Threatened Miscarriage

Threatened abortion (Abortus imminens); is a clinical presentation of vaginal bleeding occurring during the first half of pregnancy, typically within the first 20 weeks, without cervical dilation or effacement. In this clinical picture, ultrasonographic evaluation confirms the presence of an intrauterine pregnancy with a viable fetus; however, there is a threat to the continuation of the pregnancy.

This condition is one of the most common complications of pregnancy, affecting approximately 15-25% of clinically recognized pregnancies. About half of these cases result in spontaneous abortion, while the other half proceed with ongoing pregnancy. Increased risk has been reported in women over 35 years of age and under 20 years of age, as well as in those with a parity of more than three.^【1】

The etiology of threatened abortion is multifactorial. In early pregnancy, inadequate trophoblast invasion (implantation of placental cells into the uterine wall) can lead to reduced placental blood flow and oxidative stress, contributing to threatened abortion. Low levels of Kisspeptin-10 (Kp-10), which regulates trophoblast invasion, have been associated with ineffective placentation.^【2】

Other etiological factors include chromosomal abnormalities (trisomy, polyploidy), inadequate endometrium, hormonal imbalances (particularly luteal phase deficiency), placental anomalies, and maternal systemic diseases (diabetes, hypertension, thyroid dysfunction). In conditions with heightened systemic inflammatory response, increased fibrinogen levels and decreased albumin levels are observed; a high Fibrinogen/Albumin Ratio (FAR) is considered an independent risk factor. Environmental factors such as advanced maternal age, prior history of spontaneous abortion, IVF treatment, multiple gestations, infections, and poor nutrition also play a role in disease development.

The most prominent symptom of threatened abortion is vaginal spotting or bleeding occurring early in pregnancy. This bleeding may be accompanied by mild abdominal, inguinal, or back pain; however, the cervix remains closed. Diagnosis involves a combined assessment of clinical symptoms and imaging methods:

• Ultrasonography: It is critical for diagnosis. The presence of fetal heart activity (FHR) is the most important prognostic indicator; in cases with detected FHR, the likelihood of pregnancy continuation is approximately 90%, whereas in cases without detectable FHR, the risk of abortion may rise to 60%. Additionally, an irregular gestational sac is associated with a poor prognosis.^【3】
• Subchorionic Hematoma (SCH): A collection of blood between the chorionic membrane and the uterine wall. The presence of SCH, particularly when its size and volume increase, can elevate the risks of pregnancy loss, preterm delivery, and cesarean section.^【4】
• Laboratory: Serial beta-hCG measurements and progesterone level monitoring are performed to exclude conditions such as ectopic pregnancy or molar pregnancy.

Various parameters have been studied to predict pregnancy outcomes:

^{Threatened abortion (Abortus imminens)}

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1. Hormonal Markers: Combined assessment of serum progesterone, beta-hCG, and estradiol levels provides diagnostic accuracy of up to 97%. Progesterone levels below 10 ng/ml and inadequate beta-hCG rise increase the likelihood of pregnancy loss.
2. Kisspeptin-10 (Kp-10): Low levels of this marker are directly correlated with intrauterine growth restriction (IUGR) and low birth weight.
3. Anti-Cardiolipin Antibodies (ACA): Positive ACA status in cases with subchorionic hematoma is associated with adverse pregnancy outcomes.^【5】
4. Alpha-Fetoprotein (AFP): Findings indicate that maternal serum AFP levels alone are not a definitive prognostic marker.

Women diagnosed with threatened abortion who continue their pregnancies face an increased risk of various obstetric complications in later weeks. These complications include preterm birth (preterm labor), preterm premature rupture of membranes (PPROM), low birth weight, and increased rates of cesarean delivery.

In particular, among groups classified as "high risk" (e.g., recurrent miscarriage history, IVF pregnancy, etc.), neonatal intensive care unit admission and low APGAR scores are more frequently observed. Additionally, even among patients with threatened abortion who are in the low-risk group, an increased risk of postpartum uterine atony (failure of uterine contraction after delivery) has been observed. In cases accompanied by subchorionic hematoma, pregnancy tends to end earlier, and rates of operative delivery (cesarean section) are elevated.^【6】

Therapeutic approaches are generally empirical and include the following:

• Rest: Reduction of physical activity and bed rest are the most commonly recommended interventions. Although bed rest is widely practiced clinically, randomized controlled trial data on its efficacy are limited.
• Pharmacological Support: Progesterone supplementation is used to reduce uterine contractions and modulate the immune response. In Rh-incompatible cases, administration of Anti-D immunoglobulin is recommended.
• Sexual Abstinence: Sexual abstinence is advised in cases of threatened abortion for several reasons. Oxytocin released during sexual arousal or orgasm can trigger contractions in the myometrium, thereby increasing the existing risk of abortion. Additionally, prostaglandins present in seminal fluid are biochemical agents that promote cervical softening and stimulate uterine contractions. In the presence of vaginal bleeding, the cervical region becomes more susceptible to infection; therefore, changes in vaginal flora due to sexual activity are presumed to elevate infection risk and consequently the likelihood of pregnancy loss. Another contributing factor is mechanical trauma; sexual intercourse may irritate the delicate vascular structures of the cervix, exacerbating existing bleeding.
• Psychosocial Support: The uncertainty associated with bleeding can increase fear, anxiety, and stress levels, negatively affecting physiological responses. Therefore, accurate information and psychosocial support are critical during treatment.^【7】

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