Irregular periods (aka irregular menstruation, irregular cycles) is irregular/abnormal variation in length of menstrual cycles, but can also be used to refer to other conditions that mimic it.
Patient information
What are irregular periods?
So it's where there's are variations in the length of the menstrual cycle.
Classification
Variations in cycle length, between the shortest and longest cycle:
<8 days, is normal
8-20 days, is moderate irregular
21+ days is very irregular
Alternatively, a single menstruation period is irregular if it is <21 days, or >35 days. However, if it is regularly <21 days, it is polymenorrhea (aka frequent periods); or if regularly >35 days, is oligomenorrhea.
Patient information
So periods are supposed to be periodical, so around 28 days. What are irregular periods?
So remember the key So you're exactly correct. It's supposed to be 28 days, and we give leeway of +/- 1 week. So it's irregular if it's <21 days, or >35 days.
DDx
Metrorrhagia (vaginal bleeding between expected menstrual periods)
Oligomenorrhea (infrequent menstruation, >35 days, thus only permitting 4-9 periods in a year)
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