Urinary tract infections and resolution of renal pelvic dilatation in infants

Introduction: Spontaneous resolution is the most common outcome of postnatal renal pelvic dilatation (RPD). Factors which delay spontaneous resolution are poorly studied.  Objectives: To study whether urinary tract infection (UTI) delays spontaneous resolution of RPD and to study the outcomes of postnatally detected RPD at one year of age.Design: Prospective one year study in a tertiary care hospital in Kerala, India.                                       Method: All inborn babies detected to have at least grade 1 Society for Fetal Urology (SFU) scale of RPD, between postnatal days 3-5, were followed up until resolution or till one year of age. The subjects were divided into mild group (SFU grades 1 and 2) and moderate to severe group (SFU grades 3 and 4). The outcomes assessed were resolution, UTI and need for surgery.Results: A total of 50 cases were followed up. The mean age of resolution in the mild group was 13 weeks whereas in the moderate to severe group, it was 30.3 weeks. UTI occurred in 9 (18%) patients. Resolution, in those with UTI, occurred at a mean age of 25.7 weeks compared to 14 weeks in those without UTI (p=0.01). Four cases with anteroposterior renal pelvic diameter (APRPD) >10mm with cortical thinning and recurrent UTI resulted in persistent RPD requiring pyeloplasty within one year of life. All preterms showed resolution (p=0.006). Bilateral RPDs showed significantly delayed resolution (p=0.002).Conclusions: UTIs significantly delay resolution of RPD. Mild RPD resolves within 3 months and moderate RPD resolve around 7.5 months of age. Bilateral RPDs significantly delay spontaneous resolution. Preterm RPDs almost always resolve within one year of life.Sri Lanka Journal of Child Health, 2021; 50(1): 69-74