Placental abruption (abruptio placentae) is the partial or complete separation of the placenta from the uterine wall before delivery. It occurs in approximately 1% of all pregnancies and is a significant cause of perinatal morbidity-mortality. Risk factors include hypertension, preeclampsia, trauma, cocaine use, smoking, prior abruption history, and advanced maternal age. Clinically presents with painful vaginal bleeding, uterine tenderness, and fetal distress — however, in 20% of cases, bleeding may remain concealed. Ultrasound is the primary imaging modality; however, its sensitivity is limited (25-50%) because acute hemorrhage can be isoechoic to the placenta. The echogenicity of retroplacental hematoma changes over time: hyperechoic in acute phase, hypoechoic/complex in subacute phase. MRI is complementary, especially in cases with high clinical suspicion but negative US.
Age Range
18-45
Peak Age
30
Gender
Female predominant
Prevalence
Uncommon
Placental abruption begins with hemorrhage in the decidua basalis layer due to rupture of uterine spiral arteries. Hematoma accumulation creates pressure between the placenta and uterine wall, advancing separation → retroplacental hematoma. As the separation area enlarges, maternal-fetal gas exchange decreases → fetal hypoxia. Bleeding may drain externally (revealed) or accumulate in the retroplacental space (concealed). Hematoma echogenicity changes over time: acute blood (minutes-hours) is hyperechoic-isoechoic due to fibrin and cellular density → may be indistinguishable from placenta on US. In the subacute phase (hours-days), the hematoma undergoes lysis → liquefaction → hypoechoic/mixed appearance. In the chronic phase (days-weeks), organized hematoma may liquefy into an anechoic collection. This evolutionary change explains the limited sensitivity of US in acute abruption. On MRI, methemoglobin gives high T1 signal and can clearly demonstrate the hematoma even in the acute phase.
Retroplacental collection between placenta and myometrium — pathognomonic ultrasonographic finding of abruption. Echogenicity is time-dependent: acute hyperechoic → subacute hypoechoic → chronic anechoic.
A retroplacental collection is seen between the placenta and myometrium. In the acute phase (0-48 hours), the hematoma may be hyperechoic or isoechoic to the placenta — detection is difficult in this phase. In the subacute phase (2-7 days), the hematoma transforms to hypoechoic or mixed echogenicity. In the chronic phase (>1 week), it may become an anechoic fluid collection. Hematoma localization is important: retroplacental (most common), subchorionic (membrane-lifting), or precervical (draining below internal os).
Report Sentence
A retroplacental collection is seen between the placenta and myometrium, consistent with placental abruption.
Focal thickening or heterogeneous appearance of the placenta is seen at the abruption site. When the retroplacental hematoma cannot be clearly differentiated (isoechoic hematoma), focal placental thickness increase (>5 cm) may be a clue for abruption. Additionally, marginal hematoma at the placental edge or jelly-like trembling echogenicity suggests acute blood accumulation.
Report Sentence
The placenta is focally thickened with heterogeneous appearance; abruption should be considered in the clinical context.
Loss of subplacental (retroplacental) flow is seen at the abruption site on color Doppler. In normal pregnancy, spiral artery flows are demonstrated in the retroplacental area. Hematoma disrupts flow in this area → Doppler signal is lost or reduced. However, in large hematomas, active bleeding points (arterial jets) may be visible at edge zones.
Report Sentence
Loss of retroplacental flow is noted on color Doppler, consistent with abruption.
On T1-weighted MRI, a high signal intensity hematoma is seen in the retroplacental area. Methemoglobin (subacute hemorrhage product) causes T1 shortening producing bright signal. MRI has particular diagnostic value when US is inadequate (posterior placenta, obese patient, isoechoic hematoma). Hematoma size and localization are clearly evaluated.
Report Sentence
A high signal intensity collection in the retroplacental area is seen on T1-weighted MRI, consistent with subacute hematoma/abruption.
On T2-weighted MRI, the retroplacental hematoma shows heterogeneous signal. In the acute phase, intracellular deoxyhemoglobin causes T2 shortening → low signal. In the subacute phase, extracellular methemoglobin mixes with free water → high T2 signal. In the chronic phase, hemosiderin creates a T2 hypointense rim. This heterogeneous pattern helps assess the age and evolution of the hematoma.
Report Sentence
A heterogeneous signal intensity collection in the retroplacental area is seen on T2-weighted MRI, consistent with hematoma/abruption.
Criteria
Blood drains externally through the vagina — clinical bleeding is visible
Distinct Features
Earlier diagnosis, hematoma may be small because blood drains, hematoma may not be detected on US
Criteria
Blood accumulates in the retroplacental space — no or minimal vaginal bleeding
Distinct Features
More dangerous, large hematoma accumulation, risk of delayed diagnosis, large retroplacental collection on US, higher DIC risk
Criteria
Recurrent small hemorrhages, organized and chronic hematoma
Distinct Features
Anechoic collection on US, organized hematoma at placental margin, association with intrauterine growth restriction, oligohydramnios
Distinguishing Feature
In previa, bleeding is painless with placenta over the os; in abruption, bleeding is painful with retroplacental hematoma
Distinguishing Feature
Subchorionic hematoma collection is between chorionic membrane and uterine wall, usually in first trimester; abruption hematoma is retroplacental, presenting with painful bleeding in second/third trimester
Distinguishing Feature
In PAS, the placenta invades the myometrium with lacunae and clear space loss; in abruption, the placenta has separated with retroplacental hematoma
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralAcute placental abruption is an obstetric emergency — emergent cesarean is indicated in fetal distress and maternal hemodynamic instability. In mild cases (small hematoma, stable fetal heart rate), conservative management with hospitalization is possible. Massive abruption can be complicated by DIC, renal failure, and maternal death. Serial US follow-up and fetal growth monitoring are recommended in chronic abruption. Anti-D immunoglobulin should be administered to all Rh-negative patients.
Placental abruption is an obstetric emergency. The triad of painful vaginal bleeding, uterine tenderness, and fetal distress is characteristic. Severe cases may develop DIC, hemorrhagic shock, and fetal death. Diagnosis is primarily clinical — US is normal in 50% of cases (isoechoic acute hematoma may be missed). Extensive abruption requires emergent delivery.