What is the diagnosis for a pregnant woman presenting with a history of passing tissue at home and mild vaginal bleeding, with an examination showing mild vaginal bleeding and a closed cervix?

Diagnosis: Threatened Abortion

Based on the clinical presentation of mild vaginal bleeding with a closed cervix and history of passing tissue at home, the most likely diagnosis is threatened abortion, though this requires urgent ultrasound confirmation to definitively rule out other diagnoses.

Clinical Reasoning and Diagnostic Classification

The classification of early pregnancy complications depends on specific clinical findings, particularly cervical status and tissue passage 1, 2:

Key Diagnostic Features by Type:

Threatened Abortion:

• Vaginal bleeding with closed cervix 1, 3
• Pregnancy may still be viable 4, 3
• Most common presentation of first trimester bleeding 3

Inevitable Abortion:

• Vaginal bleeding with open cervix 1
• Pregnancy loss is imminent but tissue has not yet passed 3

Incomplete Abortion:

• Products of conception visible in vagina or cervical os 1
• Open cervix with partial passage of tissue 2
• History of passing tissue mass associated with >90% chance of non-viable pregnancy 1

Complete Abortion:

• All products of conception have passed 3
• Cervix typically closed after complete passage 5
• Bleeding usually diminishing 5

Critical Diagnostic Dilemma in This Case

The history of passing tissue at home creates diagnostic uncertainty 1. While a closed cervix typically indicates threatened abortion, the tissue passage history suggests possible incomplete or complete abortion 1, 2. This discrepancy mandates immediate ultrasound evaluation rather than relying on clinical examination alone 1, 2.

Why Clinical Examination Alone is Insufficient:

• Clinical assessment of threatened abortion by history and physical examination has poor reliability (kappa = 0.57) 2
• Clinicians cannot accurately predict pregnancy status from examination alone 1, 2
• Transvaginal ultrasound achieves diagnostic accuracy of kappa = 0.96 2
• Approximately 20% of recognized pregnancies present with threatened abortion 4

Immediate Management Algorithm

Step 1: Urgent Transvaginal Ultrasound (Within 12-24 Hours)

This is the single most important diagnostic step 6, 2:

• Assess for intrauterine gestational sac with yolk sac or embryo 6
• Evaluate for retained products of conception 2
• Rule out ectopic pregnancy (7-20% of pregnancy of unknown location cases) 6, 7
• Measure mean gestational sac diameter if present 6

Step 2: Obtain Quantitative β-hCG Level

Essential for correlation with ultrasound findings 6, 3:

• If β-hCG >3,000 mIU/mL and no intrauterine pregnancy visible, strongly suspect ectopic pregnancy 6, 8
• If β-hCG <1,500 mIU/mL, ultrasound may not yet show gestational sac 6
• Serial β-hCG every 48 hours if pregnancy location uncertain 6, 7

Step 3: Risk Stratification Based on Combined Findings

If viable intrauterine pregnancy confirmed:

• Diagnosis is threatened abortion 3
• Expectant management with precautions 3
• No evidence supporting bed rest 3
• Insufficient evidence for progesterone therapy 3

If retained products visible on ultrasound:

• Diagnosis is incomplete abortion 2
• Offer expectant, medical, or surgical management 3

If empty uterus with declining β-hCG:

• Likely complete abortion 5
• Monitor β-hCG to zero 6

If pregnancy of unknown location:

• 7-20% risk of ectopic pregnancy 6, 7
• Serial monitoring mandatory 7
• Never discharge without reliable follow-up 8

Critical Pitfalls to Avoid

• Never rely on cervical status alone to make the diagnosis, as clinical examination has poor diagnostic accuracy 1, 2
• Never assume complete abortion based solely on history of tissue passage without ultrasound confirmation of empty uterus 2
• Never defer ultrasound based on "low" β-hCG levels, as 22% of ectopic pregnancies present with β-hCG <1,000 mIU/mL 6, 8
• Never use β-hCG discriminatory threshold alone to exclude ectopic pregnancy 6, 8
• History of passing tissue mass has >90% association with non-viable pregnancy, but ectopic pregnancy can still present this way 1, 2

Poor Prognostic Indicators Requiring Close Monitoring

If threatened abortion is confirmed, the following increase miscarriage risk 1, 4:

• Maternal age >35 years 1
• Heavy bleeding similar to normal menstruation 1
• Increasing vaginal bleeding 1
• Uterine size discrepancy ≥4 weeks from expected dates 1
• Low serum progesterone or β-hCG levels 4