CH 10 Pediatric Renal and Adrenal Flashcards
Kidneys
excretory organs that maintain the body’s chemical equilibrium through the excretion of urine. Kidneys originate in the pelvis and ascend into the upper abdomen. the ureters carry urine to the bladder and the urine is then excreted through the urethra.
urinary and genital systems are closely related, if anomalies are found in the genital system, check the kidneys and vice versa.
Functions of the urinary system:
detoxification
blood pressure regulation
maintenance of the correct balance of PH, minerals, iron, and salt levels in the blood.
Kidney location
kidneys and ureters are paired structures lying deep to the muscles of the back and are retroperitoneal. The right kidney is inferior to the left kidney due to the liver
Adrenals location:
paired structures, superior to the kidneys and the diaphragm, psoas muscles and quadratus lumborum muscles are posterior aspect to the kidneys.
renal parenchyma
consists of a cortex and medulla. The cortex is the outer portion from the renal sinus to the renal capsule. The medulla is the inner portion from the base of the pyramids to the center of the kidney. The renal pyramids are situated in the medulla, and are prominent in the neonate and pediatric patient. The renal sinus contains blood vessels, fat and lymph channels. The fibrous covering of the kidneys is called Gerota’s fascia
Functional unit of the kidney:
Nephron. contains the renal corpuscle, proximal and distal convoluted tubule, descending and ascending limbs of the loop of Henle and the collecting tubules.
The renal corpuscle (malpighian body) consists of Bowman’s capsule and the glomerulus (knot of capillaries)
Urinary bladder appearance
should appear anechoic and squared due to its relationship with the psoas muscles. The walls should be smooth and appear as a hyperechoic line when distened.
Blood flow into kidney
Main renal artery > segmental arteries > Interlobar arteries > Arcuate arteries > Interlobular arteries
Renal size in pediatric patients
0-12 months = median length 5 - 6.5 cm (+/- 1cm)
1 yr- 15 yrs = median length 6.5 - 11cm (+/- 1.75cm)
Normal renal appearance:
premature infant= prominent cortex more echogenic than liver
Term infant = sinus echoes ot prominent due to lac of fat, renal cortex equals liver echogenicity, larger prominent medullary pyramids “chocolate chip cookie”
Young child = renal cortex is slightly less echogenic than liver and renal sinus central fat begins to develop.
Older child = normal cortex, hypoechoic pyramids and echogenic renal sinus
Teenager = normal renal echogenicity (same as adult)
Renal agenesis
Bilateral renal agenesis, associated with Potter’s syndrome, also associated with oligohydramnios and pulmonary hypoplasia. Incompatible with life.
Unilateral renal agenesis may be an isolated congenital malformation or may be associated with chromosomal abnormalities.
Renal agenesis is more common in males.
Renal agenesis associated abnormalities:
renal and urinary/genital abnormalities go together.
Bicornuate or didelphys uteri in females seminal vesicle agenesis in males congenital cardiac malformations VACTERL sydrome V-vertebral defects A-anal atresia C- cardovascular anomalies TE- tracheoesophgeal fistula R- renal anomalies L- limb defects MURS syndrome MU- mullerian agenesis R- renal agenesis CS- crvicothroracic somite abnormalities
VACTERL sydrome
V-vertebral defects A-anal atresia C- cardovascular anomalies TE- tracheoesophgeal fistula R- renal anomalies L- limb defects
MURS syndrome
MU- mullerian agenesis
R- renal agenesis
CS- crvicothroracic somite abnormalities
Ectopic Kidneys:
one or both kidneys are in an abnormal position. The most common place for and ectopic kidney is the pelvis (pelvic kidney)
Horseshoe kidney
The *lower poles of the kidney are fused.
The normal ascent of the kidney is prevented by the IMA. *There is a higher incidence of this anomaly in Turner’s syndrome. Horseshoe kidneys are the most common fusion anomaly.
Crossed fused renal ectopia
Developing kidneys fuse in the pelvis and one kidney ascends to its normal position, carrying the other one with it. More commonly the left is ectopic
Crossed fused renal ectopia sonographically:
2 kidneys are visualized on one side of the abdomen with absence of a contra-lateral kidney.
The ureters connect on both sides of the bladder. There is an increase risk of VUR (vesicular ureteral reflux) with this anomaly.
*most commonly associated with VACTERL syndrome
Dromedary Hump
- common variant of focal bulging on the lateral aspect of the left kidney due to splenic impression onto the superolateral left kidney.
Junctionla parenchymal defect
extension of sinus fat into the cortex.
sono: triangular hyperechic area on the anterior aspect of the upper pole of the right kidney.
Persistent fetal lobulation
normal variant seen occasionally in adult kidneys. Occurs when there is incomplete fusion of the developing renal lobules.
Embryologically, the kidneys originate as distinct lobules that fuse as they develop and grow.
Often seen as smooth indentations of the renal outline in between the renal pyramids.
Column of Bertin (septal cortex)
- normal variation of prominent renal cortical parenchyma located between two medullary pyramids. This may give the appearance of a mass effect although the echogenicity is equal to the peripheral cortical tissue.
Duplex Kidney
Duplication of the collecting system.
Complete: 2 ureters
Incomplete: 1 ureter
Duplex Kidney (duplication of the collecting system) sonographically:
duplex kidney is typically longer than normal and has a complete central cortical break within the hyperechoic sinus.
- with complete double ureters, the ureter draining the upper pole typically inserts in an ectopic location on the bladder.
- a frequent complication of the ectopic ureter is a uterterocele (prolapse of the distal ureter into the bladder) this results in a hydroureter and hydronephrosis of the upper collecting system.
