<s>[INST] My 10 yr old son went to the emergency room last nigh because he was urinating blood. He had an ultrasoud of his kidneys to check for possible kidney stones . We will be getting an appointment with a nephrologist in the next week or two, but I was concerned about the findings from the ultrasound . The ER doctor said it could be normal, but that makes me feel that it could also be something else. What does mild pelvic fullness is noted in both kidneys without frank hydronephrosis mean? Thanks. [/INST] Hi  scruggsm. Your son had acute onset blood in urine.there are so many causes of it but the most common are-Renal stone,ureteric stone,bladder stone,may be stone in the urethra,acute post streptococcal glomerulonephritis and other type of kidney infection,UTI,ingestion of any drug like aspirin,tumor in the kidney,rarely bleeding disorders. But it seems to be from renal stone. Do some investigation like-USG-KUB,Urine for routine,blood for count,urea,creatinine,bleeding and clotting time as early as possible and consult a urosurgeon or a nephrologist for opinion. Mild pelvis fullness is a vague term it can not make any diagnosis but in renal stone mild pelvic fullness is seen.And hydronephrosis means if a stone obstruct renal pelvis outlet then urine can not drain properly and it become swollen that is called hydronephrosis.It is a bad sign as due to back pressure of stored urine kidney function gradually deteriorate. Best wishes, Dr Sourav Ganguly </s>