Predicting bleeding risk in placenta accreta spectrum with placenta previa managed by prophylactic balloon occlusion: Utility of cervical venous plexus volume on MRI.

OBJECTIVE

To investigate whether cervical venous plexus (CV) volume measured by MRI predicts massive intraoperative blood loss (IBL) in patients with placenta accreta spectrum (PAS) and placenta previa managed with prophylactic balloon occlusion of the internal iliac arteries, differentiating between anterior (APP) and posterior placenta previa (PPP).

METHODS

Overall, 59 patients with PAS and placenta previa underwent a cesarean section with PBOIIA. CV volume was quantitatively measured using T2-weighted MRI. Associations between CV volume and IBL were analyzed and stratified according to placental location.

RESULTS

Patients with PPP had significantly greater CV volumes than that of patients with APP (20.5 ± 10.8 vs 14.7 ± 10.7 cm3, p = 0.032). Operative time (172.2 ± 42.1 vs 122.7 ± 33.2 min, p = 0.023) and transfusion requirements (7.8 ± 4.1 vs 3.1 ± 2.2 units, p < 0.001) were higher in APP; however, total IBL did not differ significantly (3927.7 ± 2847.6 vs 2742.4 ± 1514.5 mL, p = 0.267). In PPP, smaller CV volume significantly correlated with increased IBL (Spearman's ρ = -0.541, p = 0.002), predicting massive hemorrhage (IBL ≥ 2500 mL) with modest accuracy (area under the curve = 0.727; cutoff ≤ 21.0 cm3, sensitivity = 70.6 %, specificity = 78.6 %). No correlation was observed in APP cases (ρ = -0.098, p = 0.638).

CONCLUSION

In PAS with placenta previa managed by PBOIIA, a reduced CV volume on preoperative MRI predicted a higher intraoperative bleeding risk, particularly in PPP. In PPP, a smaller CV volume (≤21.0 cm3) was associated with massive intraoperative hemorrhage.