1. health and fitness
2. therapy

Women, Children’s and Sexual Health Division
Maternity Services
Guideline: Venous Thromboembolism in Pregnancy
1.
Introduction
18 deaths occurred due to Venous Thromboembolism in pregnancy and postpartum, reported in the
CMACE report 2006-2008, which represent a significant fall, and is the lowest rate since reporting
commenced. For many years it has been suggested that many of these deaths are preventable, there is
now evidence to support this. Risk assessment in early pregnancy is a key factor in reducing mortality
(CMACE 2011).
Adopt a low index of suspicion and if necessary treat on clinical grounds while
awaiting definitive test results
If pulmonary embolism is suspected refer to Guideline No 333 available on the Trust
Intranet:

Guideline for the assessment of women presenting with possible pulmonary
embolism during pregnancy and the puerperium.
These women should be referred to the Emergency Department or Emergency
Assessment Unit for further assessment
This guideline includes sections on:
 Risk assessment and Antenatal Thromboprophylaxis
 The diagnosis and management of Acute Venous Thromboembolism
 Anticoagulant therapy during labour and delivery
 Postnatal Thromboprophylaxis
All women should undergo an assessment of risk factors for venous thromboembolism (VTE) in early
pregnancy.
All woman admitted to hospital should have an electronic risk assessment undertaken, following the ‘VTE
link’ on the computer desktops.
Regardless of their risk of VTE, immobilisation of women during pregnancy, labour and the puerperium
should be minimised and dehydration should be avoided.
2.
Risk Assessment at Booking
Midwives at the antenatal booking visit will record the woman’s past medical history. Any past or present
VTE risk factor, or on-going anticoagulant therapy should prompt referral for consultant care. For further
information see appendix One.
2.1
Risk Assessment for women admitted to hospital during pregnancy
Women who are admitted to hospital in pregnancy should be assessed using the electronic VTE risk
assessment tool. Please refer to Appendix one to determine the required management pathway.
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
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Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
3.
Thromboprophylaxis
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3.1
3.2
Prophylactic Doses of LMWH (Antenatal and Postnatal)
4.1
Early pregnancy weight
Enoxaparin (Clexane®)
Weight <50 kg
20 mg daily
Weight 50-90 kg
40 mg daily
Weight 91 to 130 kg
60 mg daily
Weight 131 to 170 kg
80 mg daily
Weight > 170 kg
0.6mg / kg / day
Very high risk Previous VTE (+/-)
thrombophilia on long term warfarin
Seek support and advise form
Consultant Haematologist.
Monitoring
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4.
Low molecular weight heparins (LMWHs) are the agents of choice for antenatal
thromboprophylaxis.
Prophylaxis should be commenced as early in pregnancy as practical and appropriate.
Postpartum prophylaxis should begin as soon as possible after delivery (taking precaution
following regional anaesthesia).
Expert haematological advice should be sought in cases when the obstetric team are uncertain
about thromboprophylaxis.
A clear plan of peri-partum management and postnatal management should be documented in
the woman’s handheld healthcare records
Pre-treatment clotting screen and full blood count
Repeat platelet count five to seven days after commencing treatment
Thereafter therapeutic monitoring is at the discretion of clinician
Diagnosis of V.T.E.
Deep vein thrombosis (DVT)
Clinical features
 Painful swollen leg (left commoner than right)
Investigations
 Doppler ultrasound scan
NB D-Dimer is NOT helpful in pregnancy
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
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Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
4.2
Pulmonary Embolism
Adopt a low index of suspicion and if necessary treat on clinical grounds while awaiting
definitive test results
If Pulmonary Embolism is suspected Refer to Trust Guideline for the assessment of
women presenting with possible pulmonary embolism during pregnancy and the
puerperium, Guideline No 333 available on the Trust Intranet.
These women should be referred to the Emergency Department/ Emergency
Assessment Unit for further assessment
4.3.
Cerebral Vein Thrombosis
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5.
There were two deaths from this reported in CMACE 2011.
The risk factors appear to be the same as for Pulmonary Thrombosis,
Women may present with a headache or neurological symptoms, and should be reviewed by
a senior obstetrician.
