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Renal Neoplasms

Nephrogenic Rests and Nephroblastomatosis Overview and Pathophysiology. Embryologic development of the kidneys is completed by the 36th gestational week. Residual embryonic fetal tissue (metanephric blastema) that persists beyond 36 weeks' gestation is called a nephrogenic rest . Multifocal or diffuse nephrogenic rests are termed nephroblastomatosis . Nephrogenic rests are identified in about 1% of neonatal autopsies. The vast majority of nephrogenic rests resolve spontaneously by 4…

Acquired Abnormalities

Renal Infection Acute Bacterial Pyelonephritis Overview. The term pyelonephritis encompasses infections of the renal parenchyma and pelvocaliceal system. Renal infections can be acute or chronic; unilateral or bilateral; and focal, multifocal, or diffuse. Potential complications include renal or perinephric abscess. Pathophysiology and Clinical Presentation. The most common cause of acute bacterial pyelonephritis is ascending infection from the lower urinary tract. Parenchymal renal infection may also occur…

Congenital and Neonatal Abnormalities

Kidney and Ureter Multicystic Dysplastic Kidney Overview, Etiology, and Clinical Presentation. A multicystic dysplastic kidney (MCDK) is the most common form of cystic renal dysplasia. With high-grade obstruction or atresia of the upper urinary tract (renal pelvis and/or ureter) during early renogenesis, disordered parenchymal development results in an MCDK. Two types of MCDK exist: the pelvoinfundibular type (common) and the hydronephrotic type (uncommon). MCDK can occur…

Prenatal Imaging and Intervention

Overview Fetal genitourinary system abnormalities encompass a wide spectrum of disorders varying in degrees of severity and include developmental anomalies, obstructive lesions in the urinary tract, and renal parenchymal diseases. The prenatal evaluation of the genitourinary system includes assessment of the amniotic fluid, the kidneys, the bladder, and associated anomalies. Amniotic fluid is important for normal fetal development, particularly the fetal lungs. In the first trimester,…

Imaging Techniques

Radiographic Procedures Intravenous Urography Intravenous urography (IVU) was historically the imaging method of choice for the kidneys and upper urinary tracts but has been supplanted by magnetic resonance imaging (MRI) and computed tomography (CT). It is rarely the preferred imaging method in current pediatric practice. IVU uses the physiologic excretion of injected iodinated contrast media for anatomic visualization of the renal cortex, medulla, collecting system, and…

Embryology, Anatomy, and Variants of the Kidneys and Genitourinary Tract

The urinary system and the genital system are closely associated embryologically and begin to develop during the fourth week of gestation. Both develop from the intermediate mesoderm along the posterior wall of the abdominal cavity. A longitudinal elevation of the mesoderm, the urogenital ridge, forms on both sides of the abdominal aorta. Part of the urogenital ridge gives rise to the nephrogenic cord, which will form…

Abdominal Trauma

Overview Trauma in children accounts for more than 500,000 hospital admissions and 20,000 deaths per year. After cranial trauma, the abdomen is the second most common site of injury, and approximately 80% of abdominal injuries are due to blunt force trauma. The most common reported mechanism is motor vehicle crashes, followed by automobile–pedestrian injuries. Other common causes of injury include bicycle trauma and falls from a…

Tumors and Tumor-like Conditions

Tumors and tumor-like conditions affecting the colon in children can be divided into several categories. For the purpose of this chapter, we will discuss benign lymphoid hyperplasia, vascular lesions of the colon, and neoplasms. Several neoplasms arise in patients with genetic disorders, and in those cases, 1 * The author acknowledges the contributions to this chapter of Jeffrey Traubici and Alan Daneman from the previous edition.…

Intussusception

Overview Intussusception is an acquired invagination of the bowel into itself ( Fig. 107.1 ). The more proximal bowel that invaginates into more distal bowel is termed the intussusceptum , whereas the recipient bowel that contains the intussusceptum is termed the intussuscipiens . Invagination of the bowel, if sustained, leads to edema, and ischemic changes eventually supervene. Intussusception is thus an urgent condition, and delay in…

Inflammatory and Infectious Diseases

Colitis encompasses a spectrum of infectious and noninfectious inflammatory conditions. Infectious colitides, with etiologies often overlapping with enteritis (see Chapter 104 ), are typically acute in onset and may be localized as in acute appendicitis. The causative agent may not be known in inflammatory colitis. Some patients with hemolytic uremic syndrome (HUS) or inflammatory bowel disease (IBD) are recognized as having altered immune regulation, and more…

