Diagnosis: Luteal Phase Defect
What a Luteal Phase Defect (LPD) Means and Its Impact on Fertility
In order to talk about the important things like progesterone levels, you need to know something about your cycle. Simply put, your cycle is broken down into two parts. Pre-ovulation, it's called the follicular phase. As it sounds, this is the part of the cycle where the follicle is growing and preparing to release an egg. After ovulation, the second part of your cycle is called the luteal phase. This is the time where the embryo implants and (hopefully) gets cozy for the next nine months. If the embryo fails to implant--or going even more basic, the egg fails to fertilize--the cycle ends and begins anew with your period.
Follicular phases can vary in length. Sometimes, they fit the average 28 day cycle and the person has a 14 day follicular phase and a 14 day luteal phase. But the length of time is determined by the follicle's rate of growth because the follicular phase will continue until the egg is released. That could happen earlier than 14 days or much later than 14 days.
The luteal phase isn't really supposed to vary in length like the follicular phase. The length of the luteal phase is determined by the corpus luteum (the "yellow body" that is left after the egg is released from the follicle). The breaking down of the corpus luteum and the end of the cycle usually happens around 12--14 days after ovulation (unless the embryo implants).
But in some women, it happens much sooner. Or the corpus luteum doesn't secrete enough progesterone. Or the progesterone it does secrete doesn't build up the endometrial lining for implantation. Which means that the person either cannot become pregnant or maintain a pregnancy.
There are several tests that are used to determine a luteal phase defect. The least invasive is what is called a "day 21 progesterone test." It actually needs to be drawn around 7 days post ovulation (7 dpo). Therefore, it would only occur on the 21st day of your cycle if your cycle was 28 days long and you ovulated on the 14th day. Most doctors want to see at least 10 ng/mLs of progesterone and some give a diagnosis of low progesterone for anything under 20 ng/mLs.
Some doctors will treat a LPD with progesterone supplements and follicular-stimulating hormones without conducting more tests. But those who have normal progesterone levels and adequate follicles may have an endometrial biopsy performed if a day-21 sonogram (again, 7 dpo) reveals endometrial lining that is too thin. Whether or not your doctor progresses to performing an endometrial biopsy will be determined by his comfort with diagnosing from blood work and sonograms.
The corpus luteum is only as good as the follicle that creates it. Therefore, many doctors begin by attempting to nurture great follicles which will in turn become strong corpus luteums. Doctors will prescribe Clomid (oral) or an follitropin like Follistim or Gonal-F (sub-cue injectible) to stimulate follicle growth. After ovulation, vaginal suppositories of Prometrium are prescribed (there are also IM injections of progesterone).
We began suspecting there was a problem once I began charting my temperature. Most months, my luteal phase was only 10 days long (or less). But on other months, my luteal phase would stretch as long as 21 days without tipping a positive home pregnancy test (though blood work showed low hcG levels). Blood work 7 dpo confirmed low progesterone. My first blood draw had a result of less than 5 ng/mL. Every subsequent test showed under 3 ng/mL.
We took Clomid (days 3--7) and then Follistim (over the course of many days based on sonograms and hormone levels). After few days after an hcG shot to trigger ovulation, I took Prometrium twice a day until I received a negative beta (or in the case of the month I got pregnant, I continued taking Prometrium until my 15th week of pregnancy).