Showing posts with label Genitourinary system. Show all posts
Showing posts with label Genitourinary system. Show all posts

Sunday, March 4, 2018

UTI Series: Pathogenesis, risk factors and diagnosis

Hello Awesomites! :)

This post on Urinary Tract Infection (UTI) is brought to you by our passionate MSGA Calvin Ong K.Y. and me, Upasana Y. 

The following parts can be infected in an UTI:
- Kidney
- Urinary bladder
- Ureter

Infections of urethra is known as Urethritis, which is dealt under different clinical syndromes. Infection of the urethra is mainly caused by N. gonorrhoeae, C. trachomatis, M. genitalium. T. vaginalis, HSV, and adenovirus can also cause urethritis.


Escherichia coli - It is the most common urinary pathogen.

Proteus, Klebsiella, Pseudomonas species and Staphylococcus aureus are associated with hospital acquired infections because their resistance to antibiotics favor their selection. Catheterization and gynecological surgery increase risk for these infections.

Proteus infections are associated with renal stones. Proteus produces a potent urease which acts on ammonia, rendering the urine alkaline.

S. saprophyticus infections are found in sexually active young women.

Candida infection is usually seen in diabetic patients and in the immunosuppressed.

M. tuberculosis is carried in blood to kidney from another site of infection. (eg. respiratory TB)

Polymicrobial bacteruria is due to fistulas, urinary retention, infected stones or catheters.

Pathogenesis of UTI

1. COLONIZATION - Pathogens colonizes the periurethral area and ascends through urethra upward towards the bladder.

2. UROEPITHELIUM PENETRATION - Fimbria allow bladder epithelial cell attachment and penetration. Bacteria continue to replicate and may form biofilm.

3. ASCENSION  -Bacterial toxins may also play a role by inhibiting peristalsis (reducing the flow of urine)



Risk factors of UTI

  • Indwelling catheter
  • Antibiotic use
  • Spermicides
  • Voiding dysfunction
  • Frequent or recurrent sexual intercourse
  • Vesicoureteral reflux
  • Female sex (short urethra ~4cm)
  • Pregnancy (progesterone mediated smooth muscle relaxation to the bladder and ureters and compression of ureters by the uterus)
  • Familial tendency
  • Susceptible uroepithelial cells 
  • Vaginal mucus properties
Route of spread
  • Ascending route
  • Hematogenous
  • Lymphatic
Signs & Symptoms of Urinary Tract Infection
Urinary tract affected:
1. Urethra – cause urethritis
-Burning and pain with urination 
(Urethritis is classified as an STI and not UTI by many textbooks)

2. Bladder – cause cystitis
-Painful urination
-Frequent and persistent urge to urinate
-Lower abdomen discomfort
-Cloudy/Strong-smelling urine

3. Kidneys – cause pyelonephritis
-Flank pain (Upper back and side)
-Nausea and vomiting

Diagnostic Testing for Urinary Tract Infections:

Types of urine Samples
-Mid stream Urine sample
-Catheter specimen of urine during cystoscopy
-Suprapubic aspirate
-Early morning urine (TB of urinary tract)
-Initial flow (Urethritis, prostatitis)
1. Urine microscopy
-Pyuria (pus presented in urine + elevated white blood cells in urine)
-Hematuria (red blood cells in urine)
RBCs may be found in the urine during menstruation in a woman’s urine sample, thus leading to a false positive result.
-Motile bacteria – E.Coli, Proteus, Pseudomonas
-Non-motile bacteria – Klebsiella
-Presence of cocci – Staphylo-, Strepto-, Enterococci 
**Presence of WBC casts indicates pyelonephristis rather than cystitis
**If urine sample contains abundant squamous epithelial cells - sample is contaminated and results are not reliable

2. Urine dipsticks 
-Use different chemicals reagants on a strip that is dipped in urine to diagnose urinary tract diseases
-E.g. of dipstick result (positive leukocyte esterase, positive nitrite, positive haemoglobin)

3. Urine culture
-Culture of mid-stream urine – Blood agar, Mac Conkey agar
-Midstream void - ≥1 × 105 CFU/μL is consistent with infection
-Samples collected via catheterization -≥1 × 102 CFU/μL is consistent with infection
**Contamination of samples may occur when urine passes through outer third of urethra
**Therefore, numeric threshold of colony-forming units (CFU) per millilitre is used to confirm infection.

4. Imaging test:- 
It is not routinely done in case of UTI.

Ultrasonography is indicated
-Obstruction in urinary flow
-Measurement of bladder residual volume in BPH 
-Recurrent UTI 
-Pyelonephritis or hematuria.

KUB is most useful in suspected case of urolithiasis.

