THROMBOPROPHYLAXIS IN PREGNANCY, LABOUR AND THE PUERPERIUM
Introduction
There is a 5 fold increase in thrombotic risk to women throughout pregnancy and a 25 fold increase in the puerperium. The incidence of venous thromboembolism (VTE) in pregnancy including the puerperium is 1 to 2 per 1000. With a previous pregnancy VTE the recurrence risk is 2 to 11%. As thrombosis and thromboembolism continue to be a leading cause of maternal mortality in the UK, it is essential that women who are at risk are identified and have appropriate, preventative measures put in place.
This document contains general guidance. Some women will require individual management e.g. women with artificial heart valves, antithrombin III deficiency or those on long term pre- pregnancy anticoagulation. Where possible, such women should have pre pregnancy counselling.
Complex cases will require discussion with a haematologist specialising in obstetrics.
ASSESSMENT OF RISK OF VENOUS THROMBO EMBOLISM (VTE)
- All women should undergo a documented assessment of risk factors for VTE in early pregnancy or prepregnancy
- Risk assessment should be repeated if the woman is admitted to hospital for any reason or develops intercurrent problems
- Generally, if admitted to hospital with an illness, it is appropriate to give thromboprophylaxis (during the admission).
Exclusions would include:
bleeding issues (e.g APH / placenta praevia)
labour, suspected labour or an imminent need for delivery
uncontrolled severe hypertension (i.e where there is a risk of an intracranial bleed)
- Risk assessment should be repeated immediately postpartum
Appendix 1 indicates risk factors and scoring system
Appendix 2 details management of women with previous VTE or known thrombophilia.
Management
- Women requiring thromboprophylaxis should be referred to an obstetrician.
- Women who are offered anticoagulation should be informed of the benefits and the possible complications of the medication.
- Where thromboprophylaxis is required, a plan of care for the antenatal, intrapartum and postnatal periods should be documented.
- Women who are on anticoagulation antenatally should be advised to suspend taking it if they have any vaginal bleeding or once labour starts. This advice should be documented in the woman’s own records. In such clinical situations the woman should be reviewed by medical staff and any further doses should be prescribed after discussion with senior medical staff.
THROMBOPROPHYLAXIS MEASURES
These include:
Anticoagulant drugs –
Low molecular weight heparin e.g. enoxaparin, tinzaparin, dalteparin
Unfractionated heparin e.g. sodium heparin
Warfarin
Graduated Elastic Compression Stockings
LOW MOLECULAR WEIGHT HEPARIN (LMWH)
- This is the usual anticoagulant drug used in pregnancy.
- Heparins do not cross the placenta so they do not anticoagulate the baby.
- A woman taking heparin can safely breastfeed her child.
- It has a longer half life (duration of action) and is less easily reversed by protamine sulphate than unfractionated heparin.
- It is given by subcutaneous injection
Monitoring of the amount of LMWH given is not routinely required. It is sometimes required in complex cases. This is done by measuring the anti Xa level in a blood sample taken 4 hours after a dose of heparin has been administered.
UNFRACTIONATED HEPARIN
This has a shorter half life and better reversibility with protamine sulphate than LMWH, so it is useful if there is a high chance that the anticoagulant will need rapid withdrawal, e.g. in relation to delivery or surgery.
When used it is necessary to monitor blood platelet levels every 2 days from 4 to 14 days after it is commenced
WARFARIN:
- is rarely used during pregnancy as it crosses the placenta and anticoagulates the fetus also.
- can cause miscarriage and fetal abnormalities.
- may be appropriate where the woman has a metal heart valve prosthesis.
- can be given to the woman in the postpartum period and is safe for the baby to breast feed.
CAUTIONS AND CONTRAINDICATIONS TO ANTI COAGULANTS INCLUDE:
- Active bleeding
- Increased risk of major haemorrhage, e.g. placenta praevia
- Haemophilia and other haemorrhagic disorders (e.g. platelets less than 75×109/l)
- Severe / uncontrolled hypertension
- Acute stroke in previous 4 weeks (haemorrhagic or ischaemic)
- Aneurysm
- Endocarditis
- Hepatic / renal failure (Use caution if any impairment. Consider dose reduction)
- Oesophageal varices
- Active peptic ulceration
- Hypersensitivity to heparin
Remember that a number of the above are features of pre-eclampsia.
Seek advice from an obstetric consultant and consider consulting the haematologist.
