Threatened Early Pregnancy Loss

Case Presentation

Examination and Evaluation

The patient was hemodynamically stable with normal vital signs and denied any trauma, uterine contractions, or cramps. On per-speculum examination, minimal fresh bleeding was seen with a healthy, closed cervix and no products of conception. On bimanual examination, the uterus was consistent with 8–10 weeks gestation, soft, non-tender, with a closed cervix and no adnexal mass or tenderness.

Transvaginal ultrasound revealed a single live intrauterine pregnancy with a Crown-Rump Length (CRL) of 8 weeks ± 5 days and a fetal heart rate of 170 bpm. A small subchorionic hematoma of 4.2 cc was noted, with a partially open internal cervical os (~8 mm) but closed external os and adequate cervical length (~35 mm). Serum β-hCG was appropriate for gestational age, complete blood count was normal, serum progesterone was 15 ng/mL, and thyroid and blood sugar levels were within normal limits.

Differential diagnoses — missed abortion, inevitable abortion, incomplete abortion, ectopic pregnancy, molar pregnancy, and local cervical causes — were ruled out, and a final diagnosis of threatened abortion with subchorionic hematoma was made.

Management of the Case

The patient was managed expectantly with folic acid, alpha lipoic acid (300 mg twice daily), and oral dydrogesterone (30 mg/day), along with close monitoring. She was counseled to return immediately for heavy bleeding, severe abdominal pain, fever, or other concerning symptoms.

A follow-up ultrasound after two weeks showed a single live embryo with adequate choriodecidual reaction, a CRL of 37 mm (corresponding to 10 weeks 4 days), and a fetal heart rate of 164 bpm. The cervical os remained closed with adequate canal length. Her bleeding gradually subsided, and subsequent ultrasounds confirmed a continued healthy pregnancy.

Discussion: What is Threatened Abortion?

Threatened abortion, also known as threatened miscarriage, occurs when vaginal bleeding and uterine cramping appear in early pregnancy (before 20 weeks), while the cervix remains closed — indicating the pregnancy may still be viable. It is the most common complication of early pregnancy and is often associated with anxiety and stress about the outcome. It occurs in about 20% of recognized pregnancies, and roughly half of these will eventually result in an actual miscarriage.

Etiopathogenesis & Risk Factors

Threatened miscarriage reflects partial detachment or bleeding from the decidua/chorion while the pregnancy remains viable, often due to subchorionic hemorrhage or localized disruption at the implantation site. Inadequate luteal function and insufficient progesterone production may impair decidualization and uterine quiescence, predisposing some women to bleeding and pregnancy loss.

What Causes It?	Risk Factors
Chromosomal abnormalities; immunological dysfunction; endocrine factors (poorly controlled diabetes, PCOS, thyroid disease); physical problems with the uterus or cervix; bacterial, viral, parasitic, fungal, or sexually transmitted infections	Previous miscarriages (≥2); age >34 years; smoking or drinking; cocaine or illegal drug use; history of IVF, embryo transfer, or artificial insemination; environmental toxins; low folic acid levels; certain antibiotics

Table 1: Possible etiology and risk factors of threatened miscarriage.

The exact cause of threatened miscarriage cannot always be determined; possible explanations include subchorionic hemorrhage, eventual spontaneous miscarriage, or non-obstetric bleeding. Bleeding from subchorionic hemorrhage occurs in 18% to 22% of pregnancies, secondary to bleeding between the fetal membranes and the decidua basalis.

Evaluation & Investigations

Clinically, threatened miscarriage is diagnosed in a woman with first-trimester bleeding, a closed cervical os on examination, and ultrasound evidence of a viable intrauterine pregnancy. History should assess gestational age, pain, prior miscarriages, assisted conception, Rh status, co-morbidities, and hemodynamic stability. Examination focuses on vital signs, abdominal tenderness, and pelvic findings to exclude hemodynamic compromise or ectopic pregnancy.

Key investigations include:

• Serial serum β-hCG levels to monitor trends (should double every 48–72 hours in viable pregnancies)
• Progesterone levels — below 10 ng/mL suggests higher miscarriage risk
• Baseline hemoglobin/hematocrit, blood group, and Rh status (with anti-D for Rh-negative women with bleeding)
• Karyotyping of products of conception if miscarriage occurs (per RCOG 2019)
• Thyroid function, blood glucose, or infectious screens based on history

Transvaginal ultrasound confirms intrauterine location, fetal cardiac activity, crown–rump length, gestational sac size, and any subchorionic hematoma. A combination of fetal heart rate >113 bpm, CRL >19.9 mm, and gestational sac diameter >27.3 mm predicts continuation to 28 weeks with 98% specificity.

