The corpus luteum echo appears 7-8 days after ovulation and is monitored by doing ultrasound. When a woman ovulates, the follicle wall collapses after the egg is expelled from the ovary, and the connective tissue and capillaries and other tissues inside form a cellular mass called the corpus luteum because of its yellowish color. When a woman is ovulating, the egg and sperm do not unite and develop into a fertilized egg, i.e., she does not conceive, and the corpus luteum shrinks in about 14 days. If the corpus luteum grows faster and larger during the luteal phase, the corpus luteum may rupture and women may experience severe lower abdominal pain, which may require surgery if necessary.