash)

VUR Managment

• Controversial• Some studies have shown increased number

of post-tx uti’s if not addressed prior to transplant

• If recurrent infections with VUR (pretransplant) should do reimplant or bilateral N-U

Timing of Transplant

• Living donors allow for transplant prior to initiation of dialysis

• However, deceased donors have now reached equivalent graft survival in the first few years of transplant

The Live Donor

• Many pediatric transplants are live donor – the parent

• Need extensive information and medical work up

• Newer – live donor exchange program (first done in 2001)

Living Donor Medical Evaluation

• Primary - H&P - blood type - tissue type - psych eval - pregnancy test

Living Donor Medical Evaluation

• Secondary - CBC, Coag, AMA-renal, Chol, LFT, UA, US,

Renal Arteriography, CXR - Infection screen: Epstein Bar, HIV, Hep B/C,

PPD, ucx - Pelvic exam, pap, if >40 then mammogram - Rectal in male, if >40 then PSA

Living Donor Medical Evaluation

• Tertiary - FMHx DM: 2 hr post-prandial glucose - If cardiac risk factors: stress test, echo - If pulm symptoms: PFT’s

Transplantation - Recipient

• Pt supine• Foley placed, antibacterial solution instilled• Central venous access• Second-generation cephalosporin

Transplantation

• >20kg retroperitoneal• 10-20kg retroperitoneal if small kidney• <10kg intraperitoneal

• Retroperitoneal is ideal to preserve peritoneal cavity for PD if necessary

Transplantation

• Infant/toddler – aorta or aorto-iliac junction• Young child – common iliac• Adolescent/adult – external iliac

• Aggressively avoid hypotension• Expand blood volume to CVP of 12-16• Adult allograft can sequester 200-300 ml of

blood from the circulation

Transplantation

• Reimplant can be either intra/extravesical

• Extravesical advantages – shorter OR time, less obstruction, less hematuria, less urinary extravasation

Post-Op Care

• Fluid and electrolyte management

• Fresh transplant has decreased concentrating ability so may have excessive uop first few days

• 1:1 replacement

Early Graft Dysfunction

• Mostly preventable• Signs – oliguria, Cr does not fall• No uop – concern for arterial thrombosis,

most centers do immediate doppler US after closure

• Most have native kidneys so uop as measure can be challenging

Initial Good UOP, then Drop

• Low intravascular volume – bolus• CI toxicity - >20 ng/ml• Rejection – dx by biopsy• Venous thrombosis• Urine leak

Post-Op Fluid Collection

• Lymphocele – intervene if symptomatic, expanding or obstructive

• Urine leak

• Hematoma

Immunosuppression

• Very individualized but usually triple therapy with CI, antimetabolite, steroids

• Target ranges based on estimated rejection risk balanced against side effects of the medications

Immunosuppressive Therapy

• LESS• First-time caucasian

recipient• Live donor kidney• No evidence of pre-

sensitization

• MORE• Repeat transplant• Deceased donor• Evidence of pre-

sensitization• Recipients who are

african-american

Prophylaxis• Bacterial: peri-op for wound infection, then

targeted toward uti and pneumocystis carinii (Bactrim)

• CMV – determined by risk (recipient and donor history of CMV exposure and strength of immunosupp)

• Epstein Barr virus – no effective prophylaxis, many peds recipients are neg, adult donors are positive

• Antifungals – first few months while immunosupp is highest

Prophylaxis

• If pt has acute rejection and need to increase immunosuppressive therapy, recycle the full spectrum of prophylactic meds as well

• GI – H2 blocker for steroid-induced gastritis and ulcers

Urologic Complications

• 5.6% of all cases - urinary extravasation - ureteral anastomotic obstruction - ureteral necrosis - symptomatic VUR• Urologic problems result in allograft loss 31%

of the time

Renovascular Complications

• 5.5% of all cases - technical (3.2%):anastomotic defect,

vascular angulation, vascular compresseion

• 86% of all vascular complications result in allograft loss

Urolithiasis

• 6% of adults, 5% of pediatric tx kidneys

• Etiology - low uop

- elevated calcium excretion - disturbance in uric acid metabolism secondary to CI therapy - increased frequency of uti - hypocitraturia, hypomagnesuria, hypophosphaturia - suture material present

Post-transplant VUR

• Post-tranplant VUR without pyelonephritis has not been linked to allograft loss in either adult/kids

• Post-transplant VUR with pyelonephritis has been linked to allograft loss, these should be corrected

• Attempts at deflux have failed to correct it• In kids, VUR can be from incompletely

managed bladder…may need Ach or CIC

Long-term

• Transition to adult can be hard• Decreased compliance in teenage years is an

issue• Need long term follow up of donors who may

develop htn/proteinuria• Attempting to create Donor Database to

better follow these pt• If donor loses solitary kidney, placed at top of

transplant list

Summary33% of pediatric tx pt require urologic surgery

prior to transplant

No pt is transplanted while diverted

Living donors have better graft survival long term

Improvements in immunosuppression have significantly improved graft survival, specifically in the first few years