- Clinical science
Congenital anomalies of the kidneys
Abstract
Congenital anomalies of the kidneys and urinary tract (CAKUT) are one of the most common malformations diagnosed in newborns. Even though most cases are initially asymptomatic, up to 50% of children with end-stage renal disease have an underlying CAKUT. For this reason, early identification of these malformations is essential in order to prevent renal damage. The pathogenesis of CAKUT is multifactorial; both specific genes and environmental factors (e.g., in utero exposure to ACE inhibitors) have been implicated in the development of CAKUT.
Etiology
- Disturbance of embryonic development
- Environmental factors
- In utero exposure to ACE inhibitors or angiotensin II receptor blockers → juxtaglomerular hyperplasia, absent proximal convoluted tubules, or renal fibrosis
References:[1]
Clinical features
- Most CAKUT are incidental findings with no clinical significance.
- CAKUT are considered clinically significant if they can lead to chronic kidney disease, vesicoureteral reflux, urinary tract infections, hydronephrosis, or urinary incontinence.
- Signs that an underlying clinically significant CAKUT may be present include:
- Hydronephrosis on prenatal ultrasound
- Urinary tract infection in children < 24 months of age
- Recurrent urinary tract infections in children of any age
References:[1]
Diagnostics
-
Ultrasound imaging of the kidneys and bladder
- First-line imaging modality
- Detects anatomical abnormalities
- Renal ultrasound is warranted for all children with recurrent UTIs or UTI in children < 24 months of age.
-
Voiding cystourethrogram
- Detects retrograde movement of urine from the bladder to the urinary tract
- Although the test is invasive and involves radiation exposure, it is warranted in patients with recurrent UTIs or single UTI and abnormal findings on renal ultrasound.
- Intravenous pyelogram: detects anatomic abnormalities; has largely been replaced by ultrasound and CT urography
- CT scan: detects anatomic abnormalities; can complement renal ultrasound if findings on ultrasound are equivocal
References:[2]
Differential diagnoses
Floating kidney
-
Description
- Downward displacement of the kidney due to reduced perirenal fat (thin individuals, anorexia nervosa)
- Hypermobility of the kidney
-
Symptoms
- Flank and lower abdominal pain with exacerbation in upright position (nephroptosis causes painful strain)
- Alleviation of pain in supine position
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Diagnostics
- Renal ultrasound in upright and supine position
- Intravenous pyelogram in upright and supine position
-
Treatment
- Conservative: abdominal muscle training and stabilization with abdominal wall binders
- Surgical: laparoscopic nephropexy
References:[3]
The differential diagnoses listed here are not exhaustive.
Overview
Kidney
Condition | Anomaly | Important notes |
---|---|---|
Duplex kidney |
|
|
Renal agenesis |
|
|
Renal aplasia |
| |
Renal dysplasia | ||
Renal hypoplasia | ||
Renal dystopia/renal ectopia |
| |
Malrotation |
| |
Horseshoe kidney |
|
|
Ureter
Condition | Anomaly | Important notes |
---|---|---|
Bifid Ureter | ||
Double Ureter | ||
Bifid collecting system |
| |
Ectopic ureter |
|
|
Ureterocele |
|
Treatment
- The majority of cases do not require treatment.
- If there is vesicoureteral reflux → antibiotic prophylaxis (see vesicoureteral reflux)
-
If there is vesicoureteral reflux and recurrent cystitis or pyelonephritis → surgical correction
- Abnormalities of the ureter or its insertion into the bladder (e.g., ureterocele or ectopic ureter) are treated with resection of the distal ureter and reimplantation of the ureter into the bladder.
- Laparoscopic nephrectomy may be indicated in cases with recurrent pyelonephritis and loss of kidney function.