Page 125 - 86 human physiology part-2

Chapter 17

mother's fault.

If the products of conception are not completely expelled after fetal death this is known as a
missed abortion and is usually treated sugically by a procedure known as a D&C or dilation and
curattage.

Bleeding During Pregnancy

Vaginal bleeding at any stage should be taken seriously. Severe bleeding in the early weeks may
be a sign of miscarriage. However, 25% of pregnant patient bleed in the first trimester. After 24 weeks
the mother should seek medical advice immediately. Third trimester bleeding in pregnancy is often one
of the first signs of placenta previa; placenta is across the opening of the cervix. An ultrasound should
be performed to establish the location. Other causes of late term bleeding include:

• Preterm Labor or labor that occurs before 38 weeks gestation that can have multiple
causes

• Placental Abruption is a condition in which the placenta is torn away from the uterine
wall causing loss of oxygen and nutrients to the baby, and hemorrhage of mother and baby from
the large blood vessels in the placenta. Most women, but not all experience heavy bleeding and
abdominal pain. This is a life threatening emergency as a fetus can only survive as long as 50%
of the placenta is still attached.

Blood Conditions

Individuals either have, or do not have, the Rhesus factor (or Rh D antigen) on the surface of their
red blood cells. This is usually indicated by 'RhD positive' (does have the RhD antigen) or 'RhD
negative' (does not have the antigen) suffix to the ABO blood type i.e. A+ B- blood typing. This is a
problem only when an Rh-negative woman has a partner who is Rh-positive resulting in an Rh-positive
baby. If the mother's and the baby's blood come into contact during the birth, her body produces
antibodies against the baby's blood. This problem usually does not affect the current pregnancy but can
be dangerous for future pregnancies as the antibodies stay in the blood causing an immune response
against future Rh+ fetus. In essence the mother's body "rejects" the fetus as it would a foreign body. A
drug called Rhogam is now given by injection given at 28-30 weeks gestation and given again if there
is confirmation that the baby is Rh positive within 24 hours after birth to protect the future pregnancies.
Rh isoimmunization is rare in our day. Rh- mothers should also be given the injection after miscarriage
or abortion.

If a mother is untreated they are at risk to subsequently deliver babies who suffer from hemolytic
disease of the newborn. Hemolytic disease of the newborn, also known as HDN, is an alloimmune
condition that develops in a fetus, when the IgG antibodies that have been produced by the mother and
have passed through the placenta include ones which attack the red blood cells in the fetal circulation.
The red cells are broken down and the fetus can develop reticulocytosis and anemia. This fetal disease
ranges from mild to very severe, and fetal death from heart failure (hydrops fetalis) can occur. When
the disease is moderate or severe, many erythroblasts are present in the fetal blood and so these forms
of the disease can be called erythroblastosis fetalis (or erythroblastosis foetalis). Hemolysis leads to
elevated bilirubin levels. After delivery bilirubin is no longer cleared (via the placenta) from the

340 | Human Physiology