Heat-Stable Carbetocin versus Oxytocin to Prevent Hemorrhage after Vaginal Birth

Refractory uterine atony: still a problem after all these years

Postpartum hemorrhage is a leading cause of maternal morbidity and mortality, and uterine atony is the leading cause of postpartum hemorrhage. Risk factors for uterine atony include induced or augmented labor, preeclampsia, chorio-amnionitis, obesity, multiple gestation, polyhydramnios, and prolonged second stage of labor. Although a risk assessment is recommended for all parturients, many women with uterine atony do not have risk factors, making uterine atony difficult to predict. Oxytocin is the first-line drug for prevention and treatment of uterine atony. It is a routine component of the active management of the third stage of labor. An oxytocin bolus dose as low as 1 IU is sufficient to produce satisfactory uterine tone in almost all women undergoing elective cesarean delivery. However, a higher bolus dose (3 IU) or infusion rate is recommended for women undergoing intrapartum cesarean delivery. Carbetocin, available in many countries, is a synthetic oxytocin analog with a longer duration than oxytocin that allows bolus administration without an infusion. Second line uterotonic agents include ergot alkaloids (ergometrine and methylergonovine) and the prostaglandins, carboprost and misoprostol. These drugs work by a different mechanism to oxytocin and should be administered early for uterine atony refractory to oxytocin. Rigorous studies are lacking, but methylergonovine and carboprost are likely superior to misoprostol. Currently, the choice of second-line agent should be based on their adverse effect profile and patient comorbidities. Surgical and radiologic management of uterine atony includes uterine tamponade using balloon catheters and compression sutures, and percutaneous transcatheter arterial embolization.

Formative research to design an implementation strategy for a postpartum hemorrhage initial response treatment bundle (E-MOTIVE): study protocol

BACKGROUND

Postpartum hemorrhage (PPH) is the leading cause of maternal death worldwide. When PPH occurs, early identification of bleeding and prompt management using evidence-based guidelines, can avert most PPH-related severe morbidities and deaths. However, adherence to the World Health Organization recommended practices remains a critical challenge. A potential solution to inefficient and inconsistent implementation of evidence-based practices is the application of a 'clinical care bundle' for PPH management. A clinical care bundle is a set of discrete, evidence-based interventions, administered concurrently, or in rapid succession, to every eligible person, along with teamwork, communication, and cooperation. Once triggered, all bundle components must be delivered. The E-MOTIVE project aims to improve the detection and first response management of PPH through the implementation of the "E-MOTIVE" bundle, which consists of (1) Early PPH detection using a calibrated drape, (2) uterine Massage, (3) Oxytocic drugs, (4) Tranexamic acid, (5) Intra Venous fluids, and (6) genital tract Examination and escalation when necessary. The objective of this paper is to describe the protocol for the formative phase of the E-MOTIVE project, which aims to design an implementation strategy to support the uptake of this bundle into practice.

METHODS

We will use behavior change and implementation science frameworks [e.g. capability, opportunity, motivation and behavior (COM-B) and theoretical domains framework (TDF)] to guide data collection and analysis, in Kenya, Nigeria, South Africa, Sri Lanka, and Tanzania. There are four methodological components: qualitative interviews; surveys; systematic reviews; and design workshops. We will triangulate findings across data sources, participant groups, and countries to explore factors influencing current PPH detection and management, and potentially influencing E-MOTIVE bundle implementation. We will use these findings to develop potential strategies to improve implementation, which will be discussed and agreed with key stakeholders from each country in intervention design workshops.

DISCUSSION

This formative protocol outlines our strategy for the systematic development of the E-MOTIVE implementation strategy. This focus on implementation considers what it would take to support roll-out and implementation of the E-MOTIVE bundle. Our approach therefore aims to maximize internal validity in the trial alongside future scalability, and implementation of the E-MOTIVE bundle in routine practice, if proven to be effective.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04341662.

The effect of trehalose, antioxidants, and acetate buffer concentration on oxytocin stability

Oxytocin is a cyclic nonapeptide used to induce labor and prevent bleeding after childbirth. Due to its instability, storage and transport of oxytocin formulations can be problematic in hot/tropical climates. The aim of this study was to investigate the effect of trehalose and select antioxidants (uric acid, butylated hydroxytoluene, and l-ascorbic acid) on oxytocin stability in solution. The effect of buffer composition and acetate buffer concentration was also studied. Acetate buffer was found to work better than citrate/phosphate buffer for the oxytocin stability. Lower acetate buffer concentrations (0.025 M or less) were also found to yield improved oxytocin stability compared to higher concentrations. Although known degradation pathways of oxytocin include oxidation, the antioxidants uric acid and butylated hydroxytoluene had negligible effect on the oxytocin stability while l-ascorbic acid led to significantly faster degradation. Despite trehalose's reputation as a great stabilizer for biomolecules, it also had small to negligible effect on oxytocin stability at concentrations up to 1 M in acetate buffer. These results were surprising given the present literature on trehalose as a stabilizer for various biomolecules, including proteins and lipids.

Side-effects of carbetocin to prevent postpartum hemorrhage: A systematic review and meta-analysis of randomized controlled trials

Postpartum hemorrhage (PPH) increases the risk of maternal death worldwide. Heat-stable carbetocin, a long-acting oxytocin analog, is a newer uterotonic agent. Clinicians do not fully understand its side-effects, particularly the unanticipated side-effects. The aim of this study is to investigate the side-effects of carbetocin to PPH. The Cochrane Library, Web of Science, PubMed, Elsevier ScienceDirect, Embase, and ClinicalTrials.gov were searched from the inception to September 2020. Randomized controlled trials (RCTs) that considered pregnant women who received carbetocin before delivery and provided at least one adverse event were included. Statistical analysis included random or fixed-effect meta-analyses using relative risk. Stratified analyses and sensitivity analyses were also performed. Begger's and Egger's test and funnel plots were used to assess the publication bias. Seventeen RCTs involving 32,702 women were included, and all these studies ranked as medium- to high-quality. Twenty-four side-effects were reported. The use of carbetocin had a lower risk of vomiting in intravenously (0.53, 0.30 to 0.93) and cesarean birth (0.51, 0.32 to 0.81) women, and had a slightly higher risk of diarrhea (8.00, 1.02 to 62.79) compared with oxytocin intervention. No significant difference was found among other side-effects. Evidence from our systematic review and meta-analysis of 17 RCTs suggested that the risk of vomiting decreased with carbetocin use in the prevention of PPH after delivery.

