Foreword: Our Kidneys: A Lot Is Riding on Their Shoulders. Preface: Renal and Urologic Abnormalities in the Perinatal Period

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1 Renal and Urologic Issues Foreword: Our Kidneys: A Lot Is Riding on Their Shoulders Lucky Jain xv Preface: Renal and Urologic Abnormalities in the Perinatal Period Michelle N. Rheault and Larry A. Greenbaum xix Acute Kidney Injury in the Neonate 487 Jennifer G. Jetton and David J. Askenazi Critically ill neonates are at risk for acute kidney injury (AKI). AKI has been associated with increased risk of morbidity and mortality in adult and pediatric patients, and increasing evidence suggests a similar association in the neonatal population. This article describes the current AKI definitions (including their limitations), work on novel biomarkers to define AKI, diagnosis and management strategies, long-term outcomes after AKI, and future directions for much-needed research in this important area. Chronic Kidney Disease in the Neonate 503 Joshua J. Zaritsky and Bradley A. Warady An increased emphasis has been placed on the early identification of chronic kidney disease (CKD) in the neonatal population, given the longterm health consequences that can accompany this diagnosis. The definition of CKD in neonates and young infants differs from that of children older than 2 years and, if severe, treatment may mandate dialysis with appropriate ethical considerations. Special attention must also be directed to optimal nutrition because of its impact on height, weight, and brain development in the young child experiencing impaired kidney function. There has been steady improvement in patient survival over the last decade. Renal Replacement Therapy in Neonates 517 Ahmad Kaddourah and Stuart L. Goldstein Video of PD catheter accompanies this article The incidence of acute kidney injury (AKI) has steadily increased in the last decade in neonates and infants. Despite the extensive proposed pharmacologic approaches to treat or prevent AKI, renal replacement therapy is the only available therapeutic approach to manage the consequences of significant AKI and maintain electrolyte homeostasis and fluid balance in infants with AKI. The objective of this article is to summarize the different approaches and modalities of renal replacement therapy in neonatal intensive care units.

2 viii Neonatal Hypertension 529 Donald L. Batisky The incidence of neonatal hypertension (HTN) remains low, at less than 2%, and its etiology is varied. Strict definitions of HTN in neonates are unavailable, and the decision to treat is based on opinion rather than evidence. More studies are needed to define normal blood pressure in neonates and to refine current reference values, thus permitting a better definition of HTN. Most causes of neonatal HTN, the most common of which seems to be renovascular disease, are determined by history and basic clinical investigations. Treatment is guided by clinical judgment and expert opinion, given the limited number of clinical trials. Neonatal Polycystic Kidney Disease 543 Priya Verghese and Yosuke Miyashita This article provides an up-to-date comprehensive review and summary on neonatal polycystic kidney disease (PKD) with emphasis on the differential diagnosis, clinical manifestations, diagnostic techniques, and potential therapeutic approaches for the major causes of neonatal PKD, namely hereditary disease, including autosomal recessive and autosomal dominant PKD and nonhereditary PKD, with particular emphasis on multicystic dysplastic kidney. A brief overview of obstructive cystic dysplasia and simple and complex cysts is also included. Long-Term Renal Consequences of Preterm Birth 561 Megan Sutherland, Dana Ryan, M. Jane Black, and Alison L. Kent The normal development of the kidney may be affected by several factors, including abnormalities in placental function, resulting in fetal growth restriction, exposure to maternal disease states, including hypertension and diabetes, antenatal steroids, chorioamnionitis, and preterm delivery. After preterm birth, several further insults may occur that may influence nephrogenesis and renal health, including exposure to nephrotoxic medications, postnatal growth failure, and obesity after growth restriction. In this review article, common clinical neonatal scenarios are used to highlight these renal risk factors, and the animal and human evidence on which these risk factors are based are discussed. Electrolyte Disorders 575 Detlef Bockenhauer and Jakub Zieg Electrolyte disorders can result in life-threatening complications. The kidneys are tasked with maintaining electrolyte homoeostasis, yet the low glomerular filtration rate of neonatal kidneys, tubular immaturity, and high extrarenal fluid losses contribute to increased occurrence of electrolyte disorders in neonates. Understanding the physiologic basis of renal electrolyte handling is crucial in identifying underlying causes and initiation of proper treatment. This article reviews key aspects of renal physiology, the diagnostic workup of disorders of plasma sodium and potassium, and the appropriate treatment, in addition to inherited disorders associated with neonatal electrolyte disturbances that illuminate the physiology of renal electrolyte handling.