GRADUATED ELASTICATED COMPRESSION STOCKINGS (GECS)
GECS are recommended in pregnancy and the puerperium for:
- those with indications for VTE prophylaxis but who have contraindications to, or decline, anticoagulation
- combined with LMWH for those who are hospitalised and considered to be at particularly high risk of VTE (such as previous VTE, more than 4 risk factors antenatally or more than 2 risk factors postnatally)
- women travelling long distance for more than 4 hours
GECS with a calf pressure of 14-15 mmHg are recommended. Full lower limb length stockings are preferred but, if these are not being kept in place, then calf length stockings can be used.
See the Covidien guide “T.E.D.™ Anti-Embolism Stockings Nursing Procedure Guide”
CONTRAINDICATIONS TO GECS AND INTERMITTENT PNEUMATIC CALF COMPRESSION
- Lower limb ischaemia
INTRAPARTUM MANAGEMENT
Generally, heparin is discontinued during labour and delivery (vaginal or caesarean) in case an epidural or spinal anaesthetic is needed. Also there is a risk of excessive bleeding at delivery, especially at caesarean, if a treatment or high prophylactic dose is being given.
There are some circumstances where some heparin may be given throughout labour and delivery (such as if the woman has very recently sustained a venous thromboembolism) If so, the details should be documented by medical staff for the individual case. Regional anaesthesia would be avoided.
If an induction of labour is prolonged then consider reintroducing LMWH prophylaxis at times during the process when labour is unlikely.
REGIONAL ANALGESIA/ ANAESTHESIA
A spinal anaesthetic should not be inserted or an epidural cannula inserted or removed within
- 12 hours following administration of a standard prophylactic dose of LMWH
- 24 hours following administration of a high prophylactic or treatment dose of LMWH
LMWH should not be given for 4 hours after use of spinal anaesthesia or after the epidural catheter has been removed.
IF ON STANDARD PROPHYLACTIC DOSES OF LMWH:
Spontaneous labour –withhold further heparin until after delivery
Planned delivery – give the last dose of heparin on the day before (>12 hours) the start of the induction of labour or the elective caesarean section
Emergency caesarean section – if within 12 hours of the last heparin dose, then only use regional anaesthesia if the anaesthetist thinks the benefits outweigh the risks
IF ON TREATMENT OR HIGH PROPHYLACTIC DOSES OF LMWH
Spontaneous labour –withhold further heparin until after delivery. There may be some increased risk of bleeding at delivery, but whether to give protamine sulphate will depend on clinical judgment (taking into account the timing and amount of the last heparin dose) – bleeding risk with a vaginal birth is much lower than with a Caesarean section and rarely would reversal treatment be given. Cross match blood.
The timing and dose of LMWH to be resumed following delivery will depend on individual circumstances.
Planned delivery – it is advisable to plan the delivery when treatment or high prophylactic LMWH regimens are being used. Give the last dose of heparin on the morning before (>24 hours) the start of the induction of labour or the elective caesarean section. Resume LMWH at a standard prophylactic dose as soon as possible after delivery, i.e. immediately after if no regional anaesthesia was involved (see post partum management below) and return to a higher dose about 12 hours after delivery if there are no bleeding problems.
Emergency caesarean section – if within 24 hours of the last heparin dose, then regional anaesthesia will be avoided. Cross match blood. Whether to give protamine sulphate prior to operating will depend on clinical judgment (taking into account the timing and amount of the last heparin dose). Consider siting drains at the operation site. Close the wound with interrupted sutures or staples.
The timing and dose of LMWH to resume following delivery will depend on individual circumstances.
POSTPARTUM MANAGEMENT
Reassess and document level of risk, see Appendix 3.
After spontaneous vaginal delivery the first dose of LMWH should be given within 4 hours except in cases with regional analgesia use (as above) or with bleeding concerns (when management should be discussed with medical staff).
Where the guideline recommends ‘at least’ 10 days of postnatal LMWH then usually interpret this as 10 days but it is appropriate to prolong the course if circumstances are complicated, e.g. a prolonged admission, wound infection, additional post partum surgery.
Where thromboprophylaxis is required, but anticoagulants are contraindicated, GECS should be worn for at least six weeks following delivery.
If LMWH is to be replaced by warfarin this should be started on the fifth postpartum day. The LMWH can be withdrawn when the INR has reached the target range (2.0-3.0) for 24 hours.
For postpartum LMWH please prescribe the FULL required course for the woman on discharge from hospital, e.g. the amount required to complete her 10 day or 6 week course.
Heparin and warfarin are NOT contraindicated in breastfeeding
ADDITIONAL GUIDANCE ON THROMBOPHILIA SCREENING FOR PREGNANCY
See Appendix 4
References
SIGN (2014) Prevention and Management of Venous Thromboembolism: A national clinical guideline No 122
RCOG (2015) Reducing the risk of venous thromboembolism during pregnancy and the puerperium Greentop Guideline No 37a