EXPERTddx : Obstetrics: (EXPERTddx™) by Paula J. Woodward MD, Anne Kennedy MD, Roya Sohaey MD, Karen

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This unruptured ectopic was successfully treated with methotrexate. (Left) Coronal ultrasound shows a tubs! gestational sac l1li adjacent to the right ovary l1:li. (Right) Coronal color Doppler ultrasound in the same patient as previous image, shows the classic "ring of fire " appearance of ectopic pregnancy. The gestational sac wall contains vascular trophoblastic tissue and "lights up" with color Doppler. 1 36 Corpus luteum Cyst FIRST TRIMESTER PELVIC PAIN Ectopic Pregnancy Ectopic Pregnancy (Leh) Sagittal transvaginal ultrasound shows a "pseudo gestaUonalsac" Endometrial fluid may mimic an intrauterine pregnancy_ (Right) Coronal ultrasound shows a large complex adnexal mass lEI and echogenic fluid lEI in the =_ same patient as the previous image.

S! : I- ii: Common • Spontaneous Abortion • Tubal Ectopic less Common • • • • Uterine Duplication Interstitial Ectopic Cervical Ectopic C-Section Scar Ectopic Rare but Important • Heterotopic Pregnancy • Abdominal Ectopic ESSENTIAL INFORMATION Key Differential Diagnosis Issues • Confirm intrauterine pregnancy (IUP) o Exclude ectopic pregnancy • Beware of pseudosac: Fluid centrally located in endometrial canal o Should have typical signs of early IUP depending on gestational age • Intradecidual sac sign: Echogenic ring around sac within endometrium • Double decidual sac sign: Paired echogenic rings around early sac • Double bleb sign: Yolk sac and amniotic sac • Diamond ring sign: Yolk sac with associated early embryo • Clarify location of implantation site o Should be eccentric within endometrium o Sac should be within the body of the uterus above internal os o Myometrium should be completely surrounding sac Helpful Clues for Common Diagnoses • Spontaneous Abortion o Use color Doppler to differentiate ectopic implantation from abortion in progress • Early IUP has increased surrounding flow; "ring of fire" appearance due to trophoblastic tissue • Spontaneous abortion is much less vascular o If embryo visualized, assess for heart beat • If heart rate detected, usually indicates an implanted pregnancy o Evaluate internal os 1 16 • Will be open for abortion in progress • Closed in cervical ectopic o Correlate with serial hCG • Should be decreasing with spontaneous abortion • Tubal Ectopic o Most specific diagnostic clue: Adnexal gestational sac ± embryo o Most common presentation: No IUP, tubal/adnexal mass, echogenic free fluid in cul-de-sac • Decidual reaction in uterus • May have pseudosac • Heterogeneous tubal hematoma • Pulsed Doppler shows low resistance flow in tubal pregnancy o Ectopic often on same side as corpus luteum o Ultrasound negative in 5-10% of cases Helpful Clues for less Common Diagnoses • Uterine Duplication o May give the appearance of ectopic implantation o Implantation actually within one horn of uterine anomaly • Didelphys: 2 separate endometrial cavities • Bicornuate: 2 separate uterine horns with concave outer uterine contour • Septate: Variable length of septum separating cavities, normal outer uterine contour o Myometrium completely surrounds sac as implantation is normal • Interstitial Ectopic o Look for interstitial line sign • Echogenic line from endometrium to ectopic sac o Myometrium around sac should be at least 5 mm thick o Can grow to be larger than tubal ectopic as blood supply better • Within intramural portion of fallopian tube o May present as echogenic mass within cornua without sac • Mass is combination of trophoblastic tissue and hematoma • Cervical Ectopic o Prior instrumentation of uterus considered key risk factor ABNORMAL SAC POSITION Assess for "hourglass" shape of uterus • Cervix distended but internal os is closed • Transabdominal ultrasound helpful to evaluate landmarks and shape o Eccentric implantation into wall of cervix • Distinguishes from spontaneous abortion in progress which is central • C-Section Scar Ectopic o Multiple prior C-sections may increase risk • Look for implantation near scar and thinned/absent anterior myometrium o Assess for other associated complications if presenting later in pregnancy • Placenta accreta, increta, percreta • Placenta previa • Placental abruption o Trophoblastic tissue in scar may invade into bladder o Helpful Clues for Rare Diagnoses • Heterotopic Pregnancy o Correlate with clinical history • < 1:30,000 in spontaneous pregnancies • Much more common if history of assisted reproduction • Damage to endometrium or fallopian tubes predisposes to ectopic implantation o IVP identified but adnexal mass seen o Beware of misdiagnosis due to "ring of fire" around corpus luteum • Intraovarian ectopics exceedingly rare • Tissue around corpus luteum can normally be hypervascular Spontaneous Abortion Sagittal transvaginal ultrasound shows an amorphous 8 week embryo and sac 112 in the cervix.

Twins in the first trimester. There is a single chorionic sac III with two embryos (calipers) seen in close apposition. There is only one yolk sac III and no dividing membrane. (Right) Ultrasound shows cranial fusion in another case. The profife of one twin. is seen fused to an axial plane EilII of the other twin's head. Common vessels were seen between the brains as well as a contiguous bone and skin covering. Twin Reversed Arterial Perfusion Twin Reversed Arterial Perfusion (Leh) Segittsl transvaginal ultrasound shows an abnormal, grossly edematous twin fetus with absent cranial structures Ill.