Weigert-Meyer law
describes the relationship of the upper and lower renal moieties in duplicated collecting systems to their drainage inferiorly.
with a duplex kidney and complete ureteral duplication, the upper renal and lower renal moiety have their own ureters with each ureter having its own reteral orifice in the bladder.
The upper renal moiety has an ectopic insertion medial and inferior to the lower pole moiety ureter and frequently ends in a ureterocele.
The lower renal moiety has an orthotopic (normal) insertion lateral and superior to the ureter draining the upper pole and reflux typically occurs.
Extrarenal pelvis
renal pelvis normally is located within the renal sinus. Extrarenal pelvis lies outside the renal sinus sonographically appearing as a cystic collection medial to the renal hilum.
Posterior urethral valve
Posterior urethral valve (PUV) most common cause of urninary obstruction in the MALE neonate.
This obstruction is due to a flap of mucosa that has a slit-like opening in the area of the prostatic urethra.
“keyhole” sign
PUV is associated with vesicoureteral reflux.
Sono: large bladder, urinoma, hydronephrosis, hydroureter
Multiclocular cystic nephroma
rare, non-herediatary, benign cystic neoplasm that is more common in males between 3 months and 2 years.
range in size from a few cm to 10 cm.
present with palpable abdominal mass. difficult to distinguish from a cystic renal cell carcinoma or cystic Wilm’s tumor.
surgical excision required
Wilm’s tumor (nephroblastoma)
most common childhood renal tumor. mean age for diagnosis 3.5 years. Present with large asymptomatic flank mass, can have hypertension, fever and hematuria.
mets can be to the lungs, liver, bone, lymph nodes, and retroperitoneum. with proper treatment 90% survival rate.
tumor extension can be into the renal vein and IVC.
wilm’s tumor destroys renal contour. if normal contour, mass most likely and adrenal neuroblastoma.
Cystic Wilm’s tumor
malignant tumor on the “favorable” end of the Wilm’s tumors. occurs in children younger than 5.
Present with palpable abdominal mass, pain, hematuria or HTN.
associated with Beckwith-Wiedemann syndrome, drash syndrome, heihupertrophy, crytorchidism and sporadic aniridia (absence of the Iris)
5-10% have bilateral Wilm’s tumors, majority are solid but a small percentage are cystic.
surgical excision is the preferred treatment
Mesoblastic Nephroma (fetal renal hamartoma)
benign renal tumor composed of connective tissue which is *most common in the neonatal period.
Presents as a palpable abdominal mass.
Sono: complex, well-defined mass with increased vascularity.
Rhabdoid tumor
rare, aggressive tumor associated with early onset of mets. chemo resistant. chemo and surgery are usual treatment. Poor prognosis.
mets invade lungs, liver, abdominal lymph nodes, brain, and bone.
presents as large complex renal mass.
sono: peripheral subcapsular crescent-shaped fluid collection is seen (due to hemorrhage or necrosis)
Hydronephrosis
- most common abdominal mass in neonates and infants.
3 most frequent causes of hydro:
PUV (posterior urethral valve)
UPJ (ureteropelvic junction) obstruction
UVJ (uereterovesical junction) obstruction
UPJ (ureteropelvic junction) obstruction
most frequent cause of sever hydronephrosis and the most common urinary obstruction in children.
Presents with palpable abdominal mass and abdominal distension. Hematuria is often present.
Hydro ends abruptly at the UPJ and is associated with a normal downstream ureter. if severe, pelvis is enlarged more compared to calyces.
UPJ (ureteropelvic junction) obstruction causes:
may be due to abnormal smooth muscle arrangement of the proximal ureter that impairs distensibility, abnormal innervation of the proximal ureter which impairs peristalsis or a crossing vessel/fibrous scar at the UPJ.
Pyeloplasty is the treatment (surgical reconstruction/revision of the renal pelvis to drain and decompress the kidney)
UPJ (ureteropelvic junction) obstruction associated anomalies include:
Multicystic dysplastic kidney renal agenesis (contralateral) duplicated collecting system horseshoe Kidney Ectopic kidney
UPJ (ureteropelvic junction) obstruction diagnosed:
often in utero. Initial u/s after birth should be done on day of life 7.
newborns are extremely dehydrated at birth so it is best to wait to evaluate this anomaly after birth.
sono: dilated collecting system and non-visualization of the distal ureter.
*UVJ (ureterovesical junction) obstruction
Megaureter is the most frequent type. renal collecting system and ureter are dilated due to functional aperistalsis of the distal ureter at the juxtavesicular ureteral segment.
*other causes may be a ureterocele and/or distal ureteral stricture
Vesicular ureteral reflux (VUR)
VUR is most commonly due to a congenital anomalous development of the UVJ (ureteral vesicular junction)
about 1/2 of males with PUV have VUR (reflux). Most children with prune belly syndrome have some form of VUR.
2 types: Primary VUR and secondary VUR
primary VUR
congenital defect in the urinary valve. the ureter did not grow long enough in utero and the bladder valve did not close properly. Improves with age.
Secondary VUR
due to a urinary tract blockage due to infection which causes ureter swelling due to PUV.
Multicystic Dysplastic Kidney
non hereditary renal dysplasia
most common cause of an abdominal mass in neonates.
*a form of renal dysplasia characterized by multiple non-communicating cysts with the absence of renal parenchyma.
occurs as result of atresia of the ureteropelvic junction during fetal development. fatal if bilateral.
20-50% have contralateral vesicoureteral reflux, UPJ obstruction and primary megaureter. (unknown etiology)
Multicystic Dysplastic Kidney
(non hereditary renal dysplasia)
Sono:
associated with:
renal pelvis/sinus absent; multicystic masses of variable shape and size with absent/dysplastic renal parenchyma.
MCDK occurs in various syndromes such as: Beckwith-wiedemann, trisomy 18, and VACTERL
