Early Pregnancy Loss (Spontaneous Abortion)

Introduction

Early Pregnancy Loss (EPL), widely referred to as spontaneous abortion, is defined as the loss of a pregnancy before 20 weeks of gestation. It is the most common complication of early pregnancy, affecting approximately 15% to 20% of clinically recognized pregnancies in Canada.

For MCCQE1 preparation, understanding the classification, diagnostic criteria, and management options (expectant, medical, and surgical) is critical. Candidates must demonstrate competence in the Medical Expert role by diagnosing the type of abortion and the Communicator role by providing sensitive counseling and shared decision-making.

🍁

Canadian Context: In Canada, the term “Early Pregnancy Loss” is preferred over “Spontaneous Abortion” when communicating with patients to minimize stigma and distress. However, medical classification systems still utilize the terminology of abortion.

Etiology and Risk Factors

Understanding the etiology is vital for patient counseling and assessing recurrence risk.

Common Causes

Chromosomal Abnormalities: Responsible for approximately 50% of EPLs (e.g., autosomal trisomies, monosomy X).
Maternal Anatomical Factors: Uterine septums, fibroids, cervical insufficiency.
Endocrine Factors: Uncontrolled diabetes mellitus, thyroid disease, luteal phase defect.
Immunologic Factors: Antiphospholipid syndrome (APS).

Risk Factors

Advanced Maternal Age: Risk increases significantly after age 35 (>40 years old carries >40% risk).
Previous history of EPL.
Smoking, alcohol, and cocaine use.
Extremes of BMI (underweight or obesity).

Classification of Spontaneous Abortion

This is a high-yield topic for the MCCQE1. You must be able to differentiate these based on history and physical exam (specifically the status of the cervical os).

Type	Vaginal Bleeding	Abdominal Pain	Cervical Os	Passage of Tissue	Ultrasound Findings
Threatened	Yes	Minimal/None	Closed	No	Viable intrauterine pregnancy
Inevitable	Yes	Moderate/Severe	Open	No	Intrauterine pregnancy (often non-viable)
Incomplete	Yes	Severe	Open	Yes (Partial)	Retained products of conception (RPOC)
Complete	Yes (Subsiding)	Subsiding	Closed	Yes (All)	Empty uterus
Missed	None/Brown spotting	None	Closed	No	Non-viable fetus (no cardiac activity)
Septic	Yes (Purulent)	Severe + Fever	Open/Closed	Varies	RPOC + signs of infection

Diagnostic Approach

Step 1: History Taking

Focus on the “Three Ps”:

Pregnancy: Last Menstrual Period (LMP), previous ultrasound confirming dating.
Pain: Character, location, severity.
Passage: Bleeding (amount, clots) or tissue.
Red Flags: Dizziness, syncope, shoulder tip pain (suggesting ectopic pregnancy).

Step 2: Physical Examination

Vitals: Assess hemodynamic stability (HR, BP). Tachycardia or hypotension suggests significant hemorrhage or ruptured ectopic.
Abdominal Exam: Check for peritoneal signs.
Pelvic Exam (Speculum & Bimanual):
- Inspect vaginal vault for tissue/blood.
- Assess Cervical Os: Is it open or closed?
- Assess uterine size and adnexal tenderness.

Step 3: Laboratory Investigations

Beta-hCG (Quantitative): To assess pregnancy viability and trend.
CBC: To assess hemoglobin and platelet count.
Blood Group & Screen: Essential to determine Rh status for WinRho administration.

Step 4: Imaging (Transvaginal Ultrasound)

The gold standard for diagnosis. Look for:

Location of gestational sac (intrauterine vs. ectopic).
Fetal pole and cardiac activity.
Retained products of conception.

Diagnostic Criteria for Non-Viability

According to Canadian and international guidelines, a pregnancy is non-viable if:

Crown-Rump Length (CRL) ≥ 7 mm with no cardiac activity.
Mean Sac Diameter (MSD) ≥ 25 mm with no embryo.
Absence of embryo with heartbeat ≥ 2 weeks after a scan showed a gestational sac without a yolk sac.

