Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: A retrospective evaluation was done of 102 consecutive in in vitro fertilization-embryo transfer (IVF-ET) treatment cycles that culminated in surgical intervention for oocyte pickup. In 35% of these patients, a disparity was noted in the number of mature follicles present on the day of human chorionic gonadotropin administration, compared with the day of surgery. This suggests the occurrence of undetected ovulation. An endogenous luteinizing hormone (LH) surge was detected in 14 of these patients. Another cohort showed evidence of early luteinization without a detected endogenous LH surge. Finally, a group without early luteinization was defined. Possible explanations for these outcomes and the implications for success of IVF-ET are discussed.

Ovulation