Dipstick test shows blood trace in the urine

Case Study: A new patient check reveals blood in the urine. Dr Harry Brown suggests a plan of action.

A 46-year-old man presented for a new patient check to the practice nurse. He had no significant medical history of note, was on no medication and is well. He is a non-smoker. On dipstick testing of his urine, a trace of blood was found. There was no history of gross haematuria or any other genitourinary problems.

The nurse sent off an MSU, which shows the presence of red blood cells (RBC). On a separate sample of urine, the GP confirmed the nurse's finding of microscopic haematuria, and on history and physical examination nothing else of note was found.

Diagnosis

The diagnosis is microscopic haematuria which has been defined as more than three RBC per high-powered field in the centrifuged urinary sediment, and as two or more RBC in a high-powered field on microscopic examination.

It is also suggested that a single episode of microscopic haematuria should be confirmed by repeat urine examination.

Asymptomatic microscopic haematuria detected by screening, as in this case, is common - between 2.5 per cent and 13 per cent of a healthy adult population.

Investigations

Ensure that the sample has not followed sexual activity, trauma to the genitourinary tract (such as recent surgery), exercise or, in the case of a woman, a period.

Assuming these have been eliminated and you have an isolated and asymptomatic but persistent microscopic haematuria, then you must decide what to do next.

First, take the BP, family history of renal or bladder disease, and examine the abdomen. If the patient is a man, check the testicles and perform a rectal examination (for size and consistency of the prostate). Measure renal function by checking U&Es.

Also enquire if the patient is on medication, especially on warfarin, even though those on warfarin who have haematuria should be investigated in same way as those not on warfarin.

An ultrasound scan of the urinary tract including the bladder and kidneys could be helpful, and if all is negative there is the option of referring to a urologist who may proceed to do a cystoscopy.

Cystoscopy

It has been suggested that routine cystoscopy should be performed in all individuals aged over 50 who have persistent microscopic haematuria. However, other experts say that microscopic haematuria in all over-40-year-olds should also be investigated this way.

A decision on its management should be based on a risk assessment of the patient and sharing with the patient that there are areas of uncertainty.

However, despite adequate investigation, no reason for the microscopic haematuria can be found in a number of patients.

Possible causes of microscopic haematuria include various renal diseases, inflammation in the genitourinary tract, stones, malignancies within the genitourinary tract, and prostatic disease.

The decision to investigate or refer to either a urologist or a nephrologist should be based on a number of factors, for example age - the older a person is, then the higher the chance of pathology.

Referral guidelines

Painless gross haematuria should be referred urgently under the two-week rule to exclude malignancy. Consider referring all patients with microscopic haematuria under the age of 40 to nephrology, especially if there is proteinuria or evidence of renal impairment or hypertension.

All patients above the age of 50 with unexplained microscopic haematuria should be referred to an urologist.

People who smoke or who have a family history of significant urinary tract disease such as malignancy should be referred.

Another relevant abnormality, such as proteinuria, may precipitate a referral.

If investigations are fruitless, a urine analysis should be performed and the BP should be checked every year for three years and two years thereafter.

The patient in this case decided to have his U&Es checked and had a renal ultrasound. All were normal and he elected not to have a cystoscopy. So far he has remained well, and he knows that if he has any urological symptoms or signs he should report them to his GP.

- Dr Brown is a GP in Leeds.

LESSONS LEARNT FROM THIS EPISODE

- New patient checks can provide important information about patient's health.

- Always investigate further for possible causes of microscopic haematuria such as renal disease.

- Asymptomatic microscopic haematuria is common.

- A single episode of microscopic haematuria should be confirmed by repeat urine examination.

- Always check the testicles and perform a rectal examination in men.

- Routine cytoscopy should be performed in all individuals aged over 50 who have persistent microscopic haematuria.

- Painless gross haematuria should be referred urgently.

RESOURCES

- http://renux.dmed.ed.ac.uk/EdREN/Unitbits/HaematGuide.html

- www.aafp.org/afp/20010315/1145.html

- www.attract.wales.nhs.uk/question_answers.cfm?question_id=824

- www.renal.org/eGFR/haematuria.html

REFERENCES

- Cohen R, Brown R. Microscopic haematuria. N Engl J Med 2003; 348(23): 2,330.

- Malmstrom P. Time to abandon testing for microscopic haematuria in adults? BMJ 2003; 326: 813-5.

- Del Mar C. Asymptomatic haematuria... in the doctor BMJ 2000; 320: 165-6.

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