What are the symptoms of a current or pending miscarriage?

Symptoms of Current or Pending Miscarriage

The most common symptoms of miscarriage are vaginal bleeding and abdominal pain, with the severity and pattern of bleeding being the most critical indicator requiring immediate assessment. 1

Primary Warning Signs

Vaginal Bleeding

• Heavy bleeding requiring changing a pad soaked with blood and clots more than once an hour indicates severe hemorrhage and requires immediate referral 1
• Bleeding severity should be assessed by the time taken to saturate a sanitary pad, not just by patient's subjective description 1
• Vaginal bleeding is present in the majority of women experiencing miscarriage and is often the first presenting symptom 1, 2

Abdominal Pain

• Painful vaginal bleeding in early pregnancy suggests possible miscarriage in progress or other complications such as ectopic pregnancy 3
• Pain may range from mild cramping to severe abdominal discomfort 1
• The combination of pain and bleeding is more concerning than bleeding alone 3

Ultrasound Findings Indicating Current or Impending Loss

Concerning Features (Worrisome but Not Definitive)

• Embryonic crown-rump length (CRL) less than 7 mm with no cardiac activity 3
• Mean sac diameter (MSD) 16-24 mm with no embryo visualized 3
• Absent embryo 6 or more weeks after last menstrual period 3
• Small gestational sac compared with embryo size 3
• Abnormal size or shape of the yolk sac 3
• Embryonic bradycardia (slow heart rate) 3

Diagnostic Features (Definitive for Miscarriage)

• CRL 7 mm or greater with no cardiac activity confirms embryonic demise 3
• MSD 25 mm or greater with no embryo confirms nonviable pregnancy 3
• Products of conception visible on examination 3

Clinical Assessment Considerations

History and Physical Examination Findings

• Approximately 10-15% of all clinically recognized pregnancies end in first trimester miscarriage 1
• Traditional classification based on speculum examination has been replaced by transvaginal ultrasound as the standard diagnostic test 1
• If symptoms persist beyond 14 days after confirmation of viable intrauterine pregnancy, repeat referral to early pregnancy unit is indicated 1

Risk Factors Associated with Miscarriage

• Advancing maternal and paternal age 1
• Being underweight or overweight 1
• Smoking and high alcohol consumption 1

Important Clinical Pitfalls

Distinguishing from Other Conditions

• After clinical assessment suggesting complete miscarriage, 45% of women will still have retained tissue on ultrasound 2
• Women with an empty uterus on ultrasound and history suggestive of miscarriage will have an ectopic pregnancy in 6% of cases 2
• Ectopic pregnancy must be carefully excluded when intrauterine pregnancy is not definitively identified 3

Time-Based Diagnostic Criteria

• If initial transvaginal ultrasound shows MSD less than 25 mm with a yolk sac but no embryo, nonviable pregnancy can be diagnosed if there is no embryonic cardiac activity 11 or more days later 3
• If initial scan shows gestational sac without yolk sac (MSD less than 25 mm), nonviable pregnancy can be diagnosed if no cardiac activity is present 14 or more days later 3

Special Considerations

• Women who are Rh-negative at 12 weeks' gestation or beyond with bleeding symptoms require anti-D prophylaxis 1
• Approximately 50% of women experience significant psychological effects after miscarriage diagnosis, which may last up to 12 months 2