Retained products of conception

Last revised by Amanda Er on 25 Jun 2022

Retained products of conception (RPOC) refer to the persistence of placental and/or fetal tissue in the uterus following delivery, termination of pregnancy or a miscarriage

RPOC complicate ~1-5% of all routine vaginal deliveries 12.

According to one prospective study, RPOC was present after a third-trimester delivery in around 2.7% of women, whereas it was diagnosed in pregnancies ending during the second and first trimesters in 40% and 17% respectively 12

It occurs with greater frequency with:

Common symptoms include vaginal bleeding and abdominal or pelvic pain, similar to patients with gestational trophoblastic disease. Some patients may have a fever 11.

Differentiation of these entities is important because retained products of conception are treated conservatively or with curettage, while gestational trophoblastic disease may require chemotherapy.

ß-human chorionic gonadotropin (beta-hCG) remains elevated in patients with gestational trophoblastic disease but falls to an undetectable level over 2-3 weeks, in cases of retained products.

Ultrasound is typically the first-line investigation in suspected retained products of conception:

  • a variable amount of echogenic or heterogeneous material within the endometrial cavity 
  • in some instances, this may present as an endometrial or intrauterine mass
  • presence of vascularity within the endometrial echogenic material supports the diagnosis but the absence of color Doppler flow has a low negative predictive value because retained products of conception may be avascular 9
  • calcification may be present

Retained products of conception can be suspected on ultrasound if the endometrial thickness is >10 mm following dilatation and curettage or spontaneous abortion (80% sensitive) ref.

Three vascularity patterns have been established on Doppler ultrasound 12:

  • type 1: minimal endometrial vascularity less than the myometrium
  • type 2: moderate vascularity with nearly equal endometrial and myometrial vascularity
  • type 3: marked endometrial vascularity more than adjacent myometrium
    • arterial flow velocities >100 cm/sec can occur with low-resistance spectral waveform and large vessels present, potentially mimicking a uterine arteriovenous malformation

MRI appearance is variable and consists of soft tissue within the endometrial cavity, which may be variably enhancing. There may be a variable degree of associated myometrial thinning and obliteration of the junctional zone.

Signal characteristics include 1:

  • T1: variable heterogeneous signal
  • T2: variable heterogeneous signal
  • T1 C+ (Gd): variable enhancement

For ultrasound appearances consider:

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Cases and figures

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