Guest Blog Post by Dr Stuart Winearls, ACCS trainee
Being presented with a urine dip result is a very common clinical scenario in the emergency department. We are taught in medical school that the urine dip has a high sensitivity and specificity for urinary tract infection based on nitrites and leukocytes however this is based on otherwise healthy adults with clear symptomology aka not your average ED patient.
Interpreting a dip stick urinalysis result is hugely dependent on the patient group and the clinical context. The same result can mean different things in different patients.
This post is written to provide you with information to improve your approach urinalysis and urinary tract infection in the emergency department. We’ll cover the differences from the very young, to the very old and all those in-between.
1. Infants & Children
Can be challenging choosing who and how to investigate
This is a challenging group due to
- Non specific presentations
- Communication barriers
- Difficult to collect samples
- High frequency voiding and low residual volumes (leading to false negative urine dips)
Nice and simple, what we learnt at med school…?
- There is clear guidance on the intranet
- The presence of > 3 symptoms of UTI has a PPV of 90%. In this situation dipping the urine does not reduce the post-test probability enough to exclude UTI as a diagnosis. Therefore consider treating an adult for a UTI if you have a high clinical suspicion, even with a negative dip. Send the MC&S but the culture may not be done if the Microscopy is normal.
- Asymptomatic positive urinalysis and bacteriuria can occur in adults as well as older persons and generally doesn’t need treating.
3. Pregnant Women
Always dip the urine
- 25% of pregnant women have asymptomatic bacteria and of these 75% will go onto develop pyelonephritis
- In this group you should always perform urinalysis especially in the first trimester
- Treat all positive dips (and negative ones if you have a high suspicion)
4. Long term catheters
Never dip the urine
- All catheters become colonised therefore never dip a CSU.
- If the patient is febrile / septic and no other source is found then treat
- It will only get processed if you put the relevant clinical details on. Just asking nursing staff “to send a urine” is liable to result in a nurse, porter and lab worker all wasting their valuable time as these get thrown in the bin!
- If you think catheter is the source think – blood cultures, antibiotics then catheter change!
5. The elderly
Challenge what you think you know – UTI’s cause far less problems than you think! Confused?
- Be aware of how children of different ages may present and in which children to suspect UTI
- Beware of false negative urine dips choose – age appropriate investigations
- Treat in combination with NICE febrile child guidelines
- Treat as per standard guidelines
- Treat even asymptomatic bacteriuria
- Only treat if clinically has an infection not asymptomatic colonisation
- Never use urine dip
- Older Patients
- If capable of a clear history treat using normal adult guidelines
- If no history or your patient is confused, look for supporting evidence of infection; signs, symptoms, labs, before starting treatment pending culture
- Do not treat asymptomatic bacteriuria or urinalysis
- Always think of other causes of delirium before blaming UTI
- Interpreting asymptomatic bacteriuria – Testing for and treating bacteriuria in children and non-pregnant adults without specific symptoms of urinary tract infection or sepsis is of uncertain benefit M. Cormican, AW Murphy, A Vellinga BMJ 2011;343:d4780
- Can urine cultures and reagent test strips be used to diagnose urinary tract infection in elderly emergency department patients without focal urinary symptoms? J Ducharme, S Neilson, J L Ginn Can J Emerg Med 2007;9(2):87-92
- Urinary tract infection in children Diagnosis, treatment and long-term management NICE clinical guideline 54 August 2007
- Quality Care for Older people with Urgent & Emergency Care needs “Silver Book” The british Geriatric Society 2012
- Optimal management of urinary tract infections in older people L A Beveridge, P G Davey, G Phillips, M McMurdo Clinical Interventions in Aging 2011:6
- Investigation of urinary tract infection in older people S Ninan, C Walton, G Barlow,BMJ 2014 349;g4070
- Challenges in assessing nursing home residents with advanced dementia for suspected urinary tract infections. E D’Agata , MB Loeb, SL Mitchell; J Am Geriatr Soc. 2013 Jan;61(1):62-6. doi: 10.1111/jgs.12070