PV Conversion Route Map

29 February 2012

Based on customer experience the steps for converting from ESR to PV have been highlighted in the following table.

A sample letter for GPs is also provided in the Support Literature.






Review of clinical picture and patient data repeatedly
shows that PV provides a more consistent indicator of disease progression and demonstrates the clinical significance of very small  changes (0.05mPas)
Duplicate test data for ESR and PV shows there is no
conversion table between the two systems


Consultation to highlight changes

The simplification of the test profile by the potential
elimination of additional blood collection tubes (PV can use the  full blood count sample) 
Improvements due to plasma sample stability and viscosity
testing quality control 
Rheumatology/Speciality patient monitoring change to CRP
for acute phase  
Handling of clinical trial requirements

Issue notice period  for switch
to PV
Include summary evidence for the change 
Include table for results interpretation
Plan for a short switch over period 
Support clinicians and specialities Provide laboratory staff with training to answer questions from clinicians.   
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About PV

Benson Viscometers Ltd is a British company that manufactures, distributes and maintains a range of clinical viscometers, tuned to analyse blood plasma viscosity.

The range includes a fully automated walk away high volume analyser (BV200) capable of processing 60 samples per hour for large laboratories and a semi automated analyser (BV1) suitable for small laboratories performing up to 50 samples a day.

The company also supplies a full range of control and maintenance reagents to give operators confidence in their results.


BV1 Unit
For confidence in your results

An increasing number of laboratories are electing to use Plasma Viscosity routinely in preference to erythrocyte sedimentation testing (ESR). This is because Plasma Viscosity results are easier to imterpret and results can be fully validated.

What They Say

"Benson Viscometers is the UK leader for plasma viscosity testing systems and we have had a long relationship with Bernie Benson. The BV1 is superbly engineered and easy to use, with a modified PC cabinet and a small footprint. Customer support is second to none." Graham Gibbs MSc CSci FIBMS, Lead Biomedical Scientist, Haematology Dept., Musgrove Park Hospital.

Read More
BV200 Unit
Some PV Facts
  • Patient plasma viscosity (PV) is unaffected by patient anaemia or polycythaemia 
  • Samples can be analysed up to one week after centrifugation 
  • Test results are not affected by anti-inflammatory drugs 
  • Patient PV is not affected by age (>3 years), gender or smoking 
  • A rise of PV in the third trimester of pregnancy is predictable 
  • The only diagnostic test for plasma hyperviscosity