[Pink-red discoloration in the diaper of a neonate]

Pink-red discoloration in the diaper of neonates is often attributed to harmless urate crystals, formed from uric acid. However, clinicians should remain alert to other possible causes of pink-red discoloration. Here we present two cases of pink-red discoloration in neonates: one due to a congenital mesoblastic nephroma and the other one due to renal vein thrombosis as underlying cause. Additional diagnostics should be considered at a low threshold, starting with a simple urine dipstick. If the dipstick is negative for haem, hematuria can be excluded. If positive, urine sediment analysis is the next step to differentiate between hematuria, myoglobinuria or hemoglobinuria. In case of persisting haem-negative pink-red discoloration or in case of hematuria, myoglobinuria or hemoglobinuria consultation with a pediatrician is recommended, as further diagnostic evaluation is recommended.