Abstract In the United States, approximately 30% of reproductive aged women suffer from AUB and the associated symptom of heavy uterine bleeding (menorrhagia), a menstrual disorder that drastically impairs quality of life and has an annual economic burden of $37 billion. Women afflicted by AUB experience limitations in social, physical, and leisure activities, and incur a substantial personal financial burden due to work absence and home management costs (>$2,000 per year). Despite the high prevalence of this medical condition, clinicians rely on women who are distressed by their menses to give a subjective self-assessment of their menstrual blood loss (MBL), which has proven to be unreliable for accurate diagnosis and can lead to unnecessary surgery. Given that these symptoms account for one-third of all office visits to the gynecologist, choosing an appropriate treatment course is critical for providing high-quality care to Americans. Current methods for quantifying MBL have key drawbacks that limit their use. Alkaline hematin (AH) testing is the standard required by regulatory bodies for objective quantification of MBL. Unfortunately, AH testing is impractical for routine clinical practice as it is expensive (~$1000 per cycle) and has poor acceptability, requiring patients to collect all used sanitary products and mail them to a lab facility for analysis. While pictorial blood loss assessment charts (PBLACs) offer a less costly, semi-quantitative method for MBL quantification, they demonstrate a high rate of false positive results (~59%), which leads to the over-diagnosis of menorrhagia. To address the need for a cost-effective, easy- to-use, and objective method to quantify MBL in premenopausal women, TheraNova has developed a cell phone- based diagnostic tool, the electronic MBL Diary (eMBLD). Previously, in a proof of concept clinical study, we demonstrated a strong correlation between eMBLD and AH testing, the gold-standard method for objective quantification of MBL. The goals of this Phase II proposal are to determine the effectiveness of our device for accurately diagnosing menorrhagia. First, we will verify the sensitivity of the image processing algorithm to accurately quantify MBL in women with both normal and heavy menses (Specific Aim 1). Second, we will conduct a pivotal clinical study to validate the effectiveness of eMBLD for diagnosing menorrhagia (Specific Aim 2). The data obtained will support FDA 510(k) clearance and will allow us to commercialize the system within four years of the funding of this proposal.