Ectopic Pregnancy

Summary

Definition and Epidemiology

Ectopic pregnancy refers to implantation of a fertilized ovum outside the endometrial lining of the uterine cavity. The majority (≈95%) occur within the fallopian tubes, particularly the ampulla (≈70%), followed by the isthmus (≈12%) and fimbrial region (≈11%). Less common sites include the interstitial portion of the tube, ovary, cervix, abdominal cavity, and broad ligament. In the UK, ectopic pregnancies occur in approximately 1 in 80–90 pregnancies, and globally account for significant morbidity and mortality in the first trimester.

Etiology and Risk Factors

The pathogenesis is linked to impaired tubal transport of the fertilized ovum, usually secondary to anatomical distortion or functional impairment.

Risk factors include:

• Past medical history: previous ectopic pregnancy, pelvic inflammatory disease, endometriosis, ruptured appendix.

• Surgical factors: tubal surgery, reversal of sterilisation, pelvic or abdominal surgery causing adhesions.

• Contraceptive/iatrogenic factors: intrauterine device, progesterone-only contraception, assisted reproduction (IVF, embryo transfer).

• Other: smoking, advanced maternal age, congenital uterine anomalies (e.g., DES exposure, bicornuate uterus), tubal motility disorders (e.g., Kartagener syndrome).

Notably, while contraception reduces overall pregnancy risk, conceptions occurring with an IUD or progesterone-only pill have a higher likelihood of being ectopic.

Diagnosis and Investigations

Every woman of reproductive age with abdominal pain should have a pregnancy test, Diagnosis relies on β-hCG dynamics and transvaginal ultrasound.

Investigations include:

• β-hCG testing:

  • Normal intrauterine pregnancy: β-hCG doubles every 48 hours.

  • Plateauing or suboptimal rise suggests ectopic or non-viable pregnancy.

  • Discriminatory threshold: β-hCG >1500 IU/L without an intrauterine pregnancy on TVUS strongly suggests ectopic pregnancy.

• Ultrasound (preferably transvaginal):

  • Findings: empty uterus with thickened endometrium, adnexal mass, “tubal ring” sign, free fluid in pouch of Douglas.

  • Interstitial pregnancy: “interstitial line” sign, thin myometrial mantle (<5 mm).

• Pregnancy of unknown location (PUL): requires serial β-hCG and repeat scanning.

• Other studies: FBC (to assess anaemia), blood type/Rh status, baseline renal and liver function (prior to methotrexate).

• Definitive diagnosis: laparoscopy, especially in unstable patients or inconclusive cases.

Conditions mimicking ectopic pregnancy include:

• Miscarriage (threatened, incomplete, complete)

• Ovarian cyst accidents (rupture, torsion, haemorrhage)

• Acute pelvic inflammatory disease

• Urinary tract infection

• Appendicitis or diverticulitis

Management

Management depends on haemodynamic stability, β-hCG level, ultrasound findings, and patient fertility desires.

1. Conservative (Expectant) Management

• Appropriate in select stable patients with low and falling β-hCG, small unruptured ectopic, minimal symptoms, and access to emergency care.

• Requires close follow-up with serial β-hCG monitoring.

• Risks include rupture and need for emergency intervention.

2. Medical Management

• Methotrexate (IM, single dose): folate antagonist inhibiting trophoblastic proliferation.

• Indications: stable, unruptured ectopic, no fetal cardiac activity, mass <3.5 cm, β-hCG typically <5000 mIU/mL, and reliable follow-up.

• Contraindications: haemodynamic instability, rupture, high β-hCG, fetal cardiac activity, renal/hepatic disease, breastfeeding, immunodeficiency.

• Monitoring: serial β-hCG (≥15% decline by day 4–7); if inadequate response, repeat dosing or surgery required.

3. Surgical Management

• Indicated in unstable patients, ruptured ectopic, high β-hCG (>5000), visible fetal cardiac activity, or failed medical therapy.

• Procedures:

• Salpingectomy: removal of affected tube (standard, especially with contralateral tubal disease).

• Salpingotomy: incision to remove ectopic while preserving tube (fertility-sparing, but requires β-hCG follow-up to exclude persistent trophoblast).

• Approach: laparoscopy preferred in stable patients; laparotomy for unstable or massive haemorrhage.

• All Rh-negative women should receive anti-D prophylaxis.

Complications

• Untreated ectopic pregnancy: tubal rupture, massive haemoperitoneum, hypovolaemic shock, maternal death.

• Treatment-related:

• Methotrexate: hepatotoxicity, myelosuppression, teratogenesis.

• Surgery: bleeding, infection, damage to adjacent organs, adhesion formation, recurrent ectopic risk.

• Ruptured ectopic pregnancy is a life-threatening emergency requiring immediate resuscitation and surgery.

Prognosis

• Maternal mortality is rare in high-resource settings but ectopic pregnancy remains a leading cause of first-trimester maternal death worldwide.

• Recurrence risk is ≈10–15%, depending on underlying tubal pathology.

• Fertility outcomes are best when the contralateral tube is healthy.