1) To recognize the sonographic appearance of a "classic" intradecidual sac. 2) To recognize the spectrum of sonographic appearances for a pseudosac. 3) To appreciate how to use US to detect an ectopic pregnancy. 4) To recognize the sonographic features that are consistent with hemoperitoneum.
I. ROLE OF ULTRASOUND
A. Primary: Detect ectopic pregnancy
B. Secondary: Screen at risk patients; Determine Rx; Guide Rx; Monitor post Rx
II. FIRST, EVALUATE THE UTERUS
A. Because up to 90% of women referred to “rule out EP” have an IUP.
B. Because it is easier to diagnose an IUP than an EP
C. Because the incidence of heterotopic pregnancy is about 1:7000
D.With ectopic, endometrium is usually “empty”; ~ 20% of pts have “pseudosac”
E. With only intrauterine fluid (no yolk sac), do follow-up scan
III. DETERMINE THE hCG LEVEL AND CORRELATE IT WITH THE US FINDINGS
A. If negative, EP is excluded.
B. If > than discriminatory level (2000mIU/ml) and no IU sac->EP likely
(exception is with heavy bleeding ->consider SAB)
C. If
IV. SECOND, EVALUATE THE ADNEXAE
A. Identify ovary 1st because >95% of EPs are in tube located adjacent to the ovary
B. Criteria for diagnosing EP
Living EP: sensitivity = 20% (strictest criterion)
Ectopic YS / embry sensitivity = 37%
Echogenic tubal ring: sensitivity = 65% (in ~90% of cases, more echogenic than ovarian parenchyma or corpus luteum)
Extraovarian mass: sensitivity = 84% (most liberal criterion, but it works!!)
B. “Probe with the probe”: To localize site of pain; to separate EP from contiguous ovary
V. THIRD, EVALUATE FOR FREE FLUID
A. Look for echogenic fluid, which suggests an hemoperitoneum
B. Note that clot can be very echogenic and easily mistaken for bowel (always
scan upper abdomen as well to look for free fluid)
VI. UNUSUAL AND NONTUBAL LOCATIONS FOR EP
A. Most common in women following assisted reproductive technology
B. Locations:
Intersitial: 2-4%; Has significant morbidity / mortality with rupture
Cervical: .15%; Look for yolk sac/embryo in Cx (Ddx = ongoing SAB)
Abdominal: Typically occur following tubal rupture/tubal abortion. Can
grow to large size and be difficult to diagnose
VII: MANAGEMENT OF ECTOPICS
A. Medical management guidelines: hCG
B. Methotrexate: Intramuscular or inject into the sac
KCl inject into the sac
Laing, F,
Ultrasound Evaluation of Possible Ectopic Pregnancy. Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL.
http://archive.rsna.org/2006/4402471.html
