Urogenital - anatomical disorders Flashcards
congenital malformations
abnormalities in size/number
- Renal Agenesis
- Renal Hypoplasia
abnormalities in shape/position
- kidney displacement
- Horseshoe Kidney
renal agenesis
- definition
- bilateral vs unilateral occurrence and consequence
Lack of metanephric primordium (for kidney development)/
failure of ureteral bud development/
failure of contact of ureteral bud and metanephros
-> missing kidney
- Bilateral:
Incompatible with life - stillborn. Rare.
Male : Female = 25 : 1 - Unilateral :
Male : Female = 2 : 1
Opposite kidney usually enlarged due to compensatory hypertrophy
Renal hypoplasia
- gross features
- micro features
Reduced number of lobules and calyces (<5) (normal >10).
Small kidney
- Microscopic: Primitive glomeruli and tubules in dense fibrous or fatty interstitium.
Renal hypoplasia with oligomeganephronia:
small kidney w/ hypertrophied glomeruli
displacement of kidneys
- location
- complications
- Above pelvic brim/ within the pelvis.
Complications:
- Kinking or tortuosity of ureters -> obstruction -> urinary infection
horseshoe kidney
- definition
- complication
2 kidneys fused together
- most commonly at the lower poles
- renal calculi (kidney stones)
cause urine in conjoint area will have problem draining
cystic kidney diseases (5)
- Cystic renal dysplasia
- Polycystic kidney disease
- > Autosomal dominant (adult)
- > Autosomal recessive (childhood) - Medullary cystic disease
- Acquired cystic disease (dialysis associated)
- Localized (simple) renal cysts
cystic renal dysplasia
- cause
- association
Due to abnormal metanephric differentiation, with persistence of primitive / abnormal structures.
- May be unilateral or bilateral.
- May be associated with other abnormalities such as ureteric atresia (non-functioning kidney) or agenesis (missing kidney)
cystic renal dysplasia
- gross and micro appearance
- Usually enlarged, irregular in shape and multi-cystic
- Lobar disorganisation
- Multiple cysts lined by flattened epithelium
- Presence of primitive / immature structures:
Islands of undifferentiated mesenchymal cells/ cartilage tissue/ Primitive ductal structures
Autosomal-Dominant (Adult) Polycystic Kidney Disease
- location
- pathogenesis
- complication
- bilateral
- start off as small cysts which gradually enlarge
- Eventually, the kidneys are composed almost entirely of cysts, with very little parenchyma remaining (Each kidney may weigh up to 4 kg - cause of the weight of the cysts)
- caused by mutations in PKD1 and PKD2 genes (code for the proteins polycystin-1 - PC1 - and polycystin-2 respectively)
- deterioration of renal function over time -> renal failure (usually in mid to late adulthood)
Polycystic Kidney Disease
- gross and histo appearance
- abdominal swelling
thin residual parenchymal, rest of kidney filled w/ cysts
be careful when palpating!!
flattened cuboidal epithelium
urolithiasis
- definition
- location
Formation of a calculus or calculi (stones) within the urinary tract
begins in the calyces and pelvis; some calculi develop in the lower urinary tract.
causes of urolithiasis
- primary
- secondary (4)
- primary: supersaturation of the urine with crystalline material; most commonly calcium salts
secondary causes:
- Urinary tract infection:
Crystalline material encrust on a necrotic focus on mucosa calyx, pelvis or bladder.
- Indwelling catheter or foreign body in the bladder
- Vitamin A deficiency -> squamous metaplasia of upper urinary tract mucosa
- Low urinary pH -> formation of uric acid stones
types of renal calculi (stones) (4)
- calcium oxalate**
- “triple stones” - magnesium ammonium phosphate**: caused by infection
- urate** (from uric acid): gout/leukemia pts
- cystine**: genetic defect in renal transport
calcium oxalate stones formation cause
due to supersaturation secondary to hypercalciuria
due to:
- idiopathic (55%) causes
- > Absorptive hypercalciuria: hyperabsorption of calcium from the intestine, with prompt increased renal output without hypercalcaemia
- > Renal hypercalciuria due to intrinsic impairment in renal tubular reabsorption of calcium
- associated hypercalcaemia (hyperparathyroidism/ diffuse bone disease/ vitamin D intoxication/ sarcoidosis/ milk-alkali syndrome/ renal tubular acidosis of Cushing’s syndrome)
‘triple stones’ = magnesium ammonium phosphate
- cause + pathogenesis
- size
caused by infection by urea splitting bacteria (Proteus sp.)
Urea -> ammonia: urine becomes alkaline
-> precipitation of magnesium ammonium phosphate salts.
