11.2 Ectopic Pregnancy, Miscarriage & Gestational Trophoblastic Disease

Ectopic Pregnancy: Anatomy, Risk Factors & Pathophysiology

An ectopic pregnancy occurs when a blastocyst implants at any anatomical site other than the endometrial lining of the uterine cavity. Extrauterine pregnancy remains the leading cause of first-trimester maternal mortality, primarily due to catastrophic hemorrhage following tubal rupture.

Anatomical Distribution

• Fallopian Tube (Tubal Gestation): Accounts for > 95% of all ectopic pregnancies:
  • Ampullary: 70% to 80% (most frequent site overall, characterized by a wider lumen).
  • Isthmic: 12% (narrow muscular lumen; tends to rupture early, typically at 6 to 8 weeks gestation).
  • Fimbrial / Infundibular: 5%.
  • Cornual / Interstitial: 2% to 3%. Implantation occurs within the intramural segment of the fallopian tube that traverses the thick muscular uterine horn. Because the myometrium can expand, cornual ectopics often remain asymptomatic until 8 to 14 weeks of gestation. When rupture inevitably occurs, it lacerates the major ascending branches of the uterine artery and the ovarian arterial arcade, causing sudden, catastrophic hemoperitoneum and rapid circulatory collapse.
• Non-Tubal Ectopic Sites (2% to 5%):
  • Cervical Pregnancy: Implants within the endocervical canal below the internal os; carries extreme risk of torrential hemorrhage during evacuation.
  • Caesarean Scar Pregnancy: Implants within the fibrous myometrial defect of a prior hysterotomy scar; carries high risk of uterine rupture and morbidly adherent placenta.
  • Ovarian Pregnancy: Implants directly onto the ovarian cortex (fulfills Spiegelberg criteria).
  • Abdominal Pregnancy: Primary or secondary peritoneal implantation; carries maternal mortality rates up to 7 times higher than tubal ectopics.

Risk Factors

The primary mechanism driving ectopic implantation is impaired tubal ciliary transport and delayed blastocyst transit. Major risk factors include:

• Prior Ectopic Pregnancy: The strongest single risk factor, imparting a 10-fold increase in recurrence (10-15% after one ectopic, > 25% after two).
• Previous Pelvic Inflammatory Disease (PID): Particularly Chlamydia trachomatis and Neisseria gonorrhoeae, which cause permanent destruction of ciliated endosalpingeal cells, mucosal plicae agglutination, and intraluminal diverticula.
• Prior Tubal Surgery: Tubal re-anastomosis, salpingostomy, or failed tubal sterilization.
• Assisted Reproductive Technology (ART): In vitro fertilization (IVF) and embryo transfer increase risks of both tubal and heterotopic pregnancies (coexistent intrauterine and ectopic gestations, occurring in 1 in 100 to 1 in 500 IVF pregnancies compared to 1 in 30,000 natural conceptions).
• Intrauterine Device (IUD) in Situ: While IUDs provide exceptional protection against intrauterine pregnancy, if a conception occurs with an IUD in place, up to 50% are ectopic.
• Maternal Cigarette Smoking: Nicotine alters smooth muscle contractility and ciliary beat frequency within the fallopian tube.

Clinical Presentation & Signs of Rupture

The classic clinical triad consists of:

1. Amenorrhea: Typically 6 to 8 weeks since the last normal menstrual period.
2. Abdominal / Pelvic Pain: Unilateral, dull aching or sharp colicky lower abdominal pain.
3. Abnormal Vaginal Bleeding: Characteristically scanty, dark brown 'prune-juice' spotting resulting from the sloughing of the hormonally unstable decidualized endometrium.

Signs of Tubal Rupture & Hemoperitoneum:

• Sudden, tearing, excruciating lower abdominal pain followed by generalized peritonitis (abdominal rigidity, involuntary guarding, rebound tenderness).
• Referred Shoulder Tip Pain (Kehr Sign): Diaphragmatic irritation from pooling hemoperitoneum stimulates the phrenic nerve (C3, C4, C5), producing referred pain to the cutaneous dermatomes of the supraclavicular nerve.
• Syncopal Collapse & Hemodynamic Instability: Postural dizziness, tachycardia, hypotension, cold clammy extremities, and confusion.
• Pelvic Examination: Extreme cervical motion tenderness (the chandelier sign) and a full, exquisitely tender pouch of Douglas (blood collecting in the cul-de-sac, sometimes causing rectal pressure).

