To prevent further haemorrhaging patients with major placental praevia are recommended to have a caesarean delivery. Abnormal placentation
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 absence of a decidua basalis, trophoblast cells on the developing blastocyst form an abnormally deep attachment to the uterine wall, this is known as abnormal placentation. Abnormal placentation can categorised into 3 types, depending on the depth of infiltration of the chorionic villi into the uterine wall:
In placenta percreta, the chorionic villi have grow entirely through the myometrium and invade into the perimetrium. Placenta percreta results in the most intense haemorrhaging that can be expected caused by abnormal placentation. 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. The chance of abnormal placentation increases in subsequent pregnancies, if there is scar tissue present from previous pregnancies. For example, previously undergoing a caesarean or placenta previa increases the likelihood of abnormal placentation, therefore increasing the chances of antepartum haemorrhaging. Placental abruption
Placental abruption occurs when the placenta detaches from the endometrium. Detachment causes antepartum haemorrhaging at the location of abruption. Depending on the site of detachment, haemorrhaging may or may not be apparent. If abruption occurs behind the placenta where blood cannot escape through the cervix, blood will pool and form a retroplacental clot.
Abrasion or slight trauma caused by intercourse, clinical examinations and pap smear may also cause spotting  from the cervix. Vaginal bleeding from atrophy, vaginitis, and ulcers also attribute to minor haemorrhaging. Similarly, varicosities, tumours or inflammation in the vulva can cause minor antepartum haemorrhaging. Non genital tract bleeding caused by haematuria or haemorrhoids can often be mistaken for antepartum haemorrhaging and are typically harmless. Diagnosis
Differential diagnosis
GI bleed - haemorrhoids, inflammatory bowel disease

See also
Obstetrical haemorrhage

References


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