Bladder infections are more common in some families. Other risk factors include diabetes, being circumcised, and having a large prostate (a gland around the urethra in males). Complicating factors are not completely clear. These factors may include some anatomic problems (relating to physical narrowing), functional, or metabolic problems. A complicated UTI is more difficult to treat and usually needs more aggressive evaluation, treatment, and follow-up. In children, UTIs are linked to vesicoureteral reflux (an abnormal movement of urine from the bladder into ureters or kidneys) and constipation.