Congenital and Neonatal Disorders

Overview Congenital and neonatal abnormalities of the colon can be divided into those that present in the neonatal period, such as colonic atresia and stenosis, imperforate anus, and functional colonic abnormalities, such as small left colon syndrome and meconium plug. Entities such as Hirschsprung disease, anorectal stenosis, duplication cysts, and chronic intestinal pseudoobstruction (CIPO) are congenital abnormalities that can or even typically present later in life,…

Acquired Lesions of the Small Intestines

The pediatric duodenum, jejunum, and ileum are subject to a range of acquired pathologies. In this chapter, the etiology, pathophysiology, and clinical manifestations of small bowel obstruction (SBO), infectious and noninfectious inflammatory bowel disease (IBD), and intestinal infiltrative and neoplastic disorders will be discussed. Small Bowel Obstruction Overview. Acquired SBO may be partial or complete, acute or chronic, and intermittent. It is relatively uncommon in children,…

Acquired Abnormalities

Acquired duodenal abnormalities can be generalized into conditions that cause obstruction, inflammation, and neoplasia. Abnormalities That Result in Duodenal Obstruction Superior Mesenteric Artery Syndrome Overview. First described at autopsy by von Rokitansky in 1861, the term superior mesenteric artery or SMA syndrome refers to obstruction to the third portion of the duodenum at its crossing between the aorta and the superior mesenteric artery. It is also…

Duodenum and Small Bowel: Congenital and Neonatal Abnormalities

Part I: Duodenum Congenital anomalies of the duodenum often present with obstructive symptoms and consist of intrinsic obstructing lesions, such as duodenal atresia and stenosis, or extrinsic lesions that affect the duodenum, such as midgut volvulus or Ladd bands, annular pancreas, preduodenal portal vein, and duplications cysts; intrinsic and extrinsic lesions may coexist in the same patient. Intrinsic Lesions: Duodenal Atresia and Stenosis Overview. Duodenal atresia…

Acquired Disorders

Overview Acquired disorders of the stomach in children are uncommon and may be the result of an underlying congenital predisposition, such as gastric volvulus; an inflammatory process, such as peptic ulcer disease (PUD); or a neoplastic or neoplastic-like condition. In addition to fluoroscopic contrast studies, ultrasonography (US), computed tomography (CT), and, less frequently, magnetic resonance imaging (MRI) and nuclear medicine may be used for evaluation. Gastric…

Hypertrophic Pyloric Stenosis

Overview Hypertrophic pyloric stenosis (HPS) is the most common urgent surgical entity affecting infants during the first 6 months of life. Incorrectly assumed to be congenital by Hirschsprung in his seminal postmortem description in two patients, empirical data indicate that pyloric stenosis is not present at birth; although some exceptions may exist, the symptoms and characteristic anatomic changes of pyloric stenosis typically present in infants between…

Congenital and Neonatal Abnormalities of the Stomach

Congenital abnormalities of the stomach, and those manifested in the neonatal period, are uncommon and include such entities as duplication cysts, diverticula, microgastria, and anomalies involving the antropyloric region. Gastric Duplication Cyst Overview. Duplication cysts may occur anywhere along the gastrointestinal tract, from the mouth to the rectum (see Chapter 96, Chapter 102, Chapter 105 ). Gastric duplication cysts are rare and comprise approximately 4% to…

Acquired Esophageal Disorders

Overview The esophagus is a muscular tube that transports food and oral secretions from the mouth to the stomach via coordinated peristalsis of striated and smooth muscle. Acquired abnormalities of the esophagus can be separated into several broad categories: gastroesophageal reflux (GER), trauma including foreign bodies, inflammatory conditions, infections, motility disorders, postsurgical changes, neoplasms, and other conditions. An esophagram or upper gastrointestinal (UGI) series is the…

Disorders of Swallowing

Overview Swallowing, the coordinated movement of liquids, purees, and/or solids, is a complex sensorimotor process that depends on integrated information from multiple levels of the central and peripheral nervous system. It involves complex excitatory and inhibitory signals from multiple regions of the cortex and subcortex, and ascending sensory signals from the oropharyngeal area that trigger the central pattern generator in the bulbar reticular formation. This makes…

Congenital and Neonatal Abnormalities

Overview Severe congenital esophageal malformations, such as esophageal atresia, are usually diagnosed in the neonate; other congenital lesions, such as isolated tracheoesophageal fistulae (TEF), may remain undetected until later in life. Others, such as duplication cysts, may remain asymptomatic and identified incidentally later in life or even in adulthood. Esophageal Atresia With and Without Tracheoesophageal Fistula Overview. Esophageal atresia with and without TEF is part of…