Diagnostic Triage: TVS & Quantitative Beta-hCG

Accurate diagnosis requires correlating transvaginal ultrasonography (TVS) with serial quantitative serum beta-human chorionic gonadotropin (beta-hCG).

+--------------------------------------------------------------------------+
|                  TVS + QUANTITATIVE hCG + CLINICAL STATUS                 |
+--------------------------------------------------------------------------+
                                    |
            +-----------------------+-----------------------+
            |                       |                       |
            v                       v                       v
 [Definite intrauterine]   [Definite extrauterine]  [No pregnancy located]
 [pregnancy on TVS]        [yolk sac / embryo]      [PUL at ANY hCG level]
            |                       |                       |
            v                       v                       v
 Assess viability;         Confirm diagnosis;        Prompt clinical review;
 examine adnexa if         select surgery or         repeat hCG at 48 hours
 heterotopic risk          MTX by clinical criteria   and arrange expert TVS
                                                            |
                              +-----------------------------+--------------------+
                              |                             |                    |
                              v                             v                    v
                     [Appropriate hCG rise]       [Plateau / slow rise]     [hCG falling]
                     Possible developing IUP;     Review within 24 hours;    Likely failing PUL;
                     location unconfirmed         location unconfirmed    continue follow-up
                              |                             |                    |
                              v                             v                    v
                        Repeat expert TVS          Establish diagnosis      Confirm resolution
                        to locate pregnancy       before active treatment  and safety-net

 New/worsening pain, syncope or instability overrides any reassuring hCG trend:
 urgent reassessment, resuscitation and surgery when rupture is suspected.

The Discriminatory Zone

The discriminatory level is an hCG concentration above which an intrauterine sac is usually visible on good-quality TVS. It varies with equipment, operator and gestation number;1500–2000 IU/L is a traditional range, while ACOG advises a conservative level as high as 3500 IU/L when used. No single hCG threshold establishes pregnancy location or justifies treatment of a stable PUL.

• An empty uterus, even above the selected discriminatory level, raises concern for ectopic or failing intrauterine pregnancy. Arrange prompt expert review and follow-up; exclude a potentially viable IUP before destructive treatment.
• A gestational sac separate from the ovary containing a yolk sac or embryo, with or without cardiac activity, establishes tubal ectopic pregnancy. An empty tubal ring, complex adnexal mass or free fluid is suspicious, requiring correlation with the full scan, symptoms and hCG rather than diagnosis from that feature alone.
• Pseudo-gestational sac: A central, round, fluid accumulation within the endometrial cavity without a double decidual sign or yolk sac, present in 10-20% of ectopics due to decidual breakdown.

Pregnancy of Unknown Location (PUL)

A PUL means a positive pregnancy test with neither an intrauterine nor an ectopic pregnancy identified on TVS, regardless of hCG level. It may represent an early IUP, a failing pregnancy or an ectopic pregnancy. In a stable patient, repeat quantitative hCG as close as possible to 48 hours later and arrange expert TVS:

• Rising hCG: A rise compatible with a viable IUP does not prove its location or exclude ectopic pregnancy. NICE uses>63% over 48 hours to guide repeat TVS in 7–14 days, earlier when hCG>=1500 IU/L.
• Plateau or Slower Rise: Requires clinical review within 24 hours and further assessment, rather than automatic methotrexate.
• Falling hCG: Suggests a failing pregnancy but does not establish intrauterine location; follow until resolution. Give 24 hour emergency access instructions because worsening pain, syncope or instability overrides the hCG trend.

Medical vs. Surgical Management of Ectopic Pregnancy

Medical Therapy: Methotrexate Protocol

Methotrexate is a folic acid antagonist that competitively inhibits dihydrofolate reductase, halting purine and thymidylate synthesis, thereby arresting cellular replication in rapidly dividing trophoblastic tissue.

Eligibility Criteria for Methotrexate: Confirm the ectopic diagnosis and exclude a viable intrauterine pregnancy before treatment. Then assess:

1. Hemodynamically stable with no signs of active intraperitoneal hemorrhage.
2. Serum beta-hCG concentration < 5000 IU/L (success rate > 90%; success drops significantly if hCG > 5000 IU/L).
3. Ectopic adnexal mass size < 3.5 cm in maximal diameter on ultrasound.
4. Complete absence of embryonic cardiac motion on TVS.
5. Absence of intra-abdominal free fluid extending beyond the pouch of Douglas.
6. Normal baseline renal function (serum creatinine), liver function tests (transaminases), and full blood count.
7. Reliable patient capable of compliant, long-term outpatient monitoring.

