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
What is vasa praevia?
Occurs when foetal vessels run in the membranes below the presentin part of the foetus - unsupported by placental tissue or umbilical cord
I: 1:2500 - 1:2700
May present with PV bleeding after ROM followed by rapid foetal distress - classically foetal bradycardia
RFs: low lying placenta, multiple pregnancy, IVF pregnancy, bilobed placenta
30% of pregnancies affected by vasa praevia result in hysterectomy
