Renal medullary hyperechogenicity in a neonate with oliguria

In healthy neonates, urine production starts within 24 h after birth [1]. If urine production does not start on the first day, a fluid challenge is administered and—if unsuccessful—a work-up to identify pre-renal, renal and postrenal causes of oliguria or anuria is initiated, which includes an ultrasound examination of the kidneys. Neonatal ultrasound may reveal renal medullary hyperechogenicity, a phenomenon which has been described in this setting in pathological conditions like nephrocalcinosis but may also be seen in the setting of benign, transient renal dysfunction [2]. Here, the case of an oliguric neonate with Tamm Horsfall nephropathy, i.e. transient renal medullary hyperechogenicity, is presented, and a guideline for differentiation from other causes of medullary hyperechogenicity is given.