Severe hypocalcemia during surgery for placenta accreta spectrum: The case for empiric replacement

Introduction: We aimed to determine predictive factors for severe hypocalcemia in women with placenta accreta spectrum. Material and methods: Study of 123 women with histology-proven placenta accreta spectrum with cesarean hysterectomy between 2011 and 2017. Two groups were selected: Cases: critically low (“panic value”) serum total calcium (≤7 mg/dL) and Controls: normal serum total calcium (≥8.5 mg/dL). Regression and receiver operating characteristic (ROC) analyses were performed to evaluate the potential associations. Results: There were 13 women with critically low (cases) and 18 with normal calcium (controls). Baseline characteristics were not statistically different. The median estimated blood loss, units of red blood cells (RBCs) transfused and volume of crystalloid transfused, were higher in the low calcium group. Six out of 13 (46.2%) cases had received ≥4 units of RBCs during surgery vs 2 of 18 (11.1%) controls (P = 0.04). ROC analysis showed that estimated blood loss, units of RBCs transfused, and crystalloid transfused were associated with severe hypocalcemia and univariate regression analysis confirmed that estimated blood loss ≥1500 mL, RBC transfusion ≥4 units, and crystalloid transfused ≥4L were associated with severe hypocalcemia. Conclusions: Intraoperative transfusion of ≥4 units RBCs is predictive of the development of severe hypocalcemia in placenta accreta spectrum patients experiencing active bleeding. Empiric replacement of 1 g CaCL₂ is recommended for every 4 U RBC transfused.