Answer :USMLE step 2 Mcq 242:A woman with a twin gestation and a history of maternal hypertension presents at 34 weeks of gestation



Correct Answer: D

The location and extent of the placental abruption identified onultrasound has definite clinical significance. Retroplacental hematomas carry a worse prognosis for fetal survival than subchorionic hemorrhages. Ultrasound can identify three predominant locations for placental abruption. These are subchorionic (between the placenta and the membranes), retroplacental (between the placenta and the myometrium), and preplacental (between the placenta and the amniotic fluid). The diagnosis of placental abruption is clinical. Although vaginal bleeding is present in 80% of cases, it may be concealed in the remainder (that is, retroplacental bleeding). Thus, the maternal hemodynamic situation may not be explained by observed blood loss. Pain and increased uterine tone are typically present. Risk factors include prior history of abruption,maternal hypertension, cigarette or cocaine use, increasing maternal age or multiparity. Abruption may be associated with preterm premature rupture of membranes, twin gestation after delivery of first infant and trauma. The premature separation of the normally implanted placenta from its attachment to the uterus is called abruptio placenta or placental abruption. This event occurs with a frequency of approximately 1 in 120 births but accounts for nearly 15 percent of perinatal mortality. Diagnosis of placental abruption is certain when inspection of the placenta shows an adherent retroplacental clot with depression or disruption of the underlying placental tissue; however, this frequently is not found if the abruption is of recent onset. Clinical findings indicating placental abruption include the triad of external or occult uterine bleeding, uterine hypertonus and/or hyperactivity, and fetal distress and/or fetal death.


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