Coordination and planning of clinical research on a national and global level

In reproductive medicine, the needs and desires of infertility patients drive future research, with the most important outcome being live birth of a baby. Large, multicenter, randomized clinical trials are considered the best research tool to evaluate the effectiveness of medical interventions, but they can often take a long time to find definitive answers. Advances in individual participant data (IPD) and network meta-analysis have enabled research questions to be answered more quickly, but better planning could streamline this process further. To harmonize research findings that are taking place globally in this way, it is crucial that the same outcomes are collected in clinical trials conducted in reproductive medicine. Furthermore, the conduct of clinical trials often requires collaboration on an international scale; however, individual countries have their own processes for research prioritization and delivery. We describe the perspective of high- and low-resourced settings and industry as well as the mechanisms of prioritization and coordination that are in place in different settings. In addition, we discuss the importance of the patient perspective, which can help shape the research question, clinical trial design, and the logistical operations of trial delivery. The need for increased global collaboration and coalitions within and between stakeholders is evident for the research community to accelerate advances and maximize benefits in reproductive medicine.

Circular suture of the uterine serosa and myometrium layer around placental attachment site for refractory postpartum hemorrhage

OBJECTIVE

The aim of the study was to analyze the clinical outcomes of circular suture at placental attachment site for refractory postpartum hemorrhage (PPH), which could block blood supply of the serosa and myometrium layer.

METHODS

Eighty cases of refractory PPH were enrolled and retrospective analyzed in this study for further analysis from a consecutive single center database between 2010 and 2018. After undergoing circular suture of the uterine serosa and myometrium layer around placental attachment site, surgical and perioperative outcomes were recorded and analyzed.

RESULTS

Among all the patients enrolled, 28 cases (35.0%) of refractory PPH were mainly caused by uterine inertia, 36 cases (45.0%) caused by ectopic placenta, and 2 cases (2.5%) caused by coagulation disorders. After circular suture of the uterine serosa and myometrium layer at placental attachment site, all the uterine active bleeding was controlled below 40 ml without recurrence. The perioperative results were similar between the vaginal and cesarean sections groups.

CONCLUSIONS

Circular suture of the uterine serosa and myometrium at the placental attachment site could control refractory PPH with few postoperative complications. Circular suture around placenta site could be applied in time to protect the endometrium even in primary hospital.

Cost of hospital care of women with postpartum haemorrhage in India, Kenya, Nigeria and Uganda: a financial case for improved prevention

OBJECTIVE

Access to quality, effective lifesaving uterotonics in low and middle-income countries (LMICs) remains a major barrier to reducing maternal deaths from postpartum haemorrhage (PPH). Our objective was to assess the costs of care for women who receive different preventative uterotonics, and with PPH and no-PPH so that the differences, if significant, can inform better resource allocation for maternal health care.

METHODS

The costs of direct hospital care of women who received oxytocin or heat-stable carbetocin for prevention of PPH in selected tertiary care facilities in India, Kenya, Nigeria, and Uganda were assessed. We collected data from all women who had PPH, as well as a random sample of women without PPH. Cost data was collected for the cost of stay, PPH interventions, transfusions and medications for 2966 women. We analyzed the difference in cost of care at a facility level between women who experienced a PPH event and those who did not. Key findings The mean cost of care of a woman experiencing PPH in the study sites in India, Kenya, Nigeria, and Uganda exceeded the cost of care of a woman who did not experience PPH by between 21% and 309%. There was a large variation in cost across hospitals within a country and across countries.

CONCLUSION

Our results quantify the increased cost of PPH of up to 4.1 times that for a birth without PPH. PPH cost information can help countries to evaluate options across different conditions and in the formulation of appropriate guidelines for intrapartum care, including rational selection of quality-assured, effective medicines. This information can be applied to national assessment and adaptation of international recommendations such as the World Health Organization's recommendations on uterotonics for the prevention of PPH or other interventions used to treat PPH. Trial registration HRP Trial A65870; UTN U1111-1162-8519; ACTRN12614000870651; CTRI/2016/05/006969, EUDRACT 2014-004445-26. Date of registration 14 August 2014 Access to quality, effective lifesaving medicines in low and middle-income countries remains a major barrier to reducing maternal deaths from bleeding after childbirth. Information on to what extent treatments for bleeding increases the cost of care of women after childbirth is important for informed resource allocation. We collected data from all women who had bleeding after childbirth, as well as a random sample of women without bleeding in selected hospitals in India, Kenya, Nigeria, and Uganda. Cost data was collected for the cost of stay and interventions to manage bleeding for 2966 women. We compared the difference in cost of care between women who experienced a bleeding event and those who did not. The mean cost of care of a woman with bleeding in the study sites exceeded the cost of care of a woman who did not experience PPH by between 21% and 309%. There was a large variation in cost across hospitals within a country and across countries. Our results indicate an increased cost of bleeding of up to 4.1 times that for birth without bleeding. Effective prevention reduces the cost of care. Cost information can help countries to evaluate options across different conditions and in the formulation of appropriate guidelines for intrapartum care, including rational selection of quality-assured, effective medicines. This information can be applied to national assessment and adaptation of international recommendations such as the World Health Organization's recommendations on medications for the prevention of bleeding after childbirth or other interventions used to treat bleeding.

Evaluating efficacy of intravenous carbetocin in reducing blood loss during abdominal myomectomy: a randomized controlled trial

OBJECTIVE

To evaluate the efficacy of carbetocin versus placebo in decreasing intraoperative blood loss and the need for blood transfusion during abdominal myomectomy.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Tertiary university hospital from September 2019 to February 2020.

PATIENT(S)

A total of 138 women with symptomatic leiomyoma who were candidates for abdominal myomectomy (n = 69 in each group).

INTERVENTION(S)

We randomized the study participants in a 1:1 ratio to carbetocin and placebo groups. Intravenous 100 μg carbetocin or placebo was administered slowly after induction of anesthesia.

MAIN OUTCOME MEASURE(S)

Intraoperative blood loss, need for blood transfusion, postoperative hemoglobin, operative time, length of hospitalization, and drug side-effects.

RESULT(S)

The baseline characteristics were similar among all groups. Carbetocin had significantly lower intraoperative blood loss compared with placebo (mean difference 184 mL). Hemoglobin level 24 hours after surgery was significantly lower in the placebo group than in the carbetocin group (9.1 ± 0.8 vs. 10.3 ± 0.6 g/dL). Eight women in the carbetocin group needed blood transfusion compared with 17 in placebo group. Operative time, length of hospitalization, and side-effects were similar in both groups.

CONCLUSION(S)

A single preoperative intravenous dose of 100 μg carbetocin is a simple, practical, and effective method of decreasing intraoperative blood loss and the need for blood transfusion during abdominal myomectomy, with tolerable, few, nonsignificant side-effects.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04083625.

Intramuscular oxytocin versus Syntometrine® versus carbetocin for prevention of primary postpartum haemorrhage after vaginal birth: a randomised double-blinded clinical trial of effectiveness, side effects and quality of life

OBJECTIVE

To compare intramuscular oxytocin, Syntometrine^® and carbetocin for prevention of postpartum haemorrhage after vaginal birth.

