Fecal impaction detected by imaging predicts recurrent urinary tract infection.

Background: Few studies have evaluated the efficacy of ultrasonography (US) and abdominal radiography in assessing bladder and bowel dysfunction in children aged <24 months. We aimed to investigate the association between the risk of urinary tract infection (UTI) recurrence and fecal impaction using imaging findings.

Methods: The medical records of 121 children (aged <24 months) with initial febrile UTI (fUTI) who were admitted to the authors' institution from January 2004 to September 2019 were reviewed retrospectively. We evaluated the rectal diameters of children with suspected fecal impaction that were measured using transabdominal US, or the rectal diameters divided by the distance between the ischial spines that were measured using abdominal radiography. Based on previous reports, we defined fecal impaction as a transabdominal US score of >30 mm or an abdominal radiography score of >0.5. The definition of functional constipation was based on the child/adolescent Rome IV criteria - i.e., a maximum stool frequency of twice per week.

Results: The median age at initial fUTI diagnosis was 4 months. The occurrence of fecal impaction identified via imaging was significantly greater in patients with UTI recurrence than in those without recurrence: yes/no: 17/9 (65.4%) versus 35/60 (36.8%); P = 0.013. On the other hand, the occurrence rates of constipation based on stool frequency did not differ between the two groups. In multiple logistic analyses, fecal impaction detected via imaging was identified as an independent risk factor for fUTI recurrence.

Conclusions: Fecal impaction observed via US and abdominal radiography may be useful in predicting the recurrence of fUTI in children.