Laparoscopy
Visualization of the ovaries and the exterior of the Fallopian tubes and uterus by means of the inserting a surgical instrument through a small incision below the naval; one or two other punctures may be made through which additional instruments can be inserted and manipulated.

Laparotomy
A surgical opening of the abdomen.

Leiomyoma (fibroid)
A benign tumor of the uterus.

Leutenizing Hormone (LH)
The increase in LH level during the middle of a woman’s cycle triggers ovulation, the release of a ripened egg from a follicle.

Leydig cells
The cells in the testicles that make testosterone.

LH surge
The sudden release of luteinizing hormone (LH) that causes the follicle to release a mature egg.

Luteal phase
Post-ovulatory phase of a woman’s cycle; the corpus luteum produces progesterone, which in turn causes the uterine lining to secrete substances to support the implantation and growth of the early embryo.

Luteal phase defect (LPH)
Inadequate function of the corpus luteum that may prevent a fertilized egg from implanting in the uterus or may lead to early pregnancy loss.

Luteal phase protocol
A LH-RH (GnRH) agonist is administered in the luteal phase of the prior cycle to cause pituitary down-regulation. The exogenous gonadotropins administered are the only stimulation given to cause follicles to develop. This protocol does not utilize the “flare” potential of a LH-RH agonist.

Luteinized Unruptured Follicle (LUF) syndrome
The failure of a follicle to release the egg even though a corpus luteum has formed.

Luteinizing hormone (LH)
The pituitary hormone that causes the testicles in men and ovaries in women to manufacture sex hormones.