Persistent Foul-Smelling Brown Vaginal Discharge After Period: Causes and Workup

Brown discharge = old blood (oxidized hemoglobin). Foul odor suggests infection or necrosis. Persisting >1 week post-menses requires evaluation.

Differential Diagnosis

• Bacterial vaginosis (BV): Fishy odor, gray-white discharge; clue cells, pH >4.5.
• STIs: Trichomonas (frothy, yellow-green), gonorrhea/chlamydia (mucopurulent).
• Retained products: Post-miscarriage/D&C; tissue necrosis → foul discharge.
• Endometritis: Postpartum/post-procedure; fever, uterine tenderness, purulent discharge.
• Foreign body: Forgotten tampon → profuse foul discharge.
• Cervical/endometrial cancer: Watery, blood-tinged, foul discharge (advanced).
• Fistula: Vesicovaginal/rectovaginal → fecal/urinary odor.

Workup

• Speculum exam, wet mount, pH, whiff test, NAAT for STI.
• Pelvic ultrasound (retained tissue, mass).
• Endometrial biopsy if >45 or risk factors.
• Colposcopy if abnormal cytology.

Do not douche—worsens dysbiosis. Treat based on diagnosis (metronidazole for BV/trich, antibiotics for STI/pelvic infection, removal for foreign body).