Table 3. Characteristics of the included studies (n=23).
| Author, year | Country | Study design | Surgical type (Specific procedure) | Sample size (Development/Validation) | Data source | EBLa definition |
|---|---|---|---|---|---|---|
| Akazawa and Hashimoto [10], 2023 | Japan | Single-Center Retrospective Cohort Study | Obstetric (Cesarean section) | 48 | MRIb + EMRc | ≥2000 mL |
| Akazawa and Hashimoto [18], 2024 | Japan | Multi-Center Retrospective Cohort Study | Obstetric (Cesarean section) | 63 (50/13) | MRI + EMR | ＞2000 mL |
| Chen et al [12], 2024 | China | Multi-Center Retrospective Cohort Study | Obstetric (Cesarean section) | 1975 (1680/295) | EMR | ≥300 mL |
| de Reus DC et al [19], 2025 | United States, Netherlands, and United Kingdom | Multi-center Retrospective Cohort Study | Orthopedic (Spinal decompression) | 880 | EMR | >2500 mL |
| Li et al [20], 2024 | China | Single-Center Retrospective Study | Hepatic (Tumor resection) | 406 (284/122) | EMR | ≥1000 mL |
| Liu et al [21], 2020 | China | Single-Center Retrospective Study | Obstetric (Cesarean section) | 210 | MRI | ≥500 mL |
| Mo et al [22], 2023 | China | Multi-center Retrospective Study | Gynecological (Hysteroscopic surgery) | 200 (120/80) | EMR | ≥200 mL |
| Park et al [23], 2022 | South Korea | Single-Center Retrospective Study | Hepatic (Transplantation) | 414 | EMR | ≥5000 mL |
| Shi et al [13], 2024 | China | Multi-center Observational Cohort Study | Orthopedic (Spinal decompression) | 276 (200/76) | EMR | ≥2500 mL |
| Shi et al [24], 2023 | China | Single-Center Retrospective Cohort Study | Multi-departmental surgeries | 48,543 | EMR | >200 mL |
| Stehrer et al [25], 2019 | Austria | Single-Center Retrospective Study | Craniofacial (Orthognathic surgery) | 950 (760/190) | EMR | Calculated using hemoglobin balance method |
| Sun et al [26], 2025 | China | Single-Center Retrospective Study | Orthopedic (Lumbar fusion) | 2054 (1437/617) | EMR | ≥500 mL |
| Wang [27], 2023 | China | Single-Center Retrospective Study | Obstetric (Cesarean section) | 168 (117/51) | EMR | >1000 mL |
| Wakiya et al [28], 2021 | Japan | Single-Center Retrospective Cohort Study | General (Pancreatic cancer resection) | 175 (128/47) | EMR | >20% of circulating blood volume |
| Xu [29], 2024 | China | Single-Center Retrospective Study | Obstetric (Cesarean section) | 249 (149/50/50) | MRI + EMR | ≥1000 mL |
| Xue et al [30], 2021 | China | Single-Center Retrospective Study | Hepatic (Tumor resection) | 665 (466/199) | EMR | ≥800 mL |
| Yang et al [31], 2022 | China | Single-Center Retrospective Study | Orthopedic (Spinal fracture) | 161 | EMR | Hidden blood loss (no explicit quantitative threshold) |
| Yang et al [32], 2023 | China | Multi-center Retrospective Cohort Study | Obstetric (Cesarean section) | 125 (85/40) | MRI + EMR | ≥1500 mL |
| Yin et al [33], 2021 | China | Single-Center Retrospective Study | Oncological (Pelvic/sacral tumors) | 810 | CTd + EMR | >3000 mL |
| Zheng et al [34], 2024 | China | Single-Center Retrospective Study | Obstetric (Cesarean section) | 346 (156/68/122) | MRI + Coagulation tests + EMR | >1000 mL |
| Zheng et al [35], 2022 | China | Single-Center Retrospective Study | Hepatic (Tumor resection) | 336 (268/68) | EMR | ≥300 mL |
| Zong et al [36], 2024 | China | Single-Center Retrospective Cohort Study | Obstetric (Cesarean section) | 323 (227/96) | MRI + EMR | ≥1500 mL |
| Li [37], 2024 | China | Single-Center Retrospective Case-Control Study | Obstetric (Cesarean section) | 231 | EMR | ≥1500 mL |
a
EBL: estimated blood loss.
b
MRI: magnetic resonance imaging.
c
EMR: electronic medical record.
d
CT: computed tomography.