Biography

Professor Rath graduated from the Georg-August University, Göttingen, Germany. Following his medical registration in 1976, Professor Rath had a brief experience of military service before returning to the University Hospital at Göttingen where he carried out his residency, became a Specialist in Obstetrics and Gynaecology and undertook his PhD. In 1987, he became the first Senior Physician and Vice Head of the Department of Obstetrics and Gynaecology before taking up his current role. Professor Rath has published more than 540 articles mostly in peer-reviewed journals as well as 150 book chapters and 45 publications for education. His areas of interest include; biochemistry of cervical ripening and dilatation, prostaglandins, induction of labour, treatment of preterm labour, post-partum haemorrhage, thrombophilia, maternal diseases in pregnancy and pre-eclampsia/HELLP-syndrome.

Presentation

View the presentation "Definitions and diagnoses of PPH: underestimated problems" by Professor Werner Rath

Transcript

Slide 1
Mr Chairman, ladies and gentlemen, dear colleagues, first of all, many thanks to Ferring Company for the invitation to this exciting meeting. It is a little bit difficult for me after this amazing lecture by Dr Draycott to come back to a more dry material, and that is definitions and diagnoses of PPH.

Slide 2
We have already heard some data and the first slide is a summary. Fourteen million cases of PPH occur each year worldwide, with a case fatality rate of one percent. This is a total of 140,000 women. What we have already heard, one woman dies every four minutes. PPH has been estimated to cause 25 percent of all maternal deaths. Nearly half of post partum deaths are due to immediate PPH. Considering these data, a high number of unreported cases must be taken into account, and the true incidence of maternal death due to PPH is certainly much higher.

The absolute risk of death is much lower in high-income countries with a rate of 1:100,000 deliveries, as compared to low-income countries with the incidence of an estimated rate of 1:1000 deliveries. A recent WHO analysis of causes of maternal death reported a wide variation in the incidence of death due to obstetric haemorrhage, which is the single most important cause of both maternal morbidity and morbidity worldwide.

In high income countries, haemorrhage, mainly due to PPH, is responsible as we have shown by the slide by Professor DiRenzo for 13.5 percent of maternal death while it accounts for 34 percent and nearly 31 percent in Africa and Asia respectively. It is noteworthy that last reported confidential inquiries into maternal and child death judged over 60 percent of the women who died received major sub-standard care.

Slide 3
Major haemorrhage, that is blood loss above 1,000 ml mostly, is also the most common cause of severe maternal morbidity, including adult respiratory distress syndrome, renal failure, coagulopathy, shock myocardial ischemia, even in young women, hysterectomy and finally, long-term morbidity such as anaemia, a serious, underestimated clinical problem especially in low-income countries. Approximately 20 million women worldwide suffer from acute or chronic disability following immediate PPH each year. Severe maternal morbidity due to PPH was estimated 7:1000 deliveries in a new case study. Interestingly, recently published population-based studies on severe maternal morbidity demonstrated that the rate of PPH and related serious adverse outcomes have significantly increased in some high-income countries.

Slide 4
Now before discussing definitions and diagnosis let me briefly point out the major problems. We have shown this by Dr Draycott, and the risk management of PPH, First of all the lack of consensus in terms of PPH and underestimation of blood loss. Second, the lack of availability of local, easy to use action protocols or plans, and the lack of facility of education and training. I think this will be better in the future as per the talk by Dr Draycott. The common clinical problem, too little is done too late, was recently highlighted by the Seamark Report. Finally, deficiencies in the organizational system failures are common and may lead to a delay in diagnosis and proper treatment.

Slide 5
There is no doubt that proper definition of PPH is mandatory. Definition of PPH should be easy, easy to use, simple, and appropriate for use in every day clinical practice, not only in high income but also in low income countries. It should include clinical findings, and finally the definition should facilitate prompt diagnosis and advocate treatment. Proper definition of PPH should also be considered in the light of recent advances in anaesthesia, resuscitation therapy, new pharmacological drugs such as carbetocin and pabal, active management of the third stage of labour and improvement of surgical procedures. It is generally accepted to classify PPH as primary within the first 24 hours of delivery and secondary, more than 24 hours after delivery but less than 12 weeks.

