Imaging to investigate UTI in children

The role of routine imaging to investigate for anatomical abnormalities after the first episode of urinary tract infection (UTI) in children is controversial. The current trend is to limit imaging; in particular, the use of dimercaptosuccinic acid (DMSA) scans is rarely indicated and results in a large radiation exposure.

Perform a renal ultrasound during the acute phase of a UTI for children withMcTaggart, 2015National Institute for Clinical Excellence (NICE), 2022Pauchard, 2017Riccabona, 2016Shaikh, 2016Shaikh, 2014:

  • septic shock from a urinary tract source
  • UTI caused by organisms other than Escherichia coli
  • a first UTI in a child who did not have a morphology scan at 20 weeks of gestation or a normal second or third trimester antenatal ultrasound that included the urinary tract
  • age less than 3 months
  • failure to clinically improve within 48 hours of initiating appropriate antibiotics; fever may persist for 72 hours and an ultrasound should not be requested for fever alone
  • poor urinary stream
  • significant electrolyte abnormality or kidney impairment
  • abdominal mass.

Perform a renal ultrasound 4 to 6 weeks after a UTI for childrenNational Institute for Clinical Excellence (NICE), 2022Riccabona, 2016Tullus, 2015:

  • younger than 2 years
  • with recurrent symptomatic UTIs.

If the renal ultrasound is normal, further imaging is not required.

Perform a micturating cystourethrogram (MCUG) to detect vesicoureteric reflux (VUR) for children with recurrent pyelonephritis or bilateral hydroureteronephrosis on ultrasound, or renal scarring evident on dimercaptosuccinic acid (DMSA) scanMcTaggart, 2015. Males1 with bilateral hydroureteronephrosis on ultrasound may have urethral pathology. The micturating cystourethrogram should be performed at least 2 weeks after the infection has resolvedMcTaggart, 2015.

If micturating cystourethrogram is required, give oral antibiotic prophylaxis for 3 days, starting on the day before the testNational Institute for Clinical Excellence (NICE), 2022Sinha, 2018. Suitable regimens are:

1trimethoprim+sulfamethoxazole (child 1 month or older) 4+20 mg/kg up to 160+800 mg orally, 12-hourly for 3 days2trimethoprim + sulfamethoxazole

OR (if a suitable trimethoprim formulation is available)

1trimethoprim 4 mg/kg up to 150 mg orally, 12-hourly for 3 days23trimethoprim

OR

2cefalexin 12.5 mg/kg up to 500 mg orally, 6-hourly for 3 days cefalexin

OR if adherence to a 6-hourly regimen is unlikely

2cefalexin 20 mg/kg up to 750 mg orally, 8-hourly4 for 3 days. cefalexin

1 In this topic, the term ‘male’ is used to include all people presumed male at birth.Return
2 If the child has been treated with trimethoprim or trimethoprim+sulfamethoxazole in the previous 6 months, or had a trimethoprim-resistant (or trimethoprim+sulfamethoxazole-resistant) Escherichia coli isolate during this time, use an alternative antibiotic for empirical therapyBryce, 2016.Return
3 An oral liquid formulation of trimethoprim is not commercially available; for formulation options for children or people with swallowing difficulties, see Don’t Rush to Crush, which is available for purchase from the Advanced Pharmacy Australia website or through a subscription to eMIMSplus.Return
4 Unpublished pharmacokinetic and pharmacodynamic modelling data for cefalexin show similar levels of target attainment with the 6- and 8-hourly regimens above. It is the consensus view of the Antibiotic Expert Group that either regimen can be used for children.Return