Single-Dose Methotrexate Regimen:

• Administer 50 mg/m2 body surface area intramuscularly on Day 1.
• Measure serum beta-hCG on Day 1, Day 4, and Day 7.
• Expected Trajectory: Beta-hCG commonly rises between Day 1 and Day 4 due to ongoing trophoblastic lysis. Therapeutic success requires a >= 15% reduction in beta-hCG between Day 4 and Day 7.
• If a >= 15% reduction is achieved, measure serum beta-hCG weekly until levels become completely undetectable (< 5 IU/L).
• If the reduction is < 15% between Day 4 and Day 7, administer a second dose of methotrexate (50 mg/m2 IM) or proceed to surgical intervention.
• Patient Counseling: Avoid intercourse, strenuous exercise, folate-containing vitamins, NSAIDs (which decrease renal clearance of methotrexate), and sunlight exposure.

Surgical Intervention

Surgery is mandatory in the presence of: hemodynamic instability, suspected tubal rupture, acute peritonitis, initial beta-hCG >= 5000 IU/L, mass >= 3.5 cm, detectable fetal heartbeat, or contraindications/failure of methotrexate.

• Laparoscopic Salpingectomy: Surgical excision of the affected fallopian tube is the definitive gold standard. It is preferred over salpingostomy in the presence of severe tubal damage, previous ectopic in the same tube, completion of family planning, or when the contralateral tube is normal.
• Salpingostomy: Linear antimesenteric incision with unroofing and suction extraction of the ectopic mass, leaving the tube in situ. Reserved for women with compromised or absent contralateral fallopian tubes who strongly desire future fertility. Requires weekly serum beta-hCG monitoring postoperatively until negative to detect persistent trophoblastic disease (occurs in 5-10% due to incomplete excision).
• Emergency Laparotomy: Indicated in patients with severe hemorrhagic shock, gross hemodynamic collapse, extensive pelvic adhesions, or in regional Caribbean district centers lacking advanced laparoscopic equipment.
• Anti-D Immunoglobulin: For an unsensitized RhD-negative patient, give prophylaxis when indicated by the event, gestation and local protocol, usually within 72 hours. Keep units correct: 250 IU=50 mcg;500 IU=100 mcg;1500 IU=300 mcg. Early-pregnancy indications differ between surgical, medical and expectant management and between guidelines.

Miscarriage: Clinical Syndromes & Management

Miscarriage (spontaneous abortion) is the spontaneous loss of a pregnancy before the threshold of viability, conventionally defined as < 24 weeks of gestation or fetal weight < 500 g.

Septic Miscarriage: Emergency Protocol

Septic miscarriage occurs most frequently following unsafe, illegal abortions or neglected incomplete abortions. Infection ascends rapidly into the myometrium, parametrium, and systemic circulation, risking endotoxic septic shock and DIC. Management mandates:

1. Immediate hemodynamic stabilization with IV crystalloids.
2. Parenteral triple broad-spectrum coverage: Ampicillin 2 g IV q6h + Gentamicin 5 mg/kg IV daily + Metronidazole 500 mg IV q8h (or Ceftriaxone 2 g IV daily + Metronidazole 500 mg IV q8h).
3. Tetanus toxoid booster.
4. Urgent Surgical Evacuation: Evacuation of infected retained tissue via suction curettage or MVA must be performed within 2 to 4 hours of initiating antibiotic coverage. Delaying evacuation until the patient is completely afebrile is obsolete and significantly increases mortality.

Gestational Trophoblastic Disease (GTD)

Gestational Trophoblastic Disease encompasses a spectrum of proliferative disorders of placental trophoblast cells, categorized into benign hydatidiform moles and malignant gestational trophoblastic neoplasia (GTN).

