What does this medical term mean?

In addition to the information below, a full glossary of infertility terms is maintained by the InterNational Council on Infertility Information Dissemination (INCIID).

What is a "blighted ovum"?

A blighted ovum is an embryo that stops developing early in the pregnancy, usually due to an incomplete genetic code. The cells divide and develop until the code runs out and then everything stops. The embryo is then either reabsorbed by the body or miscarried.

What is a "missed abortion"?

A missed abortion occurs when the embryo/fetus has died but the body hasn't shown any signs of miscarriage yet. This is usually diagnosed by either an ultrasound or hcg decline. If a miscarriage does not occur to expel the pregnancy, a D&C or D&E is usually required.

What is a "molar pregnancy"?

A molar pregnancy is a rare condition where a tumor develops in place of the embryo. One of the early symptoms is being very large for dates in early pregnancy. Surgery is required to remove the growth and monthly check-ups for a year or more are needed to ensure the mole does not redevelop. Pregnancy is not recommended for 1 year after a molar pregnancy. Occurrence of a mole slightly increases future risk of uterine cancer.

What is "CVS" or "chorionic villus sampling"?

Chorionic villus sampling (or CVS) is a test that takes cells from the placenta to test for chromosomal or other genetic diseases. It is considered a higher-lever test than amniocentesis and also has a slightly higher risk of complications than an amnio. However, risk declines with a more highly experienced doctor. The advantage over amnio is that it is done much earlier (by the end of the first trimester) and gives faster results (some within 24 hours, as opposed to two weeks). CVS does not measure AFP (alpha fetal protein) levels.

What is "cordocentesis" or "fetal blood sampling"?

In cordocentesis (or fetal blood sampling), blood is drawn from the umbilical cord for karyotyping, detection of fetal virus or other abnormalities. Used for very high-risk cases or late detection of problems; can be done at 18-40 weeks. Needle is inserted into umbilical cord where it connects to placental wall and 1-4 ml of blood is withdrawn. Risk of miscarriage is 1-2%, risk of preterm labor is 3-4%, risk of IUGR is 8-9%.

What is "HCG"?

HCG is a hormome secreted by the placenta. Detecting HCG is the easiest test for confirming pregnancy, and this method is used by most urine test kits. HCG stands for Human Chorionic Gonadotropin.

HCG levels may be used to monitor the progress of a pregnancy. Normally, HCG levels double about every 3 days. Quantitative serum HCG tests are used to measure HCG levels. The following table gives a general guide to expected HCG levels for a normal single pregnancy:

Pregnancy from LMP

HCG level

3 weeks

5 - 50

4 weeks

40 - 1,000

5 weeks

100 - 5,000

6 weeks

600 - 10,000

7 - 8 weeks

1,500 - 100,000

9 - 10 weeks

16,000 - 200,000

11 - 14 weeks

12,000 - 300,000

Second trimester

24,000 - 55,000

Third trimester

6,000 - 48,000

HCG info published by the
Center for Human Reproduction in Chicago

SPALS members have collected numerous links to sites with information about HCG levels and monitoring -- these are provided for information only:

What is a "level II" or "level III" ultrasound?

The higher levels refer generally to greater resolution of the ultrasound image. Ultrasound machinery ranges in price from $10,000 to $300,000, so you can imagine the quality of what you see on the scan can be tremendously different. A higher resolution machine can give much clearer details of the embryo/fetus and is often used as a non-invasive means of ascertaining fetal problems.

What are "AC", "BPD", "FL" and "HC" in ultrasound measurements?

Abdominal Circumference (AC) measures the mother's belly in cross section. Especially later in pregnancy, it is used as an indicator of fetal weight and growth. Sometimes, serial measurements are taken to ensure an accurate reading.

BPD stands for Biparietal Diameter and is an ultrasound measurement taken of the baby's head (from side to side). Along with the Femur Length (FL) and Abdominal Circumference (AC), it is used to estimate the fetal weight.

Femur Length (FL) often is measured along with AC and BLD measurements. The femur is the longest bone in the body and measurement of this bone is taken to estimate fetal growth.

AC, BPD and FL are combined in a formula to estimate fetal weight. While most ultrasound machines contain calculators, here is the formula used to figure the fetal weight: 1.4 X BPD X FL X AC (all in centimeters) - 200 = Fetal weight. (This is an estimate and becomes less accurate as baby gets farther from about 5.5 lbs.)

HC indicates Head Circumference. Babies of the same weight can have different head sizes.