Menstrual flow, finally measurable.
Joii turns a pad and a phone photo into objective menstrual measurement - built and registered as a medical device.
Why it matters
Sixty years of guesswork.
Heavy menstrual bleeding is one of the most common reasons women seek gynaecological care - yet it is almost always judged by estimation. The only objective measure of blood loss, the alkaline haematin laboratory method, is so slow and impractical that it is virtually never used in routine care. And estimation correlates poorly with what is actually happening.
The result: women dismissed when something is wrong, and women treated for a problem they may not have. Joii makes objective measurement practical.
Our story
Why I built Joii.
Joii began with my own body. For about a week every month, I lived in what I can only describe as survival mode - heavy bleeding, pain and anaemia, and days I couldn’t get out of bed, let alone go to work. It took more than three years to be diagnosed with fibroids.
Along the way I kept meeting women in exactly the same position: debilitating symptoms, dismissed as “the norm”, and years spent waiting for answers. None of us could answer a simple question - how much am I actually bleeding?
I built Joii so that question finally has an objective answer. What began as my own frustration became a five-year effort to build, test and register a real medical device - one that takes a measurement that used to need a lab and puts it in your hand.
— Justyna Strzeszynska, Founder & CEO
How it works
A measurement in three steps.
The science
Built to a medical-device standard, backed by evidence.
Registered medical device - UKCA-marked Class I, MHRA-registered.
What Joii measures today - Objective menstrual fluid volume and clot size, from a single pad scan.
Validating the measurement - Menstrual fluid is not the same as blood loss, and blood loss is the clinical signal that matters. With Dr Bassel Al Wattar at Anglia Ruskin University, Joii's fluid measurement is first being validated against the gravimetric (weighed-pad) reference; blood-loss validation against alkaline haematin, the laboratory gold standard, follows in a dedicated lab now being established.
Real-world study · University of Bradford — In a five-month real-world study, women's confidence in gauging their own blood loss rose from under 5% to over 80%. Period health literacy improved by a median of 52%, communication with clinicians by 33%, and symptom screening by 36%.
NHS primary-care evaluation · NIHR i4i — NHS GPs strongly backed it: 90% agreed Joii improved patients' period health literacy, 82% that its scanner could replace current methods of assessing period volume and clot size, and the large majority said they'd use it in practice if NHS-approved.
The Evaluation Pads
Pads designed for accurate measurement.
Day Evaluation Pads
Night Evaluation Pads
For partners and researchers
Objective measurement for clinical research and care.
Joii is used as an objective measurement tool in clinical research and care settings. If you are running a study or service where menstrual blood loss needs to be measured objectively, we’d like to talk - including about the alkaline haematin validation now underway.