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Pee Values

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Author: Craig Davidson, Tim Wright / Codes: C3AP1b, CMP3, HMP3 / Published: 27/10/2015

Routine urinalysis in patients with a blunt abdominal trauma mechanism is not valuable to detect urogenital injury
Dominique C Olthof, Pieter Joosse, Cornelis H van der Vlies, Theo M de Reijke, J Carel Goslings.
Emerg Med J doi:10.1136/emermed-2013-202651

Description

This was a retrospective observational cohort study conducted by a group of Dutch trauma specialists in the Netherlands between 2008-2011.

Summary

1815 consecutive adult (>16yrs) trauma patients who passed through the ED. Data was retrieved from a local trauma registry. The study looked at whether patients had urinalysis and/or imaging performed. Imaging included: FAST, AUSS, or CT. Investigation results were correlated with clinical consequences.
Clinical consequences were defined as
-additional imaging
-intervention eg embolisation, catheterisation, laparotomy
-patient admitted for a period of observation
-patient scheduled for follow-up as outpatient.

Results

75% of patients had urinalysis performed. The remaining patients had no urinalysis but may have had imaging.
In all the patients who had urinalysis, approximately 80% had no haematuria. 20% had microscopic haematuria. Approximately 1 % had macroscopic haematuria
8% of all patients in the study had a urogenital injury diagnosed.

Patients were divided into 4 groups depending on whether they had urinalysis and or imaging performed.

Group A: Urinalysis and imaging performed. (1032 patients):

Urogenital injury in this group was 5%

20% (220 patients) had microscopic haematuria.
– 5% (11 patients) of patients with microscopic haematuria had clinical consequences.-
– However 9 of these 11 clinical consequences were further scans or follow-up.-
– 1 of the other 2 patients had massive abdominal injuries and therefore the dipstix test was unlikely to be the decision maker.
– Only 0.5% of patients (n=1) with microscopic haematuria had an intervention.

2% (16 patients) had macroscopic haematuria.
– 69% (11 patients) had clinical consequences.
– 2/11 were interventional procedures for abnormalities picked up on imaging. The rest was observation, more scans and follow-up.

Patients with a negative urine dip (77%) had no clinical consequences.

Group B Urinalysis performed. No Imaging. (332 patients):
16% had micro haematuria. No clinical consequences.

Group C Imaging but no urinalysis. (268 patients):
1% (4 patients) of this group had urogenital injury and all had an interventional procedure. All interventions were variations on catheterisation.

Group D consisted of patients who had neither urinalysis nor imaging. (184)
As such no injuries were detected and no clinical consequences arose..

Headline Results

Group A (1031, 57%) had both imaging and urinalysis
Findings of microscopic haematuria was associated with clinical consequences in only 5% of patients. 1% of patients required an intervention.

Findings of macroscopic haematuria was associated with clinical consequences in 69% of patients – whether a procedure , observation, further imaging or follow-up. The number of interventions was low (2) and in fact most people either had further imaging or were admitted for observation.

Group B (332, 18%) urinalysis, no imaging.
Findings of microscopic haematuria wasnt associated with clinical consequences in any patients.

Limitations

Validity:
Retrospective study
No gold standard limits analysis obviously it isnt ethical to CT scan every patient.
Whether the scan was done because of the urine results or for another reason. The authors say that only imaging performed to diagnose urogenital injury were analysed, which would imply it was because of the dip. However, they included FAST scans..
What type of scan- not surprising had a normal fast.
If a patient had an intervention and was then admitted for observation was that counted twice?
Follow up period- how long were they followed up for.

Generalisability:
No issues noted
Similar population to UK
Similar type of trauma
Similar access to CT

So what now?

Urinalysis does not carry much weight over and above the rest of your clinical assessment in the decision to scan or not to scan.

Could it add unnecessary investigation and follow-up?

A study mentioned in the introduction suggests that abdominal tenderness and haematuria had a sensitivity of 64% for intra-abdominal injury. This isnt very impressive as a screening test, and the study was in 1998 prior to the widespread use of early trauma CT.

In both studies the absence of haematuria does appear to be re-assuring. But we cannot infer that a negative dip would be the deciding factor in the decision to image.

The paper suggests potential subgroups in whom urinalysis may be useful, (eg fall from height, fall from horse, direct blow to the flank) however in practice we think these groups will have a higher chance of being scanned, and we question whether urinalysis would be the deciding factor in this decision.

Finally – patients with microscopic haematuria should be followed up by the GP for repeat testing, in case there is a medical cause for the haematuria.

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