What is normal blood loss during menstruation?

Scottish scientist, Dr Steve Campbell, has created a website, which allows women to see if their menstrual blood loss is small, average, or too much. The concept behind the site is that most women lack a visual reference (or calibration in scientific terms) when assessing menstrual loss.

The website provides a reference using donated venous blood on sanitary towels [napkins or pads]. There is also an interactive blood loss calculator, record sheets, information on tests and treatments and a section for women with language difficulties, learning disabilities or for use by learning disability nurses. The site makes it possible use to improve research on dysfunctional endometrial bleeding by helping the patients report menstrual loss better to their doctors.

In the following article Dr Campbell tells the funny tale about how he created the website and why.

During the course of research carried out here by my medical colleagues it became obvious that a female research nurse measuring menstrual blood loss in research studies could very accurately estimate whether or not women were suffering heavy periods without making measurements. This was despite other studies, which suggest women have difficulty scoring loss and reporting it accurately to their doctors.

The reason the nurse was so good at estimating was that she had measured loss many times and simply came to know what 'heavy' looked like. The nurse, a fastidious person, had never undertaken laboratory work before and so kept a visual score to check that the results of her chemical tests made sense. She tried 2 methods a ‘rough score’ where she just looked at the collection and made a guess and a more precise method where she sorted the used tampons and towels into piles of increasing loss then giving a score to every towel or tampon. By attributing numbers to the visual score she became confident that she could make a good tally and so produce a very good guess about the volume of blood loss. We used her notes to show that her system produced very useful guesses and have presented these findings at 2 small medical research meetings.

We have also shown that a group of gynaecology nurses can accurately grade a group of towels to which known amounts of donated blood have been added (actually, the same ones as those featured on the site).

The exercise was then repeated with female laboratory staff and secretaries. These women could also grade loss very accurately despite having no professional medical experience. Indeed one woman later returned and told me what level would be regarded as heavy. In view of what I had read in research papers I found this surprising. The reason she knew was that she had had normal periods and then suffered a menstrual problem that required treatment. Her experience and level of knowledge did illustrate very clearly one thing that doctors and gynaecologist are well are of: women know when they are experiencing a menstrual change. It also impressed upon me the possible usefulness of informed estimation.

One of my senior academic medical colleagues happened to be in my office to ask a question about computers. I said, “take look at this” and showed him a graph of the nurse’s estimate versus the measured loss. Being a bright guy, he instantly suggested that if other women could be shown what loss looked like then they could report it better to the doctors and nurses involved in their healthcare. He stressed to me how women would often tell him how severe their loss in the toilet is and how concerned they become about it. He immediately suggested having an Internet site to explain loss. Ironically it was a man looking at a graph, who felt that menstruation should not be a taboo subject, although admittedly a gynaecologist.

I discussed the gynaecologist’s idea with my wife and mother, who also happened to be there at the time. Neither saw any problem with what my mother, despite her strict religious upbringing and socially conservative views, referred to as ”a natural biological function”.

Encouraged by this I announced that when I was going out that Friday evening to buy the food I would purchase a large number of sanitary towels from the supermarket so that we could add known amounts of blood to them in the laboratory. Both my wife and mother immediately jumped in saying that they would do that for me. “'Nonsense'” I said, “after having to buy heavy duty sanitary towels following childbirth, this is nothing to me'”.

I duly unloaded the food at the checkout then the small mountain of sanitary towels and placed the 'next customer' divider between them and the food. In as masculine a voice as I could muster I asked for a "separate receipt for the sanitary towels please". My face started to grow crimson and felt if it was about to catch fire.

I had to say something to the young female checkout assistant, who was possibly in her mid 20s. "Its for medical research" I said again in my most masculine voice. "Well, somebody’s got to do it", she said softly with a gentle and unembarrassed smile. Of course! She was absolutely correct. It is a subject where more research is needed.