DESIGN

Randomised double-blinded clinical trial.

SETTING

Six hospitals in England.

POPULATION

A total of 5929 normotensive women having a singleton vaginal birth.

METHODS

Randomisation when birth was imminent.

MAIN OUTCOME MEASURES

Primary: use of additional uterotonic agents. Secondary: weighed blood loss, transfusion, manual removal of placenta, adverse effects, quality of life.

RESULTS

Participants receiving additional uterotonics: 368 (19.5%) oxytocin, 298 (15.6%) Syntometrine and 364 (19.1%) carbetocin. When pairwise comparisons were made: women receiving carbetocin were significantly more likely to receive additional uterotonics than those receiving Syntometrine (odds ratio [OR] 1.28, 95% CI 1.08-1.51, P = 0.004); the difference between carbetocin and oxytocin was non-significant (P = 0.78); Participants receiving Syntometrine were significantly less likely to receive additional uterotonics than those receiving oxytocin (OR 0.75, 95% CI 0.65-0.91, P = 0.002). Non-inferiority between carbetocin and Syntometrine was not shown. Use of Syntometrine reduced non-drug PPH treatments compared with oxytocin (OR 0.64, 95% CI 0.42-0.97) but not carbetocin (P = 0.64). Rates of PPH and blood transfusion were not different. Syntometrine was associated with an increase in maternal adverse effects and reduced ability of the mother to bond with her baby.

CONCLUSIONS

Non-inferiority of carbetocin to Syntometrine was not shown. Carbetocin is not significantly different to oxytocin for use of additional uterotonics. Use of Syntometrine reduced use of additional uterotonics and need for non-drug PPH treatments compared with oxytocin. Increased maternal adverse effects are a disadvantage of Syntometrine.

TWEETABLE ABSTRACT

IM carbetocin does not reduce additional uterotonic use compared with IM Syntometrine or oxytocin.

Storage conditions of oxytocin in a tropical climate in a low-income country

OBJECTIVE

To establish the storage conditions of oxytocin in a health facility in a low-income country with a tropical climate, as suboptimal storage may lead to ineffectiveness of drugs essential to prevent and treat postpartum hemorrhage.

METHODS

At Mulago National Referral Hospital (28 000-33 000 deliveries/year) in Kampala, Uganda, temperature logging Safe-Rx cards were placed in boxes of oxytocin and in every known storage location. The route of the boxes through the hospital was tracked for 54 days, and storage conditions were observed.

RESULTS

Oxytocin was stored within the recommended temperature range (2°C-8°C) 24% of the time. The average temperature measured within the oxytocin boxes was 18.2°C, with a minimum of -2.3°C and maximum of 30.4°C. Six out of twelve known storage places had a refrigerator, but not one location stored medication at the recommended temperature constantly. The average temperature in the storage places ranged from 9.5°C to 27.6°C, with a minimum temperature of 2.3°C and maximum of 30.9°C.

CONCLUSION

Oxytocin is not stored in the recommended temperature range for the majority of time. The presence of refrigerators does not ensure adherence to advised temperature storage conditions.

Uterotonic agents for first-line treatment of postpartum haemorrhage: a network meta-analysis

BACKGROUND

Postpartum haemorrhage (PPH), defined as a blood loss of 500 mL or more after birth, is the leading cause of maternal death worldwide. The World Health Organization (WHO) recommends that all women giving birth should receive a prophylactic uterotonic agent. Despite the routine administration of a uterotonic agent for prevention, PPH remains a common complication causing one-quarter of all maternal deaths globally. When prevention fails and PPH occurs, further administration of uterotonic agents as 'first-line' treatment is recommended. However, there is uncertainty about which uterotonic agent is best for the 'first-line' treatment of PPH.

OBJECTIVES

To identify the most effective uterotonic agent(s) with the least side-effects for PPH treatment, and generate a meaningful ranking among all available agents according to their relative effectiveness and side-effect profile.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (5 May 2020), and the reference lists of all retrieved studies.

SELECTION CRITERIA

All randomised controlled trials or cluster-randomised trials comparing the effectiveness and safety of uterotonic agents with other uterotonic agents for the treatment of PPH were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed all trials for inclusion, extracted data and assessed each trial for risk of bias. Our primary outcomes were additional blood loss of 500 mL or more after recruitment to the trial until cessation of active bleeding and the composite outcome of maternal death or severe morbidity. Secondary outcomes included blood loss-related outcomes, morbidity outcomes, and patient-reported outcomes. We performed pairwise meta-analyses and indirect comparisons, where possible, but due to the limited number of included studies, we were unable to conduct the planned network meta-analysis. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