Treatment of VTE in pregnancy
Treatment is with low molecular weight heparin (LMWH); Enoxaparin.
Dose of Enoxaparin is based on the early pregnancy weight
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6.
Early pregnancy weight
Initial Dose of Enoxaparin
<50 kg
40 mg twice daily
50-69 kg
70-89 kg
>90 kg
60 mg twice daily
80 mg twice daily
100 mg twice daily
Check the platelet count* at the onset of treatment and repeat five to seven days later (Risk of
Heparin induced Thrombocytopaenia).
Ensure follow up appointment made for consultant antenatal clinic.
Record in the woman’s handheld healthcare records in antenatal section.
Therapeutic anticoagulation should usually be continued for at least six months.
If VTE occurs later in pregnancy then anticoagulation should still continue for six months.
If VTE occurs early in pregnancy and provided there are no additional risk factors, after six
months the dose of LMWH should be reduced to prophylactic levels.
Following delivery, prophylaxis should continue for 6 weeks
Heparin Induced Thrombocytopaenia*
Pregnant women who develop heparin-induced thrombocytopenia and require continuing
anticoagulant therapy should be referred to a haematologist for on-going management.
7.
Anticoagulant Therapy during Labour and Delivery
Advise the woman to stop any further LMWH injection once she thinks that she is in labour.
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
Page 3 of 8
Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
7.1
On admission;
 Obstetric review as soon as possible
 Complete electronic VTE risk assessment (Obstetrician to sign)
 Anticoagulant therapy should be prescribed with an on-going plan
 Ensure good hydration
 Encourage mobilisation
 Apply anti-embolism stockings
7.2
Induction of Labour
Any woman on thromboprophylaxis should stop the LMWH on the day before.
Any woman on therapeutic doses should have a clear plan agreed by consultant obstetrician and
haematologist.
7.3
Elective caesarean section
 Administer a thromboprophylactic dose of LMWH on the day prior to the caesarean.
 Omit LMWH on the day of delivery and aim to perform the operation that morning.
 Administer the thromboprophylactic dose of LMWH three hours post-operatively but over four
hours after removal of the epidural catheter, if applicable and continue daily.
 Restart the therapeutic dose in accordance with plan (see 7.1 above).
NB:-In women receiving therapeutic doses of LMWH, wound drains should be considered at
caesarean section and the skin incision should be closed with staples or interrupted sutures to allow
drainage of any haematoma. Pay meticulous attention to achieving haemostasis prior to closure.
7.4
Epidural analgesia/anaesthesia
 Must be discussed with a senior anaesthetist
 To minimise or avoid the risk of epidural haematoma, regional techniques should not be used
until at least
 12 hours after the previous prophylactic dose of LMWH and
 24 hours after the previous therapeutic dose of LMWH.
 The epidural catheter should not be removed within 12 hours of the most recent injection
 LMWH should not be given until at least four hours have elapsed after the epidural catheter has
been removed
7.5
Emergency Surgical procedures
 Urgent clotting screen
 Discuss case with duty Consultant Haematologist regarding need for reversal of anticoagulation
(protamine sulphate).
7.6
Women at high risk of haemorrhage
 Care of women who are considered at high risk of haemorrhage, and in whom continued
heparin treatment is essential, should be discussed with the duty consultant haematologist.
 They require intravenous unfractionated heparin which has a shorter half-life, and its activity is
completely reversible with protamine sulphate.
 Close monitoring of APTT is required until the risk factors for haemorrhage have resolved.
8
Postnatal management of established VTE
 Further guidance: see Appendix Two
 Anticoagulant therapy should be continued for six weeks postpartum, and until at least six
months of therapy has been completed in total. This depends on whether the VTE occurred
early or late in pregnancy, and the presence of underlying thrombophilia and/or other risk
factors.
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
Page 4 of 8
Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
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9.
Discuss with consultant haematologist if any doubt.
Women may be offered the choice of either continuing subcutaneous LMWH or commencing
oral Warfarin; breast feeding can occur with either therapy.
If the woman chooses to commence warfarin postpartum, this can usually be initiated on the
second or third postnatal day. See Appendix Three.