Secondary PPH, affecting one to three percent of all deliveries, may have received little attention because it is perceived as being associated with maternal morbidity, rather than mortality. Despite immense advances made in medical and surgical treatment there has been no significant change in the definition of PPH over the past 50 years. And there is currently no single satisfactory definition of primary PPH.

Slide 6
The most commonly used, or let me say traditional definition that has been proposed by the WHO in 1990, is any blood loss from the genital direct during delivery above 500 ml. This is a volume that untreated may be sufficient to cause hemorrhagic shock and death. Traditionally PPH following caesarean section has been defined as blood loss greater than 1,000 ml. There is therefore a degree of overlap in the acceptable range of blood loss for vaginal and caesarean deliveries.

Definitions based on quantification of blood loss have their origin, as you see in the slide, in historical studies published in the early 1960s of the last century. Using spectrometric methods or radio labelled erythrocytes, average blood loss measured was found to be 300 to 550 ml after vaginal delivery, and 500 to 1100 ml after c-birth. Up to 23 percent of caesarean deliveries were associated with blood loss between 1000 and 1500 ml and up to eight percent with the loss greater than 1500 ml.

Slide 7
The latest studies shown on this slide during radioisotope dilution technique has shown that the mean accurate blood loss at the first caesarean section is in fact nearly 1300 ml and above 1000 ml for repeated operations, significantly more than the estimated blood loss recorded by most obstetricians. Thus, the traditional definition of primary PPH is in reality a reflection of the almost universal tendency to underestimate delivery blood loss. On the other hand, direct measurements of blood loss have also shown that the average blood loss for vaginal and caesarean deliveries frequently exceeds 500 and 1000 ml respectively.

Slide 8
This is the overview of the definitions, "traditional" definitions of PPH based on quantification of blood loss and its use in various guidelines. While you see some guidelines accept the traditional definitions others advocate alternative cut off levels of blood loss, or a combination of both estimated blood loss and clinical science of hypovolaemic shock. Many authors criticize that reliance on a definition solely based on the amount of blood loss without consideration of clinical signs and symptoms may lead to inconsistency for management. It is also a matter of debate if traditional definition is clinical appropriate regarding the amount of blood loss, or should be revised to identify a group of women who became ill and at real risk of severe morbidity after the haemorrhage.

Consequently, it has been proposed that it may be better to think of the term of major or severe PPH using a definition of loss more than 1000 ml or more than 1500 ml rather than define PPH as blood loss greater than 500 ml. However, it should be kept in mind that a blood loss of 1500 ml reflects the point when physiological compensatory mechanisms begin to fail. A generally accepted definition of PPH may not neglect the conditions and the circumstances in low income countries where women are likely to be severely anaemic.

Anaemia is a big problem in these countries and there are other factors like co-morbidity as malaria, and to experience limited access to treatment facilities. While healthy women can usually tolerate acute blood loss up to 1000 ml or more without significant hemodynamic problems, this is certainly not the case in severely anaemic women. Anaemia was estimated to affect half of all pregnant women in the world. In severely anaemic women a mere 250 ml blood loss may result in hemorrhagic shock and death.

Slide 9
The most important limitations of a definition based on cut-offs of estimated blood loss, is that blood loss is notoriously not measured or clinically underestimated with the rates of underestimation approaching 90 percent. A vaginal delivery resulting in delayed diagnosis and treatment had a preventable adverse outcome.

Previous studies have shown that visual estimation of blood loss underestimates loss by 33 to 50 percent compared with a gold standard photo spectrometry.

A recent prospective single blind observation study conducted at London Teaching Hospital demonstrated that clinical experience did not appear to have a confounding effect on accuracy. A further study from Dallas compared visually estimated and calculated blood loss in vaginal and caesarean deliveries. Visual estimated blood loss was statistically different from calculated loss between each degree of laceration and all modes of delivery demonstrating an underestimation of VEBL with increasing EEBL, as shown by Stafford in 2008. This is in accordance to previous studies using a corollary metric method.

Now the message of these studies was the higher the metric blood loss the greater the underestimation by visual assessment. Blood loss was found to be overestimated at low volumes, volumes below 200 to 300 ml. This applies also to blood loss with caesarean section. Inter-operative loss, blood loss measured by the Hematin method during elective lower segment caesarean section, was found to be approximately 500 ml and did not differ significantly from visually estimated blood loss. However, observer error in estimated blood loss was higher if measured blood loss exceeds 600 ml.

