Ectopic pregnancy

Introduction

Ectopic pregnancy is a potentially life-threatening condition in which a fertilized ovum implants outside the endometrial lining of the uterine cavity. The most common site is the fallopian tube (ampulla, isthmus, fimbrial end), but implantation can also occur in the ovary, cervix, abdominal cavity, or a previous cesarean section scar.

Because the implanted embryo cannot develop normally outside the uterus, ectopic pregnancy inevitably results in pregnancy loss, and in many cases, can cause tubal rupture, intra-abdominal hemorrhage, and maternal death if not promptly diagnosed and treated.

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Epidemiology

• Incidence: 1–2% of all reported pregnancies.

• Common site distribution:

  • Ampullary: ~70%

  • Isthmic: ~12%

  • Fimbrial: ~11%

  • Interstitial (cornual): 2–3%

  • Other rare sites: cervical, ovarian, abdominal, cesarean scar

• Mortality: Accounts for ~2–4% of pregnancy-related deaths in developed countries, higher in low-resource settings.

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Etiology and Risk Factors

Ectopic pregnancy results from delayed or impaired transport of the fertilized ovum to the uterine cavity, often due to tubal damage or dysfunction.

Risk Factors

1. Tubal Damage or Surgery

   • Previous pelvic or tubal surgery (e.g., salpingectomy, tuboplasty)

   • Previous ectopic pregnancy

   • Pelvic inflammatory disease (especially Chlamydia trachomatis)

2. Assisted Reproductive Technology (ART)

   • In vitro fertilization (IVF) increases the risk of both tubal and heterotopic pregnancy.

3. Anatomical Abnormalities

   • Congenital tubal malformations

   • Endometriosis

4. Contraceptive Use

   • Intrauterine device (IUD) presence (overall pregnancy risk is low, but if pregnancy occurs, more likely to be ectopic)

   • Progestin-only contraception (alters tubal motility)

5. Other

   • Smoking (affects tubal ciliary function)

   • Maternal age >35 years

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Pathophysiology

• Fertilization typically occurs in the ampulla of the fallopian tube.

• Normally, the zygote travels to the uterus over 3–4 days via ciliary movement and muscular contractions.

• Any disruption in tubal motility or anatomy can cause the zygote to implant prematurely in the tube or other ectopic sites.

• The trophoblast invades the surrounding tissue, leading to bleeding and potential rupture as the gestation enlarges.

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Clinical Features

Classic Triad

1. Amenorrhea – typically 6–8 weeks from last menstrual period.

2. Abdominal or pelvic pain – often unilateral.

3. Vaginal bleeding – usually light or spotting.

Other Symptoms

• Shoulder tip pain (due to diaphragmatic irritation from hemoperitoneum)

• Syncope, dizziness (suggesting significant blood loss)

• Gastrointestinal symptoms (nausea, diarrhea)

Signs on Examination

• Abdominal tenderness

• Adnexal tenderness or mass on bimanual examination

• Cervical motion tenderness

• Signs of shock in severe cases (tachycardia, hypotension, pallor)

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Differential Diagnosis

• Threatened, incomplete, or complete miscarriage

• Ovarian torsion

• Ruptured ovarian cyst

• Pelvic inflammatory disease

• Appendicitis

• Urinary tract infection

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Diagnosis

Prompt diagnosis is critical to prevent complications. Diagnosis relies on a combination of history, examination, serial serum β-hCG measurement, and transvaginal ultrasound (TVS).

Laboratory

• Serum β-hCG:

  • In a viable intrauterine pregnancy, β-hCG levels approximately double every 48 hours in early gestation.

  • Plateauing or slow-rising β-hCG suggests abnormal pregnancy (ectopic or nonviable intrauterine pregnancy).

• Progesterone: Low levels (<5 ng/mL) suggest nonviable pregnancy.

Imaging

• Transvaginal ultrasound:

  • Absence of intrauterine gestational sac when β-hCG is above the discriminatory zone (~1500–3500 mIU/mL) raises suspicion.

  • Adnexal mass or gestational sac with yolk sac/embryo outside uterus confirms diagnosis.

  • Free fluid in pouch of Douglas or peritoneal cavity suggests rupture.

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Management

Management depends on hemodynamic stability, size and site of ectopic pregnancy, β-hCG levels, and patient’s fertility wishes.

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1. Emergency Surgical Management

Indicated for:

• Hemodynamic instability

• Signs of rupture (peritonitis, large hemoperitoneum)

• High β-hCG and large ectopic mass with fetal cardiac activity in a non-viable location

Procedures:

• Salpingectomy: Removal of affected tube (preferred if tube severely damaged or fertility not desired).

• Salpingostomy: Incision to remove ectopic tissue, preserving tube (fertility conservation).

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2. Medical Management

Methotrexate (folate antagonist) is the mainstay.

• Indications:

  • Hemodynamically stable

  • No fetal cardiac activity

  • β-hCG < 5000–10,000 mIU/mL

  • Ectopic mass < 3.5–4 cm

• Regimens:

  • Single dose: 50 mg/m² intramuscularly; monitor β-hCG on days 4 and 7; additional doses if decline <15%.

• Contraindications:

  • Hemodynamic instability

  • Breastfeeding

  • Liver/renal dysfunction

  • Immunodeficiency

  • Peptic ulcer disease

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3. Expectant Management

• Selected for stable, asymptomatic patients with falling β-hCG levels and no signs of rupture.

• Requires close monitoring with serial β-hCG and ultrasound.

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Complications

• Tubal rupture with massive hemoperitoneum

• Hemorrhagic shock

• Recurrent ectopic pregnancy (~10% after one, higher with multiple)

• Infertility (especially if both tubes affected)

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Prognosis

• Excellent if diagnosed early and managed appropriately.

• Fertility outcomes depend on extent of tubal damage and remaining tubal function.

• Recurrence risk: 7–15% after one ectopic pregnancy.

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Prevention and Risk Reduction

• Prompt diagnosis and treatment of pelvic infections

• Smoking cessation

• Careful reproductive planning after tubal surgery or ART

• Early ultrasound in future pregnancies for women with prior ectopic