On a recent us it came back as hydronephrosis and no nephrolithiasis or focal renal parenchymal lesion mean in the right kidney. what does this mean?

Normal ultrasound: It means your ultrasound of the right kidney shows obstruction of the urinary tract (that is hydronephrosis), no kidney stone (no nephrolithiasis), and no focal mass/tumor. Better be evaluated with CT urogram/ pyelogram and a urologist for the site and nature of the obstruction!

Kidney swelling: from urine within kidney, but no stone, tumor area of abnormality in functioning part of kidney. Ultrasound was likely performed because you have symptoms of kidney infection which needs to be treated. US should be repeated after infection & back tenderness gone. You may have some obstruction to outflow of right kidney or reflux of urine from bladder. Best evaluated by urologist if hydro remains.

? kidney infection: Hydronephrosis is a condition of expansion of the internal areas of the kidney that hold urine. This is seen with a blockage of the system, an infection or sometimes as a normal variant. When it is on one side, with your symptoms, it is likely due to kidney infection. You should be on antibiotics if you are not already. Please see your doctor right away if you are not.