Stones and Infections of the Urinary System Flashcards
State possible causes of obstruction in the ureter.
- Calculi
- Ca
- Retroperitoneal fibrosis
State possible causes of obstruction in the bladder.
Neuropathic
State possible causes of obstruction in bladder neck.
Hypertrophy
State possible causes of urinary tract obstruction related to the prostate.
BPH
Ca
State possible causes of obstruction in the urethra.
Stricture
Outline the host factors responsible for urinary tract infections.
- Shorter urethra: females > males
- Ureteric reflux: Ascending infection to the bladder especially in children
- Obstruction: tumour, stones, enlarged prostate, pregnancy
- Neuropathic: incomplete emptying, residual urine
State organisms that are commonly implicated in urinary tract infections.
- Coliforms (commonest): e.g. E. coli, Klebsiella, enterobacter - gram negative pink rods
- Proteus spp
- Coagulase negative staph - biofilm production
- Enterococci
- Pseudomonas
State the signs and symptoms of cystitis.
- Frequency
- Dysuria
- Urgency
- May have low grade fever
- Pain or burning sensation in urethra while passing urine
State the signs and symptoms of pyelonephritis.
- Fever
- Loin pain
- May have dysuria and frequency
What is an uncomplicated infection?
Defined as infection by a usual organism in an individual with a normal urinary tract and normal urinary function
What is a complicated infection?
When 1 or more factors are present that predispose the patient to recurrent/persistent infections or treatment failure
State examples of UTIs that would be considered complicated.
- Abnormal urinary tract: indwelling catheters, Vesicoureteric reflux
- Virulent organisms, e.g Staph aureus
- Impaired host defences: poorly controlled diabetes, immunosuppression
- Impaired renal function
State the types of urine specimens that can be collected.
- Mid stream urine samples: cleansing not required in women
- Clean catch in children: no antiseptic
- Supra-pubic aspiration
- Catheter sample
- Transportation: 4 degrees celcius +/- boric acid (preservative in powder or crystal form which prevents organisms multiplying excessively and changing the original picture)
- Collection bag: 20% false positives
Indicate what substances can be tested for in the urine in near patient testing (screening) with a dipstick.
- Leukocyte esterase- enzyme produced by leukocytes, indicates presence of leukocytes in urine - pyuria
- Nitrites: some bacteria produce enzymes reducing nitrates to nitrites
- Proteinuria
- Haematuria: inflammation, damage to epithelium and release of red blood cells
What is negative predictive value?
How helpful a test is in excluding infection
State some risk factors for bladder stones.
- Increased oxalate consumption
- Low protein diet
- Chronic diarrhoea and dehydration
- Vitamins A, B1 and B6 deficiency
- Magnesium deficiency
What is a lithotomy?
Surgical removal of a calculus from the bladder, kidney or urinary tract
Why was it difficult to perform lithotomies suprapubically in ancient times?
- Before the time of anaesthesia
- Rectus muscles go into spasm
What are the complications associated with a lithotomy?
- Infection
- Haemorrhage
- Fistulae
- Urinary incontinence
- Erectile dysfunction
- Mortality rate up to 50%
State some causes for bladder stones seen in modern times.
- Bladder outflow obstruction: neuropathic bladder, urethral stricture, prostate obstruction
- Foreign body: catheters, non-absorbable sutures
- Many are passed down from the upper urinary tract
State the symptoms of bladder stones.
Bladder outflow obstruction:
- Anuria: difficulty passing urine
- Painful bladder distension
What can renal stones be made of?
Calcium stones (99%)
- Calcium phosphate (apatite) usually with calcium oxalate - 65%
- Calcium phosphate alone - 15%
- Uric acid - 3-5%
- Struvite stones - “infection stones” (10-15%)
Other types (1-2%):
- Cysteine stones: seen in rare genetic disorder cystinuria
- Drug stones: e.g. indinavir (HIV treatment), triamterene (diuretic), sulphadiazine (sulphonamide antibiotic)
- Ammonium acid urate stones
What are struvite stones? Which gender are they more commonly seen in?
- Infection stones
- Urease stones
- Triple phosphate stones: magnesium ammonium phosphate hexahydrate
- Seen with infection by bacteria which have urease
Females
How can urine become supersaturated with minerals?
- Decrease in water content
- Increase in mineral content
- Decrease in solubility of solute in urine (change in urinary pH)
