The androcentric vision runs through biomedical research from start to finish: from the mouse chosen for a preclinical study (males were selected by default) to the diagnosis of a heart attack (in women it is detected later and worse). The history of medicine is full of scandalous examples of these gender biases and, although attempts are currently being made to balance the balance, there are still large imbalances that crystallize the gaps that the study of women’s health drags. The last paradigmatic case is postpartum hemorrhage, an obstetric emergency defined as excessive blood loss after childbirth (more than 500 milliliters): a study published this Wednesday in the journal The Lancet Obstetrics, Gynecology and Women’s Health alerts that the prevalence of bleeding with these characteristics may be three times higher than previously thought.
The key to this discrepancy between estimates and actual cases that occur has to do with the method of detection: historically, the way these hemorrhages were reported was based on visual estimates. That is to say after observing the stains on the sheets and the blood-soaked compresses, for example. According to this diagnostic formula, the prevalence of this type of obstetric emergency was 4%. However, the new meta-analysis highlights that when detection is done with more precise tools, such as special calibrated tissues that collect and measure blood, this figure rises to 13% of women who gave birth vaginally. Postpartum hemorrhage is one of the main causes of maternal death: 70,000 women die each year worldwide from this reason.
Adam Devall, author of the study, explains that after giving birth, “light bleeding” is expected, not hemorrhage. This condition occurs when blood loss exceeds 300 milliliters and there are signs that the heart is not pumping blood well or when bleeding exceeds 500 milliliters, whether or not there are signs of abnormal blood flow and pressure. Regardless, it’s a serious problem, Devall said in an email response: “Postpartum hemorrhage remains a common cause of maternal death worldwide and can lead to serious complications, such as anemia, the need for transfusion, surgery, or organ dysfunction.” »
This is the most dangerous complication during childbirth, but the scientific community does not know for sure how often it occurs. Studies on the prevalence of postpartum hemorrhage are disparate and inconsistent, as are their detection methods; and experts do not have a clear picture of the extent of this phenomenon.
Inaccurate detection methods
It is suspected that cases are underestimated, especially due to the detection methods used, based on subjective observation. Devall explains that this system “is what most doctors usually do”: “It is fast, but inaccurate and has been shown to miss many cases. »
In their review and meta-analysis of more than 80 studies, the researchers found that when objective measurement methods are used—gravimetric (weighing soaked tampons and subtracting dry weight, for example) and volumetric (bowls or containers) tools are available—postpartum hemorrhage turns out to be much more prevalent than previously thought. The authors assure in their study that subjective evaluation methods “are inaccurate and miss up to half of the cases of postpartum hemorrhage”.
Devall speculates that behind this lack of rigor in detecting postpartum hemorrhage lies a combination of factors. On the one hand, he says, there are the “practical and logistical” variables, since resorting to the objective methods described implies higher costs and changes in workflows to be able to carry them out, not to mention that in cesarean sections this objective quantification is “technically more difficult” because it is more possible to mix liquids, for example. On the other hand, he adds, “historical practice and inertia” also influence: “Visual estimation is a long-standing practice in maternal care; changing usual practice requires training, supplies and support from the system,” he explains.
Another important variable is the impact of the research, because as there were fewer large-scale studies using objective methods, “until recently, the literature reinforced the subjective approach,” he acknowledges.
Consequences of underdiagnosis
However, he warns: “Persisting with this inaccurate method of diagnosis will result in disadvantage and risk to women giving birth. Objective methods of assessing blood loss should be made available to all women in childbirth. » And let us remember that “objective methods exist, they are validated and they are feasible”. “The obstacle lies in its large-scale implementation rather than the absence of a method. »
Toni Payà, head of the gynecology and obstetrics department at the Hospital del Mar in Barcelona, assures that this subject has been the subject of discussion for some time in the scientific community. He himself participated in a study 15 years ago on the subject and admits that, in the midst of the explosion of precision medicine, these systems for subjective measurement of postpartum hemorrhages are “anachronistic”. But he does not believe that we should only focus on changing the diagnostic method: “It is very difficult to objectify the loss because there can be mixtures of things, such as amniotic fluid. Having objective tools, sufficiently sensitive and effective, is very difficult. What we have to do from the start is to put in place measures so that there is no blood loss.”
In any case, underdiagnosis has direct consequences on maternal health. “Undetected postpartum hemorrhage means delayed or no treatment, which increases the risk of serious morbidity and death,” says Devall. And it also adds that at the population level, underestimation of cases “leads to under-resourced services (fewer supplies, less blood available, lower intensive care capacity, less training), particularly in low- and middle-income countries, where mortality is higher.”
Devall does not rule out that there are other conditions under which measurement bias could be a problem. “When a common disease among women is diagnosed using imprecise and subjective methods, its true burden can be hidden,” she admits.
Medicine still has a long way to go to address grievances related to women’s health, Payà acknowledges. And he gives an example: “Ovarian torsion: it is an emergency, but it is minimized more than testicular torsion, for example. »
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