| Parameter | Normal | Abnormal |
| Frequency | ≥24 and ≤38 days | Absent (no bleeding): amenorrhea |
| Frequent (<24 days) | ||
| Infrequent (>38 days) | ||
| Duration | ≤8 days | Prolonged (>8 days) |
| Regularity | Regular: shortest to longest cycle variation: ≤7 to 9 days* | Irregular: shortest to longest cycle variation: ≥10 days |
| Flow volume (patient determined) | Patient considers normal | Patient considers light |
| Patient considers heavy | ||
| Intermenstrual bleeding (bleeding between cyclically regular onset of menses) | None | Random |
Cyclic (predictable):
| ||
| Unscheduled bleeding on progestin±estrogen gonadal steroids (contraceptive pills, rings, patches, IUDs, or injections) | Not applicable for patients not on gonadal steroid medication | Present |
| None (for patients on gonadal steroid medication) |
IUDs: intrauterine contraceptive devices.
* Normal variation depends on age; these data are calculated excluding short and long outliers.