[The LUF syndrome. A possible cause of unexplained infertility]

It is probable that one or several conditions may exist in which the oocyte is not released at the expected time of ovulation but where the follicle luteinizes around it. This cannot be demonstrated with the usual criteria for ovulation. A diphasic temperature curve, normal increase in progesterone and secretory development in the endometrium are observed. The reason for this phenomenon is not known but it may be induced experimentally by intake of prostaglandin-synthesis-inhibitors. It is difficult to determine with certainty in the individual case whether the egg has been released. The presence of an ovulation opening, a stigma which may be seen on the follicle by laparoscopy, marked increase in the concentration of progesterone and 17-beta-oestradiol in the peritoneal fluid and ultrasound demonstration of a collapsed follicle are good indicies. Defective release of the egg cell probably occurs periodically in cycli in normal fertile women but the condition appears to be more frequent in infertile women with endometriosis, with changes after pelvic inflammation and with "unexplained" infertility. As definite criteria for the condition are not available, no convincing investigations of the frequency are available and no controlled investigations of therapeutic method exist. Gametic intrafallopian transfer and in vitro fertilization and embryo transfer have been proposed as therapeutic measures.