Computed tomography urography is used to view the kidneys and adjacent structures, and may be considered to further evaluate patients with possible abscess, obstruction, or suspected anomalies when ultrasonography is not diagnostic.

If urinalysis is unrevealing, cystoscopy can be performed to evaluate for bladder cancer, hematuria, and chronic bladder symptoms.

Urodynamic studies can be performed for persistent voiding symptoms.

Intravenous urography - for hematuria evaluation if CT urography is not available.

Men with UTI
US with abdominal X-RAY and flow rate
  • No abnormality detected  - no further imaging 
  • Abnormal upper tract 
  • Abnormal lower urinary tract - further investigation (e.g.cystoscopy,urodynamics or transrectal US)
We are grateful to our teachers. :)

- Upasana Y. and Calvin Ong K.Y.

Saturday, February 24, 2018

Urinary Bladder and Clinical Correlates

Hello everyone! This write-up attempts to organize the seemingly confusing nerve supply of the bladder and associated pathology aka the neurogenic bladder.


(beta 2 and alpha 1 are adrenergic receptors of SANS ; muscarinic type 3 is a cholinergic receptor of PANS)

  • SANS inhibits micturition while PANS facilitates micturition. You don’t want to pee when you’re running a 100m sprint, an SANS-dominant activity but you can comfortably pee at rest, a PANS-dominant activity.
  • Sensory fibres of pudendal nerve tell your CNS when the bladder is full. The motor fibres of pudendal nerve maintain EUS tonic contraction by default so that you’re not always peeing.
  • The reflex arc, after higher centre commands, causes voluntary micturition by inhibiting the “contraction-effect” of motor fibres of pudendal nerve.
  •  To oversimplify matter (so that it’s easy to understand and remember): Level 2 control inhibits reflex arc. Level 3 control facilitates reflex arc, causing micturition at will, once the bladder is full.


-- Aka Incomplete Spastic OR Uninhibited bladder.

Postcentral cortex
         --  Loss of awareness of bladder fullness
         --  Incontinence
Precentral cortex
         --  Hesitancy = Difficulty in initiating micturition
Frontal cortex
         --  Precipitancy = micturition with ‘easy’ stimulus, eg: sound of running water
         -- Inappropriate micturition/ loss of social inhibition (infant-like)

Associated with:
Multiple Sclerosis
Parkinson’s disease
Stroke, among others.

-- UMNL/ Complete spastic type of bladder.

Spinal cord ABOVE S2, S3 and S4.

        --  Urge incontinence = patient passes low-volume urine frequently
        --  Less post-voidal urine volume, so less risk of UTIs
        --   More intra-vesical pressure, more risk reflux nephropathy

-- LMNL/ Flaccid type of bladder.

        --  Spinal cord AT S2, S3, S4
        --  Cauda equina/ Conus medullaris
        --   Peripheral nerves

        --  Overflow incontinence =  urine retention, overtime, forces IUS to mechanically open causing dribbling micturition
        --  More post-voidal urine volume, more risk UTIs

2 subtypes are:
  • Motor Paralytic bladder – Motor (efferent) pathway is damaged. However, patient can sense bladder fullness, resulting in prompt diagnosis. Associated with:
--  Complication of abdominal/ pelvic surgery
--  Lumbar canal stenosis
--  Lumbo-sacral meningo-myelocele
  • Sensory Paralytic bladder – Sensory (afferent) pathway is damaged and hence, patient canNOT sense bladder fullness, resulting in delayed diagnosis. Associated with:
--  Diabetes mellitus
--  Syringomyelia
--  Tabes dorsalis

Medicine pearlWhen we talk about bladder pathology, we only refer to PANS (lesions above/ at/ below it) as SANS lesions doNOT cause bladder pathology per se. However, bilateral lesion to L1 causes retrograde ejaculation and hence, infertility.

Topics for further reading:
--  Age-related urine continence
--  Nocturnal enuresis
--  Barrington reflexes

Hope this helps! Let me know if anything needs clarification. Happy studying!
-- Ashish Singh.

Tuesday, October 3, 2017

Fact of the day : Easier approach shot to the pouch of Douglas

Hey Awesomites

The posterior fornix of the vagina is separated from the peritoneal cavity by a single layer of peritoneum and the posterior vaginal wall. Therefore, vaginal approach from its posterior aspect for evacuation of pus in the pouch of Douglas can be done without much difficulty.

On the other hand, approach to uterovesical pouch ( anterior relation ) is much more difficult from the vaginal route and consists of a series of steps :
- Incise the vagina
- separate bladder from cervix
- Traverse the vesicocervical space ( till the uterovesical fold of peritoneum is reached )

This difference is due to the normal physiological position of the uterus that is anteverted and anteflexed; the direction of external os being downwards and backwards.

