Treatment with lytics for acute PE (mostly massive or with arrest) in pregnancy out to 6 weeks postpartum was associated with 94% overall maternal survival and 88% fetal survival. Major bleeding occurred in 17% of pregnant women and 58% of those in the postpartum period.
Why does this matter?
Acute massive PE during pregnancy or the postpartum period is devastating. The diagnosis and treatment are the definition of "stuck between a rock and a hard place." To diagnose PE requires a large radiation dose. To treat life-threatening large PE may cause torrential bleeding and loss of the pregnancy. Pregnancy is a relative contraindication to thrombolysis. When we are faced with this dilemma, the evidence is sparse. This study attempted to pool as many publications as possible to give us a better idea of the risk and benefit.
Between a rock and a hard place
This was a systematic review of 118 studies and 7 cases from a PE registry. They pooled 127 cases of PE in pregnancy out to 6 weeks postpartum with submassive or massive PE objectively diagnosed, for which there was an intervention: lytics, catheter-based therapy, anticoagulation, or ECMO. All the studies were small case series. So this is just a compilation of very low quality data, but it is the best we have so far. Most were in the 3rd trimester or postpartum period. 83% were massive (with hemodynamic instability); 17% were submassive; 23% had cardiac arrest. 58% were given thrombolytic treatment only; 28% surgical thrombectomy; 12% catheter-based thrombectomy; 11% ECMO. 70% of postpartum PE’s were diagnosed 48 hours after delivery. Overall maternal survival with systemic thrombolytics was 96%; fetal survival 76%; major bleeding 26%. Survival rates and bleeding risk were similar with surgical thrombectomy and percutaneous thrombectomy. Major bleeding was much more common when lytics were given in the postpartum (58%) rather than the antepartum period (18%). Recombinant thrombolytics are theoretically the preferred agent since they do not cross the placenta.
My take home is that treatment of critically ill, hemodynamically unstable pregnant patients with severe PE with any of these modalities is associated with high maternal survival, fair fetal survival, and a high rate of major bleeding. However, beware that these reported high survival rates are susceptible to a high risk of publication bias.
Treatment options for severe pulmonary embolism during pregnancy and the postpartum period: a systematic review. J Thromb Haemost. 2017 Oct;15(10):1942-1950. doi: 10.1111/jth.13802. Epub 2017 Sep 12.
Co-written and reviewed by Thomas Davis, MD.