Usually aim for INR of  2.5 before stopping LMWH
References
Centre for Maternal and Child Enquiries (CMACE) 2011 Saving Mothers Lives: reviewing maternal deaths
to make motherhood safer 2006-2008. Wiley & Blackwell
Royal College of Obstetricians and Gynaecologists. Thromboembolic Disease in Pregnancy and the
Puerperium: Acute Management Guideline No 28 RCOG Press 2001
Royal College of Obstetricians and Gynaecologists. Thromboprophylaxis during pregnancy, labour and
after vaginal delivery; Guideline No 37 RCOG Press 2004
Nelson–Piercy C. Handbook of Obstetric Medicine; Martin Dunitz. Second edition 2002
…………………………………………
Dymphna Sexton-Bradshaw
Associate Director of Women,
Children's and Sexual Health Division
/ Head of Midwifery
………..……………………….
Aban Kadva
Consultant Obstetrician
Lead Delivery Suite
…………………………………………
Marion Wood
Consultant Haematologist
……………………………………
Anne Regan
Lead Pharmacist
Version
Author (s)
Date
Circulation
One
Lata Kamble
1998
Clinical Practices
Sub-Group
2005
Clinical Practices
Sub-Group,
Clinical Practices
Sub-Group,
Obstetric Registrar
Marion Wood
Comments
Consultant Haematologist
Two
Joanne Osborne
Consultant Obstetrician/Gynaecologist.
Three
Aban Kadva
2009
Consultant Obstetrician/Gynaecologist
Four
Sally Price
Consultant Obstetrician / Gynaecologist
Julie Hinchcliffe
2012
All Consultant Obstetrician
Supervisors of Midwives
Reviewed and
revised
Reviewed and
revised
Reviewed and
revised
Senior Midwife Risk Management
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
Page 5 of 8
Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
Appendix One
Antenatal assessment and management (to be assessed at booking and repeated if admitted)
Obstetric thromboprophylaxis risk assessment and management
Single previous VTE+
o Thrombophilia or family history
o Unprovoked/estrogen-related
Previous recurrent VTE (>1)
Single previous VTE with no family
history or thrombophilia
Thrombophilia + no VTE
MEDICAL COMORBITIES, e.g.
Heart or Lung Disease, SLE, Cancer,
Inflammatory Conditions, Nephrotic
Syndrome, Sickle Cell Disease,
Intravenous drug user
Surgical procedure, e.g.
Appendectomy
Age > 35 years
Obesity (BMI >30kg/m2)
Parity >3
Smoker
Gross varicose veins
Current systemic infection
Immobility, e.g. paraplegia, SPD, longdistance travel
Pre-eclampsia
Dehydration/hyperemesis/OHSS
Multiple pregnancy or ART
High Risk
Requires antenatal prophylaxis with LMWH
Discuss with Consultant Haematologist
Intermediate Risk
Consider antenatal prophylaxis with LMWH
Discuss with Consultant Haematologist
3 or more risk factors
2 or more if admitted
< 3 risk factors
Lower Risk
Mobilisation and avoidance of dehydration
Antenatal and postnatal prophylactic dose of LMWH
Weight < 50 kg = 20 mg enoxaparin/2500 units dalteparin/3500 units tinzaparin daily
Weight 50–90 kg = 40 mg enoxaparin/5000 units dalteparin/4500 units tinzaparin daily
Weight 91–130 kg = 60 mg enoxaparin/7500 units dalteparin/7000 units tinzaparin daily
Weight 131–170 kg = 80 mg enoxaparin/10000 units dalteparin/9000 units tinzaparin daily
Weight > 170 kg = 0.6 mg/kg/day enoxaparin; 75 units/kg/day dalteparin/75 units/kg/day tinzaparin
Key
ART = assisted reproductive therapy, BMI = body mass index (based on booking weight), gross varicose veins =
symptomatic,above the knee or associated with phlebitis/oedema/skin changes, immobility = ≥ 3 days, LMWH = low-molecularweight heparin, OHSS = ovarian hyperstimulation syndrome, PPH = postpartum haemorrhage, SLE = systemic lupus
erythematosus,SPD = symphysis pubis dysfunction with reduced mobility, thrombophilia = inherited or acquired, long-distance
travel = > 4 hours, VTE = venous thromboembolism
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
Page 6 of 8
Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
Appendix Two
Postnatal assessment and management (to be assessed on delivery suite)
Obstetric thromboprophylaxis risk assessment and management
Any previous VTE+
Anyone requiring antenatal LMWH
Caesarean section in labour
Asymptomatic thrombophilia
(Inherited or acquired)
BMI > 40 kg/m2
Prolonged hospital admission
MEDICAL COMORBIDITIES, e.g.