Finding	Description / Cutoff	Prognosis Impact
Absent fetal heartbeat	No cardiac activity detected	Imminent miscarriage
Low fetal heart rate	<100–113 bpm	17–30% miscarriage risk
Small gestational sac	<15 mm	Poor viability
Small CRL	<19.9–22 mm	Progression to loss
Irregular sac walls	Irregular gestational sac shape	Increased miscarriage odds
Large yolk sac	Above normal diameter	Correlates with loss
Subchorionic hematoma	Large perigestational hemorrhage	Preterm labor / miscarriage

Table 2: Predictive ultrasound findings in threatened abortion.

Newer biomarkers like serum CA125 show promising prognostic value (89% sensitivity, 91% specificity) for predicting miscarriage risk, outperforming traditional markers like β-hCG and PAPP-A. Emerging tools include the sFlt-1:PlGF ratio and machine-learning models.

Subchorionic Hematoma (SCH)

A subchorionic hematoma is a collection of blood between the chorion and the uterine wall, commonly seen with first-trimester bleeding and threatened abortion. It is frequently seen in women admitted with threatened miscarriage who have a viable embryo.

The most clinically useful grading is by hematoma size as a fraction of gestational sac (GS) size:

• Small: SCH <10–20% of GS volume
• Medium: SCH ~20–50% of GS
• Large: SCH >50% of GS

Hematomas found at ≤7–8 weeks have higher demise rates than those diagnosed later, independent of size (19.6% vs 3.6% loss when detected ≤7 vs >8 weeks).

Luteal Phase Defect & Threatened Abortion

The ASRM 2021 Committee Opinion acknowledges that luteal phase defect (LPD) is biologically linked to early pregnancy loss and threatened miscarriage, in both spontaneous and infertility-treated pregnancies — though the association is modest and the diagnosis remains controversial. The 2024 ESHRE opinion notes that luteal phase support is not necessary as a blanket policy in all IUI/timed intercourse cycles; potential benefit appears confined to high-risk or heavily stimulated protocols.

Commonly used forms of luteal support include:

• Vaginal micronized progesterone capsules or gel (600–800 mg/day, or 90 mg/day gel)
• Intramuscular progesterone in oil (50–100 mg/day) in some centers
• Oral dydrogesterone (10 mg twice daily, or 20–30 mg/day)

FOGSI practice documents recommend combining baseline vaginal progesterone with add-on oral dydrogesterone when bleeding occurs. Continuation beyond the first positive test is generally not required, but Indian units often extend support to 8–10 weeks (sometimes 14–16 weeks) in “precious” pregnancies or high-risk groups such as IVF and recurrent pregnancy loss patients.

Differential Diagnoses

Condition	Key Distinguishing Features
Ectopic pregnancy	Bleeding and abdominal pain; no definite intrauterine pregnancy at discriminatory β-hCG level; adnexal mass or free fluid
Early pregnancy loss	Open cervix, heavier bleeding, passage of tissue, absent cardiac activity
Gestational trophoblastic disease	Disproportionately high β-hCG; “snowstorm” appearance on ultrasound
Cervical causes (ectropion, cervicitis, polyps)	Contact bleeding; closed internal os; abnormal speculum findings
Vaginitis / STIs	Bleeding with discharge, itching, odor, or dyspareunia
Vaginal/vulvar trauma	Bleeding unrelated to uterine pathology; localized findings
Urinary tract pathology	Lower abdominal pain or apparent bleeding; urinary symptoms
Gastrointestinal causes	Abdominal pain with minimal vaginal bleeding

Table 3: Differential diagnoses for first-trimester bleeding.

General Management Principles

Most viable pregnancies with threatened miscarriage are managed expectantly with outpatient follow-up once ectopic and nonviable pregnancy are excluded. Patients should return for increased bleeding, pain, or tissue passage, with a repeat ultrasound if symptoms persist.

