Medicare contractor Palmetto’s MolDx program proposed new local coverage determinations restricting the number of surveillance tests allowable for transplant patients to monitor allograft rejection. The proposal significantly reduces testing frequency compared to current recommendations by companies like CareDx, potentially halving the market for transplant diagnostic tests. The draft also introduces stricter validity standards and uncertain coverage for combined molecular testing. The proposal has caused a sharp decline in CareDx stock prices, reflecting market concerns over its impact.