Genito-Urinary tract Congenital anomalies
Terms in this set (33)
The embryological development of the kidney is a long and continuous process which begins in the 3rd week and is completed by about 34-35 weeks of fetal life.
Kidney organogenesis is characterised by 3 distinct and linked stages:
-Mesonephros appears in the 4th week of gestation as a more complex structure immediately after the involution of the pronephric tubules.
-Mesonephros contains the vesicles -the precursor of mesonephric nephron and the mesonephric duct. The proximal end of the mesonephric duct forms a 2-layered cup, Bowman's capsule.
-The glomerulus is completed after capillaries vascularise this primitive Bowman's capsule.
-The mesonephric nephrons are capable of producing urine by the 9th weeks of gestation and continue to do so until their involution.
-At the mesonephric stage, most cells in this organ have involuted by the 11th-12th week as the metanephros begins functioning.
class if renal anomalies
1. anomalies of the numbers
a) renal agenesis
b) supernumerary kidney
2. anomalies of the size
a) renal hypoplasia
3. anomalies of kidney structure
a) polycystic kidney
b) medullary sponge kidney
4. anomalies of position
a) ectopic pelvic kidney
b) ectopic thoracic kidney
c) crossed ectopic kidney w and w/o fusion
5. anomalies of fusion
a) horseshoe kidney
b) crossed ectopic kidney w fusion
6. anomalies of rebal collecting system
a) calcyeal diverticulum
c) ureterpelvic junction stenosis
7. anomalies of the renal vasculature
a) arteriovenous malformations & fitulae
b) aberrant & accessory vessels
c) renal art stenosis
failure of dev of the ureteral bud => absence of ipsilateral kidney w its hemitrigone
congenitally small kidney but otherwise N
=> reno vascular htn & hence treated by nephrectomy
- hereditary cond @ by progressive distortion of the renal parenchyma by multiple cysts & peritubular fibrosis
types of polycystic kidney
1. infantile polycystic kidneys: autosomal recessive, rare dis in which life expectancy is short dt rapid destruction of the renal parenchyma of BOTH sides
2. adult polyc: autosomal dominant slowly progressive dis causing slow destruction of the renal parenchyma of both sides
cyst of the liver, spleen, and pancreas mb noted in both types
etiology & parhogenesis
-renal cyst occur dt failure of fusion of the collecting tubules w the convoluted tubules of the same nephron.
- as the cysts enlarge, they compress adjacent parenchyma destroy it by ischemia & occlude N tubules
- the result is progressive renal destruction
- both usually enlarged & very firm in consistency
- surfaces: multiple cysts of varying size on section
- cyst: scattered trough out the parenchyma
- all cysts are non communicating to each other & also non communicating to the pelvicalcyceal system
- fluid in cystid : amber colored but mb hgic
- cysts are lined w flat epithelial lining, & are reduced in number, some of which mb hyalinized
pt w adult type of polycystic k dis remains asymp till the age fourties
- adult: at middle age w
. renal pain in one or both dt the drag on the vascular prdicle by heavyweighted kidney
. hematuria: dt rupture of a vessel in the cyst wall into calyx
. fever & chills: dt infection commonly complicate polycystic kidneys
. sympt of renal insufficiency (headache, nausea & vomiting)
-htn in 60-75% of cases
- renal swelling: bilateral & tender
- urine analysis
. renal cast
. dec in the sp gravity of the urine (indicating renal failure)
- plain xray film (KUB): inc renal shadow on both sides
- IV urogram (IVU): compressed & stretched calyces w elongated narrowed calcyeal necks (spider leg apperance)
- US: diffuse small echo lucent cysts on both kidneys
- bilat hydronephrosis
- bilat renal tumor
- simple renal cyst: usually unilateral w preserved renal function
- infected cysts
- gross hematuria which mb life threatening
- end stage renal failure
1. general measure: low ptn diet, ample fluids, limited exercise, control htn & hemodialysis if needed
2. surgery: only indicated in large cyst compressing the upper ureter. also renal transplantation
3. tx of cx
- in a 6 weeks embryo, normally both kidneys present in the pelvis, close to the midline, with each renal pelvis facing anteriorly
- at full term, both kidneys become located at the level of the 3rd lumbar vertebrae, further away f the midline, w each renal pelvis facing medially
dt failure of ascent of the kidney to its N position
i) pelvic kidney
- the commonest type of ectopic kidney in which the kidney lies over the pelvic brim or over the pelvis & its renal pelvis is facing anteriorly. it takes bl supply f adjacent vessels w short ureter. such a kidney mb palpable.
