Calculated Versus Estimated Blood Loss in Plastic Breast Surgery

Estimated blood loss (EBL), based on surgeons' visual estimation of blood loss, guides patient care but is often inaccurate. Calculated blood loss (CBL), a measurement of the volume of blood lost, is a more accurate substitute. Our aim was to assess the differences between EBL and CBL in plastic surgery.

A retrospective analysis was conducted on 35 patients who underwent deep inferior epigastric perforator flaps, oncoplastic surgery, breast reductions, or mastectomies in 1 hospital over 18 months.

The surgeons underestimated EBL (median EBL 250 versus CBL 388 cc, P < 0.001). EBL and CBL from surgeon 2, a senior surgeon, were not statistically different compared with those of surgeon 1 (250 versus 250 cc, P = 0.958; 363 versus 501 cc, P = 0.143), but tended to have less delta EBL-CBL (113 versus 273 cc, P = 0.066). Both breast reductions/mastectomies and deep inferior epigastric perforators had higher CBL (200 versus 360 cc, P < 0.001; 300 versus 748 cc, P = 0.015), but less delta EBL-CBL (116 versus 438 cc, P = 0.054). There was a strong negative relationship between EBL and postoperative hemoglobin, and a moderate relationship between CBL and delta EBL-CBL with case duration, intraoperative fluids, and urine output.

The surgeons underestimate blood loss, but the senior surgeon tended to do so to a lesser extent. Complex and longer procedures tended to have a greater discrepancy between EBL and CBL. CBL should be considered as a reliable alternative to EBL.