Extrauterine (ectopic) pregnancy

Extrauterine (ectopic) pregnancy

Introduction

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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Sites of ectopic pregnancies | Tay, J. I., Moore, J., & Walker, J. J. (2000). Ectopic pregnancy. The Western Journal of Medicine, 173(2), 131–134. https://doi.org/10.1136/ewjm.173.2.131

Aetiology

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

Pathophysiology

ectopic-pregnancy

Clinical features

Most commonly diagnosed in the 6th through 9th 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

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 (1st 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
Mean (SE) serum concentrations of human chorionic gonadotrophin in normal pregnancy | Braunstein GD, Rasor J, Adler D, Danzer H, Wade ME. Serum human chorionic gonadotrophin levels throughout normal pregnancy. Am J Obstet Gynecol. 1976;126:678–681.

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)
Diagnostic puncture of the cul-de-sac | Cutting Off The. (2020) MCPC – Culdocentesis and colpotomy – Health Education To Villages. Retrieved October 18, 2020, from https://hetv.org/resources/reproductive-health/impac/Procedures/Culdocentesis_P69_P70.html

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

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
Algorithm for the individualized surgical treatment of tubal pregnancy (TP), | Wallwiener D, Pollmann D, Gauwerky J, Sohn C, Bastert G. Operative treatment of tubal pregnancy. In: Bastert G, Wallwiener, editors. Lasers in gynecology. Berlin, Heidelberg: Springer; 1992.
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(A) Left tubal ectopic pregnancy at laparoscopy. (B) Tubal ectopic pregnancy has been removed by salpingectomy. | Sivalingam, V. N., Duncan, W. C., Kirk, E., Shephard, L. A., & Horne, A. W. (2011). Diagnosis and management of ectopic pregnancy. The journal of family planning and reproductive health care, 37(4), 231–240. doi:10.1136/jfprhc-2011-0073
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