- it is palpable in the iliac fossa dt its superficial position
- IVU : pelvic position of the kidney w short ureter (DD: nephroptosis have long tortuous ureter)
- obstr & infection may complicate ectopic kidney & should be treated by appropriate means
- one kidney is carried up in the chest.
- 5% of ectopic kidneys dt delayed closure of the diaphragmatic aperture & renal ascent
2. crossed ectopy w/o fusion
- kidney is crossing the midline
- dt presumed migration of the ureteral bud to the other side during intrauterine life, or rotation of the caudal end of the foetus at the time of bud formation
3. crossed ectopy w fusion
- 2 kidneys are fused together in one side
renal fusion types
1. horseshoe kidney
2. crossed ectopy w fusion
the lower pole of both kidneys are fused w each other & connected by an isthmus
- both kidneys are lower than N. as there ascent are blocked by the inferior mesenteric artery during fetal dev
- the longitudinal axis of the kidneys is directed downward & medially
cong anomalies of ureter
- ureteral duplication
- ectopic ureter
embryology of the ureter
- the ureter develops f the ureteric bud
- the bud originates f the mesonephric duct above its entrance into the anterior half of the cloaca ( the future urinary bladder)
- the bud ascends to meet the metanephric blastema & divides to give rise to the ureter, renal pelvis, calyces & collecting ducts
- the mesonephric duct above the origin of the ureteric duct will obliterate in the F, but in M it will differentiate into the genital duct system ( epididymis, vas deferens, seminal vesicle & ejaculatory duct)
- below the origin of the ureteric bud, the mesonephric duct is termed the common excretory duct (carrying both future ureteric & genital duct system)
- the common excretory duct is incorporated into the urogenital sinus to form the trigone of the urinary bladder
- further absorption of the ureteric bud & mesonephric duct into the developing bladder will create separate ureteric & genital duct orifices. the ureteric bud being lower will be absorbed earlier & is carried upwards & laterally to the corners of the trigone.
- the genital duct system being higher will be absorbed later & is carried downwards & medially into the post urethra
1. if two ureteric buds arise f the mesonephric duct, complete renal duplication will result. the lower bud (connected to the lower 2/3 of the kidney) will migrate further up the trigone until the upper bud (connected to the upper 1/3 of the kidney) reaches the bladder. therefore, the ureter of the upper renal moiety will always open lower in the bladder than the ureter of the lower renal moiety.
2. if one ureteric bud arises f the mesonephric duct, but bifurcates b4 it reaches the metanephric blastema, incomplete duplication of the ureter will result. this will range f a bifid pelvis to a Y- shaped ureter w a common stem having a single opening into the bladder.
c/p of ureteral duplication
- often asympto
- cx may occur causing obstruction (hydronephrosis), vesicoureteric reflux, UTI, or incontinence if the ureter of the upper renal moiety opens in an excessively lower position below the bladder neck in females.
