Hello Good evening, Frequent UTI is common in females due to various anatomical and physiological reasons. Since you have not mentioned age of your mother, So it is little bit difficult to reach exact reason but in USG(ultrasound) there is dilation in calyx, so probably there is an obstruction in urinary tract either it is in ureter or urinary bladder or urethra. Obstruction can be of any type like minor ureteric stone or scaring or stricture in the ureter or urethra, dehydration is a add on reason to these. So please ask mother to do followings: proper hydration. do not hold urine for long due to any reason. take antibiotics as prescribed by physician urologist opinion. ultrasound KUB X-ray KUB plan for invasive cystoscopy if needed.