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Tags: Obstetrics
Obstetric haemorrhage
../Knowledge/Part 2/Obs/Postpartum haemorrhage (PPH) is the leading cause of maternal death worldwide, responsible for up to 27.1% of deaths, and is one of the most preventable causes of death
Physiology of maternal haemostasis
During normal pregnancy, there is
- 30-50% ↑ in plasma volume
- 20% ↑ in RBC volume
→ relative state of hemodilution
↓plt ∵ ↑ plasma volume combined with ↑ consumption by the uteroplacental unit, with gestational thrombocytopenia (platelet count <150x10^9/L) occurring in 5-10% of pregnancies
Overall, hemostasis is tipped towards a prothrombotic state with an ↑ in all procoagulant factors, excluding factors XI and XIII
During pregnancy, fibrinogen levels ↑ to 4-6 g/L (compared to 2-4 g/L in the non-pregnant population) whereas PT and aPTT times may shorten
Acquired protein C resistance and a ↓ in Protein S activity signify a ↓ in innate anticoagulant effectiveness
A ↓ in overall fibrinolytic activity occurs despite ↑ in D dimer (a specific fibrin degradation product)
↑ levels of plasminogen activator inhibitor 1 (PAI-1) and placental-derived PAI-2 and a corresponding ↓ in tissue plasminogen activator (tPA) also occur
In the normal process of haemostasis, the response to vascular injury is the rapid formation of a platelet and fibrin clot to prevent haemorrhage
In vivo, the cellular model of haemostasis consists of overlapping phases including
- initiation,
- amplification
- propagation
Haemostatic agents
| Agent | Indication | Considerations |
|---|---|---|
| Fibrinogen concentrate | PPH in the setting of hypofibrinogenaemia; DIC, consumptive coagulopathy | Strongly consider if plasma fibrinogen is <2 g/L |
| TXA | 1 Gram in the setting of PPH; redose at 30 min if PPH ongoing | No evidence for prophylactic use for vaginal delivery; limited evidence for prophylactic use during Caesarean delivery |
| Desmopressin | vWF type 1 patients with PPH | Consider other causes of haemorrhage in this population |
| Prothrombin complex concentrate | No current indication during PPH | No evidence for use during PPH |
| Activated factor VII | Life-threatening PPH | Limited evidence for its use; consider other agents first |
| Topical agents (e.g. Floseal™, Surgiflo™) | During Caesarean delivery with bleeding at the surgical site | Variety of options to choose from, many work via the coagulation cascade. May not be sufficient for haemostasis during a severe PPH |