Complete vs. Partial Hydatidiform Mole

+-----------------------------------------------------------------------------------------+
|                        HYDATIDIFORM MOLE: GENETIC & CLINICAL CONTRAST                   |
+-----------------------------------------------------------------------------------------+
                                             |
                   +-------------------------+-------------------------+
                   |                                                   |
                   v                                                   v
         [ COMPLETE MOLE ]                                   [ PARTIAL MOLE ]
  - Karyotype: 46,XX (90%) or 46,XY                   - Karyotype: Triploid 69,XXY, 69,XXX
  - Origin: Androgenetic (Empty egg + single sperm    - Origin: Dispermic (Normal egg + two sperm
    duplication or dispermy)                             or diploid sperm)
  - Fetal Tissue: COMPLETELY ABSENT                   - Fetal Tissue: PRESENT (Abnormal fetus/RBCs)
  - Trophoblast: Diffuse, generalized hyperplasia     - Trophoblast: Focal, mild hyperplasia
  - Villous Hydrops: Diffuse, generalized             - Villous Hydrops: Focal, variable
  - Serum beta-hCG: Markedly elevated (> 100,000)     - Serum beta-hCG: Normal or slightly elevated
  - Clinical Signs: Snowstorm US, hyperemesis,        - Clinical Signs: Apparent missed or incomplete
    theca lutein cysts, early pre-eclampsia (<20w)      miscarriage, rarely malignant
  - Malignant Risk: 15% to 20% GTN                    - Malignant Risk: 1% to 5% GTN

Clinical Manifestations of Complete Hydatidiform Mole

• Disproportionate uterine enlargement: Uterus significantly larger than expected for gestational dates in 50% of cases.
• Excessive, intractable hyperemesis gravidarum.
• Early-Onset Pre-eclampsia: True pre-eclampsia—hypertension with proteinuria or relevant organ dysfunction—before 20 weeks is unusual and should prompt urgent evaluation for molar pregnancy. Isolated hypertension, proteinuria or edema does not establish this diagnosis.
• Theca Lutein Cysts: Bilateral multilocular ovarian cysts (frequently > 6 cm) caused by massive ovarian hyperstimulation from astronomical circulating beta-hCG levels; resolve spontaneously following molar evacuation.
• Hyperthyroidism: Intact hCG has an alpha subunit shared with Thyroid-Stimulating Hormone (TSH) and a hormone-specific beta subunit. Very high hCG can stimulate TSH receptors and cause thyrotoxicosis, occasionally progressing to thyroid storm.
• Pelvic Ultrasound: Classic 'snowstorm' or 'cluster-of-grapes' echogenic pattern with diffuse vesicular swelling and absence of fetal structures.

Treatment & Surveillance Protocol

1. Uterine Evacuation: Suction curettage under general anesthesia with a large-bore cannula (10-12 mm) is the standard treatment. An IV oxytocin infusion is initiated after cervical dilation is commenced to sustain uterine contraction while minimizing the hazard of trophoblastic embolization to the pulmonary vasculature. Sharp curettage is avoided due to the high risk of uterine perforation.
2. Serial Quantitative Serum Beta-hCG Monitoring:
   • Measure quantitative hCG every 1–2 weeks until normal; obtain the next sample after 1 week if a rise or plateau appears.
   • For a complete mole, continue monthly hCG for 6 months after normalization. For a partial mole, obtain a confirmatory normal hCG 1 month after the first normal result.
3. Contraception During Surveillance: Use reliable contraception throughout the applicable follow-up period because a new pregnancy obscures hCG interpretation. Hormonal contraception can begin immediately after evacuation if otherwise medically eligible; hCG need not first normalize. Defer IUD placement until hCG has normalized and the specialist team considers insertion appropriate.
4. Diagnosis of Gestational Trophoblastic Neoplasia (GTN): Defined by FIGO criteria during post-molar surveillance:
   • An hCG plateau (<10% rise or fall) across 4measurements over>=3 weeks.
   • An hCG rise>10% across 3consecutive weekly measurements over>=2 weeks.
   • Histological diagnosis of gestational choriocarcinoma, placental-site trophoblastic tumor or epithelioid trophoblastic tumor.
   • Staging & Therapy: GTN demands immediate chest radiography or CT (lungs are the most common metastatic site, displaying 'cannonball' lesions) and WHO prognostic scoring. Low-risk GTN is treated with single-agent Methotrexate; high-risk GTN requires multi-agent chemotherapy (EMA-CO: Etoposide, Methotrexate, Actinomycin D, Cyclophosphamide, Vincristine), with overall survival rates exceeding 95%.