[4] In regard to treatment, it should be considered a medical emergency (regardless of whether there is pain), as if it is left untreated it can lead to death of the mother or baby.

[8] During pregnancy the layer of endometrium that attaches directly to developing blastocyst becomes the maternal portion of the placenta, also known as the decidua basalis.

In the event of placental detachment from the uterine wall, the depth of chorionic villi attachment dictates the amount of haemorrhaging that can be expected.

Only when the site of detachment occurs on the side facing the cervical opening can the total amount of haemorrhaging be measured by vaginal bleeding.

However, in the case of total placental separation haemorrhaging will be major and emergency delivery will typically be the course of action.

[15] Vasa praevia is the presence of unprotected foetal blood vessels running along the placenta and over the internal cervical opening.

The exposed connecting membranous vessels present risk of rupturing due to limited protection from thrombosis and trauma.

Chances of vasa previa and placental abruption increase in the presence of a bilobed placenta due to decreased surface area for attachment to the uterine wall and the exposure of membranous vessels.

Distal lobes are connected by a placental artery and vein extending from the main placenta, which tends to be centrally located and is the largest in mass.

[20] At the time of contraction or delivery the connecting placental arteries and veins may rupture resulting in significant haemorrhaging.

In the endocervix the epithelia is columnar glandular which transitions into stratified squamous towards the ectocervix and external cervical orifice.

The amount of bleeding in these areas are typically limited to spotting or minor antepartum haemorrhaging.

Non genital tract bleeding caused by haematuria or haemorrhoids can often be mistaken for antepartum haemorrhaging and are typically harmless.