In normal healthy fertile females, ovulation with rupture of the mature ovarian follicle and release of the eggs occurs within 38 hours of the surge in luteinizing hormone (LH). However, in a small percentage of women, the dominant follicle will undergo the luteinization process but will not rupture following the midcycle LH surge. This is called LUF (luteinized unruptured follicle syndrome). As a result of the increased progesterone secretion, the endometrium undergoes the secretory changes, but, obviously, without the release of the oocyte , pregnancy cannot occur. This means that the cycles are regular; and hormonal studies ( Day 21 progesterone level) , the basal body temperature curve, and the findings in an endometrial biopsy will all be consistent with ovulation.
This is obviously a difficult diagnosis to make; and can only be made by serial vaginal ultrasound scans to track ovulation. These scans show that the follicle matures; but the dominant follicle fails to rupture. The lack of follicle rupture and the lack of free peritoneal fluid around the time of ovulation are used to establish the diagnosis of LUF. This condition is also called “trapped egg syndrome”.
LUF is more commonly seen in women with endometriosis; and PCOD. Often the diagnosis is made only when patients are being monitored for follicle tracking with serial ultrasound scans. LUF is a “silent” problem; and because it does not cause any symptoms or signs, it’s very easy to miss the diagnosis as well ! Since LH is responsible for inducing follicular rupture, LUF can be treated by giving an injection of Human Chorionic Gonadotropin (hCG) in a dose of 10,000 IU intramuscularly, when the lead follicle reaches 18-20 mm in diameter. Ultrasound can be used to document ovulation. It takes about 36 to 40 hours for the oocyte to be released after the injection. Intercourse or insemination should be timed accordingly. If it still does not take place, the dose of the hCG injection can be increased. If ovulation still cannot be achieved even with an increased dose of 20000 IU , then IVF is the best solution.
In our clinic, we really do not bother to make a diagnosis of LUF ! This is because this diagnosis does not really change your treatment options . After all, if you are infertile, this means the eggs and sperm are not meeting. The next step logically is to then do an IUI – and since an HCG injection is routinely given during IUI treatment to induce ovulation, the IUI automatically helps to treat patients who have LUF !