Overview
Definition:
Pediatric nephrectomy for a nonfunctioning kidney involves the surgical removal of a kidney that has lost its physiological capacity to filter waste products and produce urine
This is typically indicated when the kidney is severely damaged, malformed, or has no functional potential, posing risks of infection, hypertension, or malignancy, or causing significant pain.
Epidemiology:
The incidence of nonfunctioning kidneys in pediatric populations is often associated with congenital anomalies of the kidney and urinary tract (CAKUT), which are a leading cause of end-stage renal disease in children
Conditions like renal agenesis, multicystic dysplastic kidney (MCDK), severe hydronephrosis, and end-stage reflux nephropathy contribute to the need for nephrectomy
The exact incidence of nephrectomy for nonfunctioning kidneys varies based on regional CAKUT prevalence and management protocols.
Clinical Significance:
Identifying and managing nonfunctioning kidneys in children is crucial
These kidneys can be asymptomatic, but they can also lead to recurrent urinary tract infections (UTIs), hypertension due to renin production, flank pain, abdominal masses, and rarely, Wilms tumor
Early detection and appropriate management, including timely nephrectomy when indicated, prevent complications and optimize the child's overall health and long-term renal function from the remaining healthy kidney.
Clinical Presentation
Symptoms:
Many nonfunctioning kidneys are asymptomatic and discovered incidentally on antenatal ultrasound or during investigations for other conditions
Potential symptoms include recurrent UTIs with fever and flank pain
Palpable abdominal mass
Hypertension
Abdominal discomfort or pain
Poor feeding or failure to thrive in infants
Hematuria (rare).
Signs:
Physical examination may reveal a palpable abdominal mass
Signs of hypertension, such as elevated blood pressure readings
Tenderness in the flank area
Signs of chronic renal insufficiency if bilateral involvement or significant single-kidney dysfunction exists.
Diagnostic Criteria:
There are no specific formal diagnostic criteria for a "nonfunctioning kidney" that necessitates nephrectomy
The decision is based on a constellation of findings from imaging, functional studies, and clinical assessment
Key indicators include absent or severely reduced renal parenchyma on imaging, lack of contrast excretion on excretory urography or CT urography, poor or absent uptake on renal scintigraphy (e.g., MAG3 renogram showing no excretion), and presence of complications like recurrent infections or hypertension attributable to the kidney.
Diagnostic Approach
History Taking:
Detailed antenatal and postnatal history focusing on urinary tract development and any prior urinary issues
History of recurrent UTIs, flank pain, fever, abdominal masses, or hypertension
Family history of renal anomalies
Developmental milestones
Feeding history.
Physical Examination:
Thorough abdominal examination to assess for masses, tenderness, or organomegaly
Careful palpation of the renal areas
Assessment of blood pressure
General examination for signs of systemic illness or chronic renal disease.
Investigations:
Renal ultrasound: Initial imaging to assess renal size, echogenicity, presence of cysts, hydronephrosis, and rule out masses
CT urography: Provides detailed anatomical information, assesses renal parenchyma, collects urine, and outlines the collecting system
crucial for demonstrating non-excretion of contrast
Renal scintigraphy (e.g., DMSA or MAG3 renogram): Essential for functional assessment, quantifying individual kidney contribution to overall renal function
shows absent or minimal uptake/excretion
Urine analysis and culture: To rule out active infection
Serum creatinine and electrolytes: To assess overall renal function, especially if bilateral involvement is suspected.
Differential Diagnosis:
Other causes of abdominal masses in children: Neuroblastoma
Wilms tumor
Lymphoma
Ovarian or testicular tumors
Hydrometrocolpos
Pelvic abscess
Severe multicystic dysplastic kidney (MCDK) can mimic a cystic tumor
Small, scarred kidneys with some residual function need careful evaluation before considering nephrectomy.
Management
Initial Management:
Management is primarily based on the underlying cause of the nonfunctioning kidney and the presence of complications
If the nonfunctioning kidney is causing acute issues like severe infection or pain, initial management may involve antibiotics and analgesia
If hypertension is present, antihypertensive medications are initiated.
