Guest Blog Post by Dr Stuart Winearls, ACCS trainee

Introduction

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)

Thankfully there is good clear NICE guidance (CG 54) with quick to access summaries which should be used in conjunction with NICE Febrile Children guidance.

Who to investigate?
How to get the sample
Disposal

2. Adults

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?

Diagnostic challenge of UTI in older patients
Why worry about UTI at all?
What to do?

Summary

  1. Children
    • 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
  2. Adults
    • Treat as per standard guidelines
  3. Pregnancy
    • Treat even asymptomatic bacteriuria
  4. Catheters
    • Only treat if clinically has an infection not asymptomatic colonisation
    • Never use urine dip
  5. 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

Bibliography

Tom Mitchell
Author: Tom Mitchell

Emergency Medicine Consultant UK