In order to find out whether or not women did have a visual reference for assessing loss I asked my wife whether anyone had ever shown her used sanitary towels either as girl, as a medical student or when she was undertaking a post-graduate medical diploma in obstetrics and gynaecology. No, not even when she was training in the most medically relevant speciality. I then asked my sister rather sheepishly, then my mother, and then some of my female colleagues.

It was clear that the site of menstrual loss had become a taboo, at least in this country. Even if a woman were to show her doctor, gynaecologist or nurse what an example of heavy loss looked like would they know? By consulting www.menstrual-blood-loss.com they would at least have a better idea.

Research has shown that 30% of women attending hospital gynaecology clinics for other menstrual problems might not appreciate that they have heavy loss (Referral for menstrual problems: cross sectional survey of symptoms, reasons for referral, and management, BMJ 2001;323:24-28).

We have therefore been motivated by the knowledge that some women suffer heavy loss without even realising it. On the other hand the research evidence suggests that some women worry unnecessarily when their personal loss is not likely to be causing a medical problem.

Around this time I became aware of a research paper that tried to include estimates of loss in the toilet when assessing menses. We therefore simulated loss using my own blood in the toilet. (Although I am now a bit squeamish about needles I could not really ask for a colleague to volunteer, as often happens when someone needs blood in a research lab.) The very academic medical immunologist who took my blood for this purpose said it was the first time in her life that somebody was going take the blood that she had just withdrawn and put it straight into the toilet. She obviously found the situation pretty bizarre, although understood why we were doing this. Never having suffered blood loss in the toilet myself, I was amazed what it actually looked like. 5ml in a man’s hospital toilet looks really alarming although this is not even half the volume of a small bottle of nail varnish.

At this point a pharmaceutical company sales person came into the toilet. He saw the medical photographer and I jammed into the toilet cubicle and my blood in tubes in a tray on the floor. “The mind boggles” he said and left with the most perplexed look on his face that you are ever likely to see. We burst out laughing, had to stop the work and calm down so that we could get steady pictures again. We then continued to add more blood. As careful reading of the research paper shows, it was difficult for us to see the difference between 5 ml and more than that.

Later, when testing an early version of this web site on my sister it became obvious she did not really understand what the volume of loss looked like, partly because she baked and cooked in fluid ounces. She also did not know how these small volumes related to the total amount of blood in her body. I therefore returned to the supermarket and purchased everyday household items on which the volume was marked and had these photographed in the elegant female hand of a trainee gynaecologist.

Clearly a photo is not as good as the real thing. The reason the nurse can estimate very well is that she is very experienced, understands the significance of dark staining and light staining and can also see and feel the weight of the real thing. The obvious question is: can pictures really help? I needed to find a volunteer. One day my sister-in-law and I were chatting at home and she asked me about how work was going? I explained we had an early version of this site. “Interesting” she said, “I think I have heavy periods”.

After we went over the site together I told her that it seemed very likely she was having a very heavy loss and emphasised that she could probably get effective treatment by seeing her doctor. Despite this knowledge she did nothing about it at first. The problem became worse; she became short of breath and eventually felt that she had had enough. Hopefully she felt more confident about talking to her doctor after having looked at the pictures. Now she has seen her doctor and has had an effective treatment. These personal experiences lead me to believe that is was worth pursuing the development of the site and that photographs could help. The programmer who has worked with us then produced a script to create printable (PDF) pages of roughly life size in the hope that this would add a touch of realism (for examples click here). The gynaecologist who worked with me then had then had the bright idea that an interactive online calculator (click here) might help women to make a decision about whether or not they had a problem.

When my wife, a psychiatrist working with those with a learning disability, saw the pictures of household items she felt it would be helpful if women with a learning disability could get access to the site. She felt that the very visual aspect of the site would be useful to those who could not read and pointed me to an excellent series of “books without words” used for medical education. This is why drawings appear on the site. A speech and language therapist, who my wife introduced me to, explained that when helping those with a learning disability it is best to start with the real thing (she suggested an unused sanitary towel for example), then in order of preference a photo, a drawing, a symbol and last of all writing. Not surprisingly there were no female volunteers to be patients in illustrative photographs, such is the taboo of menstruation, although one female gynaecologist who has carried out laboratory research with me offered to play the doctor.

