Pregnancy, Bleeding (cont.)
Laboratory Tests and Imaging
Lab tests: Several lab tests
are routinely obtained. They include a urine pregnancy test, a
urinalysis, a blood type and Rh, and a
complete blood count (CBC).
Serum quantitative bhCG,
which is a blood hormone marker of pregnancy, is also frequently obtained.
- The urine pregnancy test is extremely sensitive for
diagnosing pregnancy at or about the same time you miss your period, or
possibly a few days before. A urinalysis can diagnose
infections, regardless of whether you have symptoms of this type of infection.
This is because infections, specifically of the urinary tract, are a cause of
miscarriage. Also, a urinary tract infection with no symptoms is relatively
common in pregnancy, occurring in 2%-11% of pregnant women. Up to a fourth of
these women will go on to have kidney infections.
- Your blood type will be checked. You are being
screened for whether your type is Rh negative or positive. If you are negative
and the father of the baby is positive, your body may make antibodies against the baby's
blood cells. If this occurs without treatment, the next time you are pregnant, these antibodies will appear again and harm that baby. If this is discovered during the first pregnancy and treatment with an injection called
RhoGAM is given, this prevents the antibodies from forming.
- A blood count is routinely obtained to have an estimate of how much bleeding has already occurred.
- The bhCG level is a measure of the volume of living tissue associated with the developing pregnancy. Both ectopic and intrauterine pregnancies (IUP) produce bhCG, although there is usually a difference in the rate at which the quantitative bhCG level increases. Although a single value of bhCG isn't useful for differentiating between a normal or abnormal pregnancy or an ectopic pregnancy, a variation in the expected rate of rise of the bhCG level can be helpful. A falling bhCG does not exclude the possibility of tubal rupture. The real value of the quantitative bhCG for diagnosis of ectopic pregnancy is when it is used in correlation with the results of a pelvic ultrasound.
Ultrasound: Ultrasound can often determine if the fetus is healthy and growing inside the uterus. Ultrasound is a form of imaging using sound waves, not
X-rays. It is a test that is often able to identify a pregnancy and estimate the age of the fetus. However, a pregnancy may be too early to be seen on ultrasound.
- Ultrasound may be able to identify an ectopic pregnancy
growing outside of the uterus. It also may be used to look for blood in the
pelvis, a very serious complication that can occur when the ectopic pregnancy has ruptured the
- Late in pregnancy, placenta previa is diagnosed almost exclusively by abdominal ultrasound, which can detect it 95% of the time.
- Placental abruption is diagnosed by excluding other
causes. It often cannot be confirmed until after delivery when the placenta is
found to have a blood clot attached to it. An ultrasound is performed to make certain that the bleeding is not from a placenta previa. Ultrasound at best is only able to detect about half of placental abruptions.
- Fetal bleeding can be distinguished from maternal bleeding by performing a special test on the blood present in the vagina. Also, a special type of ultrasound (Doppler) may be used to see the blood flow within the blood vessels.
- Lower genital tract problems can easily be diagnosed
with a speculum examination. It is important that an ultrasound rule out
placenta previa prior to any vaginal exam.
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