[Ultrasonographical study on luteinized unruptured follicle]

The clinical features and the intrafollicular environment of luteinized unruptured follicle (LUF) were investigated in 60 infertile women by means of ultrasonography. LUF was diagnosed in daily ultrasound scans in 52 (13.5%) of 384 apparently ovulatory cycles. High incidences of LUF cycle were observed in the patients with polycystic ovary (37.5%), endometriosis (24.7%) and a history of pelvic surgery (26.2%), whereas LUF cycles were rare in the patients who conceived (2.7%). Mean follicular diameter measured by transvaginal ultrasonography showed no difference between LUF and ovulatory cycles during the follicular phase, whereas during the luteal phase, a continual growth pattern without follicular collapse was observed in LUF cycles. The ultrasonic aspiration of the follicle was carried out in 21 LUF cycles on the luteal phase. In 19 cases, hormonal profiles for the aspirated follicular fluid coincided with the preoperative diagnosis, and in 6 of 19 cases (31.6%), the presence of entrapped oocytes, direct evidence of LUF, was demonstrated. The morphological observation revealed that the oocytes recovered from the LUF follicle were in the stage of postmaturity, and the fertilization test in which they were used resulted in abnormal fertilization. These results indicate that LUF is an important cause of infertility and that periovarian abnormality might contribute to the failure of follicular rupture and postmaturity.