Urinary Tract Infections (UTI) in Children
Urinary tract infections (UTIs) are a common and important cause of serious bacterial infection in children. While often self-limiting, a UTI can be difficult to diagnose due to non-specific symptoms, especially in infants. A high index of suspicion is required to prevent potential long-term complications such as renal scarring.
Diagnosis and Clinical Assessment
Symptoms and Signs
The symptoms of a UTI vary significantly with age.
Infants younger than 3 months: The signs can be non-specific, including fever, vomiting, poor feeding, irritability, and lethargy. In some cases, jaundice may be the only sign.
Infants and children older than 3 months (preverbal): Common signs are fever, abdominal pain, loin tenderness, and vomiting.
Verbal children: Symptoms are more classic and include dysuria (painful urination), urgency, frequency, new onset enuresis (bedwetting), and loin pain.
Urine Collection and Testing
Sample collection: A clean-catch urine (CCU) in infants or a midstream specimen urine (MSSU) in older children is the recommended method. If these are not possible, a catheter sample or suprapubic aspirate (SPA) should be considered, as urine bags have a high rate of contamination.
Initial testing: Urine should be tested with a dipstick.
In children over 3 years old, if both leukocyte esterase and nitrite are positive, a UTI can be assumed, and antibiotics can be started. A culture should still be sent if the child has a high risk of serious illness or a history of previous UTIs.
If both are negative, a UTI is unlikely and antibiotics should not be started.
In children under 3 years old, the urine dipstick is less reliable, and a urine sample should be sent for urgent microscopy and culture, especially if they are unwell.
Management
The management of a UTI depends on whether it is an acute upper or lower UTI.
Acute Management
Lower UTI (Cystitis): This is diagnosed when a child has bacteriuria but no systemic symptoms or fever. The treatment is typically a short course (3 days) of oral antibiotics, although some local guidelines may recommend 5 days.
Upper UTI (Pyelonephritis): This is diagnosed when a child has bacteriuria and a fever of 38°C or higher. This is considered a serious infection.
Children under 3 months: All infants under 3 months with a suspected UTI should be admitted to hospital for intravenous antibiotics and a septic screen.
Children over 3 months: In a child who is systemically unwell, start intravenous antibiotics, typically ceftriaxone or co-amoxiclav. The child can be switched to oral antibiotics once they are clinically improving, usually within 24-48 hours.
Imaging and Follow-up
Routine imaging: According to NICE NG224 (2022), routine imaging after a first-time UTI is no longer recommended for most children over 6 months of age, unless there are atypical or recurrent features.
Indications for imaging:
Ultrasound Scan (USS): An USS should be performed within 6 weeks for infants under 6 months with a first-time typical UTI. It is also indicated in all children with an atypical UTI or recurrent UTIs.
DMSA scan: This is used to detect renal scarring and is not recommended routinely. It may be considered in children with atypical or recurrent UTIs or in those with a non-E. coli infection.
MCUG (micturating cystourethrogram): This is used to diagnose vesicoureteric reflux (VUR). Its use has been significantly reduced and is now only considered in high-risk cases based on the clinical picture and ultrasound findings.
Antibiotic Prophylaxis
NICE guidelines (2022) do not recommend the routine use of prophylactic antibiotics after a first UTI in children.
Prophylaxis may be considered in specific circumstances, such as in children with recurrent UTIs or those with high-grade VUR.
Parents should be provided with clear safety-netting advice on recognising the signs of a subsequent UTI and when to seek medical help.