This patient most likely has experienced a placental abruption. Abruption is commonly associated with abdominal trauma, cocaine use, hypertension, and cigarette smoking.
The patient’s constant (as opposed to episodic) abdominal pain is suggestive of abruption, even without vaginal bleeding. Although abruption classically presents with painful vaginal bleeding, some women have concealed abruptions, where the blood is trapped between the fetal membranes and decidua. This patient’s fetal heart rate tracing is also very concerning for abruption. Possible findings include frequent low-amplitude contractions, decreased variability, late decelerations, and fetal bradycardia or tachycardia. If abruption is suspected, further confirmation of diagnosis can be achieved with fibrinogen level < 200 mg/dL and ultrasound, which may show a retroplacental hematoma (Illustration A). Complications include maternal hemorrhage, DIC, and fetal distress from uteroplacental insufficiency.
Figure A shows a possible fetal heart rate tracing in placental abruption. There are frequent, low-amplitude contractions, fetal tachycardia, minimal variability, and 1 late deceleration. Illustration A shows a retroplacental hematoma, which is highly concerning for placental abruption.
Answer 2: A history of prior C-section places this patient at risk for conditions such as placenta previa, placenta accreta, and uterine rupture. Previa classically presents with painless vaginal bleeding, while accreta often results in difficulty separating the placenta after delivery. Uterine rupture causes loss of fetal station with vaginal bleeding and sudden abdominal pain. None of these is likely to cause the fetal heart rate tracings seen in this patient.
Answer 3: Dehydration is felt to cause Braxton-Hicks contractions, which are most common in the second and third trimesters but do not indicate labor or cause cervical change. They are usually mild, irregular, and infrequent, unlike this patient’s pain. In addition, they do not produce the changes seen on this fetal heart rate tracing.
Answer 4: Contaminated food can cause gastroenteritis with abdominal pain. In addition, this patient's husband had one episode of diarrhea. However, the patient herself has no gastrointestinal symptoms such as diarrhea or vomiting, and her fetal heart rate tracing is more consistent with abruption.
Answer 5: Labor is defined by uterine contractions and cervical change. This patient has contractions that are abnormal on the tracing and her pain is constant instead of episodic. Although she is fingertip dilated, most multiparous women are not completely closed in the third trimester even without onset of labor. Given the tracing, this patient is most likely having a placental abruption.
Placental abruption is associated with abdominal trauma, hypertension, cocaine use, and cigarette smoking. It presents with pain, classically with vaginal bleeding, and loss of variability and decelerations on fetal heart rate tracing.