Ultrasound Findings in Ectopic pregnancy
The clinical diagnosis of EP is difficult. The classic triad of pain, vaginal bleeding and a palpable adnexal mass is neither present in all nor specific. The history of a missed period is present in only 61% of patients. Ultrasound is helpful in this clinical situation. Correlation of ultrasound finding with serum BhCG is helpful. A negative ultrasound does not exclude this diagnosis.
· Exclusion by demonstrating IUP- US demonstration of JUP makes the concurrence of EP rare, although recent estimates are in the order of 1 in 4000. The incidence is even higher in patients undergoing ovulation induction. In patients undergoing in vitro fertilization the incidence is quoted as 1 in 100
· Direct demonstration of EP- The demonstration of ectopic embryo within an extrauterine mass has been shown in 15—30% on TVS. An adnexal ‘ring-like’ structure in the absence of an embryo has been reported in 14-- 69% and said to be specific to EP
· Fetal cardiac activity in EP-Fetal cardiac activity when seen on TVS supported by Doppler studies in an extrauterine mass is specific for EP.
· Hematosalpinx/ complex mass -An adnexal complex mass in the presence of an empty uterus and a positive pregnancy test (BhCG) makes the diagnosis of EP highly likely.
· Fluid in the cul-de-sac- There are several causes of fluid in the cul-de-sac but when such fluid is seen in conjunction with an adnexal mass and when no IUP can be demonstrated the incidence of EP rises to 70%. If the amount of fluid is moderate to large in association with an adnexal mass, the incidence of EP is even higher and quoted by some to be almost 100%.
· Pseudogestational sac-This may occur in up to 20% of patients with EP. The ‘double decidual sac’ sign (DDS) is a reliable discriminator, being present in a true GS. No yolk sac or embryo will be seen in a pseudo GS. The use of TVS has enhanced the early recognition of both IUP and EP — although it does not absolutely exclude EP nor does it confirm IUP.
· Quantitative BhCG- An empty uterus in an at risk woman in association with an hCG greater than 1800 iu/l is highly suggestive of the presence of EP.
· Endomertrail thickness 0.5-1.7cm- Endometrial changes in the form of a decidual cast occur in 50% of patients and may be indistinguishable from IUP.
· Normal US findings-Earlier reports with the use of abdominal sonography found normal US findings in 20% of patients with EP; however, the use of TVS has reduced this figure considerably.
· Doppler sonography in EP- High velocity, low impedance flow is identified in both IUP and EP. On spectral Doppler luteal flow can be confused with an EP. It is possible to demonstrate placental flow in an adnexal mass separate from ovary and uterus on transvaginal color flow Doppler. A color flow Doppler may show intense arterial flow adjoining a GS as compared with the rest of uterus.
Spontaneous resolution of EP-The exact incidence of this is difficult to determine but it is now acknowledged that it occurs
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