Reproductive · Spontaneous Abortion
The facts most likely to be tested
A missed abortion is defined as the presence of a nonviable intrauterine pregnancy with a retained fetus and a closed cervical os.
Patients with a missed abortion are typically asymptomatic and lack the vaginal bleeding or cramping associated with other forms of pregnancy loss.
The diagnosis is confirmed via transvaginal ultrasound showing an embryo or fetus without cardiac activity.
Diagnostic criteria for pregnancy failure include a crown-rump length of ≥7 mm with no cardiac activity.
A mean sac diameter of ≥25 mm without an embryo on transvaginal ultrasound confirms the diagnosis of early pregnancy loss.
Misoprostol is the preferred medical management for stable patients to induce uterine evacuation.
Surgical evacuation via suction curettage is indicated if the patient is hemodynamically unstable, has signs of infection, or prefers a definitive procedure.
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A 28-year-old G1P0 woman at 10 weeks gestation by last menstrual period presents for a routine prenatal visit. She reports no vaginal bleeding, pelvic pain, or discharge. On physical examination, the cervix is closed and the uterine size is smaller than expected for gestational age. A transvaginal ultrasound reveals an intrauterine fetus with a crown-rump length of 12 mm and no cardiac activity.
What is the most appropriate next step in management?
Medical management with misoprostol or surgical evacuation via suction curettage.
The patient meets the ultrasound criteria for a missed abortion (crown-rump length >7 mm without cardiac activity), and management options include expectant, medical, or surgical intervention.
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Etiology / Epidemiology
Fetal demise before 20 weeks with retained products of conception. Most common in advanced maternal age and prior history.
Clinical Manifestations
Patient presents with asymptomatic loss of pregnancy symptoms; cervical os remains closed on physical exam.
Diagnosis
Gold standard is transvaginal ultrasound showing absent cardiac activity in a fetus with CRL ≥ 7 mm.
Treatment
First-line is misoprostol for medical evacuation; do not use if signs of infection/sepsis.
Prognosis
Risk of septic abortion or coagulopathy if retained tissue is not evacuated promptly.
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Epidemiology & Etiology
Occurs in up to 15% of clinically recognized pregnancies. Primary risk factors include chromosomal abnormalities (aneuploidy) and advanced maternal age (>35). Other contributors include maternal endocrine disorders and uterine anatomical anomalies.
Pertinent Anatomy
The cervical os is the critical anatomical landmark; in missed abortion, it remains closed despite fetal demise. The uterus may be smaller than expected for gestational age.
Pathophysiology
Fetal death occurs, but the uterus fails to recognize the demise or expel the products of conception. This leads to a state of retained products of conception (RPOC). Prolonged retention increases the risk of disseminated intravascular coagulation due to release of thromboplastin from necrotic tissue.
Clinical Manifestations
Patients often report a sudden disappearance of pregnancy symptoms (e.g., nausea, breast tenderness). Physical exam reveals a closed cervical os and lack of vaginal bleeding. Red flags include fever, foul-smelling discharge, or hemodynamic instability, which suggest progression to septic abortion.
Diagnosis
The transvaginal ultrasound is the gold standard. Diagnostic criteria include a crown-rump length (CRL) ≥ 7 mm with no cardiac activity, or a mean sac diameter ≥ 25 mm without an embryo. Serial beta-hCG levels will show a plateau or decline rather than appropriate doubling.
Treatment
Management options include expectant, medical, or surgical evacuation. Misoprostol is the first-line medical agent to induce uterine contractions. Contraindications for medical management include hemodynamic instability, severe anemia, or suspected infection. Surgical evacuation via dilation and curettage (D&C) is indicated for heavy bleeding or patient preference.
Prognosis
Most patients recover fully after evacuation. Key complications include infection, uterine perforation during D&C, and Asherman syndrome (intrauterine adhesions). Follow-up is required to ensure complete resolution of beta-hCG levels.
Differential Diagnosis
Threatened abortion: vaginal bleeding present with a closed os
Inevitable abortion: vaginal bleeding with an open cervical os
Incomplete abortion: partial passage of products with an open os
Ectopic pregnancy: positive hCG but empty uterus on ultrasound
Molar pregnancy: 'snowstorm' pattern on ultrasound with elevated hCG