Cystitis is inflammation of the urinary bladder, usually caused by infection, which can occur alone or in conjunction with pyelonephritis.
Acute cystitis in the child older than two years and in the adolescent will be reviewed here. Urinary tract infection (UTI) in younger children (in whom it is difficult to distinguish cystitis from pyelonephritis on clinical grounds) is discussed separately. (See "Urinary tract infections in children: Epidemiology and risk factors" and "Urinary tract infections in infants and children older than one month: Clinical features and diagnosis" and "Urinary tract infections in infants and children older than one month: Acute management, imaging, and prognosis".)
The distinction between complicated and uncomplicated cystitis is based upon the presence or absence of anatomic or physiologic abnormality of the urinary tract (including pyelonephritis), host factors, and the antimicrobial resistance pattern of the uropathogen.
Uncomplicated cystitis — Uncomplicated cystitis is limited to the lower urinary tract and occurs in older children (older than two years) or adolescents with no underlying medical problems or anatomic or physiologic abnormalities. Most often it is caused by pathogens that are susceptible to the antimicrobial agents that are usually used to treat cystitis. (See 'Initial treatment' below.)
Complicated cystitis — Complicated cystitis is associated with upper tract disease, multiple-resistant uropathogens, or hosts with special considerations such as malignancy, diabetes, anatomic or physiologic abnormalities, or an indwelling bladder catheter. Patients who have urodynamic dysfunction, neurogenic bladder, or incomplete bladder emptying may harbor pathogens in residual urine, thereby creating a source for persistent or recurrent infection. Many complicated urinary tract infections (UTI) are hospital acquired and are related to indwelling urinary catheters. (See "Etiology and clinical features of bladder dysfunction in children" and "Evaluation and diagnosis of bladder dysfunction in children".)