Blood loss quantification during major abdominal surgery: prospective observational cohort study.

BACKGROUND: Blood loss during major abdominal surgery is an essential parameter in the evaluation of strategies aimed at reducing perioperative bleeding. However, blood loss quantification remains unreliable and inaccurate. The aim of this study was to compare several methods of blood loss quantification-visual estimation by surgeon and anesthesiologist, the gravimetric method, the calculation method with spectrophotometric measurement. The spectrophotometric measurement is considered as the most accurate method. METHODS: The study was designed as a prospective observational cohort single-center study. We analyzed 61 patients who underwent elective liver or pancreatic resection. The anesthesiologists' and surgeons' estimate of blood loss was based on a visual assessment. The gravimetric method was based on weighing the suction canister and surgical drapes before and after use. The basis of calculation method was anthropometric and hematological parameters, we used López-Picado's formula. The spectrophotometric method was based on the spectrophotometric determination of hemoglobin mass in the lost blood. We compared the methods using paired t-test, non-parametric Wilcoxon test and Bland-Altman analysis. RESULTS: Visual estimation by surgeons and anesthesiologists, gravimetric measurement, and calculation method were significantly different from spectrophotometric measurement at the significance level α = 0.05. All methods overestimated blood loss which was measured by spectrophotometric method. The estimate by surgeons was the closest to the spectrophotometric measurement, difference 68.7 ml (95% confidence interval [CI]: -129.3--8.2). CONCLUSIONS: We conclude that the estimate of blood loss by surgeons and anesthesiologists, as well as gravimetric method and calculation method are all significantly inaccurate in real surgical setting. We did not confirm the commonly accepted assumption that surgeons underestimate the blood loss. TRIAL REGISTRATION: The study was registered under the title " Blood Loss Quantification During Major Abdominal Surgery" at ClinicalTrials.gov with the registration number NCT05316649. Date of the first registration was 20/3/2022.

Methods of Blood Loss Quantification in Major Abdominal Surgery: A Narrative Review.

Blood loss in major abdominal surgery is an essential parameter in the evaluation of strategies aimed at reducing perioperative bleeding. It is also an important parameter of quality of the surgical procedure, along with postoperative morbidity and mortality, radicality of the surgical resection, etc. However, blood loss quantification remains unreliable and inaccurate. The methods used to measure blood loss can be categorized as visual estimation, gravimetric method, direct measurement, spectrophotometry, calculation methods, colorimetric analysis, and miscellaneous. The aim of this work is to review up-to-date knowledge about the various methods of blood loss quantification and then to introduce study, which should compare more methods of blood loss quantification in a real surgical setting.