Diagnostic Ultrasound - Abdomen and Pelvis

Unusual Ectopic Pregnancies
Diagnoses: Female Pelvis
○ Look for hemoperitoneum around the liver
• MR: Generally not necessary and avoided in first trimester
unless clinical situation warrants
○ Consider when ultrasound findings are equivocal or
preoperative planning for large ectopics
– Can delineate anatomy, location of placenta, and
vascular supply before intervention
○ Useful in evaluating for congenital uterine anomalies
DIFFERENTIAL DIAGNOSIS
Intrauterine Pregnancy vs. Interstitial
• High or eccentric implantation can be confusing
• Should always have normal myometrial coverage
• Angular pregnancy: May descend or grow into cavity
Tubal Ectopic vs. Interstitial EP
• Can be confusing if adjacent to uterine cornua
• Use ultrasound probe to gently separate structures
Septate Uterus vs. Interstitial EP
• Implantation in one horn gives eccentric appearance
• Myometrium completely surrounds GS
• 3D US helpful in showing 2 uterine cavities
Scar EP vs. IUP or Abortion in Progress
• Thin overlying myometrium or uterine serosa
• May bulge uterine contour at C-section scar if large enough
• If not diagnosed, reports of becoming placenta accreta
Abortion in Progress vs. Cervical EP
• Centrally located products of conception, ± open internal
os; may move during the examination
○ May be displaced with gentle pressure
• Cardiac activity and trophoblastic flow are more suggestive
of cervical EP with vascularity from adjacent cervical tissue
○ Cardiac activity occasionally seen with Ab in progress
Corpus Luteum vs. Ovarian EP
• Extremely difficult to differentiate from ovarian EP unless
YS or embryo is seen
• Corpus luteum wall less echogenic than trophoblast
• Very rare compared to ubiquitous corpus luteum
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Pelvic/abdominal pain; vaginal bleeding, palpable mass
• Other signs/symptoms
○ Hypotension and shock if presenting with rupture
○ May be an incidental or subtle finding on early US
• Risk factors
○ Sexually transmitted disease or pelvic inflammatory
disease; prior tubal surgery, especially salpingectomy;
prior ectopic pregnancy; assisted reproductive
technology pregnancies; previous uterine, cervical
surgery, or dilatation and curettage; endometriosis;
indwelling intrauterine contraceptive devices; Asherman
syndrome; fibroids
Demographics
• Age
○ Majority of EP are detected in women > 35 years
• Epidemiology
○ EP outside the fallopian tube occurs in 3-5% of cases
○ Interstitial 2-4%; scar < 1%; cervical < 1%; ovarian 0.15-
3%; abdominal 1-3%
Natural History & Prognosis
• Overall, ↑ morbidity and mortality than for usual tubal EP
○ Mortality rate 0.14% for usual tubal EP vs. 2-2.5% for
interstitial EP and up to 20% for abdominal EP
○ Improved blood supply from myometrium, cervix, or
parasitized visceral arterial supply allow EP to grow
larger and present later
○ Increased risk of uterine rupture and hemorrhage
○ Potential exsanguination
• Good outcome with preserved future fertility often
possible with appropriate treatment
• Important to distinguish cornual EP from interstitial EP or
angular pregnancy → different outcomes
○ Cornual EP: High risk of recurrence
○ Angular pregnancy: Can progress to live birth; ↑ risk for
spontaneous abortion (38%) and uterine rupture (23%)
Treatment
• Tailored to individual patients based on clinical
presentation, size of GS, presence of cardiac activity, and
maternal hemodynamic stability
• Conservative treatments: Generally favored for interstitial
EP due to ↑ complication risk with surgery
○ Systemic methotrexate: Requires close follow-up and
possibly additional doses
– Failed treatment goes to surgery
○ Local sac injection: Methotrexate or potassium chloride;
etoposide also used
– Via laparoscopy or ultrasound guidance
• Surgical intervention: Laparoscopy or laparotomy
○ Recommended treatment for cornual EP because of
suggested increased risk of recurrence
○ Rupture may require hysterectomy
• Uterine artery embolization may be coupled with other
treatments to control or reduce hemorrhage
• Expectant management
○ Considered only if small sac and no living embryo
DIAGNOSTIC CHECKLIST
Consider
• 3D ultrasound for improved spatial orientation of sac to
endometrial cavity
Image Interpretation Pearls
• Diagnosis of unusual ectopic pregnancy can be difficult
○ Need high degree of suspicion, especially in a high-risk
patient
○ Short term follow-up for any eccentric or unusually
located GS
SELECTED REFERENCES
1. Ghaneie A et al: Unusual Ectopic Pregnancies: Sonographic Findings and
Implications for Management. J Ultrasound Med. 34(6):951-962, 2015
2. Parker RA 3rd et al: MR imaging findings of ectopic pregnancy: a pictorial
review. Radiographics. 32(5):1445-60; discussion 1460-2, 2012
782