Seven trials, involving 3738 women in 10 countries, were included in this review. All trials were conducted in hospital settings. Randomised women gave birth vaginally, except in one small trial, where women gave birth either vaginally or by caesarean section. Across the seven trials (14 trial arms) the following agents were used: six trial arms used oxytocin alone; four trial arms used misoprostol plus oxytocin; three trial arms used misoprostol; one trial arm used Syntometrine® (oxytocin and ergometrine fixed-dose combination) plus oxytocin infusion. Pairwise meta-analysis of two trials (1787 participants), suggests that misoprostol, as first-line treatment uterotonic agent, probably increases the risk of blood transfusion (risk ratio (RR) 1.47, 95% confidence interval (CI) 1.02 to 2.14, moderate-certainty) compared with oxytocin. Low-certainty evidence suggests that misoprostol administration may increase the incidence of additional blood loss of 1000 mL or more (RR 2.57, 95% CI 1.00 to 6.64). The data comparing misoprostol with oxytocin is imprecise, with a wide range of treatment effects for the additional blood loss of 500 mL or more (RR 1.66, 95% CI 0.69 to 4.02, low-certainty), maternal death or severe morbidity (RR 1.98, 95% CI 0.36 to 10.72, low-certainty, based on one study n = 809 participants, as the second study had zero events), and the use of additional uterotonics (RR 1.30, 95% CI 0.57 to 2.94, low-certainty). The risk of side-effects may be increased with the use of misoprostol compared with oxytocin: vomiting (2 trials, 1787 participants, RR 2.47, 95% CI 1.37 to 4.47, high-certainty) and fever (2 trials, 1787 participants, RR 3.43, 95% CI 0.65 to 18.18, low-certainty). According to pairwise meta-analysis of four trials (1881 participants) generating high-certainty evidence, misoprostol plus oxytocin makes little or no difference to the use of additional uterotonics (RR 0.99, 95% CI 0.94 to 1.05) and to blood transfusion (RR 0.95, 95% CI 0.77 to 1.17) compared with oxytocin. We cannot rule out an important benefit of using the misoprostol plus oxytocin combination over oxytocin alone, for additional blood loss of 500 mL or more (RR 0.84, 95% CI 0.66 to 1.06, moderate-certainty). We also cannot rule out important benefits or harms for additional blood loss of 1000 mL or more (RR 0.76, 95% CI 0.43 to 1.34, moderate-certainty, 3 trials, 1814 participants, one study reported zero events), and maternal mortality or severe morbidity (RR 1.09, 95% CI 0.35 to 3.39, moderate-certainty). Misoprostol plus oxytocin increases the incidence of fever (4 trials, 1866 participants, RR 3.07, 95% CI 2.62 to 3.61, high-certainty), and vomiting (2 trials, 1482 participants, RR 1.85, 95% CI 1.16 to 2.95, high-certainty) compared with oxytocin alone. For all outcomes of interest, the available evidence on the misoprostol versus Syntometrine® plus oxytocin combination was of very low-certainty and these effects remain unclear. Although network meta-analysis was not performed, we were able to compare the misoprostol plus oxytocin combination with misoprostol alone through the common comparator of oxytocin. This indirect comparison suggests that the misoprostol plus oxytocin combination probably reduces the risk of blood transfusion (RR 0.65, 95% CI 0.42 to 0.99, moderate-certainty) and may reduce the risk of additional blood loss of 1000 mL or more (RR 0.30, 95% CI 0.10 to 0.89, low-certainty) compared with misoprostol alone. The combination makes little or no difference to vomiting (RR 0.75, 95% CI 0.35 to 1.59, high-certainty) compared with misoprostol alone. Misoprostol plus oxytocin compared to misoprostol alone are compatible with a wide range of treatment effects for additional blood loss of 500 mL or more (RR 0.51, 95% CI 0.20 to 1.26, low-certainty), maternal mortality or severe morbidity (RR 0.55, 95% CI 0.07 to 4.24, low-certainty), use of additional uterotonics (RR 0.76, 95% CI 0.33 to 1.73, low-certainty), and fever (RR 0.90, 95% CI 0.17 to 4.77, low-certainty).

AUTHORS' CONCLUSIONS

The available evidence suggests that oxytocin used as first-line treatment of PPH probably is more effective than misoprostol with less side-effects. Adding misoprostol to the conventional treatment of oxytocin probably makes little or no difference to effectiveness outcomes, and is also associated with more side-effects. The evidence for most uterotonic agents used as first-line treatment of PPH is limited, with no evidence found for commonly used agents, such as injectable prostaglandins, ergometrine, and Syntometrine®.

Economic evaluation of carbetocin as prophylaxis for postpartum hemorrhage in the Philippines

Background

The World Health Organization (WHO) recommends oxytocin as the drug of choice for postpartum hemorrhage (PPH) prevention. However, the WHO has also recently considered carbetocin for PPH prevention, but only if carbetocin were a cost-effective choice in the country. Consequently, we determined the cost-effectiveness and budgetary impact of carbetocin against oxytocin in the Philippines.

Methods

A cost-utility analysis using a decision tree was done to compare the costs and outcomes of carbetocin with oxytocin for PPH prophylaxis among women undergoing either vaginal delivery (VD) or cesarean section (CS) in a six-week time horizon using a societal perspective. One-way and probabilistic sensitivity analyses were applied to investigate parameter uncertainties. Additionally, budget impact analysis was conducted using a governmental perspective. Results were presented as incremental cost-effectiveness ratio (ICER) using a 2895 United States dollar (USD) per quality adjusted life year (QALY) gained as the ceiling threshold in the Philippines.

Results

Carbetocin was not cost-effective given the listed price of carbetocin at 18 USD. Given a societal perspective, the ICER values of 13,187 USD and over 40,000 USD per QALY gained were derived for CS and VD, respectively. Moreover, the ICER values were sensitive to the risk ratio of carbetocin versus oxytocin and carbetocin price. On budget impact, the five-year total budget impact of a drug mix of carbetocin and oxytocin was 25.54 million USD (4.23 million USD for CS and 21.31 million USD for VD) compared with ‘only oxytocin’ scenario.

Conclusion

Carbetocin is not a cost-effective choice in PPH prevention for both modes of delivery in the Philippines, unless price reduction is made. Our findings can be used for evidence-informed policies to guide coverage decisions on carbetocin not only in the Philippines but also in other low and middle-income countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-020-05834-x.

Oxytocin in the Male Reproductive Tract; The Therapeutic Potential of Oxytocin-Agonists and-Antagonists

In this review, the role of oxytocin and oxytocin-like agents (acting via the oxytocin receptor and belonging to the oxytocin-family) in the male reproductive tract is considered. Previous research (dating back over 60 years) is revised and connected with recently found aspects of the role oxytocin plays in male reproductive health. The local expression of oxytocin and its receptor in the male reproductive tract of different species is summarized. Colocalization and possible crosstalk to other agents and receptors and their resulting effects are discussed. The role of the newly reported oxytocin focused signaling pathways in the male reproductive tract, other than mediating contractility, is critically examined. The structure and effect of the most promising oxytocin-agonists and -antagonists are reviewed for their potential in treating male disorders with origins in the male reproductive tract such as prostate diseases and ejaculatory disorders.

Extending the I-squared statistic to describe treatment effect heterogeneity in cluster, multi-centre randomized trials and individual patient data meta-analysis

Treatment effect heterogeneity is commonly investigated in meta-analyses to identify if treatment effects vary across studies. When conducting an aggregate level data meta-analysis it is common to describe the magnitude of any treatment effect heterogeneity using the I-squared statistic, which is an intuitive and easily understood concept. The effect of a treatment might also vary across clusters in a cluster randomized trial, or across centres in multi-centre randomized trial, and it can be of interest to explore this at the analysis stage. In cross-over trials and other randomized designs, in which clusters or centres are exposed to both treatment and control conditions, this treatment effect heterogeneity can be identified. Here we derive and evaluate a comparable I-squared measure to describe the magnitude of heterogeneity in treatment effects across clusters or centres in randomized trials. We further show how this methodology can be used to estimate treatment effect heterogeneity in an individual patient data meta-analysis.

Uterotonic drugs to prevent postpartum haemorrhage: a network meta-analysis

BACKGROUND

Postpartum haemorrhage (PPH) is the leading cause of maternal mortality worldwide. Prophylactic uterotonic drugs can reduce blood loss and are routinely recommended. There are several uterotonic drugs for preventing PPH, but it is still debatable which drug or combination of drugs is the most effective.

OBJECTIVES

To identify the most effective and cost-effective uterotonic drug(s) to prevent PPH, and generate a ranking according to their effectiveness and side-effect profile.

