Definition: Ectopic pregnancy refers to the implantation
of the developing blastocyst at any other site other than the endometrium.
Over 95% of ectopic pregnancies occur in the fallopian
tubes. Within the tube, up to 80% occur in the ampulla, 25% in the isthmus,
5% in the infundibulum and up to 2% in the interstitial portion. Right-sided
ectopics are commoner than left-sided. Other sites include the ovary, peritoneal
cavity and uterine cervix.
PID is the most common antecedent factor. Abnormal tubal
motility or mucosal adhesions that impede passage of the conceptus along the
tube, endometriosis and previous pelvic surgery are other etiologic factors.
A woman with an ectopic tubal pregnancy may present with
pelvic pain or anomalous bleeding following a period of amenorrhoea. The majority
will present as an emergency with tubal rupture and hemorrhagic shock.
Ruptured ectopic tubal pregnancy involving the ampulla. Note the fetus protruding
from site of rupture (12 oclock).
Question: Which major blood vessel may be torn
by a ruptured cornual/interstitial ectopic pregnancy?