Medical Management:
Medical management is rarely the primary treatment for a structurally nonfunctioning kidney
However, if the kidney is contributing to hypertension, appropriate antihypertensive medications (e.g., ACE inhibitors, ARBs, calcium channel blockers) should be initiated and titrated
Prophylactic antibiotics might be considered for recurrent UTIs, although this is less common if the kidney is truly nonfunctioning and not contributing to stasis.
Surgical Management:
Surgical management, specifically nephrectomy, is indicated for nonfunctioning kidneys that meet specific criteria
Indications include: recurrent UTIs directly related to the nonfunctioning kidney, intractable flank pain, significant hypertension attributable to renin production by the nonfunctioning kidney, suspicion of malignancy (though rare in non-functioning kidneys, it must be ruled out), large multicystic dysplastic kidneys that are causing mass effect or discomfort, or if the kidney is at risk of trauma.
Surgical Approach:
The approach can be open or laparoscopic
Laparoscopic nephrectomy is increasingly preferred in children due to smaller incisions, reduced postoperative pain, and faster recovery
The technique involves careful dissection of the renal artery and vein, followed by the ureter, and then removal of the kidney
For large or complex cases, open flank or anterior abdominal incision may be necessary
Complete removal of the kidney and ipsilateral ureter (nephroureterectomy) is often performed, especially if there is associated ureteral abnormality or reflux into the contralateral system.
Complications
Early Complications:
Bleeding during or after surgery
Infection at the surgical site
Injury to adjacent organs (bowel, spleen, pancreas)
Injury to the remaining kidney or ureter
Pneumothorax (with flank incision).
Late Complications:
Hernia at the incision site
Adhesions leading to bowel obstruction
Phantom limb pain (rare)
Potential for increased workload on the remaining kidney, leading to progressive decline in function if that kidney is compromised
Development of hypertension in the long term if the nonfunctioning kidney was a significant contributor and hypertension is not well-controlled post-operatively.
Prevention Strategies:
Meticulous surgical technique, including careful dissection and secure ligation of vessels and ureter
Use of appropriate perioperative antibiotics
Careful patient selection and preoperative optimization
Intraoperative monitoring of vital signs and urine output
Postoperative pain management and early mobilization
Close follow-up of remaining renal function and blood pressure.
Prognosis
Factors Affecting Prognosis:
The prognosis is generally excellent if the remaining kidney has adequate function and no significant underlying pathology
Factors influencing long-term outcome include the function of the contralateral kidney, presence of other congenital anomalies, development of post-nephrectomy hypertension, and adherence to follow-up care
Successful removal of a problematic nonfunctioning kidney often improves quality of life.
Outcomes:
Removal of a nonfunctioning kidney typically resolves symptoms like pain and recurrent UTIs associated with that kidney
Hypertension may improve or be better controlled postoperatively
The long-term renal function is dependent on the health of the contralateral kidney.
Follow Up:
Regular follow-up is essential
This includes periodic blood pressure monitoring, renal function tests (serum creatinine), and urinalysis
Renal ultrasound of the remaining kidney may be performed annually or biannually, depending on initial findings and any existing concerns
Prompt management of any signs of renal insufficiency or hypertension is critical.
Key Points
Exam Focus:
Understand the indications for nephrectomy in children with nonfunctioning kidneys: recurrent infections, hypertension, pain, mass effect, or suspicion of malignancy
Differentiate between renal agenesis, MCDK, and severe hydronephrosis
Know the role of ultrasound, CT urography, and DMSA/MAG3 scans in diagnosis
Recall the common complications and preventative strategies
Laparoscopic approach is preferred when feasible.
Clinical Pearls:
Always assess blood pressure in children with known renal anomalies, even if asymptomatic
A nonfunctioning kidney can be a source of renin, causing significant hypertension
Do not hesitate to proceed with nephrectomy if the kidney is causing recurrent problems or significant hypertension, as removal often leads to better outcomes
Consider nephroureterectomy if ureteral abnormalities are present.
Common Mistakes:
Delaying nephrectomy in the presence of significant hypertension or recurrent severe infections
Failing to adequately investigate the contralateral kidney for function and structural integrity
Not performing adequate functional assessment (e.g., DMSA/MAG3) before definitive surgery, especially in children with bilateral anomalies
Assuming all abdominal masses in children are Wilms tumor without appropriate differential diagnosis and investigation.