Retained placenta

Definition

• Retained placenta is present when the placenta has not been born more than 30 minutes after the birth of the baby; however, there is no internationally agreed definition.
• The third stage of labour is the period between the birth of the baby and the birth of the placenta.

Occurrence & epidemiology

Epidemiology

• Retained placenta affects about 0.5–3% of all vaginal births; in a systematic review reported rates ranged from 0.5% to 4.8%.

Aetiopathogenesis

Aetiology and risk factors

• An important cause is placenta accreta spectrum, in which the chorionic villi are not contained by decidua but attach to the myometrium (accreta), invade it (increta) or penetrate it to the serosa (percreta).

Clinical features

Signs of placental separation

• The Ahlfeld sign describes descent of the cord clamp by approx. 10 cm.
• The Schröder sign means a narrower fundus rising to the upper right.

Retained placenta

• Uterine inversion threatens with traction on an unseparated placenta.

Clinical features and complications

• Retained placenta is an important cause of primary and secondary postpartum haemorrhage and increases maternal morbidity and mortality.
• In placenta accreta, bleeding before separation may be minimal or absent; attempts at separation typically cause massive haemorrhage.

Diagnosis

• The diagnosis is clinical when the placenta has not been born 30 minutes after the baby; placenta accreta is suspected when no plane of separation can be created and traction on the placenta causes heavy bleeding.
• In women at risk, placenta accreta spectrum can be recognised antenatally on ultrasound at the uteroplacental interface, supplemented by MRI or Doppler if findings are inconclusive.

Keep learning in the app

Further reading (selection)

1. MSD Manual Professional Edition: Placenta Accreta
2. DocCheck Flexikon, Plazentaretention

Cross-references