Primary dysmenorrhea is defined as pain occurring in the lower abdomen before or during menstrual cycle, in the absence of other diseases such as endometriosis. Primary dysmenorrhea is by far the most common gynaecological problem. It is so common that many females fail to report it in medical interview, even when their daily activities are restricted.
Primary dysmenorrhea can be distinguished from secondary dysmenorrhea by number of factors. Second dysmenorrhea may be indicative of:
- Dysmenorrhea occurring during first one or two cycles after menarche.
- Dysmenorrhea occurring after 25 years.
- Late onset of dysmenorrha after a history of painless menstruation (consider complications of pregnancy : ectopic or threatened spontaneous abortion)
- Pelvic abnormality on physical examination, infertility heavy menstrual flow or irregular menstrual cycle
- Little or no response to therapy with drugs like NSAIDs, oral contraceptives or both.
Primary dysmenorrhea usually presents at the age of adolescent within three years of menarche. However, it is unusual for symptoms to start within the first six months after menarche. Females suffering from primary dysmenorrhea may experience sharp, intermittent spasms of pain, usually centered in suprapubic area. Pain may radiate to lower back or back of legs. Systematic symptoms of primary dysmenorrhea may include nausea, vomitting, diarrhoea, fatigue, fever, headache or light-headedness.
The symptoms of primary dysmenorrhea may be accompanied by vasomotor changes that causes pallor, cold sweats and occasional fainting. Rarely syncope and collapse in severe cases may be assosciated. Pain usually develops within hours of the start of menstruation and peaks as the flow become heaviest during first day or two of the cycle. The severity of pain usually lasts for few hours, may extend to 24 hours but seldom persist beyond 48 hours.
The main cause of primary dysmenorrhea is very poorly understood but it is assosciated with initiation of uterine pain. The factor related to initiation of pain are
- Psychosomatic factor: This is due to tension and anxiety during adolescence which may explain, in part, the disappearance of pain with advancing age.
- Role of vasopressin: The release of vasopressin increases in primary dysmenorrhea during menstruation in primary dysmenorrhea. The increased release of vasopressin increases the synthesis of prostaglandins and also increases myometrial activity directly. It causes uterine hyperactivity and dysrhythmic contractions, ischemia, hypoxia which ultimately results in pain.
- Role of Prostaglandins: During endometrial sloughing, the disintegrating endometrial cells release PGF-2 alpha as menstruation begins which stimulates myometrial contractions, ischemia, and sensitization of nerve endings. The hyper-contractility results in reduced blood flow leading to hypoxia and ischemia which is believed to be the cause for pain and cramps.
NSAIDs, Diclofenac, etc.
- Oral Contraceptive Pills, etc.
- Heat Therapy,
- TENS: Review suggests that Primary Dysmenorrhea can be effectively managed with Transcutaneous Electrical Nerve Stimulation (TENS) as it is safe, portable, battery-operated, and relatively inexpensive.
- Exercises like Kegel and pilates.
- In rare cases. 
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- Elboim-Gabyzon M, Kalichman L. Transcutaneous Electrical Nerve Stimulation (TENS) for Primary Dysmenorrhea: An Overview. International Journal of Women's Health. 2020;12:1.
- Linda French. Dysmenorrhea. American Family Physician. 2005; 71(2): 285-91