Tail-End Brown Bleeding (TEB)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

Tail-End Brown Bleeding (TEB) is a Creighton Model biomarker defined as two or more days of brown or black discharge at the conclusion of menstrual flow, after the heavier bleeding days have passed.¹

Brown blood at the end of menses is old, incompletely shed endometrial tissue. In a well-functioning cycle, the endometrium clears cleanly. When it does not, TEB appears. The Creighton Model captures this pattern precisely on a standardized chart, distinguishing TEB from normal menstrual variation. The clinical question it raises is why the endometrium did not shed completely. Contributing causes include luteal phase deficiency and insufficient progesterone support in the prior cycle,²³ chronic endometritis,⁴ endometriosis, uterine polyps, and fibroids. Each is a diagnosable, treatable condition.

Women frequently normalize TEB because they have lived with it for years and no clinician has flagged it. That is a missed diagnostic opportunity. A well-kept fertility chart gives the clinician a documented pattern across cycles rather than a single reported symptom. Pattern recognition is the point. One brown day at period's end means little. Two or more days, cycle after cycle, is a signal worth pursuing.

TEB on its own does not confirm a diagnosis. It directs the clinical evaluation toward the underlying cycle physiology. NaProTechnology-trained clinicians use TEB alongside other biomarkers and cycle-timed hormone measurements to identify which diagnosis is driving the pattern. Addressing the root cause typically resolves the bleeding irregularity.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.