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Antepartum
- Placenta praevia
- Placental abruption
- Bleeding from genital tract (cervix, vagina or vulva)
- Unknown
Placenta praevia and placental abruption are the most important causes of APH.
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Intrapartum
- Placenta Praevia
- Placental Abruption
- Uterine rupture
- Amniotic Fluid embolism
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Postpartum - The 4 T’s
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Tone- uterine atony/ abnormalities of uterine contraction (the most common cause of primary PPH- 80% of cases).
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Tissue- retained products of conception e.g. placental tissue, or blood clots
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Trauma- genital tract trauma i.e. lacerations of the cervix/ vagina/ external genitalia or perineum, extensions of uterine incisions at caesarean section, uterine rupture, uterine inversion
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Thrombin- abnormalities of coagulation. These can be acquired in pregnancy e.g. gestational thrombocytopenia, pre-eclampsia with HELLP, sepsis, abruption, amniotic fluid embolus, existing e.g. Haemophilia A, von Willebrand disease, or due to therapeutic anticoagulation e.g. for a history of thromboembolic disease or cardiac valve replacement.
Early risk assessment for obstetric haemorrhage of all pregnant women is essential.
Steps to minimise the risk of MOH antenatally include-
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Investigation and treatment of antenatal anaemia (consider iron supplementation for Hb <110 g/l at first contact or <105 g/l at 28 weeks).
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Individualised PPH risk assessment of current and previous risk factors throughout the antenatal & intrapartum period.
Risk factors for primary PPH (the most common cause of MOH) include:
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Antenatal
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Anaemia or bleeding disorder (Hb <95 g/L, platelets < 100 x 109/L)
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Body Mass Index (BMI) < 18 or >35 or booking weight < 55kg
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> 5 previous vaginal births
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Previous PPH > 1000 ml
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Perinatal
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Suspicion of chorioamnionitis/ sepsis
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Labour augmented with syntocinon
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Prolonged labour
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Instrumental delivery
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Retained products of conception
