Follicle growth curves and hormonal patterns in patients with the luteinized unruptured follicle syndrome

A prospective longitudinal and standardized study is presented, dealing with ultrasonographic and hormonal characteristics of the luteinized unruptured follicle (LUF) syndrome. Among 600 cycles monitored in 270 infertility patients, 40 cycles in 27 patients showed no evidence of follicle rupture, in spite of signs of luteinization, as reflected by basal body temperature recordings and progesterone determinations. In this study, 20 LUF cycles in 20 infertile patients were compared with 45 ovulatory cycles in 45 control women. During the follicular phase, no substantial difference in follicle growth was found, but after the luteinizing hormone peak, LUF follicles, instead of rupturing, showed a typical accelerated growth pattern. Both mean luteinizing hormone peak levels and midluteal progesterone levels were significantly lower in LUF cycles than in the control cycles. However, the duration of the luteal phase was not affected. Both central and local factors can be held responsible for the lack of follicle rupture. Ultrasound offers new possibilities as a noninvasive method in diagnosing the LUF syndrome.