pathology of UTI Flashcards
How does UTI commonly present
Dysuria but specifically in the suprapubic region - pain on micturition
Frequency
Urine with weird smell
What is the renal blood flow
1200mls/minute - 20-25% of cardiac output
What happens to the urine output if fluid intake increases
urine output increases
How do ureters work
They do not store urine but urine instead continuously trickles down into the bladder
Why do ureters enter the bladder at an angle
To reduce the back flow of urine
What happens when the bladder pressure increases during filling with regards to the ureter
The ureter is closed off and this stops reflux back into the ureter
What does bacteriostatic mean
helps to stop or prevent bacteria flourishing
What are bacteriostatic properties of the normal urinary tract
Free flow of urine - assuming fluid intake is good
Low PH, high osmolarity and high ammonia content of urine
Prostatic secretions in men are bacteriostatic
All antibacterial antibodies
What part of the urinary tract is not sterile
Terminal urethra - contains flora from the gut and skin
Describe when urine becomes contaminated passing through the urinary system
The urine is sterile until it gets to the terminal urethra where it becomes contaminated
How are urine samples taken to avoid the initial contamination at the terminal urethra
Mid-stream specimen of urine
Patient is asked to void and then stop mid-stream, and then start voiding again which is what is sampled
The initial void flushes out a lot of the bacteria - mid-stream specimen will still have some bacteria but a lot less than the first void
What number of bacteria on culture usually means infection
10 to the power of 5 - when it is this high, it is less than 1% chance of the bacteria being the urethral bacterial contamination
What does a MSSU culture of 10 to the 3 or 4 mean
there is a 50% chance of infection without symptoms
What does a MSSU culture of 10 to the 3 or 4 mean with symptoms
probable infection
What does a MSSU culture < 10 to the power of 3 mean
Usually no infection
What are difficulties in MSSU
Children and elderly may struggle to stop and start urinating
What is the micro-organisms which most commonly cause UTI
E.coli
What is the most common route of infection in UTI
Ascending - perineal bacteria in the urethra begins to ascend upwards
What do UTI’s lead to and name the condition for each part of the urinary system
Inflammation
Urethra - urethritis
Bladder - cystitis
Ureter - ureteritis
Kidney - acute pyelonephritis or chronic pyelonephritis if the infection is recurrent or prolonged
What are predisposing factors to UTI
stasis of urine
Pushing bacteria from the terminal urethra
General weak immune system so predisposed to infection
What causes stasis of urine
Obstruction - congenital or acquired
Loss of sensation of the bladder - spinal cord/brain injury - loss of sensation can mean bladder can’t respond when the bladder is full
What causes bacteria to be pushed up from the urethra
Sexual activity in females
Catheterisation and other urological procedures
What is hyronephrosis
Dilatation of the kidney which is usually caused by the back up of urine
What are the consequences of obstruction
Proximal dilataion
Slowed urine flow therefore cannot flush out bacteria and therefore infections occur
Slowed urine flow leads to sediments forming which can lead to calculous(stone) formation which can cause more obstruction and lead to more infections