Routine bed rest or activity restriction has not shown benefit and is not recommended as specific therapy, although women may naturally limit strenuous exertion. Sexual abstinence is often suggested pragmatically, though evidence that it alters outcomes is insufficient.

Role of Progesterone in Threatened Abortion

• A 2018 Cochrane review found that in women with threatened miscarriage plus at least one prior loss, vaginal micronized progesterone modestly increases live birth rates.
• NICE guidelines recommend vaginal micronized progesterone 400 mg twice daily from onset of bleeding until 16 completed weeks in women with a confirmed pregnancy and prior miscarriage history.
• FOGSI’s 2024 practice document notes that oral dydrogesterone is well tolerated and effectively reduces miscarriages in affected women.
• For women with first threatened miscarriage and no prior losses, oral dydrogesterone (e.g., 40 mg loading then 10 mg three times daily) is commonly chosen.
• In women with threatened miscarriage plus recurrent pregnancy loss, progesterone is considered mainline therapy, started early and continued at least to 12–16 weeks.

Role of Other Medications

• Analgesics: Paracetamol can be used for pain relief; NSAIDs are usually avoided in early pregnancy.
• Tranexamic acid: Small observational studies suggest it can help arrest bleeding and resolve intrauterine hematomas, with no short-term safety signal.
• Antibiotics: Not routinely recommended; reserved for proven or suspected infection.
• Alpha lipoic acid (ALA): May accelerate hematoma resolution when added to progesterone, though evidence remains limited and it is considered investigational.
• Hydroxychloroquine: May improve outcomes in antiphospholipid syndrome with recurrent loss refractory to standard therapy.
• Aspirin plus LMWH: Standard for antiphospholipid syndrome or thrombophilia with prior losses, not for routine threatened miscarriage.
• Corticosteroids: Not recommended for empirical use without clear autoimmune indication.
• Tocolytics and hCG injections: Not recommended as standard treatment for threatened abortion.
• Thyroxine: Indicated only to correct abnormal thyroid function, not as bleeding-specific therapy.
• IVIG: No role in standard management; reserved for highly selected recurrent loss cases.

Threatened Abortion in IVF Pregnancies

In IVF pregnancies, diagnostic steps are identical, but expectant management usually involves more intensive monitoring, since these pregnancies already carry higher risk for miscarriage, multiple gestation, placental problems, and preterm birth. Monitoring protocols recommend early and more frequent ultrasounds with tighter surveillance of subchorionic hematomas. Early cervical-length assessment (around 14 weeks) and closer surveillance for preterm birth are also recommended when bleeding episodes occur.

Prevention of Alloimmunization (Anti-D)

• Anti-D immunoglobulin should be given to unsensitized Rh-D–negative women with threatened miscarriage after about 12 weeks, or earlier if bleeding is heavy, recurrent, or associated with pain.
• A minimum of 250 IU (<20 weeks) or 500 IU (≥20 weeks) is recommended, with higher or repeat dosing if a large fetomaternal hemorrhage is suspected.
• Anti-D should ideally be given within 72 hours of the sensitizing event, though some benefit may persist up to 10–13 days.
• Anti-D should also be given for any surgical management of miscarriage, at any gestation.

Discharge Instructions for Patients

Patients should be advised to return immediately or seek emergency care if any of the following occur:

• Heavy bleeding (soaking 1–2 large pads per hour for at least 2 consecutive hours), passage of clots or tissue, or a sudden marked increase in bleeding
• Worsening or persistent severe lower abdominal pain, shoulder pain, dizziness, fainting, fever, or foul-smelling discharge

Patients should avoid inserting anything into the vagina (tampons, douching) and use sanitary pads during the bleeding episode. If progesterone has been prescribed, adherence to the prescribed dose and duration is important — usually until at least the end of the first trimester. Only approved analgesics (typically paracetamol) should be used, avoiding NSAIDs unless specifically allowed.

Complications & Prognosis

Threatened miscarriage is also a marker for increased risk of later adverse outcomes such as preterm birth, fetal growth restriction, and placental complications. Broader risk-factor control matters — women should be counseled on smoking cessation, alcohol and drug avoidance, weight optimization, and control of chronic conditions like diabetes and hypertension.

Threatened abortion with a viable fetus usually has a favorable outcome, but the risk of miscarriage increases with early gestation, fetal bradycardia, and large subchorionic hematoma (>50% of gestational sac).

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References