Slide 10
This slide shows the incidence of PPH when comparing visual estimation with direct measurement of blood loss. The incidence of PPH you see in the slide, 5.7 percent and 27.8 percent respectively, which corresponded to an underestimation of the incidence of PPH with visual estimation by nearly 90 percent. However, the authors did not report how blood loss was measured in this study.

Slide 11
In daily obstetric practice, hidden loss, in linen, swabs, pads, and so on, or hidden loss under the drapes at caesarean section or in a slow, steady trickle is common underestimated problems. In addition, contamination with amniotic fluid, urine, solutions, they mask the real amount of blood loss. The wide variation in the amount of contaminant ranging between 4 percent and 80 percent of total volume collected illustrates major limitation of direct weighing or measuring blood loss since weight does not discriminate between blood and other types of fluid.
The total amount of blood loss can also be difficult to assess as a result of concealed bleeding within the ovarine cavity, the broad ligament, the peritoneal cavity and the retroperitoneal space.

Slide 12
In a recent study subjects were randomized to estimate simulated blood loss in calibrated or noncalibrated delivery drapes, which also contained 100 ml of urine and sponges. Visual estimation with noncalibrated drapes underestimated blood loss with worsening accuracy at large volumes. For example, 16 percent error blood loss at 300 ml up to 40 percent error at 2000 ml. The calibrated drape was below 10 to 12 percent at all volumes.

There is consistent evidence from further studies that calibrated drape estimation diagnoses PPH four times as often as the visual estimate.
Last but not least it has been criticized that these definitions do not consider the rapidity of blood loss, which better correlates with hemodynamic changes and has considerable impact on severe maternal morbidity.

Slide 13
In attempts to overcome these inconsistencies the ACOG, seen in this slide, advocated the definition of either a 10 percent decline in post partum hematocrit concentration, or a need for erythrocyte transfusion. Nearly 20 years ago coworkers pointed out that a definition of PPH based on hematocrit change has several advantages. I do not want to give this in detail. On the other hand postpartum hematocrit has shown a significant negative non-linear correlation with visually estimated blood loss. However, a definition based on hematocrit change is not clinically useful in an emergency like PPH for several reasons.

Actual blood loss is mostly not reflected by a decrease in hematocrit or haemoglobin concentrations for four hours or more, and the peak drop may be appreciated on day two or three postpartum. In other words, rapid blood loss may trigger a medical emergency prior to observation of a decrease in hematocrit concentrations. Previous studies have found no correlation between measured accurate blood loss and decline of postpartum hematocrit or haemoglobin. Therefore, laboratory changes that are not correlated with the events that endanger the patient should not be used to define a medical emergency. Furthermore the change of hematocrit depends on the time of testing and the amount of fluid resuscitation previously administered and could also be affected by pre-partum haemoconcentration as in patients with pre-eclampsia and dehydration.

Definitions based on the need of erythrocyte and transfusion alone is also of limited value as the practice of blood transfusion varies widely according to the local circumstances and attitudes for transfusions of both patients and physicians.

Slide 14
Severe PPH: speed of estimated blood loss, peripartal drop of haemoglobin concentration and the numbers of erythrocyte transfusion have been proposed to define severe PPH. However, all definitions are of limited value for the same reasons mentioned just before. Other authors have suggested abandoning altogether the numerical assessments and instead defining PPH as an excessive blood loss resulting in signs and symptoms of hypovolaemia.

Slide 15
This is the classical picture by John Bonnar. It shows the clinical signs and symptoms related to blood loss with PPH. As a consequence of increased circulating blood volume during pregnancy, vital signs of hypovolaemic shock became relatively insensitive in pregnancy. Significant tachycardia does usually not develop until blood loss exceeds 1000 ml, while blood pressure is maintained in the normal range. A blood loss of up to 1500 ml will begin to manifest clinical signs, such as a rise in pulse and respiratory rates, and a slight recordable fall in blood pressure.
Blood pressure below 80 ml mercury usually indicates a blood loss in excess of 1500 ml clinically associated with worsening tachycardia, tarrhythmia and alteration of mental status.

Definitions based on symptoms and hemodynamic instability are therefore problematic since they are late symptoms of depleted blood volume and commence in failure of compensatory mechanisms threatening the mother's life.

