Ectopic Pregnancy Comprehensive Study Notes

Ectopic pregnancy (EP): implantation of the fertilised ovum outside the uterine endometrium.
- ≈ $90\%$ occur in the uterine (fallopian) tube → hence the term “tubal pregnancy.”
- Tubal distribution (order of frequency):
- Ampulla (≈ $70\%$ of tubal EPs)
- Isthmus
- Interstitium (cornual)
- Fimbria
- Tubo-ovarian ligament
- Extra-tubal locations (documented but less common): ovary, abdominal cavity, previous Caesarean scar, cervix, uterine cornua.
Fundamental pathophysiology: obstruction or slowed transit of the fertilised ovum through the tube → implantation before reaching the endometrial cavity.
Chapter reference: Chapter $19$ , “Ectopic Pregnancy.”

Failure of normal tubal peristalsis or ciliary action is central.
- Most frequent precipitating factor: prior acute or subacute salpingitis (→ tubal scarring, luminal narrowing, loss of cilia).
Infectious agents strongly implicated in salpingitis/PID:
- Neisseria gonorrhoeae
- Chlamydia trachomatis
Other mechanical/functional causes:
- Previous tubal surgery (e.g., sterilisation, reconstruction)
- Congenital or acquired tubal anomalies
- Adhesions from prior pelvic surgery or endometriosis.

Classical triad (but present together in < $50\%$ ):
- Abdominal or pelvic pain
- Amenorrhoea (missed period)
- Vaginal spotting/bleeding
Hallmark timing: pain with spotting $6$ – $8$ weeks after LMP (missed menses).
Additional symptoms if rupture/imminent rupture:
- Sudden, severe unilateral abdominal pain
- Referred shoulder pain (diaphragmatic irritation by intraperitoneal blood)
- Dizziness, syncope
- Urge to defecate (cul-de-sac blood irritating rectum)

General:
- Abdomen tender; guarding present if peritoneal irritation
- Hypotension & tachycardia (intra-abdominal haemorrhage)
- Possible bradycardia (reflex vagal response to intraperitoneal blood)
- Afebrile (unless concurrent infection)
Pelvic exam:
- Cervical motion tenderness
- Painful bimanual exam
- Adnexal tenderness or palpable mass
- Scant blood at cervical os

Presenting with vaginal bleeding and/or pain.
Immediate or ≤ $48$ -h ultrasound—TVS (transvaginal) preferred; TAS (transabdominal) if necessary.
Three pathways:
- Intra-uterine pregnancy visualised → routine OB follow-up.
- Definite ectopic pregnancy → OB consult → consider methotrexate vs surgery.
- Indeterminate scan → obtain quantitative β-hCG and assess clinical acuity.
β-hCG interpretation:
- >1500 mIU/mL and no IUP on TVS ⇒ high suspicion EP → serial β-hCGs & OB phone consult.
- $<1500$ mIU/mL, clinically benign ⇒ repeat β-hCG & U/S in $48$ h; rescan when β-hCG > $3000$ mIU/mL for TVS (discriminatory zone).
- If unstable, immediate surgical evaluation regardless of levels.

Serum quantitative β-hCG:
- Non-doubling/plateauing levels support EP or failing IUP.
- Specific thresholds guide imaging and therapy choice.
TVS: most sensitive modality to localise gestation and detect adnexal mass, free fluid, or extra-uterine sac.
Additional tests (rule-out differentials): CBC, serum progesterone, renal/liver panels, differential diagnoses (ruptured corpus luteum, appendicitis, torsion, urolithiasis, normal early IUP).

Haemodynamically stable & reliable for follow-up.
Gestational sac unruptured.
Size < $4$ cm on ultrasound.
β-hCG < $10\,000$ mIU/mL.
No concurrent viable intra-uterine pregnancy.
Normal renal & hepatic function tests.
Dosing & monitoring:
- Single-dose MTX protocol → check β-hCG day $4$ & day $7$ .
- Adequate response = ≥ $15\%$ fall from day $4$ to $7$ .
- If < $15\%$ decline → repeat MTX dose or proceed to surgery.
Contraindications: immunodeficiency, hepatic/renal dysfunction, active pulmonary disease, peptic ulcer, breastfeeding.

Indications:
- Ruptured EP or haemodynamic instability.
- Contraindication or failure of MTX therapy.
- Patient preference or poor follow-up reliability.
Unruptured EP, fertility desired → laparoscopic linear salpingostomy (preserves tube).
Ruptured EP with uncontrolled haemorrhage → laparotomy + salpingectomy.
Post-operative care:
- Monitor β-hCG to undetectable to ensure complete trophoblastic removal.
- Administer Rh-immunoglobulin to Rh-negative women within $72$ h.

Assessment highlights:
- Pain quality, timing, localisation.
- Volume & character of vaginal bleeding.
- Haemodynamic status (BP, HR, orthostatics).
- Psychologic distress.
Interventions:
- Analgesia (NSAIDs, opioids if needed).
- Prepare & administer MTX per protocol or prep for surgery.
- Educate on rupture signs: increasing abdominal pain, shoulder pain, fainting, heavy vaginal bleeding.
- Emotional support for potential pregnancy loss & fertility concerns.

STI prevention: condom use, limit sexual partners, prompt treatment of infections to prevent PID.
If choosing an IUD: counsel on PID signs (pelvic pain, fever, abnormal discharge) → seek care early.
Smoking cessation during reproductive years (smoking linked to impaired tubal motility & higher EP risk).
Early prenatal care: confirm gestational location with first-trimester ultrasound.
After an EP:
- Discuss recurrence risk (≈ $10\%$ after one EP, higher after two).
- Advise waiting at least one full menstrual cycle (often three months if MTX was used) before attempting conception.

Recognise EP as a non-viable pregnancy with potentially life-threatening maternal sequelae → therapeutic termination is medically indicated.
Decision-making: respect patient autonomy regarding medical vs surgical approach when both are safe options.
Grief support: women may experience loss similar to miscarriage; offer counselling resources.
Fertility preservation: surgical approach chosen should balance haemostasis with future reproductive potential.