Page 181 - Registrar Orientation Manual 2016

Reference:
Effective date:
2015
Expiry date:
2018
Page:
7 of 28
Title: Laboratory Testing Guidelines (DRAFT)
Type:
Clinical Guideline
Version:
01
Authorising initials:
Thrombophilia testing (the costs of a typical screen are over $200, LAC alone is $97)
The Choosing Wisely recommendations include the following:
Don’t test for thrombophilia in adult patients with venous thromboembolism (VTE) occurring in the setting of major transient risk factors (surgery, trauma or prolonged immobility).
Don’t do an inherited thrombophilia evaluation for women with histories of pregnancy loss, intrauterine growth restriction (IUGR), preeclampsia and abruption. (Specific testing for antiphospholipid antibodies, when clinically indicated, should be limited to lupus anticoagulant, anticardiolipin antibodies and beta 2 glycoprotein antibodies).
The DHB Shared Services Laboratory Test Referral Guidelines have: Testing is indicated in the following situations:
 Idiopathic VTE in young patients (<45 years)
 Warfarin-induced skin necrosis
 Children presenting with purpura
 Siblings of patients with homozygous FVL, homozygous PT20210A or compound
heterozygotes for these mutations
 Thrombosis in unusual sites (e.g. cerebral, mesenteric, portal).
In all other situations testing should only be undertaken after consultation with a Haematologist or as part of a clinical trial.
Testing is not indicated in the following:
 Recurrent VTE
 Recurrent VTE despite adequate therapeutic anticoagulation
 VTE in the context of a family history of unprovoked VTE in a first degree relative
 VTE in association with a history of thrombophlebitis
 Arterial thrombosis (Lupus testing is indicated in this setting)
 Women with a history of miscarriage, pre-eclampsia, abruption or intrauterine growth
restriction (Lupus testing is indicated in this setting).
The genetic thrombophilia tests will only be performed once in a patient’ life time.
Biochemistry Blood gases ($17)
Blood gases are the third most costly blood test done in Waikato costing over $700,000 a year.
We recommend:
Do not do bood gases “to get a quick set of electrolytes”.
Do not do arterial gases if venous gases will give the answer.
Blood gas analysis is time-consuming and relatively (to creatinine/electrolytes) more expensive taking laboratory staff away from other duties and so affects timeliness of other work.
In most cases (including suspected metabolic conditions like DKA, lactic acidosis or bowel ischaemia) a venous blood gas (VGB) guides management as well as an arterial blood gas.
Arterial blood gas (ABG) should only be done in selected patients with severe respiratory illness if the result of the arterial pC02 or A-a gradient will aid decision making, and in intubated patients. Taking an arterial specimen is much more painful, so don’t do an ABG if a VBG will suffice.