Original Paper Neonatology 2014;106:107–113 DOI: 10.1159/000358480

Received: July 24, 2013 Accepted after revision: January 8, 2014 Published online: May 17, 2014

Ultrasonographic Study of Initial Size and Postnatal Growth of Kidneys in Preterm Infants Yun-Jung Lim a Woo Sun Kim a Han-Suk Kim b Young Hun Choi a Jung-Eun Cheon a Su-Mi Shin a In-One Kim a Jung-Hwan Choi b b

Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, and Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, Korea

Key Words Kidney · Normal range · Postnatal growth · Ultrasonography · Preterm infants · Gestational age

Abstract Background: Preterm birth is known to be associated with risks of impaired nephrogenesis. Objectives: To determine the normal range of renal sizes at birth in preterm infants as well as their short-term postnatal renal growth, to assess the correlation between initial renal size and growth parameters at birth and to compare the initial and serial renal sizes between appropriate-for-gestational-age (AGA) and small-forgestational-age (SGA) preterm infants. Methods: Initial ultrasonography (US) was prospectively performed in 125 preterm infants within the first 72 h of life and every 2 weeks thereafter until a postmenstrual age (PMA) of 37 weeks was reached. Correlation between renal size and growth parameters was investigated. Renal lengths of AGA and SGA preterm infants were compared with those of age-matched fetuses described in the literature. Results: The renal sizes at birth in preterm infants are presented. Multiple regression analysis showed the strongest correlation between initial renal size and birth weight (p < 0.0001). Initial renal lengths of AGA infants were not significantly different from those of

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age-matched fetuses at ≥30 weeks’ gestational age (GA), whereas those of SGA infants were significantly smaller at ≥28 weeks’ GA. Serial renal lengths of SGA infants were significantly smaller than fetal renal lengths at ≥30 weeks’ GA. Conclusion: With US, the normal range of initial renal sizes of AGA preterm infants was defined according to GA. In contrast to AGA infants, SGA infants showed smaller initial renal sizes and no significant catch-up growth until a PMA of 37 weeks. © 2014 S. Karger AG, Basel

Introduction

With increased birth and survival rates of preterm infants, it has become even more important to understand the postnatal organogenesis of preterm infants. Previous studies have shown that in normal-term infants, renal development occurs rapidly during the third trimester and no new nephrons are formed after birth [1–3]. Thus, unsurprisingly, preterm birth has been shown to be associated with risks of impaired nephrogenesis as well as nephron deficits [4–6]. Renal size has been an essential parameter in the evaluation of children with renal disorders [7]. Therefore, the Woo Sun Kim, MD Department of Radiology and Institute of Radiation Medicine Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu Seoul 110-744 (Korea) E-Mail kimws @ snu.ac.kr

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a

Methods Study Subjects This prospective study was performed between June 2009 and February 2011. With institutional review board approval, informed consent was obtained from all parents. During this period, 133 Korean preterm infants were admitted to our neonatal intensive care unit or neonatal unit. Preterm was defined as a GA

Ultrasonographic study of initial size and postnatal growth of kidneys in preterm infants.

Preterm birth is known to be associated with risks of impaired nephrogenesis...
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