Ectopic pregnancies are not viable and can lead to rupturing of the tube, internal bleeding, and shock. Surgery is necessary to remove the developing cells and - in the case of a rupture - to repair damaged tissue. If not diagnosed and treated, an ectopic pregnancy can endanger the mother's life.
Why would a fertilized egg develop in the fallopian tube? This can happen if the egg is slowed in its movement through the tube or is somehow blocked. Scarring of the fallopian tube is a primary cause.
About half of those who have ectopic pregnancies previously have had swelling/inflamation of the fallopian tubes or pelvic inflammatory disease.