Diagnosis and management of secondary postpartum hemorrhage

Ultrasound examination in patients with secondary postpartum hemorrhage is often not definitive as there is considerable overlap between normal postpartum ultrasound findings and findings associated with secondary bleeding.

1. Ultrasound findings are often nonspecific in endometritis. The uterus may have a thickened, heterogeneous endometrium or show common normal postpartum findings, such as intracavitary debris, fluid, or gas. Infected retained placental tissue or a hematoma may be present.
2. Retained products of conception have a variable and sometimes nonspecific appearance on ultrasound. They often appear as a solid, echogenic intracavitary mass that extends to the endometrium. However, necrotic decidua and blood clots can mimic retained placental fragments. Color and spectral Doppler showing high-velocity, low-resistance arterial flow in the mass differentiates placental tissue from hematoma but is not always present in the retained tissue. In the absence of a mass, increased vascularity in a thickened postpartum endometrium is also consistent with retained placental tissue. Rarely, a focal abnormally adherent placenta presents as secondary postpartum hemorrhage. Ultrasound findings include a mass that extends into or beyond the myometrium.
3. Bleeding diathesis and subinvolution have a similar ultrasound appearance. Ultrasound may show normal postpartum findings, such as intracavitary debris, fluid, or gas. An intracavitary hematoma may be present and appears as an echogenic mass, which can mimic the ultrasound appearance of retained products of conception. However, hematomas are not vascularized, whereas retained placenta may have vascular flow on Doppler. The uterus may be enlarged in subinvolution, and hypoechoic tortuous vessels are seen along the inner third of the myometrium. Pulsed wave Doppler sonography shows increased peak systolic velocity with a low-resistance waveform along the inner third of the myometrium. In patients with subinvolution and an intracavitary hematoma, low-resistance arterial flow within the myometrium at the placental implantation site should not be confused with low-resistance arterial flow in retained placental tissue.