The relative masking of signs during pregnancy hinders early recognition of hypovolaemia and delays treatment resulting in further blood loss and increased risk of hemorrhagic shock, and finally death. Consequently hypovolaemic women who begin to decompensate as evidenced by hypertension will deteriorate extremely rapidly.

Furthermore, confounding factors, such as drug-induced tachycardia, as in oxytocics or nifedipine or hypovolaemia due to antenatal blood loss, must be taken into account.

Slide 16
An adaption to the previously shown classification has been proposed for a more practical approach including an alert and an action line. The perceived loss of 500 to 1000 ml in the absence of clinical signs and cardiovascular instability should prompt basic measures of close monitoring and readiness for resuscitation that means the alert line. A perceived loss of above 1000 ml, or a smaller loss associated with clinical signs of shock should prompt a full protocol to measure, resuscitate, monitor and arrest bleeding, action line. These clinical classifications are in accordance with a recent Royal College guideline.

Slide 17
Proper and timely diagnosis may follow this principle shown in this slide. First, early recognition of patients at increased risk of PPH prior to delivery. Note, up to 70 percent of women with PPH have pre-existing risk factors. Second, proper estimation of blood loss before vital signs change. Third, close monitoring of the patients conditions, laboratory tests, clinical diagnosis, of course, of PPH at the earliest time.
There is consistent evidence as we have already heard that the accuracy of visual estimation of blood loss can be improved significantly by reconstructing clinical scenarios with expired blood and using pictorial algorithm as a teaching tool in labour wards. Five or more recent studies have addressed this issue.

Slide 18
I want to show this slide from the study of Bose. Twelve everyday clinical scenarios during which routine estimation of blood loss is required but devised and reconstructed in the form of objective structured clinical estimation stations. Significant underestimation of actual blood loss occurred at five of the twelve stations. Interestingly, among professional groups, the anaesthetists were the most accurate estimators, followed by mid-wives.

We have heard regular fire drills should be organized to train the staff in the assessment of blood loss and to test local systems in real time.

Slide 19
Recent studies have shown that this low cost calibrated plastic bag, like the Brass-V drape, shown in this slide was developed to measure postpartum blood loss in low resource settings. A very useful tool to measure blood loss at vaginal delivery before the maternal cardiovascular system deteriorates.

Slide 20
This slide is drape estimation. Drape estimation of blood loss was found to be 33 percent more accurate than visual estimation. The drape measures blood loss equally and as efficiently as gold-standards photospectrometry. Use of the drape has shown to lead to earlier transfer from rural areas to a higher facility. Other laboratory methods for measuring blood loss, for example photometric measures, are not practical for clinical use, are time consuming, and are not universally available.

Slide 21
If you are interested this is a recent very excellent comprehensive review by Mavis Schorn about the different methods on this topic, including 46 articles, which cannot be discussed in detail yet.

If PPH is suspected, careful surveillance and monitoring of the mothers are mandatory for a time of recognition of impending hemodynamic instability, and for the detection of concealed intra-abdominal bleeding at the earliest time, especially after c-section.

Slide 22
We have already seen this early warning chart. I think I can continue and we will not discuss this in detail. I think this model chart is only suitable for labour wards with sufficient staff facilities. But, it appears to be too complex to assess in the emergency of immediate PPH and may also not be proposed for full implementation in areas which are resource poor. Nevertheless, monitoring of the mother's vital signs is imperative. Laboratory tests, including coagulation testing, should be performed closely. It's very important to diagnose coagulopathy at the earliest moment. Finally, immediate diagnosis of the cause of PPH is required for adequate pharmacological and/or surgical treatment.

Slide 23
Conclusions: PPH is a significantly underestimated obstetrical program there is no doubt, primarily because of a lack of terms in its definition and diagnosis. There is an urgent need to unify commonly used definitions of PPH. However, it seems to be a mission impossible to create a definition which is appropriate for both high-income and low-income countries. A measured blood loss of 1000 ml may be an appropriate cut-off level to define PPH, irrespective of the mode of delivery. Since there is no reason to believe that the physiological impact of blood loss differs according to the route of delivery, accurate estimation of blood loss in conjunction with a careful assessment of vital signs and symptoms, are the most important key factors for prompt detection of PPH and may reduce maternal morbidity and mortality, especially in low-income countries.

Thank you for your attention.

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