Risk factors for intra-operative haemorrhage and bleeding risk scoring system for caesarean scar pregnancy: a case-control study

Abstract

Objectives: To investigate risk factors associated with excessive intra-operative haemorrhage during evacuation operation, and to develop a bleeding risk scoring system in patients with caesarean scar pregnancy (CSP) to guide treatment.

Study design: A case-control study was conducted. Excessive intra-operative haemorrhage was defined as active bleeding during dilation and suction evacuation (blood loss ≥200ml). The bleeding group consisted of patients who experienced excessive intra-operative blood loss. Patients with less intra-operative blood loss were included in the control group.

Results: In total, 458 admissions from 2009 to 2014 were included in this study. Compared with the control group, the bleeding group had higher serum β-human chorionic gonadotrophin (hCG), higher gestational age, larger CSP mass, richer peritrophoblastic perfusion and thinner myometrial layer before evacuation (all p<0.05). Risk factors with p<0.05 on multivariable logistic regression analysis included serum β-hCG >20,000mIU/ml [odds ratio (OR) 1.4, 95% confidence interval (CI) 1.0-3.2], gestational age >8 weeks (OR 2.1, 95% CI 1.1-4.0), maximum diameter of gestational sac or CSP mass ≥5cm (OR 7.4, 95% CI 3.4-16.1), myometrial thickness ≤0.15cm (OR 3.6, 95% CI 1.9-6.9) and significant peritrophoblastic perfusion (OR 9.8, 95% CI 4.1-23.2). These risk factors formed the final bleeding risk scoring system by conversion of their OR values into corresponding points. A total of 10 points was identified as the optimal cut-off on the receiver operating characteristic curve. Thus, patients with scores ≥10 points were identified as being at high risk of bleeding. The final bleeding risk scoring system had an area under the curve of 0.86, sensitivity of 86.8% and specificity of 73.2%.

Conclusions: Gestational age, serum β-hCG, size of gestational sac, thickness of myometrial layer and peritrophoblastic perfusion were found to be associated with excessive intra-operative haemorrhage during suction evacuation of CSP. A bleeding risk scoring system was constructed to help guide the management of patients with CSP. Patients with total scores ≥10 points were identified as being at high risk of bleeding, whereas patients with total scores ≤5 points were identified as being at low risk of bleeding.

Keywords: Caesarean scar pregnancy; Haemorrhage; Risk factors; Scoring system; Suction evacuation.