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Bleeding in The Second Half of Pregnancy

The etiology of bleeding in many cases in the second half of pregnancy can not be determined. However, among known causes of significant bleeding, placenta previa and placental abruption are the two most common etiologies. The different degrees of placenta previa are as follows:

Total placenta previa: The placenta totally covers the internal cervical os.

Partial placenta previa: The placenta partially covers the internal cervical os.

Marginal placenta previa: The edge of the placenta extends to the margin of the internal cervical os.

Low-lying placenta: The placenta is within reach of the examining finger introduced through the cervix.

Placenta previa usually is associated with painless vaginal bleeding, although uterine contractions may be present. The diagnosis is best confirmed by an ultrasound scan. Factors associated with an increased risk of placenta previa include multiparity, advancing maternal age, previous cesarean deliveries, and induced abortion. Placenta previa may be associated with placenta accreta, especially if a patient has had a previous cesarean delivery. Management depends on the amount of persistent bleeding and the gestational age at presentation. Cesarean delivery is indicated for the patient who is at term, in labor, or experiencing excessive bleeding (regardless of gestational age). Tocolytics of the beta-mimetic class are generally not recommended in women with significant bleeding because these tocolytics may be associated with tachycardia and hypotension and their efficacy is questionable. There are similar problems with the calcium channel blockers. The initial episode of bleeding in patients with placenta previa is often not excessive, and it is common for patients to bleed intermittently in the third trimester. Thus, in the patient remote from term, all efforts should be directed toward conservative care with restricted activity so that the fetus can mature. Because a significant number of newborns delivered after a bleeding episode caused by placenta previa have hypovolemia or anemia or both, there is an increasing tendency to deliver them by cesarean birth once they are mature.

Premature separation of the placenta, abruptio placentae, occurs in approximately 0.5-1.5% of pregnant women. Its clinical presentation varies from minimally painful vaginal bleeding and uterine irritability to less common severe separation with fetal demise, maternal hypotension, and disseminated intravascular coagulopathy.

In general, abruptio placentae must be managed with expeditious delivery and careful maternal and fetal monitoring. After physical examination, a complete blood count, platelet count, fibrinogen level, and partial thromboplastin time should be done. Urinary output should be monitored on an hourly basis, and an intravenous line large enough to allow rapid blood replacement should be placed.

After artificial rupture of membranes, FHR monitoring is undertaken. In the presence of a reassuring FHR pattern, vaginal delivery may be anticipated and is preferred. Cesarean delivery is used in the presence of a nonreassuring FHR pattern or failure to make adequate progress in labor. Blood replacement is directed at maintaining blood pressure and urinary output, as well as keeping the hematocrit above 25%. If a coagulopathy is present (ie, hypofibrinogenemia), component therapy based on the etiology may be required in addition to blood replacement.