METHODS

The Cochrane Pregnancy and Childbirth's Trials Register (1 June 2015), ClinicalTrials.gov and the World Health Organization (WHO)'s International Clinical Trials Registry Platform (ICTRP) were searched for unpublished trial reports (30 June 2015). In addition, reference lists of retrieved studies (updated October 2017) were searched for randomised trials evaluating uterotonic drugs for preventing PPH. The study estimated relative effects and rankings for preventing PPH, defined as blood loss of ≥ 500 ml and ≥ 1000 ml. Pairwise meta-analyses and network meta-analysis were performed to determine the relative effects and rankings of all available drugs and combinations thereof [ergometrine, misoprostol (Cytotec^®; Pfizer Inc., New York, NY, USA), misoprostol plus oxytocin (Syntocinon^®; Novartis International AG, Basel, Switzerland), carbetocin (Pabal^®; Ferring Pharmaceuticals, Saint-Prex, Switzerland), ergometrine plus oxytocin (Syntometrine^®; Alliance Pharma plc, Chippenham, UK), oxytocin, and a placebo or no treatment]. Primary outcomes were stratified according to the mode of birth, prior risk of PPH, health-care setting, drug dosage, regimen and route of drug administration. Sensitivity analyses were performed according to study quality and funding source, among others. A model-based economic evaluation compared the relative cost-effectiveness separately for vaginal births and caesareans with or without including side effects.

RESULTS

From 137 randomised trials and 87,466 women, ergometrine plus oxytocin, carbetocin and misoprostol plus oxytocin were found to reduce the risk of PPH blood loss of ≥ 500 ml compared with the standard drug, oxytocin [ergometrine plus oxytocin: risk ratio (RR) 0.69, 95% confidence interval (CI) 0.57 to 0.83; carbetocin: RR 0.72, 95% CI 0.52 to 1.00; misoprostol plus oxytocin: RR 0.73, 95% CI 0.6 to 0.9]. Each of these three strategies had 100% cumulative probability of being ranked first, second or third most effective. Oxytocin was ranked fourth, with an almost 0% cumulative probability of being ranked in the top three. Similar rankings were noted for the reduction of PPH blood loss of ≥ 1000 ml (ergometrine plus oxytocin: RR 0.77, 95% CI 0.61 to 0.95; carbetocin: RR 0.70, 95% CI 0.38 to 1.28; misoprostol plus oxytocin: RR 0.90, 95% CI 0.72 to 1.14), and most secondary outcomes. Ergometrine plus oxytocin and misoprostol plus oxytocin had the poorest ranking for side effects. Carbetocin had a favourable side-effect profile, which was similar to oxytocin. However, the analysis was restricted to high-quality studies, carbetocin lost its ranking and was comparable to oxytocin. The relative cost-effectiveness of the alternative strategies is inconclusive, and the results are affected by both the uncertainty and inconsistency in the data reported on adverse events. For vaginal delivery, when assuming no adverse events, ergometrine plus oxytocin is less costly and more effective than all strategies except carbetocin. The strategy of carbetocin is both more effective and more costly than all other strategies. When taking adverse events into consideration, all prevention strategies, except oxytocin, are more costly and less effective than carbetocin. For delivery by caesarean section, with and without adverse events, the relative cost-effectiveness is different, again because of the uncertainty in the available data.

LIMITATIONS

There was considerable uncertainty in findings within the planned subgroup analyses, and subgroup effects cannot be ruled out.

CONCLUSIONS

Ergometrine plus oxytocin, carbetocin and misoprostol plus oxytocin are more effective uterotonic drug strategies for preventing PPH than the current standard, oxytocin. Ergometrine plus oxytocin and misoprostol plus oxytocin cause significant side effects. Carbetocin has a favourable side-effect profile, which was similar to oxytocin. However, most carbetocin trials are small and of poor quality. There is a need for a large high-quality trial comparing carbetocin with oxytocin; such a trial is currently being conducted by the WHO. The relative cost-effectiveness is inconclusive, and results are affected by uncertainty and inconsistency in adverse events data.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015020005; Cochrane Pregnancy and Childbirth Group (substudy) reference number 0871; PROSPERO-Cochrane (substudy) reference number CRD42015026568; and sponsor reference number ERN_13-1414 (University of Birmingham, Birmingham, UK).

FUNDING

Funding for this study was provided by the National Institute for Health Research Health Technology Assessment programme in a research award to the University of Birmingham and supported by the UK charity Ammalife (UK-registered charity 1120236). The funders of the study had no role in study design, data collection, data synthesis, interpretation or writing of the report.

Red blood cell transfusion in obstetrics and its implication for patient blood management: a retrospective analysis in Switzerland from 1998 to 2016

PURPOSE

Peripartum hemorrhage (PPH) remains one of the main causes of maternal mortality worldwide. Treatment includes administration of packed red blood cells (RBC) in severe cases and patient blood management (PBM) may reduce it significantly. In our study, we wanted to retrospectively assess red blood cell administration in PPH to evaluate the impact of PBM in Switzerland.

METHODS

Using data from the Swiss obstetric hospital registry (Arbeitsgemeinschaft Schweizer Frauenkliniken, ASF), we included patients with deliveries from 1998 to 2016. We examined available obstetric data as well as blood loss and RBC administration in the acute and subacute peripartal phase. We categorized data into two time intervals: 1998-2011 and 2012-2016, as new PPH guidelines in Switzerland were established in 2012.

RESULTS

PPH incidence increased between 1998 and 2016 significantly. The number of vaginal instrumental deliveries and cesarean sections increased as well. Administration of three or more RBC units, as defined in the ASF registry, in the acute and subacute phase in Switzerland has decreased after 2012. Conversely, we saw an increase in the administration of one to two RBC units in the acute and subacute phase. Nevertheless, overall RBC administration has been decreasing from 1998 to 2016.

CONCLUSION

The increase of patients obtaining one or two units of RBC for PPH suggests that there may be a potential for effective implication of PBM in obstetrics. Reduction of RBC transfusion in the context of PPH may not only decrease maternal morbidity, but decrease economic costs as well.

Gerard W. Ostheimer Lecture: What's New in Obstetric Anesthesia 2018

This article summarizes the Gerard W. Ostheimer Lecture given at the 2019 Society for Obstetric Anesthesia and Perinatology annual meeting. The article summarizes key articles published in 2018 that were presented in the 2019 Ostheimer Lecture, with a focus on maternal mortality, maternal complications, analgesic and anesthetic management of vaginal and cesarean deliveries, postpartum care, and the impact of anesthesia on maternal outcomes. The reviewed literature highlights many opportunities for anesthesiologists to impact maternal care and outcomes. The major themes presented in this manuscript are maternal mortality including amniotic fluid and cardiac arrest; postpartum hemorrhage; venous thromboembolism; management of spinal-induced hypotension; postpartum care including opioid use, postcesarean analgesia, and postpartum depression. A proposed list of action items and research topics based on the literature from 2018 is also presented. Specifically, anesthesiologists should use prophylactic vasopressor infusions during elective cesarean delivery; use a structured algorithm to diagnose pulmonary embolus, and reevaluate the use of D-dimer measurements; target postpartum opioid analgesia and prescribing; use multimodal postcesarean delivery analgesia, preferably with neuraxial hydrophilic opioids; and study any association between labor analgesia on postpartum depression.

