Antepartum haemorrhage Flashcards
What is antepartum haemorrhage?
Bleeding from 24 weeks gestation
What are the most serious causes of antepartum haemorrhage
- Placental abruption (separation of placenta from uterine wall)
- Placenta praevia (placenta partially or wholly covering cervix)
- Placenta acreta (placenta abnormally adherent to myometrium, usually the scar from a previous c-section)
- Vasa previa (bleeding from foetal vessels)
Epidemiology of antepartum haemorrhage
- Bleeding after 24 weeks affects 3-5% of pregnancies
- Associated with up to 25% preterm births
- 30% of pregnancies affected by placenta acreta result in hysterectomy - partial detachment of the placenta causes massive haemorrhage
Causes of anepartum haemorrhage
Bleeding from external genitalia
- Trauma, infection, vulval or vaginal cancer
Bleeding from cervix
- ‘Show’, cervicitis, cervical polyp, cervical cancer
Bleeding from uterus
- Placental abruption, placenta praevia and acceta, vasa praveia, uterine rupture
What are the risk factors for placental abruption?
- Abdo trauma
- Multiple pregnancy
- Polyhydramnios
- Premature rupture of membranes
- Smoking
- Cocaine
- Previous abruption
How are placenta praevia and abruption differentiated?
- Abruption presents with pain and bleeding
- Placenta previa and vasa previa are painless bleeds
Diagnosis of antepartum haemorrhage
- Resuscitation if needed, obs including BP, pulse and RR and the results are used to guide management
- Abdo and speculum examinations to determine cause of bleed
- Placental location on previous scans is reviewed
- ** digital vaginal examination is not done until location of placenta is known because it can trigger significant bleeding in case of placenta previa **
Investigation of antepartum haemorrhage
- USS to exclude placenta previa - not helpful for vasa previa or diagnosis of placental abruption
- IV access is gained when blood loss >50mL
- Bloods: cross match, FBC for anaemia, coagulation tests
- Foetal HR monitored once mothers condition has stabilised
- Acid elation test (Kleihauer) for rhesus negative women - results are used to guide the amount of anti-D required
Management of antepartum haemorrhage
- Admit for significant bleeds until they have settled
- Massive bleeding or maternal compromise - induce delivery
*antepartum haemorrhage makes post partum haemorrhage more likely so active management of third stage of labour is required*
Unexplained bleeding is associated with poor outcomes so serial screening is need to look for growth restriction and oligohydramnios
Medication: corticosteroids if significant bleed occurs before 35 weeks invade delivery is required
What is placenta praevia?
Placenta overlies the cervical os
- Can be complete, partial, marginal or low-lying
- Partial, marginal and low lying may resolve as pregnancy progresses
- Associated with vasa praevia where the foetal vessels lie over the internal cervical os
Variants of abnormally adherent placenta
- Placenta accreta: placenta attaches to myometrium instead of being restricted to decidua basalis
- Placenta increta: where chorionic villi invade into the myometrium
- Placenta percreta: where chorionic villi invade through the myometrium and sometimes the adjoining tissue
Epidemiology of placenta praevia
- 0/3-0.5% pregnancies worldwide
- Once c-section increases risk in next pregnancy to 0.6%
Cause of placenta praevia
- Advanced maternal age
- Multiple pregnancies
- Smoking
- Uterine scarring
- Previous c-section/ uterine scar
Pathophysiology of placenta praevia
- Occurs when blastocyst implants in lower uterine segment near the cervical os
- Presence of a uterine scar in the lower segment is thought to interfere with the process of placentation
- Bleeding can occur due to trauma e.g. sex or vaginal examination or as the cervix opens for delivery
- Untreated haemorrhage due to PP almost always results in death
Classification of placenta praevia
- Complete: placenta covers entire internal cervical os
- Partial: placenta covers portion of internal cervical os
- Marginal: edge of placenta lies within 2cm of internal cervical os
- Low lying placenta: edge of placenta lies within 2-3.5cm of internal cervical os
- Vasa praevia: foetal vessels overlying cervical os
- Resolved praevia: low-lying placenta seen in early pregnancy that has migrated away from the os