dx & tx of ureteral duplication
- depends on IVU or asceding pyelography
- tx is tailored to the nature of the anomaly, ranging f just follow up to ureteric re-implantation of a refluxing system into the bladder or heminephrectomy of a nonfunctioning renal moiety
- dt failure of separation of the ureteric bud f the mesonephric duct as both are incorporated in the bladder
- may occur in single system when the ureteric bud originates f a high point on the mesonephric duct so that it enters the bladder late & has no chance to migrate up the trigone (more common in boys)
- it mb a part of complete renal duplication, where the ureter of the upper renal moiety opens in an excessively lower position below the bladder neck (more common in girls)
- in boys the distal sphincteric mechanism is powerful, => ureteric obstruction & hydronephrosis
- whereas the distal sphincteric mechanism in girls is weak => urinary incontinence
- if comnected renal segment is salvageable, the mx is either by uretero-ureterostomy to the normally located ureter of a duplicated system, or by re-implantation of the ectopic ureter into the bladder above the bladder neck
- if the connected renal system is not salvageable, the mx is by nephrectomy of the single system or heminephrectomy of the involved system of a duplicated system
- is a cystic dilatation of the lower end of the ureter
- it may occur w a single system or involves the ureter of one segment of a duplicated kidney
- mb located in the bladder or may open in an ectopic location below the bladder neck
- cx are related to vesicoureteric reflux => UTI, obst => hydronephrosis or voiding problems if the bulging ureterocoele interferes w competence of the bladder neck sphincteric mechanism
- depends upon the condition of the connected renal unit
- it ranges f transurethral incision of the ureterocoele, nephrectomy or heminephrectomy of the connected renal unit, or reimplantation of the ureter into the bladder above the bladder neck
ectopia vesica (extrofy of the bladder)
- this anomalies comprises:
def of infra-umbilical ant abdominal wall, wide separation of pubic rami, absence of ant wall of irinary bladder & epispadias.
- the post wall of the bladder & trigone are exposed & their mucosal edges are fused w the skin.
- there is continuous dribbling of urine f the exposed ureteric orifices
- bcause if the skeletal ab tge gait is WADDLING & there is a HERNIA made up of exotrophic bladder & its surrounding skin.
- the condition is frequently cx by : UTI & uretero-vesical obstruction (dt fibrosis of the bladder wall)
- resulting in: hydronephrosis & deterioration of kidney function.
- furthermore: adenocarcinoma is common in extrophic bladder.
- the ideal MX is: reconstruction of the bladder & correction of skeletal defect in neonatal period. the epispadias is repaired at subsequent st.
- if the pt present later, the mx will include urinary diversion, cystectomy, repair of epispasdias
- during foetal life, urogenital sinus is connected to umbilicus by allontonis, the later is eventually obliterated & become fibrous cord that extend f bladder dome to the umbilicus .... this fibrous is called urachus.
Abnormalities of obliteration sometimes occur resulting in:
1. urachal sinus: the urachus is patent at its umbilical end only
2. diverticulum at bladder dome
3. urachal cyst: dt obliteration of two ends of urachus a patent intermediate segment.
4. umbilical urinary fistula: dt non-obliteration of the whole urachus
5. adenocarcinoma of vesical
end of the urachus resulting in tumour at the dome of the bladder.
- treated by surgical excision.
adenocarcinoma treated by radical surgery.
cong of UB
- ectopia vesica
- persistent urachus
a) temperature inside the scrotum is lower than the body T by about 1 degree celcius this is essential for maturation & fuction of the semineferous tubule of the testis, undescended testis starts to show microscopic changes by age of two years, by age of 4 years there is massive collagen deposition in semineferous tubule, the later become incapable of spermatogenesis (infertile)
b) the undescended testis & ectopic testis are more liable to trauma & torsion.
c) cryptorchoid testis has greater liability to malignancy than N testis
d) a cong inguinal hernia is often ass w testicular maldescent.
- w cryptorchidism the scrotum on affected side is empty & atrophic
- undescended testis mb palpable (at the ext inguinal ring or neck of scrotum or intra abdominal)
- ectopic testis is eaaily palpable, M/C in the supf inguinal pouch.
- if testis is not palpable, US and /or CT are indicated to identify the cryptorchoid testis.
TX: the testis should be brought down to scrotum b4 age of 2 years
a) HORMONAL THERAPY
- it is successfull in only a few cases
- we use chorionic gonodotropin 500 IU weekly for 3 mo OR 3times per week for 3 weeks
- if succesful the testis wil go down within one mo
- the course should not be repeated.
b) surgical rx:
- orchiopexy + repair of ass inguinal hernia
- the testicle is mobilised diwn to the scrotum & fixed there; the vas & bl vessel must be carefully preserved
- unilateral undescended testis presenting after puberty mb brought down to the scrotum or removed for fear of malignancy.