Management of the third stage of labour: (for the Optimal Intrapartum Care series edited by Mercedes Bonet, Femi Oladapo and Metin Gülmezoglu)

The physiology of the third stage of labour is described. Active management reduces the risk of postpartum haemorrhage (PPH), due to the use of a uterotonic agent. Intramuscular Oxytocin 10 IU has the highest efficacy and lowest side effect profile, although ergometrine, carbetocin and misoprostol are also effective. The appropriate uterotonic in different settings such as home birth by unskilled attendants and at caesarean section is discussed. For the latter, there is less consensus on the optimal dose/route of oxytocin, this topic remaining on the research agenda. Delayed cord clamping enables transfusion of blood to the neonate and is recommended rather than early clamping. Controlled cord traction should only be performed by skilled birth attendants and confers minimal advantage in preventing retained placenta. The importance of early recognition of PPH, and preparedness, is emphasised. An approach to medical and surgical management of PPH is presented.

Next Generation Medical Management of Postpartum Hemorrhage

BACKGROUND

Postpartum hemorrhage remains a significant contributor to morbidity and mortality of women of childbearing age worldwide. Trends in both incidence and severity of postpartum hemorrhage are increasing which makes it imperative to identify drugs that could target prevention and/or treatment of these postpartum hemorrhages for women living in high, middle and low-income countries.

METHODS

We have reviewed current advances in the medical management of postpartum hemorrhage focusing on non-uterotonic therapy. We specifically describe the use and mechanism of action of tranexamic acid (TXA) and fibrinogen concentrate. Furthermore, we address the existing data for using these medications in postpartum hemorrhage, highlighting both strengths and limitations.

RESULTS

This review describes a new generation of medications that are promising for the prevention and/or treatment of postpartum hemorrhage. For patients at risk for significant hemorrhage, TXA has been shown to reduce intraoperative blood loss and can be given as a prophylactic agent. For the treatment of postpartum hemorrhage, early use of TXA has the potential to reduce mortality. In addition, some data exists supporting the use of fibrinogen concentrate, though more studies are required to help formulate guidelines for its use.

CONCLUSION

A promising new approach for the management of severe postpartum hemorrhage is using medications that alter coagulation. More data are needed to describe ideal patient populations, dosing, the time of administration, and infusion rate.

Maternal characteristics and causes associated with refractory postpartum haemorrhage after vaginal birth: a secondary analysis of the WHO CHAMPION trial data

Objective

To assess the maternal characteristics and causes associated with refractory postpartum haemorrhage (PPH).

Design

Secondary analysis of the WHO CHAMPION trial data.

Setting

Twenty‐three hospitals in ten countries.

Population

Women from the CHAMPION trial who received uterotonics as first‐line treatment of PPH.

Methods

We assessed the association between sociodemographic, pregnancy and childbirth factors and refractory PPH, and compared the causes of PPH between women with refractory PPH and women responsive to first‐line PPH treatment.

Main outcome measures

Maternal characteristics; causes of PPH.

Results

Women with labour induced or augmented with uterotonics (adjusted odds ratio [aOR] 1.35; 95% CI 1.07–1.72), with episiotomy or tears requiring suturing (aOR 1.82; 95% CI 1.34–2.48) and who had babies with birthweights ≥3500 g (aOR 1.33; 95% CI 1.04–1.69) showed significantly higher odds of refractory PPH compared with the reference categories in the multivariate analysis adjusted by centre and trial arm. While atony was the sole PPH cause in 53.2% (116/218) of the women in the responsive PPH group, it accounted for only 31.5% (45/143) of the causes in the refractory PPH group. Conversely, tears were the sole cause in 12.8% (28/218) and 28% (40/143) of the responsive PPH and refractory PPH groups, respectively. Placental problems were the sole cause in 11 and 5.6% in the responsive and refractory PPH groups, respectively.

Conclusion

Women with refractory PPH showed a different pattern of maternal characteristics and PPH causes compared with those with first‐line treatment responsive PPH.

Tweetable abstract

Women with refractory postpartum haemorrhage are different from those with first‐line treatment responsive PPH.

Women with refractory postpartum haemorrhage are different from those with first‐line treatment responsive PPH.

Carbetocin vs oxytocin for prevention of postpartum hemorrhage after vaginal delivery: A meta-analysis

OBJECTIVE

To evaluate the efficacy and safety of carbetocin for prevention of postpartum hemorrhage in women undergoing vaginal delivery compared with oxytocin.

METHODS

We conducted a systemic literature search in PubMed, the Cochrane Library, and Embase without language restrictions from inception of each of database to November 18th, 2018. Randomized controlled trials with outcome measure of blood loss ≥500 ml were eligible if they compared carbetocin with oxytocin to prevent postpartum hemorrhage during the third stage of labor in women undergoing vaginal delivery.

RESULTS

This meta-analysis of 5 randomized controlled trials (30,314 women) indicated that there was no significant difference between carbetocin and oxytocin in blood loss ≥500 ml in women undergoing vaginal delivery (relative risks (RRs), 0.52; 95% confidence intervals (CIs), 0.24 to 1.15; P = .11; I = 69%). Sensitivity analyses showed the same results. No significant differences were found in blood loss ≥1000 ml, use of additional uterotonic agents, blood transfusion, uterine massage, flushing, vomiting, abdominal pain, nausea, dizziness, headache, palpitation, itching, and shivering.

CONCLUSIONS

This meta-analysis showed that carbetocin was as effective and safe as oxytocin for prevention of postpartum hemorrhage in women undergoing vaginal delivery, and the choice of carbetocin for routine prophylaxis will depend on cost-effectiveness.

Developing and applying a 'living guidelines' approach to WHO recommendations on maternal and perinatal health

How should the WHO most efficiently keep its global recommendations up to date? In this article we describe how WHO developed and applied a 'living guidelines' approach to its maternal and perinatal health (MPH) recommendations, based on a systematic and continuous process of prioritisation and updating. Using this approach, 25 new or updated WHO MPH recommendations have been published in 2017-2018. The new approach helps WHO ensure its guidance is responsive to emerging evidence and remains up to date for end users.

What does basic science tell us about the use of uterotonics?

