Ultrasound: Scan has left me concerned

"I've just had a 24-week scan that shows my baby's kidneys are mildly dilated. We have been told that the baby could have urine infections and might even need surgery after birth. What does this all mean? Can dilated kidneys cure themselves, or do they always cause problems?"

Dr Fred Kavalier answers your health question:

As the quality of ultrasound scans during pregnancy has improved, obstetricians are now able to monitor a baby's progress much more closely. Dilated kidneys are now quite a common finding in antenatal scans. It is usually only part of the kidney the renal pelvis that is dilated or widened. This is the funnel-shaped area where urine begins its journey from the kidney to the bladder. If the renal pelvis is only a little bit wider than normal, it is very unlikely to cause any problems after birth. If the renal pelvis is severely dilated, the cause may be a narrowing or blockage that is preventing urine from flowing into the bladder. In one study, about two-thirds of children with severe widening of the renal pelvis developed urine infections or needed surgery after birth. Those with mild dilatation did not have any further problems. Let the obstetricians keep an eye on things with regular scans. If the widening remains mild, it will most likely look after itself without any help from paediatricians.

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.