Heart or Lung disease, LSE, Cancer,
Inflammatory Conditions, Nephrotic
Syndrome, Sickle Cell Ddisease,
Intravenous drug user
Age > 35 years
Obesity (BMI >30kg/m2)
Parity >3
Smoker
Elective caesarean section
Any surgical procedure in the
puerperium
Gross varicose veins
Current systemic infection
Immobility, e.g. paraplegia, SPD, longdistance travel
Pre-eclampsia
Mid-cavity rotational operative delivery
Prolonged labour (>24 hours)
PPH > 1 litre or blood transfusion
High Risk
At least 6 weeks postnatal prophylactic LMWH
Intermediate Risk
At least 7 days postnatal prophylactic LMWH
Note: If persisting or > 3 risk factors, consider
extending thromboprophylaxis with LMWH
2 or more risk factors
< 2 risk factors
Key
ART = assisted reproductive therapy, BMI = body mass index (based on booking weight), gross varicose veins = symptomatic,
above the knee or associated with phlebitis/oedema/skin changes, immobility = ≥ 3 days, LMWH = low-molecular-weight
heparin, OHSS = ovarian hyperstimulation syndrome, PPH = postpartum haemorrhage, SLE = systemic lupus erythematosus,
SPD = symphysis pubis dysfunction with reduced mobility, thrombophilia = inherited or acquired, long-distance travel = > 4
hours, VTE = venous thromboembolism
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
Page 7 of 8
Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J
Appendix Three
How to introduce warfarin
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Check baseline INR
Usually start Warfarin on 2nd postnatal day. However in order to avoid the need for weekend testing of
INR in the community, Warfarin should ideally be commenced on Mondays, Thursdays or Fridays.
Administer warfarin at 18.00 at a dose of 5mg daily for four days (liaise with haematologists if Baseline
INR >1.3 because dose will need to be reduced)
Check INR on day 5 and day 8 and adjust dose according to the patient group direction on
anticoagulation, which is available on the intranet (See link below).
Pharmacy will supply anticoagulation booklet for patient
INR on day 5 of
warfarin therapy
Warfarin doses
for days 5 to 7
INR on day 8 of
warfarin therapy
≤ 1.7
5mg
1.8 – 2.2
4mg
2.3 – 2.7
3mg
2.8 – 3.2
2mg
3.3 – 3.7
1mg
≥ 3.8
OMIT
≤ 1.7
1.8 – 2.4
2.5 – 3.0
≥ 3.1
≤ 1.7
1.8 – 2.4
2.5 – 3.0
3.1 – 3.5
≥ 3.6
≤ 1.7
1.8 – 2.4
2.5 – 3.0
3.1 – 3.5
≥ 3.6
≤ 1.7
1.8 – 2.4
2.5 – 3.0
3.1 – 3.5
≥ 3.6
≤ 1.7
1.8 – 2.4
2.5 – 3.0
3.1 – 3.5
≥ 3.6
≤ 1.9
2.0 – 2.9
3.0 – 3.5
Warfarin dose
from day 8
onwards
6mg
5mg
4mg
3mg for 4 days
5mg
4mg
3.5mg
3mg for 4 days
2.5mg for 4 days
4mg
3.5mg
3mg
2.5mg for 4 days
2mg for 4 days
3mg
2.5mg
2mg
1.5mg for 4 days
1mg for 4 days
2mg
1.5mg
1mg
0.5mg for 4 days
OMIT for 4 days
1.5mg for 4 days
1mg for 4 days
0.5mg for 4 days
See Trust PGD Administration of Warfarin for further information:
6.2 PGDfor the
Administration of War
Date of Original document; May 1998
Date Amended: August 2012 Version Four
Review date; August 2015
Page 8 of 8
Venous Thromboembolism in Pregnancy
Guideline No: 2.12 J