Thanks for consulting us.
This is a rather common ultrasound
finding, more common in male fetuses. We do not consider it a normal variation. It indicates there is slight obstruction to the flow of urine from the fetal kidneys to the ureter
, leading to slight dilatation of the collecting system of kidneys.
The long term prognosis depends upon any change in the degree of obstruction. Your wife should have been advised for ultrasound follow up to see any change. If it stays the same or improves ( which is the usual course in most cases) there is not much to worry about except your child will need to be seen by a child specialist after delivery.
On the other hand if it increases in severity (God forbid) your wife may need a referral to a fetal medicine center for in utero treatment of the obstruction to save fetal kidneys from damage. Please don't be scared this is very rare & I am telling it to you, just to complete the answer.
Just book your wife for antenatal with a consultant gynecologist in your area & she will guide you further. Wish you a happy & healthy end of this pregnancy
. Take care.