Spotting Between Periods: Causes and When to See a Doctor

What counts as spotting versus a period?

A menstrual period follows a predictable cycle and produces a predictable volume of blood over several days. Spotting is lighter bleeding that occurs outside of that pattern — it may be a few drops on underwear, light staining, or a brief episode of pink or brown discharge. The medical term for any uterine bleeding that falls outside a normal cycle is abnormal uterine bleeding (AUB); intermenstrual bleeding is one subcategory 1Ref 1Committee on Practice Bulletins — Gynecology, ACOG (2012).Practice Bulletin No. 128: Diagnosis of Abnormal Uterine Bleeding in Reproductive-Aged Women.Classification of abnormal uterine bleeding (PALM-COEIN system), evaluation framework including STI screening and endometrial biopsy indications, breakthrough bleeding on hormonal contraception.

Brown spotting often means older blood — blood that took longer to leave the uterus and oxidized in transit. Pink spotting often reflects light, fresh bleeding mixed with cervical mucus. Neither color alone determines the cause or urgency.

What are the most common causes?

Hormonal contraception is one of the leading causes. Breakthrough bleeding is especially common in the first few months of starting a new pill, patch, ring, hormonal IUD, or implant as the uterine lining adjusts. Missing doses of an oral contraceptive can also trigger spotting 1Ref 1Committee on Practice Bulletins — Gynecology, ACOG (2012).Practice Bulletin No. 128: Diagnosis of Abnormal Uterine Bleeding in Reproductive-Aged Women.Classification of abnormal uterine bleeding (PALM-COEIN system), evaluation framework including STI screening and endometrial biopsy indications, breakthrough bleeding on hormonal contraception.

Ovulation (mid-cycle) spotting occurs in a small proportion of people around day 14 of a 28-day cycle when the brief drop in estrogen that accompanies the LH surge can cause a small amount of spotting. It typically lasts one to two days.

Cervical causes — including cervical ectropion (where the inner lining of the cervix extends to the outer surface), cervical polyps, or inflammation — can bleed with minimal provocation, including after intercourse (postcoital bleeding).

Infections such as chlamydia or gonorrhea cause cervicitis, which can present as irregular bleeding or postcoital spotting. STI screening is a standard part of evaluation for intermenstrual bleeding in people who are sexually active [1, 2].

Uterine causes — endometrial polyps, submucosal fibroids, and endometriosis — can all produce irregular bleeding. These are more fully addressed in evaluation when spotting is persistent or accompanied by pain or heavy periods.

Perimenopause brings irregular cycles as ovulation becomes erratic. Spotting during the perimenopausal transition is common but should still be evaluated, since postmenopausal bleeding (any bleeding more than 12 months after the final period) always warrants investigation to rule out endometrial pathology 3Ref 3American College of Obstetricians and Gynecologists (2019).Screening and Management of Bleeding Disorders in Adolescents With Heavy Menstrual Bleeding: ACOG Committee Opinion, Number 785.Clinical context for evaluating perimenopausal irregular bleeding and the importance of investigating any bleeding outside expected patterns including postmenopausal bleeding.

Pregnancy-related causes — including implantation bleeding in early pregnancy, a subchorionic hematoma, or an undetected pregnancy — should be considered whenever there is any chance of pregnancy.

What will a gynecologist do to evaluate spotting?

A thorough history — cycle pattern, contraceptive use, recent changes, sexual activity, and associated symptoms — guides the workup. The physical exam typically includes a speculum exam to visualize the cervix and vaginal walls.

Common tests include: - Pregnancy test (if applicable) - Pelvic ultrasound to assess the uterine cavity, endometrial lining thickness, and ovaries - STI screening (chlamydia, gonorrhea) - Pap smear and HPV co-test if due or if cervical pathology is suspected - Hormonal labs (TSH, prolactin, or androgen levels) when a hormonal cause is suspected - Endometrial biopsy in people over 45 or when an endometrial cause needs ruling out [1, 2]

When does spotting need prompt attention?

Most intermenstrual bleeding can be evaluated at a scheduled gynecology appointment. A few situations deserve quicker attention:

• Bleeding heavy enough to soak a pad or tampon per hour
• Postmenopausal bleeding (any bleeding after 12 consecutive months without a period)
• Spotting accompanied by significant pelvic pain or fever
• Positive pregnancy test with any bleeding (to rule out ectopic pregnancy)

Spotting in early pregnancy with cramping requires same-day evaluation — it can signal an ectopic pregnancy, a potentially serious condition 2Ref 2American College of Obstetricians and Gynecologists (2013).ACOG Committee Opinion No. 557: Management of Acute Abnormal Uterine Bleeding in Nonpregnant Reproductive-Aged Women.Urgent evaluation criteria for acute abnormal uterine bleeding including ectopic pregnancy risk; endometrial biopsy and STI screening indications.

How is intermenstrual bleeding treated?

Treatment depends entirely on the cause. Breakthrough bleeding on hormonal contraception often resolves on its own; adjusting the formulation or method can help if it persists. Cervical ectropion usually requires no treatment. Polyps are typically removed in an outpatient procedure. Infections are treated with antibiotics. Fibroids and endometriosis have a range of management options depending on symptom severity and fertility goals.

Many people find that identifying and treating the underlying cause resolves the spotting completely 1Ref 1Committee on Practice Bulletins — Gynecology, ACOG (2012).Practice Bulletin No. 128: Diagnosis of Abnormal Uterine Bleeding in Reproductive-Aged Women.Classification of abnormal uterine bleeding (PALM-COEIN system), evaluation framework including STI screening and endometrial biopsy indications, breakthrough bleeding on hormonal contraception.