Foetal-maternal haemorrhage

Foetal-maternal haemorrhage may be defined as the loss of foetal blood cells into the maternal circulation. It takes place in normal pregnancies as well as when there are obstetric or trauma related complications to pregnancy.

Normally the maternal circulation and the foetal circulation are kept from direct contact with each other, with gas and nutrient exchange taking place across a membrane in the placenta made of two layers, the syncytiotrophoblast and the cytotrophoblast. Foetal-maternal haemorrhage occurs when this membrane ceases to function as a barrier and foetal cells may come in contact with and enter the maternal vessels in the decidua/endometrium

Description

Normal Pregnancy

It is estimated that less than 1ml of foetal blood is lost to the maternal circulation during normal labour in around 96% of normal deliveries. [Sebring ES, Polesky HF. Fetomaternal Hemorrhage: Incidence, risk factors, time ofoccurrence, and clinical effects. Transfusion 1990; 30:344-357.] [Medearis AL, Hensleigh Pa, Parks DR, Herzenberh LA. Detection of fetal erythrocytes inmaternal blood post partum with the fluorescence-activated cell sorter. American Journal ofObstetrics and Gynaecology 1984; 48:290-295.] The loss of this small amount of blood may however be a sensitising event and stimluate antibody production to the foetal red blood cells, and example of which is Rhesus disease of the newborn.

Abnormal Pregnancy

Causes of increased foetal-maternal haemorrhage are seen as a result of trauma, placental abruption or may be spontaneous with no cause found.

Up to 30mls of foetal-maternal transfusion may take place with no significant signs or symptoms seen in either mother or foetus. [Polesky HF Sebring ES. Evaluation of methods of detection and quantitation of fetal cells andtheir effects on Rh Ig usage. American Journal of Clinical Pathology 198 1;76(suppl):525-529.] Loss in excess of this may result in significant morbidity and mortality to the foetus. Foetal-maternal haemorrhage is one cause of interuterine death (IUD).

Treatment

If ongoing and rapid haemorrhage is occurring then immediate delivery of the foetus may be indicated if the foetus is sufficiently developed. [Massive fetomaternal hemorrhage and oxytocin contraction test: case report and review Arch Gynecol Obstet. 2004 Jan ;269 (2):149-51 14648183 (P,S,G,E,B)] If the haemorrhage has already occurred and now stopped, an inutero transfusion of red cells to the foetus may be recommended. [Massive fetomaternal hemorrhage and oxytocin contraction test: case report and review Arch Gynecol Obstet. 2004 Jan ;269 (2):149-51 14648183 (P,S,G,E,B)]

References