Please be aware that these guidelines apply to most, but not all, pregnancies. If you have any questions concerning these guidelines, please contact the office.
We utilize physical examination, blood hormone testing and ultrasound to evaluate the first critical weeks of pregnancy. At Mainline Fertility we consider the date of conception (whether by insemination or intercourse) to be gestational day 0. Thus, on the day of the missed menstrual period, a woman will be on her 14th day of pregnancy. The reader should be aware that obstetricians, in general, number the days (or weeks) of pregnancy beginning with the last normal menstrual period. The difference in these numbering systems is a never ending course of confusion when discussing the length of a pregnancy.
Physical examination yields only a little information about early pregnancy. Subtle physical signs of early pregnancy include a softening of the lower uterus and a bluish discoloration of the cervix. These signs are of modest value in our current technological world. Most examinations done in early pregnancy are performed to identify particular problems such as ovarian cysts or the pelvic tenderness which may be associated with a pregnancy in the fallopian tube (ectopic pregnancy) . Evaluation for enlargement of the ovaries is of particular importance in cases where fertility drugs have been administered.
Blood hormones are particular informative during the first three weeks of pregnancy. We measure human chorionic gonadotropin (hCG) and progesterone . Although we might detect an elevation in the hCG level of a pregnant patient about 11 or 12 days after conception, at this early stage levels of hCG can be confusing. Therefore, in most cases, we do not attempt to measure hCG levels until the time of the missed menses.
HCG levels will rise in a predictable way in normal pregnancy. The level of hCG hormone will (approximately) double every two days during the first month of pregnancy. Because of this predictable doubling time, we focus on changes in hCG level (rather than a single absolute value of that hormone) to make judgments about the health and vigor of a pregnancy. An hCG level which is not doubling appropriately may indicate a pregnancy that is going to miscarry. Because there are exceptions to this general rule, we use additional testing to evaluate questionable pregnancies.
Whereas hCG is produced by the pregnancy within the uterus, the hormone progesterone is produced by the ovary of the pregnant woman. Progesterone is required to maintain the lining of the uterus in a receptive state for the pregnancy to grow and develop. A low progesterone level in pregnancy may reflect a poorly functioning pregnancy or a weakness within the ovary. In the latter cases the administration of supplemental progesterone will help support the pregnancy.
After 3 weeks, ultrasound is the most accurate and important way we monitor early pregnancy. A pregnancy can first be visualized as a collection of fluid (gestational sac) within the uterus about 18-23 days after conception. When we are worried that a patient might have a pregnancy in her fallopian tube (ectopic pregnancy), we will perform an ultrasound to see whether a gestational sac is in the uterus. If we fail to see a gestational sac, a tubal pregnancy may exist. Alternatively, it may be too early in the pregnancy for the gestational sac to show up; or, a poorly growing pregnancy (destined to miscarry) may be in the uterus.
By the time the gestational sac has reached a diameter of 9 mm, we should visualize an internal ring-like structure within the sac, called the yolk sac. The yolk sac is the earliest visualizable feature of the fetus. If a gestational sac grows large but does not contain a yolk sac, it is termed an empty sac. An empty sac can be the first indication that a pregnancy is destined to miscarry.
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