Short-term maternal outcomes after intraoperative administration of prophylactic oxytocin during cesarean sections: a...

The objective of this study was to evaluate the impact of different intraoperative prophylactic oxytocin regimens on maternal blood loss during cesarean section, and to compare effects in procedures performed before versus after onset of labor.

This retrospective cohort study was conducted at a tertiary care center over 15 years (2006-2021). A total of 1996 cesarean sections were identified, of which 1504 women with complete pre- and postoperative hemoglobin values were included in hemoglobin delta analyses. All 1996 women were considered for descriptive and binary outcome analyses. The study population was stratified into four intraoperative oxytocin exposure groups (0 IU, 3 IU, > 3 up to ≤ 13 IU, and > 13 IU) and further analyzed according to timing before or after onset of labor. The primary outcome was perioperative hemoglobin delta, while secondary outcomes included estimated intraoperative blood loss and binary maternal outcomes such as transfusion, uterine atony, and B-Lynch procedure.

In cesarean sections before onset of labor, very high intraoperative oxytocin doses (> 13 IU) were associated with significantly increased adjusted blood loss (+ 315 ml, p = 0.007), while intermediate doses (+ 270 ml, p = 0.009) also showed higher losses compared with no oxytocin. Hemoglobin decline was greater in the 3 IU and > 3 up to ≤ 13 IU groups, but not in the > 13 IU group. In cesarean sections after onset of labor, women receiving very high doses likewise had significantly higher blood loss (+ 170 ml, p = 0.004), whereas a modest reduction was observed with 3 IU (- 116 ml, p = 0.014). Estimated blood loss did not reliably correlate with hemoglobin decline, and no consistent dose-response benefit of higher oxytocin administration was observed.

Very high intraoperative oxytocin doses were not associated with reduced blood loss and were frequently administered in women at increased bleeding risk, suggesting confounding by indication. These results should therefore be regarded as hypothesis-generating rather than definitive evidence to guide prophylactic dosing.