Introduction
Delay in placental delivery may cause heavy bleeding in late pregnancy. Therefore, it is recommended that obstetric providers use uterotonic agents immediately after delivering the foetus and deliver the placenta by controlled cord traction1). Retained products of conception (RPOC), in which placental tissue remains in the uterus after delivery, occur in about 1% of pregnant women and causes severe postpartum haemorrhage2,3). The National Institute for Health and Clinical Excellence (NICE) and the World Health Organization (WHO) recommend that obstetric providers perform manual removal of the placenta (MROP) if it is not expelled within 30 minutes to 1 hour after the baby is delivered4). However, MROP may increase the risk of hysterectomy and death due to heavy bleeding. Additionally, the placenta often remains partly after MROP5). If conservative management is chosen immediately after deliver, or RPOC occurs after MROP, there is a risk of subsequent massive haemorrhage or infection6-9). Therefore, some studies suggest that RPOC should be removed by transcervical resection (TCR) to avoid bleeding and infection during conservative management10,11). However, surgical RPOC removal also carries a high risk of massive bleeding12).
Recently, several Japanese facilities have reported that RPOC spontaneously disappeared without surgical management13,14). However, evidence for the conservative management of RPOC, especially after term delivery, is lacking, and there are no criteria to determine which cases can achieve spontaneous resolution15,16). It is also unclear when major bleeding or infection occurs and how long it will take for RPOC to be absorbed spontaneously.
Our hospital is the only university hospital in the South Osaka district, and most patients with RPOC in this area are referred to our hospital. We have treated many cases with RPOC conservatively until they spontaneously disappear. This study aimed to analyse the clinical course of RPOC after 34 weeks of gestation and to elucidate its natural history. The results of this study show that conservative management should be incorporated into the standard treatment for RPOC.