That's all
- Jaskunwar Singh

Thursday, August 3, 2017

Causes of hematuria mnemonic

Hey Awesomites

Some common Glomerular causes of Hematuria:
( mnemonic: GH )
- Glomerulonephritis ( post infectious, membranoproliferative, rapid progressive, IgA nephropathy )
- Henoch- Schonlein nephritis

Non - glomerular causes of hematuria :
( mnemonic : HEMATURIa )
- Hemorrhage ( cystitis, PCKD )
- Allergic reaction ( interstitial nephritis )
- Trauma or Tumors
- Urinary tract infections / increased Urinary calcium 

Thats all
- Jaskunwar Singh 

Renal colic : Important points

Hey Awesomites

Some important points to be noted regarding renal colic:

Saturday, June 24, 2017

Mnemonico diagnostico: Opacities that may be confused with renal calculus

Hey Awesomites

Mnemonic for opacities on a plain abdominal radiograph that may be confused with renal calculus:

Tubercular calcified lesions in the kidney
Ossified tip of 12th rib
Phleboliths (calcifications in the wall of pelvic veins)

Gall stones
Appendicular/ Adrenal gland concretions
Mesenteric lymph node calcifications
External (foreign) bodies in alimentary canal (ex., cyclopenthiazide)

Thats all
- Jaskunwar Singh

Thursday, June 22, 2017

Immunotherapy for Prostate cancer

Hey Awesomites

Immunotherapy is now an emerging and much promising intervention in the treatment of prostate cancer, apart from the traditional cancer treatments - chemotherapy, radiation and surgery.

Friday, May 5, 2017

Uric acid and struvite stones mnemonic

Well, urine is largely water which *can* be considered as transparent. That's why, uric acid stones don't show up on X-rays.

Struvite or triple phosphate stones have Proteus has the causative factor. Remember p for p

That's all!

-Sushrut Dongargaonkar

Thursday, May 4, 2017

Effects of cholinergics and anticholinergics on the bladder mnemonic

In this video I talk about:

Cholinergics, bethanechol, diabetes mellitus, denervation and overflow incontinence.

Anticholinergics, oxybutynin, urge incontinence.

And mnemonics. Enjoy!

Thursday, January 26, 2017

Potter syndrome mnemonic

Hey wait its not the Harry potter syndrome or sequence ;p
The term was first coined by Edith Louis Potter but it's a misnomer and more of a Potter sequence or the Oligohydramnios sequence. So here's the mnemonic of some of the clinical features: POTTER

P- Pulmonary hypoplasia
O- Oligohydramnios
T- Twisted face (Potter facies)
T- Twisted skin (wrinkly skin)
E- Extremity (limb) defects
R- Renal agenesis (bilateral)

That's all
- Jaskunwar Singh

Friday, November 18, 2016

Causes of priapism

Hello lovely medical students!

Priapism is persistent, painful erection that develops without sexual simulation.

Here are a few causes of priapism:

(Mnemonic: PRazosin causes PRiapism)

(Mnemonic: Trazodone causes a boner - TrazoBone)

Perineal or genital trauma

Neurogenic lesions

Sickle cell disease and leukemia

Always check medications first, since it is often drug induced.

That's all!

Tuesday, September 27, 2016

Sunday, August 28, 2016

Phimosis and paraphimosis mnemonic

What is phimosis and paraphimosis?

Phimosis is constriction of the preputial orifice. In phimosis, the foreskin can not be retracted.

In paraphimosis, the foreskin can not be reduced back on the glans. It may cause a painful glans swelling going on to proceed to a gangrene. 

I always mix up the two, so mnemonic!

Another mnemonic - Call Paramedics if paraphimosis because it's a surgical emergency. 

This one was submitted by SG on our study group, "PAra is PAinful." 

That's all!

Friday, July 29, 2016

Step 2 CK: Types of incontinence mnemonic

Here's a short post on types of incontinence. It is important to know for step 2 CK as well as step 2 CS!

Monday, June 6, 2016

Step 2 CK: Anterior and posterior urethral injuries and mnemonic


I was studying about urethral injuries today for my Step 2 CK exam and these are my notes :)
I put them in a question and answer format. Hope it helps! 

What are the pats of the male urethra?
The male urethra is anatomically subdivided into anterior and posterior segments at the level of the urogenital diaphragm.

Posterior urethra:
Prostatic urethra
Membranous urethra

Anterior urethra:
Bulbous urethra
Penile urethra

Mnemonic: PM BP

Parts of male urethra mnemonic