Peds Renal disorders Flashcards
Horseshoe Kidney
general
Renal fusion occurs when a portion of one kidney is fused to another.
The horseshoe kidney is one the most common renal fusion abnormality characterized by fusion of one pole of each kidney, typically the lower pole.
This involves abnormal migration of both kidneys (ectopy) which results in fusion.
This differs from crossed fused renal ectopy, which usually involves movement of only one kidney.
The connection or the isthmus lies in the mid-line or sometimes slightly lateral to the mid-line and can be composed of renal parenchyma or just fibrous tissue.
The renal collecting systems remain separate.
The abnormal rotation of the kidneys shifts the renal pelvis and ureter anteriorly, so when hydronephrosis occurs, it can cause confusion.
horseshoe kidney
Patho
Fusion is thought to occur before the kidneys ascend from the pelvis to their normal dorsolumbar position.
This is usually the 5th-9th weeks of gestation
If large portions of the renal parenchyma fuse, the fusion anomaly loses its horseshoe appearance and appears as a flattened disc or lump kidney
Fusion anomalies seldom ascend to the dorsolumbar position of normal kidneys and are typically found in the pelvis or at the lower lumbar vertebral level (L4 or L5).
The blood supply is variable and may come from the iliac arteries, aorta, and sometimes even the hypogastric and middle sacral arteries.
horseshoe kidney
RF
May be associated with other congenital urologic abnormalities like ureteropelvic junction obstruction (most common) and vesicourethral reflux or genital abnormalities like bicornuate or septate uterus in girls as well as cryptorchidism and hypospadias in boys
May also be seen in Turner Syndrome and Trisomy 13,18, and 21
Horseshoe kidney
S/Sx
Usually, children with horseshoe kidneys are asymptomatic, but some children develop symptoms due to complications, such as infection, renal calculi, and urinary obstruction causing hydronephrosis.
Some patients present with pain and/or hematuria due to obstruction or infection.
Hydronephrosis occurs in 80% of children with horseshoe kidneys.
Causes of hydronephrosis are vesicoureteral reflux (VUR) or obstruction of the collecting system by uteropelvic junction obstruction (UPJO), renal calculi, or external ureteric compression by an aberrant vessel.
Renal calculi are reported in 20% of cases.
Patients with horseshoe kidney are at an increased risk for infection because of the increased likelihood of urinary stasis.
Impaired drainage is due to the high insertion of the renal ureter, leading to UPJO.
1/3 to ½ of patients will have another congenital anomaly, particularly another urological abnormality, such as vesicoureteral reflux (VUR) and uteropelvic junction obstruction (UPJO).
Genital anomalies may be present in association with horseshoe kidney like hypospadias and undescended testicles in boys, and bicornuate or septate uterus in girls.
Horseshoe kidney can also be associated with many syndromes such as Turner Syndrome, Trisomy 13, 18, and 21.
Horseshoe Kidney
complications
Urine stasis leads to increased risk for pyelonephritis and kidney stone formation
They have an increased risk of renal malignancies like renal cell carcinoma (most common 45% of tumors), transitional cell cancer, and Wilms tumor
Horseshoe Kidney
Clinical Manifestations
Majority are asymptomatic and seen as an incidental finding
Hematuria or pain due to infection or obstruction
Renal calculi (20%)
Hydronephrosis
horseshoe kidney
imaging and labs
CT Urography is the best initial test to evaluate anatomy and relative renal function
Serum Creatinine should be obtained for renal function assessment to rule out obstruction.
If the horseshoe kidney is detected antenatally, postnatal ultrasound should be performed to confirm the diagnosis, define anatomy, and confirm if hydronephrosis is present.
If there is a history of urinary tract infection, part of the evaluation should include a voiding cystourethrogram to determine whether VUR is present.
Horseshoe kidney
treatment and prognosis
In majority of cases, patients have an excellent prognosis without any therapeutic intervention.
In patients with VUR, prophylactic antibiotic therapy should be considered to help prevent urinary tract infections.
Patients with obstruction of the collecting system should be referred to a pediatric urologist that has expertise in treating obstructive uropathy.
Hypospadias/ epispadias
Hypospadias
general
The urethral meatus appears on the ventral surface of the glans, the shaft, or at the penoscrotal junction
Hypospadias may be considered a form of incomplete maturation of the genitalia that occurs in 1 out of 250-300 newborn boys.
The urethral opening is not at the tip of the glans and 70-80% of affected babies will have a meatus on the mid to distal shaft or proximal glans.
A lesser number will have more proximal openings, whether penoscrotal, scrotal, or perineal.
Boys will usually have a deficient ventral foreskin with their abnormal meatus.
Hypospadias
Pathophysiology
Failure of urogenital folds to fuse during development- abnormal development of the urethral fold and the ventral foreskin of the penis
Proximal hypospadias is usually associated with additional genitourinary malformation
Hypospadias
Clin man
Increased risk of UTIs
Deflection of the urinary stream
Erectile dysfunction
Ventral placement of the urethra
Abnormal foreskin with incomplete closure around the glans (dorsal hooded prepuce)
Abnormal penile curvature (chordee)
Hypospadias
Tx
These patients should NOT be circumcised in the neonatal period because the foreskin may be used to repair the defect
Elective surgical correction may include penile straightening
Hypospadias repair usually performed in healthy full-term infants most commonly between 6 months and one year of age
Distal hypospadias can be repaired in one stage with success rates of greater than 95%, while proximal hypospadias is repaired in two stages.
Adults with corrected hypospadias usually have normal sexual function and fertility.
epispadias
general
Maldevelopment results in the meatus opening dorsally on the glans, shaft, or at the penoscrotal junction.
Epispadias is often associated with bladder exstrophy (protrusion of the bladder wall through a defect in the abdominal wall) and urinary incontinence in both sexes.
Epispadias
Types
The urethra is displaced dorsally in males and classification is based on its positions in males:
Glanduar epispadias type: urethra opens at the dorsal aspect of the glans which is broad and flattened
Seldom have urinary incontinence
Penile type: the urethra meatus is broad and gaping located between the pubic symphysis and coronal sulcus
75% have urinary incontinence
Penopubic type: the urethral opening is at the penopubic junction, and the entire penis has a distal dorsal groove extending through the glans
95% have urinary incontinence
Epispadias
Patho
Epispadias is due to failure of midline penile fusion
Bladder exstrophy occurs from in utero rupture of an overdeveloped cloacal membrane, leading to herniation of the lower abdominal contents
Bladder exstrophy
Dx
Bladder exstrophy often made via prenatal ultrasound
cryptorchidism
general
Cryptorchidism (undescended testis) affects 2-4% of full-term male newborns and up to 30% of premature infants.
Can occur in isolated fashion or associated with other findings
Often cause is unknown but abnormalities in the hypothalamic-pituitary-gonadal axis, intrinsic testicular development defects, and androgen biosynthesis can result in cryptorchidism.
Most commonly found just outside the external ring (suprascrotal), followed by the inguinal canal, and less commonly in the abdomen
What are 2 major risks of untreated cryptorchidism?
Vesicoureteral reflux (VUR)
Dx
Hydronephrosis on the renal ultrasound suggests the possibility of vesicoureteral reflux (VUR) or obstruction.
Absence of hydronephrosis does not rule out the possibility of VUR
