Spontaneous Abortion is defined as unprovoked pregnancy loss at <20 weeks gestation, is a common cause of first-trimester bleeding.
| Definition | • Pregnancy loss <20 weeks |
|---|---|
| Risk factors | • Advanced maternal age ( increased risk for fetal chromosomal abnormalities) |
| • Previous spontaneous abortion | |
| • Substance use disorder | |
| Treatment options | • Expectant |
| • Medical induction (misoprostol) | |
| • Suction curettage if infection or hemodynamic instability | |
| Additional management | • Rho(D) immunoglobulin |
| • Pathology examination | |
| Complications | • Hemorrhage |
| • Retained products of conception | |
| • Septic abortion | |
| • Uterine perforation | |
| • Intrauterine adhesions |
Some normal early pregnancies (<6 weeks gestation) can present without a fetal pole (eg, gestational sac ± yolk sac), viability is determined through repeat ultrasounds and serial β-hCG levels. Viable pregnancies have rising serial β-hCG levels throughout the first trimester, and imaging reveals continued embryonic development (eg, fetal pole with cardiac activity). In contrast, a Abortion has decreasing β-hCG levels, and repeat imaging shows halted development.
<aside> 💡 A positive pregnancy test due to retained products of conception is common.
</aside>
positive β-hCG is common in patients with a complete abortion because it can take up to 6 weeks for β-hCG levels to become undetectable while the levels clear and trophoblastic tissue resolves.
<aside> 💡 Cervical insufficiency refers to painless cervical dilation during the second trimester that results in loss of pregnancy. The presence of lower abdominal pain (from uterine contractions) excludes this condition.
</aside>
Spontaneous abortions most commonly result from fetal chromosomal abnormalities but are also associated with congenital (eg, teratogen exposure) and müllerian (eg, uterine septum) anomalies.
Spontaneous abortions are categorized based on cervical dilation and the location of the products of conception in relation to the cervix.
Suction curettage removes the retained products of conception, allowing the uterus to fully contract around open arterial vessels, which stops the bleeding.
Other ultrasound findings of an ovarian cyst (eg, corpus luteum) and free fluid in the posterior cul-de-sac are the results of the physiologic processes of pregnancy.
Septic abortion most often occurs following an incomplete elective termination of pregnancy but can occur with spontaneous abortion.
Recurrent spontaneous abortions
<aside> 💡 Oxytocin is not effective in stimulating uterine contractions or expelling retained products of conception during the first or second trimesters because few oxytocin receptors are in the uterus during early pregnancy.
</aside>
Retention of a dead fetus for > 2 weeks leads to increased systemic absorption of thromboplastin produced by the placenta and dead fetus. Thromboplastin activates the coagulation cascade and causes DIC. In this patient with DIC, thrombotic microvascular occlusion within the kidneys and glomerular endothelial dysfunction has resulted in acute renal injury. Retention of a dead fetus for > 2 weeks increases the risk of chorioamnionitis and endometritis by both gram-positive organisms (e.g., Staphylococcus aureus) and gram-negative organisms (e.g., E. coli, Klebsiella). Endometritis can result in sepsis, which would result in tachycardia and DIC.
Surgical uterine evacuation (e.g., with dilation and curettage) is the treatment of choice for spontaneous abortioncomplicated by heavy vaginal bleeding. This patient is experiencing an inevitable abortion with significant blood loss that is causing hemodynamic instability (as evidenced by hypotension and tachycardia). Following stabilization via IV fluid replacement and blood products, she should undergo urgent surgical evacuation of the retained products of conception in order to minimize further blood loss.