Urinary tract infection

Disclaimer

These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.

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Aim

This guideline provides an evidence-based framework for the investigation and follow up of children following a urinary tract infection (UTI), referred to the Department of General Paediatrics (DGP) at Perth Children's Hospital (PCH).

Background

Urinary tract infections (UTIs) are common. UTIs can lead to renal scarring and renal dysfunction or hypertension in adulthood. Abnormalities of the renal tract may predispose children to developing UTIs.

The management of UTI has changed in the past decade, with improvement in renal imaging modalities and recognition that past practices have been based on limited evidence.

Risk

Children with urinary tract infections may undergo unnecessary investigations or not receive the appropriate investigations and follow up.

Initial management

Children aged greater than 3 months presenting to PMH with a UTI should be initially managed in accordance with the UTI guideline
Febrile infants less than 3 months of age should be managed according to the Fever Without Source guideline
Antibiotic therapy should be commenced in accordance with the ChAMP antimicrobial guideline – Urinary Tract Infections

Investigations

Refer to flowchart in UTI investigation flowchart.

Renal Tract Ultrasound (US)

Renal tract ultrasound is used to assess renal anatomy.

For children less than 3 years of age:

A renal tract US for all children following their first UTI is recommended.
Children with an atypical UTI or UTI responding poorly to treatment should have a renal tract US performed acutely, ideally during their hospital admission.
All other children should have a renal tract US performed on a non-urgent schedule.

Children aged 3 years or older:

A renal tract ultrasound is not always necessary for older children with a simple UTI however:

Children of any age with recurrent UTI’s should have a renal tract US (non-urgent)
Children of any age with an atypical UTI or UTI responding poorly to treatment should have a rental tract US (urgent).

Micturating Cystourethrogram (MCUG)

MCUG provides an assessment of renal tract anatomy during voiding. Its purpose is to detect renal tract obstruction, anatomical anomalies and vesico-ureteric reflux (VUR).Routine MCUG is no longer recommended after all first UTI. A recent audit performed within our institution found that a renal tract US performed by the PMH radiology service effectively excluded high grade (4 or 5) VUR and posterior urethral valves (n=220). Good quality renal tract US may obviate the need for MCUG.

MCUG should be considered if:

The renal tract US is abnormal (with features suggestive of VUR / obstruction, scarring or poor growth).
In atypical UTIs
If there is a history of poor urine flow
If there is a family history of VUR.

Dimercaptosuccinic Acid Scan (DMSA scan)

DMSA scans are used to assess renal function. DMSA scans show areas of differential uptake of a radioisotope in the kidney. This differential uptake is presumed to be due to renal injury or scarring. DMSA scans are usually performed 4 to 6 months following acute infection.
Recent literature suggests that some scarring detected on DMSA may pre-exist the UTI. The long term outcome and prognosis of renal scarring detected on DMSA is unclear. There is no consensus within the literature as to how renal scarring should be monitored.
DMSA scans have been recommended for children up to the age of 3 years with atypical or recurrent UTI. For children greater than 3 years of age, DMSA scan is only recommended for recurrent infections.
A recent audit performed within our institution found that a normal renal tract US performed by the PMH radiology service excluded significant abnormalities on DMSA with a negative predictive value of 90% (n = 143). Of those children who had a normal ultrasound and abnormal DMSA scan, 4/9 had a small single renal scar with normal differential function and 5/9 had no scar but borderline differential function (4/5 were 44% vs 56% and 1/5 was 43% vs 57%). 5
Repeat renal tract US may be an acceptable alternative to DMSA for monitoring renal scarring.

Mercaptoacetyltriglycine scan (MAG 3 scan) or Diethylene Triamine Pentacaetic Acid scan (DTPA scan)

MAG 3 and DTPA studies provide information on differential renal function and drainage. MAG 3 and DTPA scans can be used to make some assessment of cortical abnormality however a DMSA scan is a superior study for this purpose. MAG 3 and DTPA scans can be used to assess for VUR however they are less sensitive than MCUG.
MAG 3 and DTPA studies are typically used for children in whom obstruction may be suspected. In older children where MCUG is undesirable due to age and discomfort, MAG 3 or DTPA can be used to provide an assessment of VUR.

Investigation pathways

Children less than 6 months old should have a renal tract US and be referred to a Paediatrician for follow up and consideration of the need for further investigation
Children aged 6 months – 3 years who have a normal renal tract US after their first uncomplicated UTI can be followed up by their GP
Children greater than 3 years with their first uncomplicated UTI do not necessarily need further investigation. These children can be followed up by their GP
Children who have a history of recurrent UTI, a family history of VUR or known renal abnormalities, may require further imaging such as MCUG or DMSA. These cases should be discussed with their treating Paediatrician.

Bibliography

National Institute for Health and Care Excellence (NICE). Urinary tract infection in under 16’s: diagnosis and management. Clinical guideline [CG54]. 2007. [Updated September 2017]. Available from: https://www.nice.org.uk/guidance/CG54. Accessed 15 August 2017.
Leung M, Ozanne R, Smith L, Martin AC. Utility of Screening Ultrasound After First Febrile UTI Among Patients With Clinically Significant Vesico-ureteral Reflux. Urology 2014. 83(3) pp680-681.
Tan A, Troedson R, Martin AC. A normal Renal Ultrasound Scan reliably excludes major abnormalities on DMSA in children with UTIs. J Paed Child Health. 2014. 50(12) pp1033-1034.

Approved by:	Head of Department, General Paediatrics	Date:	28 Nov 2017
Endorsed by:	Head of Department, General Paediatrics	Date:	28 Nov 2017
		Review date:	30 Nov 2020

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