congenital anomalies Flashcards
renal agenesis results when
ureteric buds do not develop OR the primordia (stalks of buds) of ureters degenerate
renal agenesis also called
renal hipoplasia
why is there kidney development failure in renal agenesis/ hipoplasia
failure of buds to penetrate metanephrogenic blastema
= no nephrons are induced by the collecting tubules to develop from blastema
causes of renal agenesis/ hipoplasia
probably has a multifactorial cause
clinical evidence suggests polycystic kidneys (many cysts) could be a cause
types of renal agensis
unilateral renal agenesis (absence of 1 kidney)
bilateral renal agenesis (absence of both kidneys)
unilateral renal agensis
1/1000 births, more common in males
non fatal
causes no symptoms
usually present kidney undergoes hypertrophy and compensates for missing kidney
should be suspected in children with a single umbilical artery
bilateral agenesis
1/3000
fatal
associated with Potter syndrome (20% of cases caused by bilateral agenesis)
associated with oligohydramnios (little/ no urine excreted into amniotic cavity)
potter syndrome characteristics
wide set eyes + palpebronasal folds (epicanthic folds) ears are low set nose is broad and flat chin is receding limb clubbing/ anomalies respiratory anomalies
common cause of death by bilateral renal agenesis
death shortly after birth due to pulmonary hypoplasia (small/ underdeveloped lungs) = respiratory insufficiency
ectopic kidneys
one or both kidneys in abnormal position
non fatal
most located in pelvis
types of ectopic kidneys
pelvic kidneys
crossed renal ectopia
unilateral fused kidney
which congenital anomalies can result in kidneys fusing together
pelvic kidneys: form a discoid/ pancake kidney
crossed renal ectopia: 90% are fused
unilateral fused kidney: developing kidneys fuse after they leave pelvis
horseshoe kidney: usually fused at lower poles
what percentage of crossed renal ectopia cases have fused kidneys
90%
horseshoe kidney
very rare: 0.2%
non fatal
associated with turner syndrome (7% of cases have horseshoe kidney)
usually no symptoms
what percentage of turners syndrome have horseshoe kidney
7%
what anomaly is associated with turners syndrome
horseshoe kidney
what anomaly is associated with potter syndrome
bilateral renal agenesis
what percentage of potter syndrome have bilateral renal agenesis
20%
malrotated kidney
hilum faces anteriorly: retains embryological position
hilum faces posteriorly: kidney rotated too much
hilum faces laterally: rotation in wrong direction
often associated with ectopic kidneys
what other anomaly are malrotated kidneys associated with
ectopic kidneys
duplications of urinary tract
non fatal
common
result from abnormal division of ureteric bud
how are duplications of urinary tract created
incomplete division IN A DIVIDED KIDNEY of ureteric bud = bifid ureter
complete division IN A NON DIVIDED KIDNEY of ureteric bud = double kidney with bifid ureter or separate ureters
ectopic ureter
non fatal
pee cannot be stored in bladder (pee will exit whenever)
differs from male and females
differences of ectopic ureters for male and females
in males: ureter inserts into urethra, ductus deferens, prostatic utricle, OR seminal gland
in females: ureter inserts into bladder, urethra, vagina OR cavity of vagina
cause of ectopic ureter
ureter not incorporated into the trigone between the openings of the ureter in the posterior part of bladder
- instead carried caudally with mesonephric duct + incorporated into middle pelvic portion of vesicle part of urogenital sinus
cystic kidney disease
autosomal recessive polycystic kidney disease
OR
multicystic dysplastic kidney disease
autosomal recessive polycystic kidney disease
fatal w/o dialysis and kidney transplant
1/20000
kidneys contain many small cysts = renal insufficiency
death occurs shortly after birth
what disease is associated with pulmonary hypoplasia
autosomal recessive polycystic kidney disease (25%) potter syndrome (100%)
what percentage of autosomal recessive polycystic kidney disease is associated with pulmonary hypoplasia
25%
mutation of what gene causes most polycystic kidney and congenital hepatic fibrosis
PKHD1 gene
mutation of PKHD1 gene causes
polycystic kidney and congenital hepatic fibrosis
multicystic dysplasia kidney disease
mostly non fatal (75% survive)
abnormal development of renal system
unilateral in 75% of cases
fewer cysts that in autosomal recessive polycystic kidney disease
which disease has more cyst formation within kidneys
a) autosomal recessive polycystic kidney disease
OR
b) multicystic dysplasia kidney disease
A) autosomal recessive polycystic kidney disease has more cyst formation which causes renal insufficiency
cause of multicystic dysplasia kidney disease
dysmorphology: abnormal development of renal system
old hypothesized cause of cyst formation in multicystic dysplasia kidney disease
old reason: failure of ureteric bud derivatives to join tubules derived from metanephrogenic blastema
new hypothesized cause of cyst formation in multicystic dysplasia kidney disease
new reason: cystic structures are wide dilations of parts of continuous nephrons (especially the loops of henle)
difference in cyst frequency and size for both cystic kidney diseases
ARPKD: most cysts, small in size
MDKD: least cysts, vary in size (from mm to cm)
probable embryological basis of defect: unilateral renal agenesis
absence of ureteric bud
= no reciprocal induction of metanephrogenic blastema by ureteric bud = no kidney on one side
probable embryological basis of defect: divided kidney + bifid ureter
divided ureteric bud
= caused growth of 2 ureter stems
probable embryological basis of defect: pelvic kidney
divided ureteric bud
= can grow around preliminary blood supply vessel (common iliac artery) and prevent ascension
probable embryological basis of defect: malrotation of kidney
complete division of ureteric bud
= allows kidney to rotate the opposite way (laterally instead of medially)
probable embryological basis of defect: double kidney (supernumerary kidney)
complete division of ureteric bud
= 2 ureteric buds that induce the formation of metanephrogenic blastema = 2 kidneys on one side
probable embryological basis of defect: fused kidneys (crossed renal ectopia)
migration of one kidney to the other side
= both kidneys on one side are pushed together and fuse
probable embryological basis of defect: discoid kidney (pelvic kidney)
fusion of kidneys
