Extrauterine Pregnancy: Causes

Pathogenesis (development of disease)

Extrauterine pregnancy (EUG) refers to a gravidity (pregnancy) in which nidation (implantation) of the blastocyst (fertilized egg; stage of embryogenesis characterized by the formation of a blastocoel (fluid-filled cavity); it emerges from the morula, a developmental stage of early embryogenesis, on approximately day 4 after fertilization) occurs outside the uterus (womb). Most commonly, implantation occurs in the tube (fallopian tube; tubaria or tubal pregnancy), occasionally in the ovary (ovary; ovarian pregnancy) and in the abdominal cavity (abdominal pregnancy). Only very rarely does a delivered tubar gravidity occur.

The cause of EUG is a disturbance in the physiological process of egg capture (disturbance in ciliary function), tubal passage (fallopian tube passage; disturbance in tubal motility) and implantation (nidation; implantation) of the blastocyst into the decidua (maternal uterine lining) of the cavum uteri (uterine cavity).

Up to 50% of women with extrauterine pregnancy have no history of risk factors (medical history).

Etiology (causes)

Biographic causes

• Age – age > 40 years of life

Behavioral causes

• Early sexual intercourse
• Multiple sexual partners
• Consumption of stimulants
  • Tobacco (smoking) (moderate increased risk with cigarette use).
• Vaginal douches

Causes related to illness

Pregnancy, childbirth and puerperium (O00-O99)

• Condition following extrauterine pregnancy
• Condition after abortion (miscarriage)

Genitourinary system (kidneys, urinary tract – sex organs) (N00-N99)

• Condition following ascending infections/adnexitis (inflammation of the fallopian tubes and ovary), e.g., due tochlamydial infections, Neisseria gonorrhoeae infection.
• Female sterility
• Pathological (pathological) changes in the tube, unspecified – e.g., after infections or surgical procedures (including after sterilization/infertility).

Medication

• Benzodiazepine-type medications → women who used benzodiazepines (e.g., diazepam, lorazepam, midazolam) in the 90 days before conception (conception) had a nearly 50% increased risk of extrauterine pregnancy compared with those who did not use such preparations.

Operations

• Abdominal (abdominal area), e.g., appendectomy (e.g., for appendicitis perforata), caesarean section (cesarean section)).
  • internal genitalia:
    • Abortion curettage – scraping of the uterus where a disturbed pregnancy has remained.
    • Surgery on the tube (fallopian tube), e.g. condition after tubal sterilization (tubal sterilization; about 30% of all pregnancies after sterilization are extrauterine pregnancies)
• Increase in assisted reproductive measures (assisted reproduction techniques).

Other causes

• Intrauterine device (IUD) (about 50% of pregnancies enclosed intrauterine device are extrauterine pregnancies).