Distension of the kidney – with urine. This is the most frequently noted abnormality on ultrasound done during pregnancy. Can be unilateral (one side) or bilateral (both sides). There are many causes for hydronephrosis including obstruction of the kidney or reflux or urine from the bladder into the kidney. Hydronephrosis can also result from transient obstruction and may persist, despite the resolution of the obstruction. The degree of hydronephrosis is classified as mild, moderate or severe. When identified before birth, evaluation and management are typically delayed until delivery. Further testing is usually required to identify the cause of hydronephrosis. The greater the degree of hydronephrosis, the more likely that intervention may be required for management.
Signs and symptoms: Most children with hydronephrosis are asymptomatic, however, older children may present with pain or urinary tract infection as the first indication of hydronephrosis.
Evaluation – with mild hydronephrosis, usually, repeated evaluation to confirm improvement or resolution is recommended. With more significant degrees of hydronephrosis, or in children presenting with an infection or pain, evaluation is done with voiding cystourethrogram (catheterization of the bladder and xrays done to check for reflux) or diuretic renal scan (done to check for obstruction) are the modailities typically utilized.
Ureteropelvic junction obstruction
Obstruction of the kidney at the junction of the renal pelvis and the ureter. Usually this is identified by marked enlargement of the kidney (one or both) on antenatal ultrasound evaluation, but can also present in later childhood. It is typically congenital, but may also be secondary to injury from the passage of a stone or prior surgery at or close to the kidney.
Signs and symptoms: Most children are asymptomatic, however in some infants, marked obstruction can present with an abdominal mass and or failure to thrive. Additionally, older children can present with urinary tract infections, flank pain and blood in the urine (hematuria).
Evaluation – Initial evaluation is with ultrasound that will demonstrate the presence of hydronephrosis. Confirmation of diagnosis of obstruction requires the performance of a diuretic renal scan. This is a nuclear medicine test that is performed with infusion of an intravenous mildly radioactive material and a urinary catheter to keep the bladder drained. The test allows evaluation of the function of each kidney as well as determining how well each kidney drains. If there is an obstruction, the function of the affected kidney will be reduced and it will take longer for the urine in the kidney to drain.
Management – the management of confirmed obstruction, is surgical correction of the obstruction with pyeloplasty (see under surgical procedures)
Multicystic Dysplastic Kidney (MCDK)
Obstruction of the kidney that occurs very early in fetal life, is presumed to lead to the development of a multicystic dysplastic kidney. This is identified during antenatal ultrasound as a kidney that is composed almost entirely of cysts. The cysts can at times be quite large or may only be a single cyst. There is a higher incidence of vesicoureteral reflux in the opposite kidney (see under ureter)
Signs and symptoms – most infants identified with MCDK are asymptomatic, but when they are very large and on the left hand side, they can sometimes lead to feeding difficulties. Confirmation of diagnosis can be made with ultrasound or with nuclear renal scan that shows lack of function of the affected kidney.
Infection of the kidney. Usually associated with infections of the lower urinary tract. The major distinguishing factor is fever. In infants, however, only sign may be poor feeding and failure to thrive. More frequently noted in children with vesicoureteral reflux (see under ureter). Urine culture is positive for infection.
Signs and symptoms – most children present with onset of fever that is not accompanied by signs of upper respiratory tract infections or other organ involvement. Older children may complain of flank pain.
Evaluation – Infants and children that are not toilet trained, should have evaluation of their urine with a sterile catheterized urine specimen. A clean catch urine specimen may be obtained in the older child that is toilet trained, but careful attention should be paid to making sure that the urethra has been cleaned properly. Ultrasound of the kidney may demonstrate the presence of hydronephrosis or other renal abnormality. Confirmation of pyelonephritis requires performance of a computed tomography (CT) scan or DMSA (dimercaptosuccinate) renal nuclear scan.
Management – Treatment is with the use of intravenous antibiotics and possible hospitalization for the child that is very ill. Usually treatment regimens are 7 – 10 days, and are tailored to the bacteria that is causing the infection. An attempt should be made to determine the cause for the infection and to treat these appropriately (congenital abnormalities or voiding dysfunction)
Stones in the kidney are less commonly seen in children as compared to adults, however there is an increasing incidence reported recently. As in adults, the most common inciting factor for stone formation in children is inadequate fluid intake. Additionally, consumption of salty food has also been associated with increased risk of stone formation.
Signs and symptoms – most children present following toilet training with passage of blood in the urine and flank pain. Voiding dysfunction is a frequent accompanying factor and should be evaluated and treated to prevent further stone recurrence. Another cause is the presence of obstruction that was unrecognized.
Evaluation – Patients presenting with flank pain should have evaluation with computed tomography (CT) scan without contrast to identify the presence of stones. Some children will have blood in the urine and also have nausea and vomiting secondary to the pain. Follow-up can be performed with ultrasound to reduce radiation to the child.
Management – Most stones in children will pass spontaneously. Good hydration and pain control will help with stone passage. Children that are unable to stay hydrated due to nausea and vomiting, should be admitted to the hospital for hydration and pain management. Those children that have difficulty with pain management, may require placement of a temporary stent to relieve the obstruction. If the stones do not pass spontaneously, surgical stone removal may be required.