Urology - Haematuria Flashcards
What is gross or macroscopic haematuria?
Gross or macroscopic or visible haematuria is visible discolouration of the urine due to the presence of blood.
What are common causes of macroscopic haematuria and what conditions would you want to rule out urgently?
Urinary tract infection, urological cancer, (predominantly bladder cancer), BPH, and urolithiasis are common causes.
Urologic cancer and glomerular disease are the most serious conditions to rule out.
Are there any differences in the causes of macroscopic and microscopic haematuria?
The causes of macroscopic and microscopic haematuria are essentially the same. But the probabilities vary for each type of haematuria. For example, macroscopic haematuria is much more likely in malignancy cf. microscopic.
What is the aetiology of haematuria?
Haematuria can originate anywhere along the urinary tract. The easiest way to think about this is to move along the urinary system from the kidneys downwards. Localising the source of bleeding is key to determining the underlying aetiology.
Renal:
- Infections - pyelonephritis, TB
- Neoplasia - RCC, renal adenoma, renal cyst
- Renal infarction
- AV malformation
- Trauma
- Glomerulonephritis
Ureteral:
- TCC
- Stone
- Appendicitis
Bladder:
- TCC
- Stone
- Interstitial cystitis
- Pyogenic cystitis
- Trauma
Urethral:
- BPH
- Stone
- Prostate carcinoma
- Trauma
What group of patients are at high risk of urological malignancy?
Macroscopic haematuria is the presenting feature in >66% of patients with urological malignancy and about 30% of patients presenting with painless haematuria have malignancy. As such it is important to screen for patients at risk of urological malignancy (ranging from renal to bladder etc) who present with haematuria. Risk factors include:
- age over 35
- irritative voiding symptoms (dysuria)
- exposure to chemicals or dyes (benzenes or aromatic amines)
- tobacco smoking
- chronic UTI
- long term indwelling catheter
- chemotherapy
What gender differences exist in the oncological signficnace of gross haematuria?
This basically comes down to age. In men over 60 years, the positive predictive value of gross haematuria in pointing to underlying malignancy is 22.1%, for women of the same age it is 8.3%.
What drugs can cause haematuria?
Cyclophosphamide is an important drug to remember. It is used as chemotherapy for solid tumours and other lymphomas. It causes haemorrhagic cystitis and haematuria should begin within 48 hours of taking cyclophosphamide.
Other medications include - aminoglycosides, diuretics, oral contraceptives, warfarin and amitryptaline.
Is diptick haemglobin sufficient to diagnose gross haematuria?
No. Discoloured urine or positive urine dipstick is insufficient to diagnose gross haematuria. Identification of intact red blood cells by microscopic exam of urine or urinary sediment is required to rule out haematuria mimics. These include myoglobin, foods such as beetroot and drugs such as adriomycin and sulfonamides.
What is the approach to evaluating a patient with haematuria?
Evaluation and diagnostic workup is exactly the same for patients with microscopic and macroscopic haematuria. Guidelines come from the American Urological Association (AUA) .
Patients presenting with haematuria require a thorough history and physical examination followed by diagnostic workup.
What questions in the history can help to identify the cause or site of bleeding?
- ask about recent ingestion of food and drugs that can mimic haematuria
- ask about potential benign causes (e.g. vigorous physical or sexual activity; trauma such as catheterisation, blunt trauma; digital rectal prostate exam; menstruation (can be confused with vaginal bleeding!)
- ask about symptoms which may suggest underlying causes (e.g. fever; dysuria; urinary frequency or urgency; abdominal or flank pain)
- ask about ability to pass urine and presence and size of clots (urinary retention can happen)
- ask about LUTS (e.g. prior hx of dysuria, urinary frequency, urgency, or urethral discharge points towards infective or inflammatory cause; BPH can cause haematuria and obstructive urinary symptoms)
- ask about family history (specifically hereditary nephritis, PCKD, and Alports)
- ask about drug history
- ask about occupational exposure, smoking history and recent travel
Why is it important to ask when the blood appears in the urinary stream?
When blood appears in the stream can help to localise the site of bleeding.
For example, bleeding at the initiation of micturition only suggests urethral origin. But blood throughout the urinary stream indicates bleeding above the bladder outlet such as the upper tract and kidneys.
If bleeding happens at the end of urination suspect prostate and bladder neck origins.
What features in the history may indicate post streptococcal or impetigo causes of haematuria?
Streptococcal tonsilitis - haematuria occuring 7-15 days post infection may suggest poststreptococcal glomerulonephritis.
In impetigo this period after the initial illness is increased. Impetigo is still caused by streptocci, but haematuria is expected 4-6 weeks post infection rather than days.
What physical examinations are important in patients presenting with haematuria?
Measurement of blood pressure.
Look for peri-orbital oedema, puffiness and peripheral oedema.
Detail general inspection to check for purpura and rashes.
Abdominal examination to check for palpable kidneys.
Genital examination (males and females).
DRE in both men and women to check for prostate cancer and masses in the retrouterine pouch of Douglas respectively.
As well as macroscopic and microscopic, how else can haematuria be classified?
Because the causes of microscopic and macroscopic haematuria are the roughly the same, it is often more useful to think about haematuria in terms of glomerula vs non glomerular. Several features can help distinguish between these two:
- Glomerular haematuria: brown/ tea coloured urine (sometimes smoky), RBC casts and dysmorphic (small, deformed, mishapen and sometimes fragmented) RBCs and proteinuria
- Non glomerular haematuria: reddish or pink urine, passage of blood clots, and eumorphic (i.e. biconcave) RBCs
NB - glomerular haematuria is normally painless!
What investigations are required in a patient presenting with haematuria? Who is it important to do a urine calcium on?
1) Urinalysis with careful microscopic review of the urine:
- confirms haematuria based on peroxidase activity of Hb
- presence of haematuria is important to confirm by microscopy because both normal and abnormal causes (e.g. myoglobinuria) can cause false positive results
2) Phase contrast microscopy to confirm the cause of haemturia:
- significant number of dysmorphic RBCs suggest a renal (glomerular) source of haematuria
- eumorphic RBCs suggest an extraglomerular cause
3) Renal function (U&Es):
- elevated creatinine and urea suggest renal disease as a cause
4) FBC and clotting profile:
- generally, clotting and FBC do not give a huge amount of additional information but can confirm suspected bleeding diatheses if patients have a history
5) Urine calcium:
- hypercalciuria is a relatively common finding in children (30% with isolated haematuria) - measurement of urine calcium excretion using either timed 24 hour urine or calcium: creatinine ratio can be helpful in establishing hypercalciuria as a cause of haematuria
- calcium excretion of >4mg/kg/d or a urine calcium: creatinine of >0.21 are considered abnormal
6) Serology:
- measuring serum complement levels is important if glomerular causes of haematuria are suspected
- low serum complement is found in post infectious glomerulonephritis, SLE, bacterial endocarditis, and membranoproliferative glomerulonephritis
- high antistreptolysin (ASO) titre suggests recent streptococcal infection
- anti-DNAse B levels also indicate recent group B streptococcal infection and may be positive even when ASO titres are negative
- Anti-dsDNA and ANA in SLE
7) Urine culture if suspected UTI
