Because its manifestations may be subtle, ectopic pregnancy is often difficult to differentiate from other pelvic disorders, such as a ruptured corpus luteum cyst, threatened abortion, pelvic inflammatory disease, or torsion of an ovarian cyst or fallopian tube. The patient may not report any menstrual irregularity. Palpation of the pelvis may reveal only mild tenderness or an unexpected mass in one of the lower abdominal quadrants. The uterus may or may not be enlarged and softened. Diagnostic Measures Prompt diagnosis and treatment of ectopic pregnancy can avert the massive internal hemorrhage often associated with rupture.
Early diagnosis allows time for conservative treatment and avoids surgical procedures.
3 Transvaginal ultrasound of the uterus reveals the tissue changes of pregnancy, but without the presence of a gestational sac. Instead, sonography may find a mass or even the presence of pulsating fetal heart tissue on an adjacent structure. While serum HCG levels continue to rise in a normal pregnancy, they plateau and begin to fall after a six-week gestation in an ectopic pregnancy. Plateauing HCG levels with either a half-life or a doubling time of more than or equal to seven days have the highest predictive value for ectopic pregnancy of any HCG pattern. Serum progesterone levels are usually not much use in making a diagnosis of ectopic pregnancy, but they can be another clue.