L4 Obstetric Haemorrhage Flashcards
What are the key impacts of obstetric haemorrhage on mothers according to the MMBRACE report?
- Report showed that 18 of 275 maternal deaths were caused by OH between 2020 and 2022
- Overall mortality of 0.89 per 100,000 maternities
- Inequalities in maternal mortality: Race, deprivation, age and obesity
Geographical differences in OH:
- Major cause of maternal death in developing countries
- ~50% of global maternal deaths
- Deaths from OH are uncommon in the UK
Types of obstetric haemorrhage: (with classification)
- Antepartum: Subdivided into minor (>50ml), major (50ml - 1000ml) and massive (>1000ml and/or signs of clinical shock
- Primary Postpartum: Minor (500 - 1000ml) or major (>1000ml)
- Major PP can be further subdivided into moderate MOH (1001-2000ml) and severe MOH (>2000ml)
Define antepartum haemorrhage and give 2 key causes:
- Antepartum: Bleeding from genital tract ocurring from 24 weeks of pregnancy and prior to giving birth to the baby
- Usually caused by either placenta praevia or placental abruption
Define primary and secondary postpartum haemorrhage:
- Primary: Loss of 500ml or more of blood from the genital tract within 24hrs of the birth of a baby -> i.e. more than should be lost immediately after birth
- Secondary: Abnormal or excessive bleeding from birth canal between 24hrs and 12 weeks postnatally -> i.e. bleeding occurring after the normal window following birth
Outline a key haematological changes that take place during pregnancy:
- Large increase in blood volume (Before pregnancy: 70ml / kg bodyweight vs During: 100ml / kg)
- Plasma volume increases 40 - 50%
- Red cell mass increases 20 - 30%
Estimated blood loss in normal vaginal vs caesarean deliveries:
- Avg. EBL (Vaginal): 300 - 500ml
- Avg. EBL (CS): 750ml
Outline the benefit of increased blood volume during pregnancy:
- Facilitates maternal and foetal exchanges of respiratory gases, nutrients and metabolites
- Also acts to dampen the impact of maternal blood loss at delivery
How does the body compensate during haemorrhage? (Give 3x mechanisms)
- Heart rate increases, with more forceful beats
- Vasoconstriction -> increased systemic vascular resistance
- Body secretes less urine -> fluid retention
Outline the 3 stages of normal response to tissue injury:
- Primary haemostasis (formation of white blood clot or platelet plug)
- Secondary haemostasis (formation of stable red blood clot; requires coagulation factors and fibrin)
- Fibrinolysis (lysis of the clot)
What haematological measures are taken to manage obstetric haemorrhage?
- Replace circulating volume (compound sodium lactate)
- Replace blood (cell salvage/allogenic)
- Correct coagulation with blood products (fibrinogen/platelets/fresh frozen plasma)
What haematological measures are taken to manage obstetric haemorrhage?
Name one additional mechanism through which the body compensates for blood loss during pregnancy:
- Autotransfusion
- Uterus contracts, shunting blood back into the body
- Up to 16% of the mothers blood supply can be stored in the uterus in the later stages of pregnancy
How is haemorrhagic shock classified?
- Class I to IV
- Depends on factors including % blood loss, HR, BP, respiratory rate, urine output, mental status and fluid replacement
Outline the risk factors for atonic bleeding:
- Prolonged labour
- Overdistended uterus (e.g. twins, large babies, polyhadramnios)
Name 2 conditions that might cause retained tissue products and thus OH:
- Placenta preavia (placenta grows against cervix)
- Placental adhesive disorder (trophoblastic tissue invades uterine walls due to decidual problems) -> various conditions grouped under one name
Causes of trauma that may result in OH:
- Inverted uterus
- Ruptured uterus (e.g. old CS scars)
- Surgical damage (e.g. broad ligament tears at CS in advanced labour)
- Genital tract trauma (i.e. vaginal tears of various degrees)
List 5 broad types of pregnancy complications that can result in acquired coagulopathy:
- Sepsis (PROM i.e. sac ruptures early, endometritis i.e. inflammation of endometrium, chorio-amnionitis i.e inflammation of placenta)
- Pre-eclampsia/eclampsia/HELLP syndrome
- Placental abruption (dislodges from wall and gets in the way)
- Retained dead foetus
- Amniotic fluid embolus (bit of fluid blocks maternal circulation)
List 5 types of platelet abnormalities:
- Gestational thrombocytopenia (low blood count)
- Idiopathic/immunological thrombocytopenic purpura
- HELLP syndrome
- Sepsis
- Disseminated intravascular coagulation (DIC)
How does a rapid infuser work?
- Rapidly infuses and warms crystalloid, colloid and blood
- Able to keep up with rapid blood loss during delivery
How does red cell salvage work?
- Collects and processes maternal blood from surgical site
- Centrifuges, washes and returns red cells to patient
4 Causes of obstetric haemorrhage:
- Tone (abnormalities of uterine contraction)
- Tissue (retained products of conception)
- Trauma
- Thrombin (abnormalities of coagulation)
Pharmacological management of OH:
- Uterotonic agents
- e.g. Syntocinon
- e.g. Ergometrine
- Carboprost
- Tranexamic acid -> stops bleeding by reducing fibrinolysis
Surgical management of OH:
- Tone: Uterine massage, bakri balloon insertion, b lynch suture
- Tissue: removal of retained products/placenta
- Surgical repair/post-delivery intervention
