Brown Vaginal Discharge: Causes, Significance, and When to See a Doctor

Common Causes

1. Menstrual cycle: Old blood at period start/end, mid-cycle spotting.
2. Hormonal contraception: Breakthrough bleeding, especially with progestin-only or low-dose pills.
3. Implantation bleeding: Light, brief, ~6–12 days post-ovulation.
4. Infections: Bacterial vaginosis (fishy odor), trichomoniasis, cervicitis.
5. STIs: Chlamydia, gonorrhea – often with other symptoms.
6. Cervical/uterine polyps, fibroids.
7. Pregnancy complications: Threatened miscarriage, ectopic (urgent).

Red Flags for Prompt Evaluation

• Persistent >3–5 days
• Foul odor, itching, burning
• Associated pelvic pain, fever
• Pregnancy possibility
• Postmenopausal bleeding

Diagnostic Approach

• History, speculum exam, pH, whiff test, wet mount
• STI NAATs (chlamydia, gonorrhea, trichomonas)
• Ultrasound if structural lesion suspected
• Endometrial biopsy if >45 or risk factors

Most causes are benign, but timely assessment rules out serious pathology.