What is the definition of antepartum haemorrhage?
- Bleeding PV after 24/40 gestation (but before the onset of labour).
- What are the causes of APH?
- In around 1/3, no underlying cause is found. In around 1/3, there is placenta praevia; in 1/3 there is placental abruption; in a small proportion bleeding may be from another source (e.g. cervical), or due to vasa praevia.
- How would you proceed if a woman presented with APH?
- Placenta praevia and placental abruption are both obstetric emergencies. This lady should therefore be admitted and I would check her obs, in particular looking for tachycardia suggestive of shock. I would gain IV access, and take blood for FBC, clotting and cross-match, of at least 2 units of blood, or 4 units for suspected abruption.
- I would not perform a vaginal examination until placenta praevia had been excluded. I would like to feel the lady’s abdomen for the “woody hard” tonic contraction of abruption, as well as monitor her vital signs and in particular check for tachycardia, suggesting impending shock.
- I would perform an urgent USS and CTG. Anti-D should be given to Rhesus-negative mothers, and corticosteroids if the baby if less than 34 weeks gestation.
- Urgent delivery by Caesarean section may be required to save the foetus.
- What is placenta praevia?
- This is when the placenta implants over the cervical os, or in the lower segment of the uterus (usually defined as <8cm from the os).
- It occurs in 1 in 200 pregnancies, with risk factors including multiparity, advanced maternal age, prior PP, smoking and prior C-section.
- It may be graded I-IV, or into major and minor categories, dependent on the exact location of the placenta.
- What is the management of asymptomatic placenta praevia?
- Most PP is picked up as a “low-lying placenta” during the 2nd trimester USS. This is seen in around 10% of women, but with uterine growth the placenta usually rises up away from the cervix before term.
- The woman should therefore have a repeat USS at 32/40. If the placenta remains low then it should be repeated fortnightly until 36 weeks. Provided the woman has not experienced any bleeding, and she is able to get to hospital easily, she need not be admitted at this stage.
- At 37 weeks, if the placenta remains low, she should be admitted and elective C-section performed at 39/40.
- If bleeding develops, she should be admitted from this point and monitored, with delivery at 37/40 by elective C section.
- What are the complications of placenta praevia?
- Maternal mortality is rare in developed countries.
- PPH is common, because the lower segment of the uterus is not contractile and so does not contract down to staunch bleeding. Bleeding can usually be stopped with oxytocics or failing that, an intrauterine balloon catheter; however, if this fails an emergency hysterectomy may be required.
- Foetal complications relate mainly to prematurity and malpresentation.
- Placenta accreta and percreta may also occur.
What are the risk factors for placenta praevia?
- Think big floppy uterus
- Twins, high parity, increasing age, scarred uterus
What are the risk factors for placental abruption?
- Previous abruption
- IUGR, pre-eclampsia, maternal smoking, hypertension
- multiple pregnancy, high maternal parity, autoimmune disease, cocaine usage
What features distinguish placenta praevia from placental abruption?
- Placenta praevia is painless, fresh red blood, may occur several times.
- Plaental abruption is usually painful, with a tender woody uterus and dark or no blood.
- What is placenta accreta?
- This is the abnormal invasion of placental villi into the uterine wall. It is more common with PP and with previous LSCS. (E.g. may implant over Caesarean scar and penetrate through the decidua and myometrium).
- It usually requires Caeasaren-hysterectomy with a high risk of DIC, and should be anticipated in any woman with a previous C-section and low-lying placenta.
- What is placental abruption?
- This is premature separation of the placenta from the uterine sidewall, causing antenatal bleeding. This may be revealed (PV bleeding) or concealed (large retrouterine blood collection may develop), and minor or major (affecting >1/3 of the placenta; foetal survival very unlikely).
- What is vasa praevia?
- Bleeding from the umbilical vessels (i.e. foetal blood) due to velamentous insertion of cord vessels crossing the cervical os.
- It usually presents with scanty bleeding at the time of RoM, along with severe foetal distress.
- An emergency C section should be performed if the foetus is viable, but foetal mortality exceeds 75%.