Table 1.

Differential diagnosis of primary and secondary dysmenorrhea

	Primary dysmenorrhea	Secondary dysmenorrhea
Onset	Within 3 yr after menarche	More than 5 yr after menarche
Age	15–25 yr old	Over 30 yr old
Aging	Gradually improve	Become worse
Marriage	Improve	No change
Postpartum	Improve	No change
Findings of internal examination	Normal	Endometriosis, fibroma, etc.
Time	Menstruation	Menstruation or other time if worse
Duration	4–48 h	1–5 d