Perinatology.  2016 Dec;27(4):244-250. 10.14734/PN.2016.27.4.244.

Clinical Outcomes of Renal Pelvis Dilatation in Very Low Birth Weight Infants

• Jeon M
• Jin J
• Shin JE
• Lee SM
• Eun HS
• Park MS
• Park KI
• Namgung R

• KMID: 2367036
• DOI: http://doi.org/10.14734/PN.2016.27.4.244

Abstract

PURPOSE
The aim of this study was to evaluate this clinical outcome of neonatal pelvis dilatation in very low birth weight (VLBW) infants.
METHODS
The medical records of 127 VLBW infants admitted to two neonatal intensive care units from January 2012 to December 2014 were retrospectively analyzed. Renal pelvis dilatation was diagnosed via ultrasound examination with cases divided into 3 groups: mild (dilatation of 5-10 mm), moderate (11-15 mm) and severe (≥15 mm). The correlation between the 3 dilatation groups and progression into hydronephrosis was evaluated.
RESULTS
Among the 127 premature infants, renal pelvis dilatation was identified in 29 (22.8%) on ultrasound examination performed, on average 13.3 days after birth, combined with calyceal ectasia in 5 (3.9%) infants. At a postmenstrual age of 40 weeks, 18 infants (14.2%) had renal pelvis dilatation, 6 (5%) infants accompanied by a dilatation of the calyx. On the last follow-up performed when children were not older than 2 years old, renal pelvis dilatation had resolved to within normal limits in 23 (79%) infants while persisting in 6 (21%) infants; 1 mild, 3 moderate, and 2 severe pelvis dilatation. The median time-to-recovery of dilatation was 10.5 months (Kaplan-Meier curve), regardless of the severity of dilatation at birth. Based on receiver operating curve analysis, a cutoff diameter of renal dilatation at birth of 11.35 mm predicted persisting severe dilatation at the final follow-up (sensitivity 83.3%, specificity 82.6%).
CONCLUSION
Although premature infants with dilatation of mild severity were all recovered, some of those with moderate-to-severe dilatation progressed to hydronephrosis. Therefore careful follow-up of premature infants with renal pelvis dilatation is recommended.

Keyword

Hydronephrosis; Premature infant; Renal pelvis dilatation; Very low birth weight

MeSH Terms

Child
Dilatation*
Dilatation, Pathologic
Follow-Up Studies
Humans
Hydronephrosis
Infant*
Infant, Newborn
Infant, Premature
Infant, Very Low Birth Weight*
Intensive Care Units, Neonatal
Kidney Pelvis*
Medical Records
Parturition
Pelvis
Retrospective Studies
Sensitivity and Specificity
Ultrasonography

Figure

• 

  Fig. 1 Ultrasound findings of pelvis dilatation. (A) severe pelvis dilatation (B) moderate pelvis dilatation (C) mild pelvis dilatation.

• 

  Fig. 2 Clinical progress of the infants with renal pelvis dilatation. Abbreviation: PMA, postmenstural age.

• 

  Fig. 3 Days to the recovery of renal pelvis dilatation in VLBW infants using Kaplan Meier curves. Quartile estimates according to the time variable duration showed as follows; 25 percentile of the recovery of renal pelvis dilatation occurred after the 5 months from birth, 50% percentile after 10.5 months from birth, and 75 percentile after 15.1 month from birth. No significant differences in the rate of recovery using log rank test were identified among three groups (mild, moderate and severe).

• 

  Fig. 4 Diagnostic accuracy of AP diameter for the diagnosis of severe pelvic dilatation. Area under the curve (AUC) values were obtained from receiver operating characteristic (ROC) curve analysis.

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