- As the amount of urea is large, the stones tend to be huge (staghorn calculi)
complications of calculi (renal crystals) formation (6)
- Urinary stasis
- Ulceration
- Bleeding
- Infection
- Pain
- Fistula formation: cause of ulceration through wall -> communicate w/ other structures
Disorders of renal TUBULES / interstitium
- Acute tubular necrosis (ATN)
- Acute interstitial nephritis (AIN)
- Acute pyelonephritis
- Chronic pyelonephritis
- Xanthogranulomatous pyelonephritis
- Tuberculosis
- Sarcoidosis
- Neoplastic infiltrates (leukemias, myeloma, etc.)
acute tubular necrosis (ATN)
- what is it
- reversible?
Common cause of acute renal failure.
- Tubular epithelial cell injury / death, resulting in reduction / loss of tubular function.
- Reversible: damaged / dead tubular epithelial cells can be replaced by regenerating residual viable cells.
Not associated with necrosis of glomeruli or adjacent renal cortical tissue (unlike zonal infarction of the kidney or renal cortical necrosis)
3 phases of acute tubular necrosis (ATN)
- Oliguric phase: Renal failure, oliguria
- Polyuric phase: Polyuria, tubular cells regenerating
- Recovery phase: Renal function recovering
causes of acute tubular necrosis (ATN)
2 types of causes
- Ischaemic causes: result in hypotension and/or hypovolaemia, which leads to *reduced renal perfusion:
1. Shock
2. Haemorrhage
3. Major surgery
4. Severe burns
5. Dehydration
6. sepsis - Toxic causes: cause direct damage to tubular cells
1. Endogenous products: Myoglobin, haemoglobin.
2. Drugs
3. Heavy metals eg. Lead, mercury.
4. Organic solvents
ATN histo features
tubular epithelial cells:
- Swelling
- Vacuolation
- Flattening
- Sloughing
- Loss of PAS-positive brush border
- Necrosis
- tubular dilation
- interstitial edema
Acute Interstitial Nephritis (AIN)
- cause
- presentation + investigation
- Mainly due to drugs
- toxins, metabolic causes, autoimmune disease, infections (nonkidney) and idiopathic
- Patients present with variable degrees of renal impairment, often acute renal failure.
- Urinalysis: may show RBCs, WBCs and eosinophils + proteinuria
Drug-induced Acute Interstitial Nephritis
- pathogenesis
- symptoms (+ how long does it take for effect to present)
form of allergic or T-cell mediated hypersensitivity reaction.
Most common drugs that cause AIN: antibiotics, diuretics, NSAIDs
Symptoms usually develop 1-2 weeks after starting the drug
- fever, rash, haematuria, proteinuria and eosinophilia (blood +/- urine), with renal impairment/failure
acute pyelonephritis
- what is it
- cause
pyelonephritis = bacterial infection -> inflammation
Bacteria may derive from:
- Ascending spread from bladder (more common)
- Lower urinary tract obstruction (stone, enlarged prostate, tumour, etc)
- Vesicoureteral reflux (VUR) - bladder back to ureters
- Diabetes mellitus (glucose always increases risk of attracting bacteria)
- Pregnancy - Haematogenous spread (less common)
acute pyelonephritis
- clinical features (5)
- complications
Clinical features
- Chills, fever
- Flank tenderness and pain
- Dysuria
- Frequency of micturition
- Often >100,000 / ml bacteria in urine
- Pyuria (pus in urine)
Complications
- Acute renal failure
- Septicaemia
- Pyonephrosis (pus collection in renal pelvis)
- Perinephric abscess
chronic pyelonephritis
- causes (2)
- Vesico-ureteric reflux
- Obstruction at any level below the kidney
causes recurrent kidney inflammation and progressive scarring
Usually begins in childhood
Xanthogranulomatous pyelonephritis
- gross and micro appearance
- Enlarged kidney, replaced by yellow nodules with firm, grayish white tissue
- Macrophages with vacuolated cytoplasm (foam cells), giant cells, lymphocytes and plasma cells
possible causes of obstruction of urinary system
Congenital Anomalies:
- Urethral valves/strictures
- Bladder neck obstruction
- Uretero-pelvic junction narrowing or obstruction.
Acquired Obstruction:
- Benign prostatic hypertrophy
- Renal calculi (kidney stones)
- Tumours – carcinoma of prostate/ cervix/ uterus/ bladder
- Inflammation of prostate/ ureter/ urethra.
Sloughed papillae or blood clots.
Functional disorder:
- Neurogenic (spinal cord damage)
hydronephrosis
- definition
- pyonephrosis
Dilatation of renal pelvis and calyces with progressive enlargement of the kidney with parenchymal atrophy due to obstruction of urine outflow
dilated calyces contain pus
hydronephrosis
- gross and histo features
Gross:
- Kidney is enlarged
- dilation of calyces
- thinning/ atrophy of renal cortex
Microscopy:
- Tubules and Bowman’s spaces are dilated
- tubular epithelium is flattened
- tubular atrophy with fibrosis
- disappeared glomeruli