Pharmacotherapy with uterotonics remains the mainstay of the management for post-partum haemorrhage. Clinical studies evaluating the efficacy of these drugs are fraught with confounders, which may influence uterine contractility and blood loss. For this reason, a range of techniques have been developed to study myometrial function in vitro, allowing for the comparison of various drugs in a controlled-simulated physiological environment. In this review, we focus on the main classes of uterotonic drugs and outline their molecular and physiological basis of action. We explore the evidence related to appropriate drug dosing and relative efficacy, and compare the evidence gleaned from clinical and in vitro studies. We discuss the mechanism of oxytocin desensitisation and how basic science has helped us understand this phenomenon. We also discuss the in vitro research findings for each of the main classes of uterotonic drugs that have contributed to an improved understanding of the management of post-partum haemorrhage and, ultimately, better care for mothers.

Practical approaches to managing postpartum haemorrhage with limited resources

Mortality from postpartum haemorrhage (PPH) is higher in low resource settings due to increased incidence, higher case fatality rates and poor general health of the population. The challenges of managing PPH with limited resources are presented. Feasible interventions for preventing and treating PPH for home births are described. Given that maternity care is organised around levels of care in low resource settings, guidance is provided for what measures can be performed to manage PPH at different levels of care (clinic, community health centre, district hospital, regional and central hospital); and by which cadre (midwife, clinical officer, general doctor, specialist). Effective management of PPH requires on-going training and emergency drills. Reducing mortality from PPH is not possible without available urgent transport from home to facility and between levels of care. In addition, the essential building blocks of the health system must be functional to enable effective management of PPH.

Development of a Highly Potent Analogue and a Long-Acting Analogue of Oxytocin for the Treatment of Social Impairment-Like Behaviors

The nonapeptide hormone oxytocin (OT) has pivotal brain roles in social recognition and interaction and is thus a promising therapeutic drug for social deficits. Because of its peptide structure, however, OT is rapidly eliminated from the bloodstream, which decreases its potential therapeutic effects in the brain. We found that newly synthesized OT analogues in which the Pro⁷ of OT was replaced with N-( p-fluorobenzyl)glycine (2) or N-(3-hydroxypropyl)glycine (5) exhibited highly potent binding affinities for OT receptors and Ca²⁺ mobilization effects by selectively activating OT receptors over vasopressin receptors in HEK cells, where 2 was identified as a superagonist ( E_Max = 131%) for OT receptors. Furthermore, the two OT analogues had a remarkably long-acting effect, up to 16-24 h, on recovery from impaired social behaviors in two strains of CD38 knockout mice that exhibit autism spectrum disorder-like social behavioral deficits, whereas the effect of OT itself rapidly diminished.

Intramuscular oxytocin versus oxytocin/ergometrine versus carbetocin for prevention of primary postpartum haemorrhage after vaginal birth: study protocol for a randomised controlled trial (the IMox study)

Background

Postpartum haemorrhage remains a major cause of maternal mortality and morbidity worldwide. Active management of the third stage of labour reduces the risk of postpartum haemorrhage. Oxytocin and oxytocin/ergometrine are commonly used in the UK, with oxytocin/ergometrine being more effective at preventing moderate, but not severe, blood loss. Many guidelines specifically recommend using oxytocin for all vaginal births, as it is associated with fewer adverse events. However, a survey conducted by the Southmead Hospital Maternity Research Team revealed that 71.4% of UK obstetric units still routinely use oxytocin/ergometrine. Carbetocin is a newer medication that may be as effective but has fewer side effects. No studies have directly compared all three medications.

Methods

The IMox study aims to determine the most effective, acceptable and cost-effective drug for primary prevention of postpartum haemorrhage following vaginal birth. The IMox study is a prospective, multi-centre, double-blind, randomised trial directly comparing oxytocin, oxytocin/ergometrine and carbetocin given intramuscularly for the prevention of postpartum haemorrhage in the third stage of labour. The primary effectiveness outcome is the use of an additional uterotonic drug. Secondary effectiveness outcomes reflect maternal morbidity and mortality within the immediate postpartum period. Participant questionnaires and subjective reporting of side effects will be used to evaluate maternal acceptability. Maternal quality of life utilities will be collected antenatally, and on days 1 and 14 after birth to enable a cost-effectiveness assessment of each studied drug.

Participants will be pregnant women planning a vaginal birth in six hospitals in England. Participants will be approached and invited to provide consent to participate from 20 weeks gestation until in established labour. A complete sample of 5712 participants (1904 per arm) providing data for the primary outcome will allow for a robust determination of efficacy between all three study drugs. Data will be collected until participants are discharged from the hospital and on postnatal days 1 and 14 regardless of location. All analyses will be on a modified intention-to-treat basis, and additionally repeated on a per protocol basis. Data collection commenced in Feburary 2015 and was completed in August 2018.

Discussion

This study is the first to directly compare oxytocin, oxytocin/ergometrine and carbetocin in the same population for the prevention of postpartum haemorrhage following vaginal birth. Furthermore, this study will be the first to directly compute health economic outcomes from such a three-way comparison. This study is limited to using short-term outcomes, and so will not provide evidence for important outcomes such as long-term maternal psychological well-being and time to next conception.

Trial registration

ClinicalTrials.gov, NCT02216383. Registered on 18 August 2014. EudraCT, 2014-001948-37. Registered on 23 September 2014. ISRCTN, ISRCTN10232550. Retrospectively registered on 6 March 2018).

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3109-2) contains supplementary material, which is available to authorized users.

Uterotonic agents for preventing postpartum haemorrhage: a network meta-analysis

BACKGROUND

Postpartum haemorrhage (PPH) is the leading cause of maternal mortality worldwide. Prophylactic uterotonic agents can prevent PPH, and are routinely recommended. The current World Health Organization (WHO) recommendation for preventing PPH is 10 IU (international units) of intramuscular or intravenous oxytocin. There are several uterotonic agents for preventing PPH but there is still uncertainty about which agent is most effective with the least side effects. This is an update of a Cochrane Review which was first published in April 2018 and was updated to incorporate results from a recent large WHO trial.

OBJECTIVES

To identify the most effective uterotonic agent(s) to prevent PPH with the least side effects, and generate a ranking according to their effectiveness and side-effect profile.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (24 May 2018), and reference lists of retrieved studies.

SELECTION CRITERIA

All randomised controlled trials or cluster-randomised trials comparing the effectiveness and side effects of uterotonic agents with other uterotonic agents, placebo or no treatment for preventing PPH were eligible for inclusion. Quasi-randomised trials were excluded. Randomised trials published only as abstracts were eligible if sufficient information could be retrieved.

