What is the appropriate emergency department workup for first trimester vaginal bleeding (first trimester bleeding)?

From the Guidelines

The emergency department workup for first trimester bleeding should begin with a thorough history and physical examination, followed by laboratory tests and imaging studies, with transvaginal ultrasound being the preferred imaging modality to confirm intrauterine pregnancy, assess fetal viability, and rule out ectopic pregnancy, as recommended by the American College of Radiology Appropriateness Criteria 1.

Initial Evaluation

The initial evaluation should include:

• Quantitative beta-hCG testing to confirm pregnancy and establish a baseline level
• Complete blood count to assess for anemia and infection
• Blood type and Rh status determination, as Rh-negative women with bleeding require RhoGAM (50 mcg if less than 12 weeks) to prevent sensitization

Imaging Studies

• Transvaginal ultrasound is crucial to confirm intrauterine pregnancy, assess fetal viability, and rule out ectopic pregnancy, with a sensitivity of 99% and specificity of 84% in a prospective study of 1,427 patients with b-hCG levels >1,500 IU/L 1
• Transabdominal ultrasound may be complementary to transvaginal ultrasound and may sometimes be adequate alone, as stated in the ACR Appropriateness Criteria 1

Management

• If the ultrasound shows an intrauterine pregnancy with cardiac activity, the risk of miscarriage is lower (approximately 5-10%)
• Serial beta-hCG measurements 48 hours apart may be necessary if the ultrasound is inconclusive; normal pregnancies typically show a 53-66% increase over this period
• Pelvic examination should be performed to assess cervical dilation, active bleeding, and to rule out other causes like cervicitis or polyps
• For hemodynamically unstable patients, establish IV access with two large-bore catheters and initiate fluid resuscitation
• Pain management with acetaminophen or opioids may be appropriate
• Patients with confirmed viable pregnancies can often be discharged with close follow-up, while those with threatened abortion should be counseled that approximately 50% will progress to complete abortion
• Non-viable pregnancies may require gynecology consultation for possible dilation and curettage

Key Considerations

• The absence of an intrauterine pregnancy when the b-hCG level is >3,000 mIU/mL should be strongly suggestive (but not diagnostic) of an ectopic pregnancy, as suggested by Doubilet et al 1
• The high specificity of adnexal findings suggestive of ectopic pregnancy includes the classic “tubal ring”
• TVUS as a screening test for ectopic pregnancy demonstrated a 99% sensitivity and 84% specificity in a prospective study of 1,427 patients with b-hCG levels >1,500 IU/L 1

From the Research

Emergency Department Workup for First Trimester Bleeding

• The workup for first trimester bleeding typically includes vital signs, physical examination, laboratory tests (such as Rh factor, hemoglobin, and possibly progesterone levels), and pelvic ultrasound (US) to distinguish among viable pregnancy, nonviable pregnancy, intrauterine pregnancy (IUP) of uncertain viability, and pregnancy of unknown location 2.
• Quantitative human chorionic gonadotropin (hCG) levels are of minimal clinical utility after IUP is visualized on US, but serial quantitative hCG levels should be measured in patients with pregnancy of unknown location 2, 3.
• Ultrasound evaluation is the mainstay of examination for first trimester bleeding, and can help identify important causes such as spontaneous abortion, ectopic pregnancy, and gestational trophoblastic disease 3.
• The discriminatory level of ß-hCG (1,500 to 3,000 mIU per mL) is the level above which an intrauterine pregnancy should be visible on transvaginal ultrasonography, and failure to detect an intrauterine pregnancy at this level should raise concern for early pregnancy loss or ectopic pregnancy 4.

Patient Expectations and Concerns

• Patients presenting to the emergency department with first trimester bleeding are most commonly motivated by a desire to have an ultrasound and blood work performed to evaluate the well-being of their fetus, and to determine whether or not they are having a miscarriage 5.
• A minority of patients are concerned about potentially emergent conditions such as ectopic pregnancy, life-threatening hemorrhage, or otherwise abnormal pregnancy 5.

Diagnostic Criteria and Treatment Options

• Ultrasound findings diagnostic of early pregnancy loss include a mean gestational sac diameter of 25 mm or greater with no embryo and no fetal cardiac activity when the crown-rump length is 7 mm or more 4.
• Treatment options for early pregnancy loss include expectant management, medical management with mifepristone and misoprostol, or uterine aspiration 4.
• Established criteria should be used to determine treatment options for ectopic pregnancy, including expectant management, medical management with methotrexate, or surgical intervention 4.