QuestionI have recently been referred for a 2nd level sonogram because my doctor found a small tiny dilation of my baby boys kidneys.. I believed this is termed bilateral renal dilation...He told me not to worry and that my quad and blood work came back normal, and that my bp, pulse and everything else look good... But I cant help to worry that he is sending me to a high risk specialist reguarding this matter... to top it all off I researched it for myself, and it is commonly associated with down syndrome and diagnosed during the second trimester which I am in!! Could this be a soft marker for down syndrome, or is there just something wrong with my perfectly normal babies kidneys? Im totally freaked out... please help.. !!!
AnswerDear Questioner Brenda:
I was NOT in any way telling you that you had a 1 in 5 chance of having a Downs Syndrome baby. If you read again, what I was sharing was statistics..."In trisomy 21 (Downs Syndrome) fetuses with the two most commonly detected markers - shortened femur and dilation of the renal pelvis -had likelihood ratios of 49.3 and 20.5, respectively among pregnant women already found to have abnormal serum biochemistry." In your particular case, your blood chem studies were NOT altered and that makes your chances much less. I was interpreting the study that I cited data from - of which there are very few found in researching what you wanted to know. You actually said nothing in your question about a correlation between males and renal pelvis dilation. But since you are now asking - some of the studies showed a slightly higher incidence in males. However, most studies did not distinguish between isolated renal pelvis dilation, progression to hydronephrosis, and/or other congenital abnormalities.
Also...you absolutely did ask "Could this be a soft marker for down syndrome". I was trying to answer that for you because you said "I'm totally freaked out". I did spend a considerable amount of time researching this answer for you, but I do apologize sincerely if my answer citing data was not what you were looking for. I hope that with the next Expert you engage in a question, you will consider the time and effort it does take and that it is all done on a volunteer basis. We do it because we truly care - or at least I do. So poor scoring does tend to discourage us and make us wonder why we take time away from our families and other things.
I do wish you well.
Brenda
Dear Brenda,
Speaking specifically of Renal Pelvis Dilation (defined as an anterior-posterior renal pelvis measurement > 4 mm at < 32 weeks' and > 7 mm at > or = 32 weeks' gestation), it absolutely can exist as an isolated finding OR with other anomalies or multiple gestations. The mean gestational age at diagnosis is approximately 24 weeks. Renal pelvis dilation progresses to hydronephrosis (distention and dilation of the renal pelvis and calyces, usually caused by obstruction of the free flow of urine from the kidney, leading to progressive atrophy of the kidney) in a total of 10.9% of cases. Of those fetuses with progression, 80% had bilateral dilation - so those with bilateral dilation are more likely to progress - 26% vs. 3.3%. Gender, gestational age at diagnosis and delivery, and birth weight did not differ between those fetuses with and without progression.
In trisomy 21 (Downs Syndrome) fetuses with the two most commonly detected markers - shortened femur and dilation of the renal pelvis -had likelihood ratios of 49.3 and 20.5, respectively among pregnant women already found to have abnormal serum biochemistry. That suggests to me that there is approximately a 1 in 5 chance of Downs with the soft marker of renal pelvis dilation IF your blood chem studies such as Quad screen were already showing an abnormality. Because they are not, I would tend to think your odds are lower. I could not find any more specific data than this, but the more sophisticated scan was definitely standard protocol. I would not be overly concerned simply due to that.
I hope this has helped you and answered your question. I wish you well.
Brenda
