Diagnostic Ultrasound - Abdomen and Pelvis

Tubal Ectopic Pregnancy
Diagnoses: Female Pelvis
• Interligamentous fibroid
Bowel
• Watch for peristalsis
Intrauterine Pregnancy
• Intradecidual sac sign, double decidual sac sign
○ May help identify an IUP, but not necessary for diagnosis
○ Nonspecific intrauterine fluid collection has greater odds
of being gestational sac (GS) than pseudosac
○ Look for eccentricity and curved edges to increase
likelihood further
• Perigestational hemorrhage is common
○ Resembles pseudosac
• Anechoic cul-de-sac fluid: Considered physiologic
PATHOLOGY
General Features
• Etiology
○ Abnormal blastocyst implantation within fallopian tube
due to delay or obstruction to transit
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Classic triad: Pelvic pain (most common presentation),
vaginal bleeding, palpable mass; nonspecific
○ Cardiovascular shock: Highly specific sign of rupture
• Other signs/symptoms
○ When hCG > 3,000 mIU/mL IRP and no IUP
– Differential: EP vs. failing IUP vs. multiple gestation
○ Lower hCG level and negative US
– Differential: EP vs. viable or nonviable IUP
○ Obtain follow-up hCG and US in indeterminate cases
– Levels double every 2-3 days with normal IUP; slower
rise with EP
– Dropping levels suggest failing pregnancy
○ No lower limit below which rupture is not seen; do not
delay US due to low hCG level
○ Maternal serum progesterone levels
– Helps predict normal IUP vs. EP/failing IUP
– Cannot differentiate EP from failed IUP
– < 5 ng/mL = nonviable pregnancy in 100%
– Office curettage can rule out failed IUP
– > 25 ng/mL excludes ectopic with 97.5% sensitivity
Demographics
• Epidemiology
○ 1.4% of all pregnancies are ectopic
○ 5-20% incidence if patient presents with pain/bleeding
○ 10-40% risk in fertility patients
○ Abnormal tube is risk factor for tubal ectopic
– Chronic salpingitis, salpingitis isthmica nodosa, tubal
surgery, prior EP
Natural History & Prognosis
• Delayed diagnosis → ↑ morbidity and death
○ Fatality rate has ↓ from 3.5 to 1:1,000
• Prognosis for future pregnancies
○ 80% will have future IUP; 15-20% will have future EP
• 24% of all EP may spontaneously resolve
○ More likely if hCG levels < 1,000 mIU/mL IRP
○ Must follow dropping hCG levels very carefully
Treatment
• Medical treatment with methotrexate (MTX)
○ Patient must be hemodynamically stable
○ No evidence for tube rupture: Little or no free fluid
○ 90% success rate for early, unruptured, small ectopic
– EP < 4 cm
– hCG levels < 5,000 mIU/mL
– ≤ 8 weeks gestation
○ 30% failure rate if living embryo
○ Ultrasound after treatment is often confusing: Mass
possible up to 3 months after treatment
– ↑ hemorrhage around EP; ↑ size of EP due to
hemorrhage and edema
– US only if suspected tubal rupture
○ Multiple doses may be necessary
• Surgical therapy
○ Salpingectomy: Segment of tube removed and
reconnected if possible → only choice for ruptured EP
○ Salpingotomy: Small lengthwise incision in tube for
removal of EP
• Ultrasound-guided local injection
○ MTX or potassium chloride (KCl)
– Injected directly into gestational sac
○ Live ectopic + unruptured tube
– Combined with systemic MTX increases success rate
over systemic MTX alone
DIAGNOSTIC CHECKLIST
Consider
• In setting of PUL, single hCG measurement is unreliable in
distinguishing IUP (nonviable or viable) from EP; reserve
treatment for visualized abnormality
• Follow serial hCG levels in indeterminate cases
○ Repeat US if hCG levels are rising
○ Dropping levels suggest failing pregnancy
• No lower limit hCG level for EP, often found with hCG levels
< 1,000 mIU/mL → do not delay US
Image Interpretation Pearls
• Presence of IUP is best negative predictor of EP in general
population
• Any extraovarian mass with empty uterus and hCG level >
2000 mIU/mL should be viewed with suspicion
• Be aware of (and beware of) CL mimic; can be cause of pain
• Be cautious in categorizing nonspecific intrauterine
collection as pseudosac of EP
○ Consider favoring more likely diagnosis of IUP in
medically stable patient
SELECTED REFERENCES
1. Ko JK et al: Time to revisit the human chorionic gonadotropin discriminatory
level in the management of pregnancy of unknown location. J Ultrasound
Med. 33(3):465-71, 2014
2. Doubilet PM et al: Diagnostic criteria for nonviable pregnancy early in the
first trimester. N Engl J Med. 369(15):1443-51, 2013
3. Rana P et al: Ectopic pregnancy: a review. Arch Gynecol Obstet. 288(4):747-
57, 2013
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