When should ectopic pregnandy suspected?
Consider ectopic pregnancy in all women of childbearing age presenting with general symptoms of ectopic pregnancy or with known risk factors (e.g., anatomical alteration of the fallopian tubes).
Describe the approach in hemodynamically unstable patients.
Start acute stabilization measures (see “Management of ruptured ectopic pregnancy”).
If trained, perform a point-of-care ultrasound
Urgently consult OB/GYN for surgical exploration based on clinical suspicion.
Obtain a formal ultrasound (transvaginal ultrasound) as soon as the patient is stable enough.
Describe the approach in hemodynamically stable patients.
Send serum β-hCG and arrange or perform a pelvic ultrasound (e.g., POCUS for early pregnancy or formal ultrasound) regardless of β-hCG level.
Ectopic pregnancy visible on imaging (diagnosis confirmed): Begin treatment.
IUP visible on imaging (ectopic pregnancy unlikely): Consider alternative diagnoses.
Indeterminate ultrasound (pregnancy of unknown location): Arrange follow-up and repeat imaging.
List lab studies (β-hCG level).
Finding: ↑ β-hCG
Additional considerations
Increased β-hCG is verifiable from the eighth day after ovulation.
β-hCG discriminatory level: the β-hCG level at which an IUP is typically visible on ultrasound [14]
Cutoff is typically β-hCG > 1,500–2,000 mIU/mL
Inability to visualize pregnancy on ultrasound above the β-hCG discriminatory level may suggest ectopic pregnancy. [5]
Multiple pregnancies may have higher β-hCG levels.
Serial β-hCG measurements (every 48 hours)
Better diagnostic accuracy than a single β-hCG level in differentiating intrauterine from ectopic pregnancies
Findings after 48 hours
The expected percentage increase in β-hCG for normal IUPs is determined based on the initial level. [1][5]
Initial level < 1500 mIU/mL: > 49% expected increase
Initial level 1500–3000 mIU/mL: > 40% expected increase
Initial level > 3000 mIU/mL: > 33% expected increase
Falling β-hCG levels may indicate a failed IUP (e.g., spontaneous abortion) or an ectopic pregnancy.
A drop of > 21% suggests failed IUP.
A drop of < 21% is more likely to indicate an ectopic pregnancy.
An insufficient decline in serial β-hCG measurements following induced abortion should raise suspicion for ectopic pregnancy
List additional studies.
CBC: Anemia may be seen in patients with vaginal bleeding.
Blood type and screen: ABO and Rh testing to identify patients who might need Rho immunization
LFT, BMP: to determine baseline liver and renal function
Describe the transvaginal ultrasound.
Can be performed as a formal ultrasound or POCUS.
Indication: best initial imaging test for determining the location of the pregnancy
Supportive findings
Empty uterine cavity in combination with a thickened endometrial lining
Possible free fluid within the pouch of Douglas (unspecific)
Additional findings in tubal pregnancy
Possible extraovarian adnexal mass
Tubal ring sign (blob sign): an echogenic ring that surrounds an unruptured ectopic pregnancy
Additional findings in interstitial pregnancy
Interstitial line sign: an echogenic line that extends from the gestational sac into the upper uterus (thought to be the echogenic appearance of the interstitial portion of the tube)
A thin myometrial layer (< 5 mm) surrounding the gestational sac
Ultrasound findings in normal pregnancy: In an intrauterine pregnancy at 5–6 weeks' gestation, a gestational sac and yolk sac are visible in the uterus.
If the gestational sac cannot be seen at all on ultrasound, the patient is diagnosed with pregnancy of unknown location.
Describe the transabdominal ultrasound.
Can be used to exclude differential diagnoses (e.g., acute appendicitis)
Provides a general picture of the pelvic anatomy and upper abdomen but is less sensitive than TVUS in detecting extrauterine pregnancy
POCUS can be performed using the transabdominal approach to rapidly rule in IUP if present.
Describe the exploratory laparoscopy.
Unstable patients suspected of having an ectopic pregnancy
In pregnancy of unknown location if the location is still uncertain after 7–10 days
Do not delay laparoscopy in unstable patients with suspected ectopic pregnancy!
Describe the endometrial biopsy.
Indication: Consider only in cases of pregnancy of unknown location where nonviability is certain.
Findings
Ectopic pregnancy: decidualization of the endometrium without chorionic villi or fetal parts
Intrauterine pregnancy loss
Chorionic villi are present
Fetal parts may be present
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