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Methods for blood loss estimation after vaginal birth

Overview of attention for article published in Cochrane database of systematic reviews, September 2018
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  • In the top 25% of all research outputs scored by Altmetric
  • High Attention Score compared to outputs of the same age (84th percentile)
  • Above-average Attention Score compared to outputs of the same age and source (56th percentile)

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19 tweeters

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Title
Methods for blood loss estimation after vaginal birth
Published in
Cochrane database of systematic reviews, September 2018
DOI 10.1002/14651858.cd010980.pub2
Pubmed ID
Authors

Virginia Diaz, Edgardo Abalos, Guillermo Carroli

Abstract

Almost 358,000 women die each year in childbirth, mainly in low-income countries. More than half of all maternal deaths occur within 24 hours of giving birth; severe bleeding in the postpartum period is the single most important cause. Depending on the rate of blood loss and other factors, such as pre-existing anaemia, untreated postpartum haemorrhage (PPH) can lead to hypovolaemic shock, multi-organ dysfunction, and maternal death, within two to six hours.This review investigated different methods for estimating blood loss. The most common method of measuring blood loss during the third stage of labour is visual estimation, during which the birth attendant makes a quantitative or semi-quantitative estimate of the amount of blood lost. In direct blood collection, all blood lost during the third stage of labour (except for the placenta and membranes) is contained in a disposable, funnelled, plastic collector bag, which is attached to a plastic sheet, and placed under the woman's buttocks. When the bleeding stops, there are two options: the bag can be weighed (also called gravimetric technique), or the bag can be calibrated, allowing for a direct measurement. A more precise measurement of blood loss is haemoglobin concentration (Hb) in venous blood sampling and spectrophotometry. With the dye dilution technique, a known quantity of dye is injected into the vein and its plasmatic concentration is monitored after the uterus stops bleeding. Using nuclear medicine, a radioactive tracer is injected, and its concentration is monitored after the uterus stops bleeding. Although hypothetically, these advanced methods could provide a better quantification of blood loss, they are difficult to perform and are not accessible in most settings. To evaluate the effect of alternative methods to estimate blood loss during the third stage of labour, to help healthcare providers reduce the adverse consequences of postpartum haemorrhage after vaginal birth. We searched Cochrane Pregnancy and Childbirth's Trials Register (2 February 2018), ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP; 21 March 2018), and reference lists of retrieved studies. All randomised trials, including cluster-randomised trials, evaluating methods for estimating blood loss after vaginal birth. Two review authors independently assessed trials for inclusion and risk of bias, extracted data, and checked them for accuracy. The search retrieved 62 reports in total. Of these, we assessed 12 reports in full, corresponding to six trials. We included three trials and excluded one; two trials are ongoing.The included trials were conducted in hospital settings. Two trials were conducted in India; the third trial was a large cluster-randomised trial, which took place in 13 European countries. Overall, we judged the included trials to be at a low risk of bias. One study evaluated the use of calibrated drapes versus visual estimation, another evaluated the use of calibrated drapes versus the gravimetric technique (weight of blood-soaked materials), therefore, we were unable to pool the data from the two studies. The third study did not measure any of the outcomes of interest, so did not contribute data to the analyses.Direct measurement using calibrated drapes versus visual estimationOne cluster-randomised controlled trial in 13 western European countries, with over 25,000 women, examined this comparison.The trial did not report on postpartum anaemia (defined as Hb lower than 9 mg/dL), blood loss greater than 500 mL, or maternal infection.Moderate-quality evidence suggests there is probably little or no difference between groups in: severe morbidity (coagulopathy, organ failure, intensive care unit admission; adjusted risk ratio (RR) 0.82, 95% confidence interval (CI) 0.48 to 1.39); the risk of blood transfusion (adjusted RR 0.82, 95% CI 0.46 to 1.46); the use of plasma expanders (adjusted RR 0.77, 95% CI 0.42 to 1.42); and the use of therapeutic uterotonics (adjusted RR 0.87, 95% CI 0.42 to 1.76).Direct measurement using calibrated drapes (Excellent BRASSS-V Drape™) versus gravimetric techniqueOne randomised controlled trial in India, with 900 women, examined this comparison.The trial did not report on postpartum anaemia (defined as Hb lower than 9 mg/dL), severe morbidity, or maternal infection.High-quality evidence showed that using calibrated drapes improved the detection of blood loss greater than 500 mL when compared with the gravimetric technique (RR 1.86, 95% CI 1.11 to 3.11). Low-quality evidence suggests there may be little or no difference in the risk of blood transfusion between the two groups (RR 1.00, 95% CI 0.06 to 15.94), or in the use of plasma expanders, reported as intravenous fluids given for PPH treatment (RR 0.67; 95% CI 0.19 to 2.35). High-quality evidence showed little or no difference in the use of therapeutic uterotonics (RR 1.01, 95% CI 0.90 to 1.13), but the use of therapeutic uterotonics was extremely high in both arms of the study (57% and 56%). Overall, the evidence in this review is insufficient to support the use of one method over another for blood loss estimation after vaginal birth. In general, the quality of evidence for our predefined outcomes ranged from low to high quality, with downgrading decisions due to imprecision. The included trials did not report on many of our primary and secondary outcomes.In trials that evaluate methods for estimating blood loss during vaginal birth, we believe it is important to measure their impact on clinical maternal and neonatal outcomes, along with their diagnostic accuracy. This body of knowledge needs further, well designed, appropriately powered, randomised controlled trials that correlate blood loss with relevant clinical outcomes, such as those listed in this review.

Twitter Demographics

The data shown below were collected from the profiles of 19 tweeters who shared this research output. Click here to find out more about how the information was compiled.

Mendeley readers

The data shown below were compiled from readership statistics for 62 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Unknown 62 100%

Demographic breakdown

Readers by professional status Count As %
Unspecified 13 21%
Student > Bachelor 12 19%
Student > Master 11 18%
Student > Postgraduate 10 16%
Researcher 6 10%
Other 10 16%
Readers by discipline Count As %
Medicine and Dentistry 31 50%
Unspecified 18 29%
Nursing and Health Professions 4 6%
Social Sciences 2 3%
Economics, Econometrics and Finance 2 3%
Other 5 8%

Attention Score in Context

This research output has an Altmetric Attention Score of 13. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 09 November 2018.
All research outputs
#1,153,177
of 12,908,018 outputs
Outputs from Cochrane database of systematic reviews
#3,593
of 10,472 outputs
Outputs of similar age
#40,653
of 260,935 outputs
Outputs of similar age from Cochrane database of systematic reviews
#57
of 132 outputs
Altmetric has tracked 12,908,018 research outputs across all sources so far. Compared to these this one has done particularly well and is in the 91st percentile: it's in the top 10% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 10,472 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 20.4. This one has gotten more attention than average, scoring higher than 65% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 260,935 tracked outputs that were published within six weeks on either side of this one in any source. This one has done well, scoring higher than 84% of its contemporaries.
We're also able to compare this research output to 132 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 56% of its contemporaries.