Urinary tract Calculi Flashcards
what is urolithiasis?
the formation of stones anywhere in the urinary tract
- kidney (most)
- ureter
- bladder
what is renal colic?
an acute, severe loin pain caused when a urinary stone:
- moves from the kidney
- obstructs the flow or urine through the ureter
What is hydronephrosis?
swelling of the renal pelvis and calyces in the kidney due to obstruction of the urinary tract causing back pressure into the kidneys
What is idiopathic hydronephrosis?
narrowing of the pelviureteric junction
Give 4 causes of obstruction within the lumen of the ureter:
1) calculus (stone)
2) blood clot
3) sloughed papilla
4) tumour of the renal pelvis, ureter or bladder
What is the renal papilla?
the tip of the renal pyramid where the collecting ducts drip urine into the minor calyx
Give 3 causes of sloughed papilla:
1) diabetes
2) analgesia misuse
3) sickle cell disease
Give 2 causes of renal obstruction from within the wall:
1) pelviureteric neuromuscular dysfunction
2) ureteric strictures
+ lots of congenital wall abnormalities
Give 5 external causes of renal obstruction:
1) tumours
2) diverticulitis
3) aortic aneurysm
4) retroperitoneal fibrosis
5) benign prostatic hypertrophy
Give 7 clinical features of urinary tract obstruction:
1) loin pain (often worsened by increased fluid intake)
2) anuria
3) terminal dribbling
4) sense of incomplete bladder emptying
5) hesitancy
6) dysuria
7) infection symptoms (malaise, fever, septicaemia)
Give 3 abdominal examination findings that support diagnosis of urinary tract obstruction:
1) loin tenderness
2) enlarged hydronephrotic kidney (palpable)
3) enlarged bladder
Give 2 examinations used to assess prostatic obstruction and pelvic malignancy in urinary tract obstruction:
1) genitalia exam
2) rectum exam
Name 6 investigations of urinary tract obstruction:
1) urinalysis (for haematuria)
2) midstream sample of urine (infection)
3) U+Es
4) ultrasound
5) X-ray (for stones)
6) CT scan (high sensitivity)
What is pyelography?
imaging of the kidneys
True or false: an obstructed and infected urinary tract is a medical emergency
true (delay can lead to septicaemia)
Give three treatments for hydronephrosis:
1) bladder/ suprapubic catheterisation
2) percutaneous nephrostomy
3) ureteric stent
Where is a suprapubic catheter inserted?
the abdominal wall above the symphysis pubis into the urinary bladder
Give one potential complication of relief of urinary tract obstruction:
massive diuresis may cause severe sodium, water and potassium depletion requiring IV replacement
(occurs in a minority of cases)
What are the most common types of kidney stones? (2)
1) calcium oxalate
2) calcium phosphate
What compound is found in struvite stones?
magnesium ammonium phosphate
Other than calcium stones, name three other types of nephrolithiasis:
1) struvite
2) uric acid
3) cystine
True or false: kidney stones rarely recur
false (more than 50% of patients will experience a second stone within 10 years of their first)
Describe why kidney stones form on a basic solute level:
solute concretions exceed saturation, particularly in dehydration
Give two causes of calcium stone formation:
1) hypercalcaemia/ primary hyperparathyroidism
2) hyperoxaluria
Give 3 causes of hyperoxaluria:
1) ingestion of oxalate foods such as spinach, rhubarb and tea
2) GI disease such as Crohns associated with increased colon oxalate absorption
3) inborn errors of glyoxylate metabolism
Give the two types of inborn errors of glyoxylate metabolism:
1) type 1: alanine-glyoxylate aminotransferase deficiency
2) type 2: glyoxylate reductase hydroxypyruvate reductase deficiency
Give a cause of uric acid kidney stones:
hyperuricaemia
Give two causes of hyperuricaemia:
1) idiopathic gout
2) myeloproliferative disorders (uric acid is the endpoint of purine synthesis)
Describe how struvite stones are formed?
infection by bacteria like Proteus mirabilis hydrolyse urea to form ammonium hydroxide, favouring stone formation
Give 3 examples of primary renal disease that can cause nephrolithiasis:
1) polycystic disease
2) medullary sponge kidney
3) renal tubular acidosis
What is medullary sponge kidney?
