Brown Spotting: Implantation, Breakthrough, Ovulation, and Other Causes

What Brown Spotting Means

Brown discharge indicates old blood (oxidized hemoglobin) that has taken time to exit the uterus/vagina. It is distinct from bright red (fresh) bleeding.

Common Causes by Context

Cause	Timing	Characteristics	Clinical Significance
Implantation bleeding	6–12 DPO (days post-ovulation)	Scant, pink/brown, 1–2 days, no clots	Early pregnancy sign; ~25% of pregnancies
Ovulation spotting	Mid-cycle (day 14 ± 2)	Light, brief, may have mittelschmerz	Normal; estrogen dip
Breakthrough bleeding (OCP)	Anytime on hormonal contraception	Light, irregular; common first 3 months	Usually benign; if persistent → change formulation
Hormonal fluctuation	Perimenopause, PCOS, thyroid dysfunction	Irregular, unpredictable	Evaluate endocrine
Cervical ectropion / polyp	Post-coital, intermenstrual	Bright red or brown; friable tissue	Benign; treat if symptomatic
Endometrial polyp / hyperplasia	Intermenstrual, heavy periods	May be brown or red	Ultrasound ± hysteroscopy
Early pregnancy loss	After positive test	Progresses to red, cramping	Urgent eval
Ectopic pregnancy	6–10 weeks	Brown spotting + unilateral pain	Emergency

When to See a Clinician

• Spotting persists >3 cycles or >7 days.
• Associated pain, fever, malodorous discharge.
• Postmenopausal any bleeding.
• Pregnancy test positive + bleeding.
• On anticoagulants or hormonal therapy with new pattern.

Diagnostic Steps

1. Pregnancy test (urine/serum β-hCG).
2. Speculum exam: cervical visualization, swabs (STI, cytology).
3. Transvaginal ultrasound: endometrial thickness, uterine/ovarian pathology.
4. Labs: TSH, prolactin, FSH/LH/estradiol (if indicated), coagulation.