A 38-year-old pregnant Caucasian female presents conscious, alert and oriented in moderate distress lying on a couch and complaining of abdominal pain and vaginal bleeding after a domestic dispute with her boyfriend. She says she was “thrown to the ground” during an argument that occurred about 24 hours ago, but denies hitting her head, being hit or any other trauma. She also denies any neck or back pain, chest pain, headache, nausea, vomiting, dizziness or loss of consciousness, but states that she does get dizzy “when I stand up and walk around.” She says the abdominal pain started immediately after the incident and has been sharp and constant. She describes the pain as a 4 on a scale of 0–10. The vaginal bleeding started about 20 hours ago, and she has used 4–5 feminine pads to soak up the flow. The patient also says she has experienced neither uterine contractions nor membrane rupture (i.e., had her “water break”).
The patient is 7½ months pregnant with a G4P2A2 obstetric history (see sidebar), with two cesarean sections and two elective abortions. She has a medical history significant for hypertension, for which she has been noncompliant with her medication for “about a year.” She smokes half a pack of cigarettes a day and admits to a history of crack cocaine use, but says she hasn’t used the drug since finding out she was pregnant. She has not received any prenatal care since being told she was pregnant during a visit to the emergency department six months ago.
Your physical exam reveals a gravid uterus and distended abdomen consistent with a 7½-month gestational period. She winces and flexes her abdominal muscles (guards) during palpation, but you are able to feel that her uterus is rigid and contracted. There are no contractions of labor during your examination. You note that her skin is dry, cool and slightly pale, with a capillary refill of 4 seconds. Her vital signs while supine are heart rate 122/min. and regular; respiratory rate 26/min. with good tidal volume; blood pressure 94/52; pulse oximetry 96% on room air; and tympanic temperature 97.9ºF (36.6ºC).
Abruptio placentae, the premature separation of the placenta from the uterine wall, is thought to account for up to 30% of all episodes of vaginal bleeding during the second half of pregnancy.6 Not all cases of abruptio will result in bleeding, though, as small separations may go undetected if blood remains trapped beneath the placenta, in which case the abruption is termed concealed. Abruptio placentae may be partial or complete. It is a serious and life-threatening issue for both the mother and fetus. It may disrupt circulation and gas exchange between the two, resulting in fetal hypoxia and death. Excessive blood loss from abruptio can easily lead to development of hypovolemic shock and death in the mother, especially since there is limited ability for vasoconstriction to slow hemorrhage when the placenta separates from the uterus. If the mother experiences hemodynamic compromise secondary to hypovolemic shock, so will the fetus!
Risk factors for abruptio placentae are listed in Table 2, and this patient has a number of them, including advanced maternal age and a history of trauma, chronic hypertension, cesarean section, smoking and cocaine use. Abruptio placentae is most commonly associated with maternal hypertension and preeclampsia, during which placental inflammation and ischemia leads to a weakening of the placenta/uterine wall interface.6,16 Abruption may occur spontaneously or be associated with seemingly minor trauma, as described in this case. This happens because of structural differences between the uterus and placenta: The uterus is relatively elastic and can stretch and contort, while the placenta is relatively inelastic and will not stretch and contort as easily. During blunt-force trauma, the shearing forces created between the elastic uterus and inelastic placenta can cause them to separate.
The clinical characteristics of abruptio placentae include vaginal bleeding, uterine pain and uterine tetany (contractions). Vaginal bleeding occurs in up to 70% of all cases. The amount can vary and gives no indication as to the severity of the event; a significant amount of blood can be lost before vaginal bleeding occurs. The description of abdominal pain can vary from mild cramping to severe tearing, and up to 20% of women with abruptio present without pain.6 Uterine tetany occurs when the uterus becomes irritated and contracts as a result. These are not true contractions of labor and should not be confused for them. Mild abruption is characterized by slight bleeding, no fetal distress and little or no uterine irritability. As the abruption progresses and involves more of the placenta, bleeding (which may or may not result in vaginal bleeding), uterine tetany and fetal distress increase. In response to the blood loss, maternal tachycardia will also develop. In cases of severe abruptio, severe blood loss leads to hypotension and fetal distress, and the uterus is contracted and painful to palpation. The patient in this case seems to fall into this category; consider her unstable and in need of ALS intervention. Fetal distress and death occur in approximately 15% of patients with abruptio placentae.6