Pronephroi
Early in 4th week gestation
Rudimentary and nonfunctioning
3 sets of kidneys in embryo
Pronephros
Mesonephros
Metanephros
Mesonephroi
Late in 4th week
Function as interim kidneys (until 9th week)
Metanephroi
Permanent kidneys
Develop from 2 sources
- Ureteric bud
- Metanephrogenic blastema
Ureteric Bud
- Forms ureter
- Renal pelvis
- Calyces
- Collecting ducts
Ureteric bud interacts with and penetrates the metanephrogenic blastema
nteraction initiates ureteric bud branching and differentiation of nephrons within blastema
Permanent kidneys start and end up where
Rotate how
By how long?
The permanent kidneys start in the pelvis and travel up and end up in the upper retroperitoneum
They rotate medially 90 degrees as they move up in the abdomen so the renal pelvis is directed anteromedially
Final location and position by 9th week
7th week urorectal septum fuses with _______
7th week urorectal septum fuses with cloacal membrane
–> Divides into Urogenital sinus and dorsal rectum
Urogenital sinus
- Bladder
Bladder at 1st is continuous with
Bladder – at 1st is continuous with allantois
–> Allantois becomes urachus (fibrous cord)
–> Urachus (also known a median umbilical ligament in adults)
As the Bladder becomes larger these 2 things occur:
- Distal mesonephric ducts becomes part of the connective tissue into the bladder trigone
- Ureters open separately into bladder
Epithelium of Female Urethra & epithelium of majority of male urethra derived from…
made up of and originate from..
Epithelium of Female Urethra & epithelium of majority of male urethra
–> Derived from the endoderm of the urogenital sinus
Connective tissue and Smooth muscle
–> Originate from adjacent splanchnic mesenchyme
Ureterocele Sagittal Image
“Cobra head” appearance
- Cystlike
- Lower end ureter
- Congenital or acquired stenosis distal ureter
- Usually small
- Asymptomatic (unless they obstruct)
- Found mostly in adults
- Unilateral or bilateral;
Ectopic Ureterocele
Mostly in children & young adults
More prevalent in females
Associated with ureteral duplication
Inserts low in bladder by bladder neck, urethra or lower genital tract
Can become stenotic (narrowed)
Associated with hydroureter and hydronephrosis
Can obstruct bladder or prolapse through urethra
Congenital Anomalies - Agenesis
- Unilateral or bilateral, bilateral is rare and incompatible with life
- Unilateral
–> Remaining kidney demonstrates compensatory hypertrophy - Associated with genital tract anomalies
- Sonographically the kidney is absent
- Take care not to confuse hypoplastic or dysplastic kidneys with agenesis
- Often the colon falls into the renal fossa, a pseudo kidney can be created
Bifid Renal Pelvis
Common
Duplication renal pelvis
One ureter
Considered normal variant
Hypoplastic Kidney
Incomplete development
<5 calyces
Normal functionally and morphologically
Incomplete Duplicatio
AKA Partial Duplication
Most frequently occurring congenital anomaly in neonate
Two collecting systems and two ureters with single ureter entering into bladder
Two ureters join to form single ureter
Can happen anywhere between kidneys and bladder
Complete Duplication
Rare
Duplex collecting system
Two entirely separate collecting systems
Each has own ureter
Each enter bladder separately
Increased chance of reflux
Upper pole ureter-enter bladder medially and distally to normal
–> Causing displacement of vagina and predisposition to urethral obstruction, ureterocele, vesicoureteral reflux
Congenital Anomalies - Supernumerary
Rare
- An extra kidney
- Can be found superior, inferior, anterior or posterior to the normal kidney
- Smaller than normal
Horseshoe kidney
Horseshoe kidney
- When the kidneys are connected, typically at the LP
Isthmus - Connection is identified anterior to the aorta and IVC - Typically functioning renal tissue forms the isthmus
- Associated with multiple anomalies and abnormalities
On sonography:
- Typically lower than normal
- LP’s project medially
- Renal parenchyma identified anterior to the aorta and IVC
Occur when kidneys are connected, usually at the lower poles
Connection (isthmus) is isoechoic to the normal renal cortex
Connection visualized anterior to the aorta, IVC, and spine
Most common
Fusion of Lower Poles 96%X
Complications:
- Malrotation
- Urolithiasis
- UPJ obstruction
- Infection
UPJ Obstruction
Ureteropelvic junction
- Men 2:1
- Typically in the LK, but can be bilateral
- Most patients present with chronic vague back or flank pain
- Obstruction of flow of urine from the pelvis to the proximal ureter
Congenital Megacalyces
- Underdevelopment of renal medullary pyramids resulting in the enlargement of the calyces.
- Males > females
- Sonographically appear as enlarged flat calyces
Congenital Megaureter
Enlargement of the ureter, not caused by a distal abnormality from the urethra or bladder
- 3 different pathophysiologys
- Sonographically appear as a large anechoic tube from the kidney to the bladder, measure >7mm
Renal Anomalies have a High association with
Genital Tract anomalies
You may need to expand your exam
Renal Ectopia
Occurs when one or both kidneys occur outside the normal renal fossa
- Locations include the lower abdominal and pelvic region
- Other ectopic locations (e.g., intrathoracic) are rare
