What is the diagnosis for a 34-week pregnant woman experiencing abdominal pain, contractions, and bleeding?

Diagnosis: Placental Abruption (Abruptio Placentae)

The diagnosis is placental abruption—the triad of abdominal pain, contractions, and vaginal bleeding at 34 weeks gestation is pathognomonic for this obstetric emergency. 1, 2

Key Distinguishing Clinical Features

Painful vaginal bleeding is the hallmark feature that distinguishes placental abruption from other causes of third-trimester bleeding. 1 The combination of:

• Abdominal pain (often severe and constant) 2, 3
• Uterine contractions (typically frequent and may be tetanic) 3, 4
• Vaginal bleeding (though 20-30% of cases present with concealed hemorrhage and no visible bleeding) 2

This clinical presentation at 34 weeks gestation makes placental abruption the primary diagnosis, as the pain component immediately excludes placenta previa, which characteristically presents with painless bleeding and a soft, non-tender uterus. 1, 2

Critical Differential Diagnosis Considerations

Placenta previa is effectively ruled out by the presence of abdominal pain—previa presents with painless vaginal bleeding and a soft uterus, affecting approximately 1 in 200 pregnancies. 1, 2

Uterine rupture is exceedingly rare in a patient without prior cesarean delivery or uterine surgery, and would typically present with more severe hemodynamic instability and potentially palpable fetal parts. 1, 2

Diagnostic Approach

The diagnosis of placental abruption is primarily clinical, not radiologic. 5, 6 Key points:

• Ultrasound has limited diagnostic value—it may show retroplacental hematoma but a negative ultrasound does not exclude abruption. 5
• Clinical presentation trumps imaging findings in making this diagnosis. 6, 4
• Assess hemodynamic stability immediately—vital signs, urine output, and signs of shock are critical. 2
• Obtain coagulation studies to assess for disseminated intravascular coagulopathy (DIC), which complicates severe abruption. 2
• Continuous fetal monitoring is mandatory to assess fetal well-being. 2

Immediate Management Algorithm at 34 Weeks

At 34 weeks gestation with placental abruption, the management depends on maternal hemodynamic stability and fetal status:

• If maternal compromise OR fetal distress is present: Emergency cesarean delivery with aggressive volume resuscitation. 2
• If both mother and fetus are stable: Close monitoring with readiness for immediate delivery if deterioration occurs. 3, 5
• At 34 weeks (near-term), fetal lung maturity is adequate—the threshold for delivery is lower than at earlier gestational ages. 3

Critical Pitfalls to Avoid

• Do not rely on ultrasound to exclude abruption—the diagnosis is clinical, and imaging has poor sensitivity. 5, 6
• Do not miss concealed hemorrhage—20-30% of abruptions present without visible vaginal bleeding but with severe pain and hemodynamic instability. 2
• Do not delay delivery in the presence of maternal or fetal compromise—abruption can rapidly progress to maternal shock and fetal death. 2, 3
• Monitor for DIC aggressively—abruption involving more than 50% of the placenta is frequently associated with fetal death and coagulopathy. 5