I did have another more academic reason for wanting to create this site that partly sprang from a conversation with a (male) pathologist with whom I collaborated in research. We were discussing why so many histopathology reports concerning the endometrial lining of uteruses removed at hysterectomies are described as ‘normal’ despite the complaint of heavy periods.

He explained that, often little or no clinically useful information is provided by the pathologist except when there is cancer (to simplify slightly). In other words, after examining microscope sections of human uterine tissue the pathologist usually does not send back a report to the gynaecologist that helps to explain why the patient had heavy bleeding. This might be partly due, he suggested, to the fact that pathologists and gynaecologists usually do not work together either on an individual patient basis or systematically in research on groups of patients to define what is normal and what tissue appearances are associated with particular clinical conditions.

The classic, but still relevant, paper on the human endometrial cycle (Noyes,R.W., Hertig,A.T. and Rock,J. (1950) Dating the endometrial biopsy. Fertil.Steril., 1, 3-25.) even includes infertile patients collected together with other women who have other types of complaints.

In addition, there might possibly be a great range of what is normal in terms of tissue appearance. The differences that cause problematic bleeding might also be so hard to detect that simple morphological observation alone might not be productive, even with ideal communication.

There have been many research studies on normal changes that occur in the endometrium (lining of the uterus) during the course of the menstrual cycle and others that have sought to investigate the causes of bleeding between periods and heavy periods. Currently there are research groups studying blood vessel development and structure in the uterus.

Like the pathologist, I would hope that one day the efforts of these doctors and scientists will pay off and help explain, diagnose and improve treatment for menstrual bleeding problems.

The other more obvious reason why it might be difficult to equate what the pathologist sees with what the gynaecologist deals with is the lack of accurate menstrual loss reporting by patients and their referring doctors. There is, and not surprisingly, a resistance amongst women to collect used towels and tampons so that chemical blood loss measurements can be made in hospital laboratories. However, even if women were to make such collections there are not routine services for measuring loss.

These days many hospital laboratories are filled with very fast robotic machines measuring complex biochemical features on small blood samples. There is simply not the scope for rooms full of large receptacles hydrolysing blood on towels on tampons and then technicians later squeezing them out by hand wearing protective clothing. The experience behind this web site suggests that there is perhaps no need for such procedures if reliable estimates can be made by a trained nurse or by women themselves.

Presently however, about fifty percent of women, recruited to some research studies on heavy menstrual loss, have less than 80 ml blood loss per cycle. In one local research study where women only had their menstrual blood loss measured if they felt they had heavy or very heavy bleeding or where their general practitioner had referred them with heavy menses, about 40% had more than 80 mls loss.
The picture is further complicated by the fact that factors other than blood loss volume are important. A summary graphic from an earlier study shows the main symptoms women have for seeking hospital-based treatment (click here)

Could there be a way to improve research on dysfunctional endometrial bleeding by helping the patients report menstrual loss better to their doctors? Perhaps www.menstrual-blood-loss.com is one step on the way forward.

Many gynaecologists regard eighty millilitres of blood loss per cycle as the level at which menorrhagia (heavy periods) can be diagnosed and should be treated, although others suggest a higher figure. In reality all figures used for treatment decisions are arbitrary as they merely correspond statistically to some percentile in the range of values that can be encountered. Sometimes these figures and have known risk factors associated with them and so can be used as the basis for rational treatment. Clearly other features need to be taken into consideration when deciding whether or not to treat.

As yet we do not have clinical research evidence to know how reliably other nurses or women can make clinically useful estimates based on the online images or pictures. Until then we hope that this site, if used wisely, will be helpful.

Perhaps gynaecology nurses, gynaecologists, community based doctors, or the nurses who work with them might also benefit from even a brief look at the site. Those interested in the research background can follow the hyperlinks on the ‘Other information’ pages.

© 2005 Dr Steve Campbell
Reprinted with permission