DATA COLLECTION AND ANALYSIS

At least three review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We estimated the relative effects and rankings for preventing PPH ≥ 500 mL and PPH ≥ 1000 mL as primary outcomes. Secondary outcomes included blood loss and related outcomes, morbidity outcomes, maternal well-being and satisfaction and side effects. Primary outcomes were also reported for pre-specified subgroups, stratifying by mode of birth, prior risk of PPH, healthcare setting, dosage, regimen and route of administration. We performed pairwise meta-analyses and network meta-analysis to determine the relative effects and rankings of all available agents.

MAIN RESULTS

The network meta-analysis included 196 trials (135,559 women) involving seven uterotonic agents and placebo or no treatment, conducted across 53 countries (including high-, middle- and low-income countries). Most trials were performed in a hospital setting (187/196, 95.4%) with women undergoing a vaginal birth (71.5%, 140/196).Relative effects from the network meta-analysis suggested that all agents were effective for preventing PPH ≥ 500 mL when compared with placebo or no treatment. The three highest ranked uterotonic agents for prevention of PPH ≥ 500 mL were ergometrine plus oxytocin combination, misoprostol plus oxytocin combination and carbetocin. There is evidence that ergometrine plus oxytocin (RR 0.70, 95% CI 0.59 to 0.84, moderate certainty), carbetocin (RR 0.72, 95% CI 0.56 to 0.93, moderate certainty) and misoprostol plus oxytocin (RR 0.70, 95% CI 0.58 to 0.86, low certainty) may reduce PPH ≥ 500 mL compared with oxytocin. Low-certainty evidence suggests that misoprostol, injectable prostaglandins, and ergometrine may make little or no difference to this outcome compared with oxytocin.All agents except ergometrine and injectable prostaglandins were effective for preventing PPH ≥ 1000 mL when compared with placebo or no treatment. High-certainty evidence suggests that ergometrine plus oxytocin (RR 0.83, 95% CI 0.66 to 1.03) and misoprostol plus oxytocin (RR 0.88, 95% CI 0.70 to 1.11) make little or no difference in the outcome of PPH ≥ 1000 mL compared with oxytocin. Low-certainty evidence suggests that ergometrine may make little or no difference to this outcome compared with oxytocin meanwhile the evidence on carbetocin was of very low certainty. High-certainty evidence suggests that misoprostol is less effective in preventing PPH ≥ 1000 mL when compared with oxytocin (RR 1.19, 95% CI 1.01 to 1.42). Despite the comparable relative treatment effects between all uterotonics (except misoprostol) and oxytocin, ergometrine plus oxytocin, misoprostol plus oxytocin combinations and carbetocin were the highest ranked agents for PPH ≥ 1000 mL.Misoprostol plus oxytocin reduces the use of additional uterotonics (RR 0.56, 95% CI 0.42 to 0.73, high certainty) and probably also reduces the risk of blood transfusion (RR 0.51, 95% CI 0.37 to 0.70, moderate certainty) when compared with oxytocin. Carbetocin, injectable prostaglandins and ergometrine plus oxytocin may also reduce the use of additional uterotonics but the certainty of the evidence is low. No meaningful differences could be detected between all agents for maternal deaths or severe morbidity as these outcomes were rare in the included randomised trials where they were reported.The two combination regimens were associated with important side effects. When compared with oxytocin, misoprostol plus oxytocin combination increases the likelihood of vomiting (RR 2.11, 95% CI 1.39 to 3.18, high certainty) and fever (RR 3.14, 95% CI 2.20 to 4.49, moderate certainty). Ergometrine plus oxytocin increases the likelihood of vomiting (RR 2.93, 95% CI 2.08 to 4.13, moderate certainty) and may make little or no difference to the risk of hypertension, however absolute effects varied considerably and the certainty of the evidence was low for this outcome.Subgroup analyses did not reveal important subgroup differences by mode of birth (caesarean versus vaginal birth), setting (hospital versus community), risk of PPH (high versus low risk for PPH), dose of misoprostol (≥ 600 mcg versus < 600 mcg) and regimen of oxytocin (bolus versus bolus plus infusion versus infusion only).

AUTHORS' CONCLUSIONS

All agents were generally effective for preventing PPH when compared with placebo or no treatment. Ergometrine plus oxytocin combination, carbetocin, and misoprostol plus oxytocin combination may have some additional desirable effects compared with the current standard oxytocin. The two combination regimens, however, are associated with significant side effects. Carbetocin may be more effective than oxytocin for some outcomes without an increase in side effects.

Distribution of postpartum blood loss: modeling, estimation and application to clinical trials

BACKGROUND

The loss of large amounts of blood postpartum can lead to severe maternal morbidity and mortality. Understanding the nature of postpartum blood loss distribution is critical for the development of efficient analysis techniques when comparing treatments to prevent this event. When blood loss is measured, resulting in a continuous volume measure, often this variable is categorized in classes, and reduced to an indicator of volume greater than a cutoff point. This reduction of volume to classes entails a substantial loss of information. As a consequence, very large trials are needed to assess clinically important differences between treatments to prevent postpartum haemorrhage.

METHODS

The authors explore the nature of postpartum blood loss distribution, assuming that the physical properties of blood loss lead to a lognormal distribution. Data from four clinical trials and one observational study are used to confirm this empirically. Estimates of probabilities of postpartum haemorrhage events 'blood loss greater than a cutoff point' and relative risks are obtained from the fitted lognormal distributions. Confidence intervals for relative risk are obtained by bootstrap techniques.

RESULTS

A variant of the lognormal distribution, the three-parameter lognormal distribution, showed an excellent fit to postpartum blood loss data of the four trials and the observational study. A measurement quality assessment showed that problems of digit preference and lower limit of detection were well handled by the lognormal fit. The analysis of postpartum haemorrhage events based on a lognormal distribution improved the efficiency of the estimates. Sample size calculation for a hypothetical future trial showed that the application of this procedure permits a reduction of sample size for treatment comparison.

CONCLUSION

A variant of the lognormal distribution fitted very well postpartum blood loss data from different geographical areas, suggesting that the lognormal distribution might fit postpartum blood loss universally. An approach of analysis of postpartum haemorrhage events based on the lognormal distribution improves efficiency of estimates of probabilities and relative risk, and permits a reduction of sample size for treatment comparison.

TRIAL REGISTRATION

This paper reports secondary analyses for trials registered at Australian New Zealand Clinical Trials Registry (ACTRN 12608000434392 and ACTRN12614000870651); and at clinicaltrials.gov (NCT00781066).

New Evidence on Carbetocin: Another Arrow in Our Quiver

Carbetocin is more heat stable than oxytocin with at least equivalent efficacy for preventing postpartum hemorrhage. It will certainly be helpful if the supplier can make it available in low-income country settings at a price comparable to oxytocin. But even so, programs will still need oxytocin and other uterotonic medications.