Risk Assessment

NICE clinical guideline 92 offers simple care pathways to direct risk assessment and prophylaxis decision making [27]. On admission to hospital, all patients should be assessed to identify those who are at increased risk of VTE. Assessing the risk of VTE is the first step in the pathway, fulfilling the audit requirements within the NHS, and acting as the trigger to consider the need for preventative measures. In addition, all patients should be assessed for risk of bleeding, which will influence whether pharmacological VTE prophylaxis is offered.

VTE risk in medical patients

Medical patients with recent reduced mobility are regarded as being at increased risk of VTE if they have had or are expected to have significantly reduced mobility for 3 days or more or are expected to have ongoing reduced mobility relative to their normal state with one or more risk factors shown in the table below.

VTE risk in surgical patients

Surgical patients and patients with trauma are regarded as being at increased risk of VTE if they meet one of the following criteria:

  • Surgical procedure with a total anaesthetic and surgical time of more than 90 minutes, or 60 minutes if the surgery involves the pelvis or lower limb
  • Acute surgical admission with inflammatory or intra-abdominal condition
  • Expected significant reduction in mobility
  • One or more risk factors shown in the table below
Risk factors for VTE
Active cancer or cancer treatment
Age over 60 years
Critical care admission
Dehydration
Known thrombophilias
Obesity (body-mass index [BMI] over 30 kg/m2)
One or more significant medical comorbidities (e.g. heart disease; metabolic, endocrine or respiratory pathologies; acute infectious diseases; or inflammatory conditions)
Personal history or first-degree relative with a history of VTE
Use of hormone replacement therapy
Use of oestrogen-containing contraceptive therapy
Varicose veins with phlebitis

VTE risk in pregnancy and up to 6 weeks post-partum

NICE highlights the risk of VTE in pregnancy and the post-partum period and recommends considering thromboprophylaxis to women who are pregnant or have given birth within the previous 6 weeks who are admitted to hospital but are not undergoing surgery and who have one or more of the risk factors shown in the table below [27].

Risk factors in pregnancy and post partum
Expected to have significantly reduced mobility for 3 or more days
Active cancer or cancer treatment
Age over 35 years
Critical care admission
Dehydration
Excess blood loss or blood transfusion
Known thrombophilias
Obesity (pre-pregnancy or early pregnancy BMI over 30 kg/m2)
One or more significant medical comorbidities (for example: heart disease; metabolic, endocrine or respiratory pathologies; acute infectious diseases; inflammatory conditions)
Personal history or a first-degree relative with a history of VTE
Pregnancy-related risk factor (such as ovarian hyperstimulation, hyperemesis gravidarum, multiple pregnancy or pre-eclampsia)
Varicose veins with phlebitis.

Bleeding risk

All patients are assessed for risk of bleeding before pharmacological thromboprophylaxis is prescribed. NICE recommends that prescribers consult the summary of product characteristics of the drugs used for thromboprophylaxis [27]. Thromboprophylaxis should not be given to patients with any of the risk factors for bleeding shown in the table below, unless the risk of VTE outweighs the risk of bleeding.

Risk factors for bleeding
Active bleeding
Acquired bleeding disorders (e.g. acute liver failure)
Concurrent use of anticoagulants known to increase the risk of bleeding (e.g. warfarin with international normalised ratio higher than 2)
Lumbar puncture/epidural/spinal anaesthesia expected within the next 12 hours
Lumbar puncture/epidural/spinal anaesthesia within the previous 4 hours
Acute stroke
Thrombocytopenia (platelets less than 75 x109/L)
Uncontrolled systolic hypertension (230/120 mm Hg or higher)
Untreated inherited bleeding disorders (such as haemophilia and von Willebrand’s disease)