Answer: The answer to the question is DIAGNOSTIC HYSTEROSCOPY.
Couple of factors can be responsible for Lena's unusual menstruation like stress, pelvic inflammatory disease, endometriosis and use of birth control pills.
Hysteroscopy is aimed at examining the uterus to know the possible cause of Lena's unusual menstruation.
Explanation: Lena's doctor will examine her Uterus using a thin lighted tube known as a hysteroscope.
The Hysteroscope will be used alongside the attached light by the doctor to view and assess her cervix and uterus to ascertain the possible cause of her unusual menstruation.
Lena's doctor can also do a pelvic examination for Lena to note and examine the positions and sizes of her pelvic organs.
Lena's doctor can as well send Lena for pelvic ultrasound to visualize the organs in her pelvic region.