UTI causes inflammatory changes in the urinary tract secondary to the presence of an invasive, infectious agent. Whereas females more commonly acquire UTI during adulthood, more boys than girls get UTIs during the first year of life. Typical symptoms include frequent urination accompanied by pain and a sudden need to urinate (urgency), small-volume voiding and lower abdominal discomfort. Urine may be cloudy and foul-smelling and if the kidneys are involved, patient may present with flank pain, fever and chills. A midstream urine sample (for adults) or a suprapubic aspirate (for infants) is initially taken to check for the presence of inflammatory cells and bacteria. A urine culture confirms the diagnosis of a UTI. No imaging study is needed for uncomplicated UTIs. However, for complicated cases, either an ultrasound or an X-ray study may be requested. Early antimicrobial coverage is the primary treatment and appears to be the most effective means of preventing complications.