PARIS—Discrepancies between donor and recipient size in pediatric renal transplantation does not adversely affect outcomes, British investigators reported here at the 14th Congress of the European Society for Organ Transplantation.

A team at St. James University Hospital in Leeds led by Niaz Ahmad, MD, tracked outcomes in a group of small pediatric recipients who received large and small kidney grafts. The researchers found that adult kidneys were successfully transplanted into very small recipients.

“While renal transplantation is the preferred treatment for children with end-stage renal disease and long-term outcome in pediatric renal transplantation has improved in recent years, surgery remains technically more challenging in younger patients and is associated with an increased risk of complications often leading to graft loss,” said co-investigator Paul J. Goldsmith, MD, a research fellow.

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“A lack of suitable size-matched donors for very small (less than 20 kg) recipients means that transplant candidates spend more time on a transplant waiting list.”

Notably, widespread concern has been cited about the placement of larger kidneys (donor greater than 55 kg) into small recipients, Dr. Goldsmith said. The operation is technically difficult because of less space, anastomosis to great vessels, and longer operating time.  Other complications include the potential for abdominal compartment syndrome and graft hypoperfusion, which may produce vascular complications.

There are multiple potential advantages to using adult-size grafts in small recipients, he continued. Such a strategy would offer access to more donor organs, provide significant reserve due to more nephrons, and possibly strengthen protection against rejection because of the increase in nephron mass.

The series included all patients weighing 20 kg or less who had undergone a renal transplant at St. James University Hospital over a recent nine-year period. The graft size to recipient size in the study population covered a broad spectrum because of recently revised criteria allowing the kidneys of donors weighing more than 55 kg to be transplanted into patients weighing less than 20 kg. The donor to recipient body weight ratio is a means of expressing this mismatch.

Participants were stratified into two groups consisting of “high” and “low” donor:recipient weight ratios based on the median value of 4. Twelve patients had low donor:recipient weight ratios (less than 4), and 11 patients had high ratios (greater than 4).  

The study found that high and low donor:recipient weight groups had comparable one-year graft survival (91% vs. 92%, respectively). Two graft losses occurred—one because of renal vein thrombosis and the other due to a cause that could not be determined.

The high and low donor:recipient weight groups had 100% primary graft function, and all patients in both groups were alive at one year. Rates of delayed graft function and acute rejection were also similar in the two groups.

Overall, the results show that transplanting large adult kidneys into very small children yields results comparable to transplanting small adult kidneys, Dr. Goldsmith observed.

The findings, he added, demonstrate the potential for safely expanding the donor pool. Additionally, the results also document the safety of the extraperitoneal approach, which was used in 22 of 23 patients, he noted.