Management Strategies

The SOGC (Society of Obstetricians and Gynaecologists of Canada) recommends offering patients a choice between expectant, medical, and surgical management, provided they are hemodynamically stable and have no signs of infection.

Expectant Management

Expectant Management (“Wait and See”)

Indication: First trimester (<14 weeks), stable patient, no infection.
Success Rate: ~80% (variable based on type of EPL).
Pros: Avoids surgery and medication side effects; “natural” process.
Cons: Unpredictable timing (can take weeks), risk of emergency surgery if bleeding becomes heavy.
Follow-up: Weekly ultrasound or serial beta-hCG until complete.

Rh Prophylaxis

💉

CRITICAL MCCQE1 CONCEPT: All Rh-negative women with vaginal bleeding during pregnancy or undergoing management for EPL must receive Rh_o(D) Immune Globulin (WinRho) to prevent isoimmunization.

Dose: Generally 300 mcg IM (standard dose), though 120 mcg may be sufficient for first-trimester loss.

Canadian Guidelines (SOGC)

The SOGC Clinical Practice Guideline on the Management of Pregnancy of Unknown Location and Early Pregnancy Loss is the standard for Canadian practice. Key takeaways include:

Ultrasound Standards: Diagnosis of non-viability should be stringent to avoid terminating a potentially viable pregnancy.
Patient-Centered Care: Women should be offered all three management options unless contraindications exist.
Misoprostol: Vaginal administration is more effective than oral.
Mental Health: Acknowledge the psychological impact. EPL is a significant bereavement event.

Key Points to Remember for MCCQE1

Most common cause: Chromosomal abnormalities (Trisomy 16 is the single most common trisomy).
Threatened Abortion: The only type where the pregnancy may continue viable. Management is reassurance and pelvic rest (no proven benefit for progesterone in unselected populations).
Septic Abortion: Requires broad-spectrum antibiotics (Ampicillin + Gentamicin + Clindamycin/Metronidazole) and prompt uterine evacuation.
Ectopic Exclusion: Always rule out ectopic pregnancy in a woman of reproductive age with abdominal pain and bleeding.
Recurrent Pregnancy Loss (RPL): Defined as 3 consecutive losses <20 weeks (or 2 in some guidelines). Requires workup for APS, karyotyping, and uterine anatomy.

Study Checklist

Memorize the table comparing types of abortion.
Know the SOGC dosage for Misoprostol (800 mcg PV).
Understand the indications for WinRho.
Review the ultrasound criteria for non-viability.

Sample Question

Case: A 26-year-old G1P0 female presents to the emergency department with moderate vaginal bleeding and lower abdominal cramping at 11 weeks gestation based on her LMP. She is hemodynamically stable (BP 115/75 mmHg, HR 88 bpm). On speculum examination, the cervical os is noted to be open, and there is blood in the vaginal vault but no tissue is visualized. A transvaginal ultrasound reveals a gestational sac within the lower uterine segment, but the fetus has no cardiac activity.

Which of the following is the most accurate diagnosis?

Explanation

The correct answer is:

C. Inevitable abortion

Detailed Explanation:

Inevitable Abortion: Defined by vaginal bleeding and cramping with an open cervical os, but the products of conception have not yet been expelled. The ultrasound finding of a non-viable fetus in the lower uterine segment supports that expulsion is impending.
Threatened Abortion (A): Would present with a closed cervical os and typically a viable fetus.
Missed Abortion (B): Would present with a closed cervical os and a non-viable fetus retained in the uterus, often with no or minimal bleeding/pain.
Complete Abortion (D): Would show an empty uterus on ultrasound and the cervix would typically be closed after the passage of tissue.
Septic Abortion (E): Would present with fever, purulent discharge, and uterine tenderness, which are not mentioned in this scenario.

References

SOGC Clinical Practice Guideline No. 364: The Management of Pregnancy of Unknown Location and Early Pregnancy Loss. Journal of Obstetrics and Gynaecology Canada. 2018.
Medical Council of Canada. MCCQE Part I Objectives: Obstetrics and Gynecology.
UpToDate. Spontaneous abortion: Management.
Toronto Notes 2024. Obstetrics Section: Early Pregnancy Complications.