I get referrals for abnormal kidneys on a regular basis, such as:
- Horseshoe Kidney
Most commonly, these abnormal kidneys are found incidentally on tests performed for non-urologic reasons. Patients are then referred to urology due to the incidental finding.
Most times the reason for the referral is just the fact that the kidney is abnormal and not UTI’s or hydronephrosis.
Referring doctors likely wonder if these abnormal kidneys could be associated with renal disease, infections, or problems in the future.
“Normal” Abnormal kidneys
This patient had an MRI to check for spinal cord problems; cross-fused renal ectopia was found:
The patient had no history of urinary tract infections and there was no hydronephrosis seen on the MRI. Because a spinal MRI is not the best study for checking renal anatomy, a renal ultrasound was ordered before the referral. It is hard to demonstrate these types of kidney anomalies on a 2D ultrasound image; the ultrasound tech and/or radiologists, diagnose these abnormal kidneys live by moving the ultrasound probe up/down/left/right to determine the configuration of the kidney. That been said, one can see there is no hydronephrosis on the renal ultrasound:
“Abnormal” abnormal kidneys
Sometimes, abnormal kidneys are associated with hydronephrosis, obstruction, symptoms or UTI’s. For example, this child presented with recurrent left lower abdominal pain and was found to have obstruction of her left pelvic kidney on the Mag 3 renal scan:
For the “normal” abnormal kidney above, I recommended no further evaluation, just follow up on as needed basis for urinary tract infections. The second patient had a robotic pyeloplasty to correct the obstruction.
Referrals for symptomatic cases or for significant hydronephrosis — “abnormal” abnormal kidneys –are likely warranted, as the patient could benefit from further evaluation and treatment. However, referrals for “normal” abnormal kidneys with no hydronephrosis when the child is completely asymptomatic, are unlikely to lead to any benefit to the patient. If the urologist or nephrologist getting the referral is very conservative and worries about not missing rare things, the referral could lead to unnecessary testing, follow-ups, stress, and even interventions.
Ectopic kidneys (pelvic or cross-fused) do have impaired function, usually contributing to about 1/3 of the overall renal function. However, ectopic kidneys are not associated with high blood pressure, proteinuria, albuminuria or abnormal kidney function.
Ectopic and horseshoe kidneys are also not associated with an increased risk of malignancy (Chapter 130, Campbell’s Urology).
Horseshoe or ectopic kidneys are commonly found incidentally. In the absence of symptoms, hydronephrosis or UTI’s, a referral is unlikely to benefit the patient and carries some risk of overdiagnosis and overtreatment.