Extrauterine (ectopic) pregnancy

Implantation of a fertilized oocyte outside the uterine cavity.

• Tubal ectopic (M/C): Ampulla (70%) > Isthmus (12%) > Infundibulum (11%) > Interstitial & cornual (least common, 2-3%)
• M/C non-tubal site: Ovary
• Least common site: Cervical ectopic/ectopic in cesarean scar

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Etiology

Extrauterine pregnancy is of multifactorial origin. Up to half of all women with an extrauterine pregnancy have no recognized risk factors for it.

• Prior tubal surgery (biggest risk factor)
• Prior ectopic pregnancy
• History of infertility
• PID (M/C cause): Salpingitis >> oophoritis, endometritis
  • M/C organism: Chlamydia
• Ruptured appendix
• Smoking
• Contraceptive methods: IUDs, PIPs, tubal sterilization
• Salpingitis isthmica nodosa (SIN): Inflammatory condition of the fallopian tubes strongly associated with infertility and an increased risk of ectopic pregnancy

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Presentation

Most commonly diagnosed in the 6^th through 9^th week of gestation.  and commonly present with pain and vaginal bleeding between 6 and 10 weeks’ gestation.

Intact tubal pregnancy:

Intact fallopian tube and embryo, perhaps with discernible cardiac function

• Usually asymptomatic

Classical triad: 30% cases

May indicate extrauterine pregnancy but can also arise in an intact intrauterine pregnancy or as a consequence of early miscarriage

1. Aching pelvic pain
2. Mild vaginal spotting
3. Secondary amenorrhea

Other features:

• Endometrial sloughing: Endometrial growth not maintained d/t fall in β-hCG & progesterone
• Decidual cast: Entire decidua expelled at once

Ruptured ectopic pregnancy:

Pelvic pain with severe hemorrhagic shock

• Hemorrhagic shock/hemodynamic instability (dyspnea, hypotension, tachycardia)
• Syncope
• Danforth sign: Shoulder pain on inspiration, due to irritation of the diaphragm by a hemoperitoneum in ruptured ectopic pregnancy
• Abdominal guarding or an acute abdomen

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Diagnosis

40% of ectopic pregnancies go undiagnosed on initial presentation.

Diagnostic criteria:

• Paalman & McElin criteria (cervical ectopic clinical criteria)
• Rubin criteria (cervical ectopic histological criteria)
• Studdiford criteria (abdominal ectopic)
• Spiegelberg criteria (ovarian ectopic)

Transvaginal ultrasonography (TVS):

Investigation of choice

• Empty uterus (1_st sign on USG)
• Tubal ring sign or bagel/blob sign: Echogenic ring surrounding an unruptured ectopic pregnancy
• Pseudogestational sac: Small fluid collection, centrally located within endometrial cavity and surrounded by thick decidual reaction
• Complex adnexal mass

Serum β-Human chorionic gonadotrophin (β-hCG):

Performed if TVS inconclusive

• Critical titre (levels at which gestational sac should be visible on USG):
  • TVS: 1500 IU/l
  • TAS: 6500 IU/l
• Repeat test done after 48hr if β-HCG < 1500 IU/l:
  • β-HCG ↑ (x2): Normal pregnancy
  • β-HCG ↓ : Abortion
  • β-HCG ↑ (< x2): Ectopic pregnancy

Culdocentesis:

Procedure to obtain free fluid from the cul de sac of women indicated in suspected ruptured ectopic pregnancy and acute salpingitis or pelvic inflammatory disease (PID).

• Non-clotting blood: Hemoperitoneum (suspect ectopic pregnancy)
• Clotting blood: Vein/artery aspirated (remove needle, re-insert to aspirate again)

Differential diagnosis:

• Appendicitis (M/C mistaken for)
• Cystic/solid adnexal tumors causing peritoneal irritation (esp by torsion or rupture)
• Adnexal infection (e.g., PID, UTI, tubo-ovarian abscess)
• Ovarian hyperstimulation syndrome with ascites

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Management

Expectant management:

Some ectopic pregnancies resolve spontaneously, and expectant management is possible in selected cases.

• Not preferred

Medical management:

Treatment of choice before rupture in haemodynamically stable patients with hCG <5000 IU/l, rising hCG level within 48 hours and a gestational sac <4 cm

• DOC: Methotrexate (folic acid antagonist) (IM/direct local injection)
  • Close follow up with serial measurements of serum concentrations of hCG required. 3 courses can be attempted before surgical intervention.
• Other drugs: Potassium chloride, actinomycin, hyperosmolar glucose, PGF2-α

Surgical management:

Indicated in rupture, hemodynamic instability, symptoms (eg., pain), diagnostic laparoscopy or suspected heterotopic pregnancy

• Radical procedure (salpingectomy)
• Conservative procedure (salpingostomy)
• Anti-D (300 µg): Alloimmunization after surgical management of ectopic pregancy