Foetus Compensates and Acute Disruption in Blood Supply

Foetus Compensates and Acute Disruption in Blood Supply

Foetus Compensates and Acute Disruption in Blood Supply

Introduction

Throughout the fetal stage of development, the maternal blood supplies the fetus with O2 and nutrients and carries away its wastes. These substances diffuse between the maternal and fetal blood through the placental membrane. They are carried to and from the fetal body by the umbilical blood vessels.

Discussion

Obstetric hemorrhage is responsible for an estimated 25% of maternal deaths in pregnancy. While hemorrhage is most common during delivery and immediately postpartum, antepartum hemorrhage is also prevalent. The causes of antepartum hemorrhage include abruptio placenta, placenta previa, and uterine rupture. Although the obstetric patient is physiologically well prepared for hemorrhage due to the changes of pregnancy, there is also a greater risk of extensive blood loss from the gravid uterus. Pregnancy induces a hypervolemic state and a pregnant patient can experience massive blood loss before manifesting any significant vital sign changes. Failure to recognize and treat the hemorrhage early can result in loss of both the fetus and the mother. Rapid assessment and initiation of appropriate resuscitative measures can greatly improve prognosis (Morrison 2006).

Placental abruption is the premature separation of the placenta from the uterine wall. There is increased risk for its occurrence with prior abruption, trauma, hypertension, cocaine abuse, smoking, premature rupture of membranes, polyhydramnios, and high parity. The elasticity of the uterus allows it to deform easily without injury; however, when the uterus changes shape, the inelastic placenta is unable to conform and is torn from the uterine wall. This abruption of the placenta causes hemorrhage between the uterine wall and the placenta. As a result fetal oxygen and nutrient supply is reduced and waste removal can be inadequate. Intrauterine hemorrhage leads to irritation of the myometrium and the uterus begins contracting. These contractions cause constriction of uterine blood vessels. resulting in a greater decrease in blood flow to the already distressed fetus. There does not appear to be a correlation between the likelihood of abruption and the location of the placenta, but the extent of abruption does correlate with the rate of fetal loss. Even a small abruption can induce premature labor; the larger the abruption, the greater is the risk to the fetus. The signs and symptoms of abruption include vaginal bleeding, uterine tenderness, abdominal cramps, maternal signs of hypovolemia, and fetal tachycardia. ...