No bleeding before, more bleeding later: The relationship between the presence of warning bleeding and the amount of bleeding during caesarean section in placenta praevia

Abstract

Massive bleeding during caesarean section (CS) is a lifethreatening complication of placenta praevia. Placenta accreta, anterior placentation, history of previous CS, and advanced maternal age, predicted massive bleeding (Hasegawa et al. 2009), which we have also demonstrated and described in a domestic journal in the Japanese language (Watanabe et al. 2002). We also had the clinical impression that, excluding placenta accreta, patients who had not experienced warning bleeding during pregnancy bled more during/after CS than those who had. We therefore reanalysed previous data. During a 10-year period (January 1991–December 2000), we performed 124 CS due to placenta praevia. Excluding five patients with multiple pregnancies and five patients with placenta accreta (with all having to undergo hysterectomy), we analysed 114 singleton pregnant women with placenta praevia. Warning bleeding was defined as painless bleeding which did not lead to emergency CS. The amount of blood loss during/after CS was defined as the sum of blood loss during CS and the 2-h post-surgical period, excluding blood loss before CS. Of 114 cases, 63 experienced warning bleeding, and the remaining 51 did not. Patients with and without warning bleeding, bled 1,276+ 688 ml (mean+ standard deviation: range: 289–3,257) and 1,563+ 790 ml (377–4,950) during/after CS, respectively, with statistical significance (p ¼ 0.02, unpaired t-test). Our clinical impression therefore proved to be correct; patients without warning bleeding bled significantly more than those with. The following may account for the mechanism of this observation. Even excluding placenta accreta, placental attachment to the decidua may differ among patients. Some placenta may be attached more tightly and thus may be difficult to separate during pregnancy, reducing the chance of warning bleeding. Tight attachment and thus a ‘difficult to separate’ condition may also occur during CS, and thus may prohibit physiological placental separation, leading to more bleeding. Ultrasound and magnetic resonance imaging have enhanced the possibility of predicting placenta accreta, and thus the possibility of massive bleeding accompanied with this condition. Some ultrasound findings, i.e. spongy-like findings in the cervix, have been reported to predict massive bleeding during CS, regardless of whether placenta accreta is present (Hasegawa et al. 2009). Here, we provide one simple, but clinically important, rule of thumb; in patients without discernible placenta accreta, a lack in warning bleeding may be an ominous sign of greater bleeding. To our knowledge, this has hitherto never been described. ‘Warning’ bleeding may warn of the presence of placenta previa, but may not warn of more bleeding during/after CS. Thus, it seems, ‘no bleeding before, more bleeding later’. We must admit that wide ranges of blood loss during/after CS were observed in patients both with and without warning bleeding. We also admit that the study population here was not large. We must await further study to confirm this, and if so, its mechanism.