Management of a Patient with a Normal Left Kidney and Extrarenal Pelvis
No specific intervention is required for an extrarenal pelvis in a patient with normal kidney size, echotexture, and no evidence of hydronephrosis, calculi, or masses. 1
Understanding Extrarenal Pelvis
An extrarenal pelvis is an anatomical variant where the renal pelvis is located outside the renal sinus. Key characteristics include:
- Appears as a hypoechoic mass just outside the renal sinus
- Can be mistaken for hydronephrosis on ultrasound
- Unlike hydronephrosis, it is not associated with:
- Dilated calyces
- Parenchymal thinning
- Hydroureter
- Enlarged kidney 1
Diagnostic Considerations
Differentiating from Hydronephrosis
When evaluating an extrarenal pelvis, it's important to distinguish it from true hydronephrosis:
- Normal kidney size (10.2 cm in this case) suggests no obstructive process
- Absence of hydronephrosis indicates normal urinary drainage
- Normal echotexture indicates healthy renal parenchyma
- Absence of calculi or masses rules out common causes of obstruction
Imaging Recommendations
For patients with extrarenal pelvis:
- No routine follow-up imaging is needed unless symptoms develop 2
- If symptoms develop (pain, hematuria, infection), consider:
- CT with contrast or MRI with delayed urographic phases for accurate characterization 2
- Ultrasound for periodic monitoring if needed
Clinical Management
Monitoring Approach
- No specific intervention is required for asymptomatic extrarenal pelvis
- Annual comprehensive metabolic panel to monitor renal function
- Urinalysis to check for hematuria or infection 2
Indications for Intervention
Intervention would only be warranted if the patient develops:
- Symptoms (flank pain, hematuria)
- Signs of infection (fever, elevated WBC)
- Evidence of obstruction (development of hydronephrosis)
- Deterioration of renal function 2
Special Considerations
While extrarenal pelvis is generally benign, be aware that:
- It is associated with higher rates of minor congenital malformations compared to the general population 3
- There is a slightly increased risk of urinary tract infections (UTIs) 3
- UTIs in patients with extrarenal pelvis are not necessarily attributed to vesicoureteral reflux 3
When to Consider Further Evaluation
Obtain additional imaging or urologic consultation if:
- Patient develops flank pain, especially during specific activities 4
- Hematuria occurs
- Recurrent urinary tract infections develop
- Changes in renal function are detected
- Follow-up ultrasound shows development of hydronephrosis or other concerning findings
Conclusion
An extrarenal pelvis with normal kidney size, echotexture, and no evidence of hydronephrosis, calculi, or masses is a benign anatomical variant that requires no specific intervention. Regular monitoring of renal function and urinalysis is sufficient, with further evaluation only necessary if symptoms or complications develop.