VTE and PE in pregnancy Flashcards
What % of women who develop VTE in pregnancy have an underlying thrombophilia?
50%
What % of PE in pregnancy are fatal?
15%
66% occur within 30 mins of embolic event.
Antenatal risk factors for VTE
- AMA
- Obesity
- Hospitalisation
- Varicose veins
- Multiple pregnancy
- Diabetes
- Inflammatory bowel disease
- Thrombophilia
- UTI
Postnatal risk factors for VTE
- AMA
- Obesity
- CS especially emCS
- PPH
- HTN and PET
- Smoking
- Medical comorbidities
- Stillbirth
- Postpartum infection
Outline the pathophysiology of why pregnancy has higher risk of VTE using Virchow’s triad
Venous stasis:
- Increased venous capacitance
- Compression of large veins by the gravid uterus.
Endothelial injury: delivery is associated with vascular injury and changes at the uteroplacental surface, which probably contribute to the increased risk of VTE in the immediate postpartum period.
Hypercoagulable state:
- Increases in factors I, II, VII, VIII, IX, and X
- Decrease in protein S
- Increase in resistance to activated protein C
- Increased activity of the fibrinolytic inhibitors PAI-1 and PAI-2 .
Discuss the utility of compression duplex ultrasound in DVT/PE diagnosis
Indication:
- Suspected PE with DVT signs/sx
- Suspected DVT
If confirms DVT, no further investigation for PE should be performed to limit radiation exposure. Commence tx.
If USS negative and low suspicion: stop anticoagulation.
If USS negative but high suspicion: stop anticoagulation but perform serial USS day 3 and day 7.
Sensitivity 95%
NPV 99.5%
What ECG changes are associated with PE?
- TWI
- S1Q3T3
- RBBB
What the advantages and disadvantages of CTPA (cf. VQ scan)?
Advantages:
- Quick and easily accessible.
- Radiation dose to fetus low with shielding
- NPV 99%
- Can diagnose other pathology e.g. aortic dissection, pulmonary oedema, pneumonia
- Can continue to breastfeed after
Disadvantages:
- Radiation dose 20-100x more than VQ scan.
- Increased risk of maternal breast cancer
What the advantages and disadvantages of V/Q scan (cf. CTPA)?
Advantages:
- Lower radiation exposure to mum.
- Better at diagnosing peripheral PE
- Less prone to suboptimal image quality due to poor contrast filling of pulmonary vessels or respiratory motion artefact.
- NPV 100%
Disadvantages:
- Increased childhood cancers
- Diagnostic accuracy compromised if CXR abnormal
- Unable to breastfeed for 12 hours after.
What is the indication for peak anti Xa activity?
- Extremes of bodyweight
- Renal impairment
- Recurrent VTE
When is platelet monitoring indicated?
- Post-op and receiving unfractionated heparin.
Every 2-3 days until stopped.
In a massive PE, is clexane or unfractionated heparin preferred and why?
Unfractionated heparin preferred.
Rapid effect.
Easier to adjust if thrombolysis is administered.
How would you manage a woman usually on clexane in labour and elective delivery?
- Advise to stop injecting clexane when labour starts.
- If injected recently, monitor APTT; if abnormal may need protamine sulphate reversal.
Planned delivery:
- Stop clexane 24 hours prior to unfractionated heparin 6 hours prior to.
When is it safe to remove an epidural catheter?
At least 12 hours after last clexane dose.
When is it safe to administer epidural or spinal?
At least 24 hour after clexane or 6 hours after heparin.