3 ix Hematuria in the Newborn 591 Stephanie M. Jernigan Microscopic and gross hematuria, while rare in healthy newborns, is more common in premature infants, particularly those cared for in the neonatal intensive care unit. Hematuria may be transient, but may require evaluation, investigation, and intervention in a timely manner. This article discusses the causes, workup, and treatment of the more common forms of newborn hematuria. Nephrotic and Nephritic Syndrome in the Newborn 605 Michelle N. Rheault Glomerular disorders in infancy can include nephrotic and nephritic syndromes. Congenital nephrotic syndrome (CNS) is most commonly caused by single gene mutations in kidney proteins, but may also be due to congenital infections or passive transfer of maternal antibodies that target kidney proteins. Prenatal findings of increased maternal serum a-fetoprotein and enlarged placenta suggest CNS. Neonatal nephritis is rare; its causes may overlap with those of CNS and include primary glomerulonephritis, systemic disease, infections, and transplacental transfer of maternal antibodies. These syndromes in the neonate can cause significant morbidity and mortality, making urgent diagnosis and treatment necessary. Renal Teratogens 619 Thomas M. Morgan, Deborah P. Jones, and William O. Cooper In utero exposure to certain drugs early in pregnancy may adversely affect nephrogenesis. Exposure to drugs later in pregnancy may affect the renin-angiotensin system, which could have an impact on fetal or neonatal renal function. Reduction in nephron number and renal function could have adverse consequences for the child several years later. Data are limited on the information needed to guide decisions for patients and providers regarding the use of certain drugs in pregnancy. The study of drug nephroteratogenicity has not been systematized, a large, standardized, global approach is needed to evaluate the renal risks of in utero drug exposures. Diagnosis and Management of Urinary Tract Infection and Vesicoureteral Reflux in the Neonate 633 Rossana Baracco and Tej K. Mattoo Urinary tract infection (UTI) is the most common bacterial infection in febrile newborns, particularly those born prematurely and with a low birth weight. Vesicoureteral reflux (VUR) predisposes to UTI and renal scarring. Half of neonates with UTI may have only low-grade fever or no fever. Jaundice in the absence of any other symptoms or signs may be the only clinical manifestation of UTI in neonates. The urinalysis may be negative in a significant number of neonates with UTI. Newborns with UTI have a high incidence of congenital anomalies of kidney and urinary tract anomalies, and hence should undergo renal imaging.

4 x Lower Urinary Tract Obstruction in the Fetus and Neonate 643 Douglass B. Clayton and John W. Brock III This article summarizes the most recent literature regarding congenital lower urinary tract obstruction in the fetus and newborn. Lower urinary tract obstruction is a heterogeneous group of rare diagnoses that have significant potential for in utero mortality and long-term morbidity in survivors. The diagnosis and management of the most common causes are reviewed. In addition, the current state of prenatal intervention for congenital lower urinary tract obstruction is discussed. Hydronephrosis: Prenatal and Postnatal Evaluation and Management 661 Dennis B. Liu, William R. Armstrong III, and Max Maizels Antenatal hydronephrosis (ANH) is one of the most frequently detected abnormalities found on routine prenatal ultrasounds, affecting 1% to 4.5% of all pregnancies. Despite its prevalence, there continues to be uncertainty regarding the clinical impact after birth. Prognosis depends on the severity of the dilation. Expectant prenatal management is the rule with fetal intervention rarely needed in a few select cases. Ureteropelvic junction obstruction and vesicoureteral reflux are the most common postnatal diagnoses. A renal and bladder ultrasound is essential in the follow-up of patients with ANH and helps dictate further investigation with voiding cystourethrography and/or diuretic renography. Upper Urinary Tract Anomalies and Perinatal Renal Tumors 679 Ellen Shapiro Congenital anomalies of the upper urinary tract are common and frequently diagnosed on prenatal ultrasound. In the absence of infection, these anomalies are often asymptomatic. This article reviews key features and long-term implications to assist in discussions with families. In contrast, a perinatal renal tumor is rare but extremely alarming. This update on the most common tumors and their treatment is useful in reassuring parents that most infants, after primary surgical resection, are cured without adjuvant therapies. To understand renal agenesis and other congenital renal malformations and their associated anomalies, a brief review of normal renal development is presented. Disorders of the Bladder and Cloacal Anomaly 695 Angela M. Arlen and Edwin A. Smith The incidence of congenital urachal, bladder, and cloacal anomalies is low. Urachal remnants are the result of failure or delay in obliteration of the allantois. Exstrophy of the bladder or cloaca can be diagnosed on prenatal ultrasonography and represent a deviation from the normal embryologic sequence. Persistent cloaca is an anomaly occurring in girls, in which a common cavity exists into which the intestinal, urinary, and reproductive tracts all open. It is also often diagnosed on prenatal imaging.

5 xi Abnormalities of the External Genitalia 709 Lauren Baldinger, Abhijith Mudegowdar, and Aseem R. Shukla Abnormalities of the external genitalia span the spectrum from subtle findings of limited clinical significance to profound anomalies that call into question such essential questions as sex determination. In addition, missing a diagnosis of congenital adrenal hyperplasia in a newborn female child with virilized external genitalia can result in near-term mortality, whereas a large inguinal hernia could present rapidly with incarceration if undetected. To that end, this article seeks to present a survey of commonly encountered genital abnormalities while highlighting those scenarios that require multidisciplinary interventions. Neuropathic Bladder in the Neonate 725 Michael C. Carr The management of infants born with myelomeningocele depends on understanding how their bladder stores and empties urine. Storage at low pressure with effective emptying periodically throughout the day is the goal. Intervention is designed to impact on one or both of these processes so that infants can remain infection-free and at the same time allow for appropriate renal growth over time. Urodynamic evaluation plays an important role, so that neonates can be stratified according to their risk. Most patients require intermittent catheterization and pharmacotherapy to achieve these goals at some point in their lives. Index 735