Congenital dysplastic cystic dilatation of the medullary pyramids due to tubular ectasia or dysplasia
What is renal tubular acidosis?
decrease in either tubular H+ secretion or HCO3- reabsorption that leads to a non-anion gap metabolic acidosis
Name 3 drugs that can cause calcium stones:
1) loop diuretics
2) antacids
3) glucocorticoids
Give two drugs that can cause uric acid stones:
1) thiazides
2) salicylates (aspirin)
Give two drugs that can precipitate into kidney stones:
1) indinavir
2) triamterene
What is renal colic?
passage of the stone through the ureter.
Give 3 ways renal colic can be managed:
1) analgesia
2) increased hydration
3) if the stone is more than 1cm, radiological or urological intervention may be needed e.g. extracorporeal shock wave therapy
What is nephrocalcinosis?
A condition of calcium deposits within the renal parenchyma
What is obstructive megaureter?
a childhood condition, only becoming evident in adult life where the ureter becomes wider due to the presence of a region of defective peristalsis at the lower end of the ureter
Is obstructive megaureter more common in males or females?
males
Give 3 symptoms of obstructive megaureter:
1) UTIs
2) flank pain
3) haematuria
What is retroperitoneal fibrosis?
inflammatory fibrotic tissue encasing the aorta and ureters, compressing the ureter
Is retroperitoneal fibrosis more common in males or females?
Males (x3)
Give 4 presentations associated with retroperitoneal fibrosis:
1) lower back pain
2) weight loss
3) testicular pain
4) haematuria
Give 3 lab findings that support diagnosis of retroperitoneal fibrosis:
1) anaemia
2) raised CRP
3) low GFR
What imaging technique is used to view the peri-aortic mass seen in retroperitoneal fibrosis?
contrast-enhanced CT
Give 3 management techniques for retroperitoneal fibrosis:
1) stenting of the ureters
2) corticosteroids
3) biopsy for underlying cause
what is the most common type of urinary tract stone?
CALCIUM STONES
- specifically calcium oxalate stones
- mainly linked to hypercalciuria
are calcium phosphate stones associated with low or high urine pH?
high
- linked to renal tubular acidosis
are uric acid stones associated with low or high urine pH?
low <5.5
- caused by diseases resulting in excessive breakdown of tissue
what causes struvite stones?
UTI
- bacteria hydrolyses urea into ammonium > high urine pH >7.2
what minerals form struvite stones?
- magnesium
- ammonium
- phosphate
what causes cystine stones?
a genetic disorder > cystinuria
what are the risk factors of developing urinary tract stones?
- obesity
- dehydration
- diets rich in oxalate (fruits, nuts and cocoa), urate, sodium and animal protein
- FH
- anatomical abnormalities in urinary tract
- medical conditions eg hyperparathyroidism, renal tubular acidosis, myeloproliferative disorders and chronic diarrhoea
- drugs
- previous urinary tract stone
what are the investigations for urinary tract stones?
- urinalysis
- urine MC+S
- vital signs
- FBC, U+Es, calcium and uric acid
- non contrast CT = gold standard
what investigation should be used for imagine urinary tract stones in pregnant women and children?
ultrasound
what surgery is used for urinary tract stones <2cm?
- extracorporeal shockwave lithotripsy (ESWL)
- ureteroscopy (middle/distal ureteric stones and pregnant)
what surgery is used for urinary tract stones >2cm?
- percutaneous nephrolithotomy
- open stone surgery (severe or above fails)
what are the complications of urinary tarts calculi?
- OBSTRUCTION OF URINARY FLOW > kidney damage or pyelonephrititis
- renal carcinoma
- CKD
- rupture
