Abnormal uterine bleeding (AUB) isn’t a final diagnosis—it’s a symptom. And when someone walks into your office with heavy, irregular, or unexpected bleeding, the question isn’t “What’s the name of the condition?” It’s “What systems could be at play here?”

This is where we stop chasing zebras, resist the urge to blindly order an ultrasound, and start grouping possible causes into one of 5 meaningful categories for more diagnostic clarity, and a plan that helps you get your patient answers fast. Let’s break it down.

Abnormal uterine bleeding is one of the most common gynecologic complaints. It is also one where patients’ concerns are often ignored. As an OBGYN, I get referrals for this symptom all the time. While almost everyone gets a pelvic ultrasound, there are often gaps in the history or simple blood tests that would have helped the patients get some reassurance or relief before a three- to six- month wait to see me. This guide outlines key causes, targeted history, and the best labs and imaging for reproductive-age patients with AUB.