Welcome to HCM.
Since you have not reproduced the scan report, I can only speculate that most likely this must be referring to the pelvi-calyceal system of the right fetal kidney
. This suggests that the baby is having back pressure from the bladder, dilating it's renal pelvis
. This may not be a serious problem and in most of the cases it subsides by the time of delivery. If it persists or increases in size the baby needs consultation by a paediatric urologist
, after delivery. Most likely it may not be of any consequence and you need not worry about it.