Benirschke and associates (2012) in that the "age" of the retroplacental clot cannot be determined exactly. In the example shown in Figure 41-15, a large dark clot is well formed, it has depressed the placental bulk, and it likely is at least several hours old.
Deining severity of placental abruption is problematic. We have considered abruption severe when the fetus dies, however, maternal and fetal complications can be serious even with a liveborn fetus. Ananth and coworkers (2016) have deined severe abruption as displaying one or more of the following: (1) maternal sequelae that include disseminated intravascular coagulation, shock, transfusion, hysterectomy, renal failure, or death; women cared for at Parkland Hospital, we
FIGURE 41-15 Partial placental abruption with a dark adherent clot.
found fetal-to-maternal hemorrhage of 80 to 100 mL in three of eight cases of traumatic placental abruption (Stettler, 1992). Importantly, in some cases of trauma, a nonreassuring fetal heart rate tracing may not be accompanied by other evidence of placental separation. A sinusoidal tracing is one example. Traumatic abruption is considered in more detail in Chapter 47 (p. 928).
Some cases of chronic placental separation begin early in pregnancy. Dugof and coworkers (2004) observed an association between some abnormally elevated maternal serum aneuploidy markers and subsequent abruption. Other have correlated irstand second-trimester bleeding with third-trimester placental abruption (Ananth, 2006; Weiss, 2004). In some cases of a chronic abruption, subsequent oligohydramnios developschronic abruption-oligohydramnios sequence-CAGS (Elliott, 1998). Even later in pregnancy, hemorrhage with retroplacental hematoma formation is occasionally arrested completely without delivery. hese women may have abnormally elevated serum levels of alpha-fetoprotein or placenta-specific RNAs as markers of the event (Miura, 2016; Ngai, 2012) .
he reported incidence of placental abruption varies because of diferent criteria used for diagnosis. hat said, its frequency averages 0.5 percent or 1 in 200 deliveries. From one database of almost 28 million births from 2006 through 2012, the incidence of placental abruption was nearly 1 percent (Ananth, 2016). From a cohort of more than 1.57 million births in the Netherlands, Ruiter and coworkers (2015) found the frequency was 0.22 percent-1 in 450. In more than 250,000 0.....) 5.
FIGURE 41-16 Frequency of placental abruption and placenta previa by maternal age at Parkland Hospital from 2000 through 2015.
deliveries at Parkland Hospital from 2000 through 2015, the incidence of placental abruption averaged 0.35 percent or 1 in 290 (Fig. 41-16).