Assessment of any free intraperitoneal fluid is important in the evaluation for an ectopic pregnancy. In this setting, echoes within the free fluid are often due to blood. Trace anechoic free fluid in the pelvis is generally normal. The presence of more than a normal small amount of free fluid or echoes within the fluid, even without identification of an extraovarian mass, is concerning for an ectopic pregnancy [42-44]. However, this finding is not specific and can also occur for other reasons, such as rupture of a hemorrhagic ovarian cyst with an early, nonvisualized IUP. A minority of ectopic pregnancies occur in locations other than the fallopian tube. The most common nontubal locations are interstitial, cervical, and within a Cesarean section scar. Three-dimensional US may be useful if an interstitial pregnancy is suspected but the diagnosis is uncertain based on 2-D US [45]. Rudimentary horn and abdominal pregnancies are less common, and ovarian ectopic pregnancy is rare. Coexisting intrauterine and extrauterine pregnancy (sometimes referred to as a heterotopic pregnancy) is rare, though is more likely to occur in women undergoing assisted reproduction techniques [46]. In general, for a woman with a spontaneously occurring pregnancy, identification of an IUP excludes a coexisting ectopic pregnancy with near complete certainty. However, the adnexa should still be routinely evaluated. Other causes of PUL include an early IUP (<4.5-5 weeks) or a nonvisualized ectopic pregnancy. A small minority of patients with PUL (probably about 7%-20% but likely more toward the lower end of that range), will later be diagnosed with an ectopic pregnancy [48]. Patients with a PUL can pose a diagnostic challenge. If the patient is hemodynamically stable, follow-up hCG and/or US should generally be performed before surgical or medical therapy is undertaken, regardless of the initial hCG level [15,16].
First Trimester Vaginal Bleeding. Assessment of any free intraperitoneal fluid is important in the evaluation for an ectopic pregnancy. In this setting, echoes within the free fluid are often due to blood. Trace anechoic free fluid in the pelvis is generally normal. The presence of more than a normal small amount of free fluid or echoes within the fluid, even without identification of an extraovarian mass, is concerning for an ectopic pregnancy [42-44]. However, this finding is not specific and can also occur for other reasons, such as rupture of a hemorrhagic ovarian cyst with an early, nonvisualized IUP. A minority of ectopic pregnancies occur in locations other than the fallopian tube. The most common nontubal locations are interstitial, cervical, and within a Cesarean section scar. Three-dimensional US may be useful if an interstitial pregnancy is suspected but the diagnosis is uncertain based on 2-D US [45]. Rudimentary horn and abdominal pregnancies are less common, and ovarian ectopic pregnancy is rare. Coexisting intrauterine and extrauterine pregnancy (sometimes referred to as a heterotopic pregnancy) is rare, though is more likely to occur in women undergoing assisted reproduction techniques [46]. In general, for a woman with a spontaneously occurring pregnancy, identification of an IUP excludes a coexisting ectopic pregnancy with near complete certainty. However, the adnexa should still be routinely evaluated. Other causes of PUL include an early IUP (<4.5-5 weeks) or a nonvisualized ectopic pregnancy. A small minority of patients with PUL (probably about 7%-20% but likely more toward the lower end of that range), will later be diagnosed with an ectopic pregnancy [48]. Patients with a PUL can pose a diagnostic challenge. If the patient is hemodynamically stable, follow-up hCG and/or US should generally be performed before surgical or medical therapy is undertaken, regardless of the initial hCG level [15,16].