Does the presence of bladder debris suggest urine infection in children?

A 1-year-old girl with vomiting, mottled skin and a fever of unknown origin improved after two days of intravenous antibiotics. Unfortunately, in the hectic emergency department (ED), the urine sample was lost, so there is no dipstick or microbiology result. An acute ultrasound scan (USS) showed debris in the bladder. The team wonders whether this debris is evidence she had a urinary tract infection (UTI).