Can an ectopic pregnancy occur with a gestational sac in the uterus and no visible viable intrauterine pregnancy (IUP)?

From the Guidelines

Ectopic Pregnancy with Gestational Sac in Uterus

Yes, it is possible to have an ectopic pregnancy even if a gestational sac is identified in the uterus on ultrasound but no viable pregnancy is seen, as the presence of a gestational sac does not necessarily confirm a viable intrauterine pregnancy (IUP) 1.

Key Considerations

• A pseudogestational sac can be mistaken for a gestational sac, but it usually has a different shape, contents, or location 1.
• The discriminatory level of hCG, which is the level at which a gestational sac should always be seen on transvaginal US in a normal singleton IUP, has been suggested to be around 3,000 mIU/mL or higher 1.
• If there is no transvaginal US evidence of a gestational sac when a single serum hCG is 3,000 mIU/mL or higher, it is unlikely there will be a viable IUP 1.
• In cases where an IUP is not identified, extrauterine locations for the pregnancy should be carefully evaluated, including the ovaries, corpus luteum, and any extraovarian mass 1.

Management Approach

• A follow-up ultrasound should be performed to confirm the presence of a viable intrauterine pregnancy.
• If the ultrasound findings are still inconclusive, serum beta-hCG levels can be monitored, and a repeat ultrasound can be done in 48 hours.
• The patient should be advised to seek immediate medical attention if she experiences any symptoms such as abdominal pain, vaginal bleeding, or dizziness.
• Methotrexate should not be administered until an ectopic pregnancy is definitively ruled out or confirmed, as it can cause harm to a viable intrauterine pregnancy.
• Close monitoring and a multidisciplinary approach are crucial in managing such cases to ensure the best possible outcome for the patient.

Important Findings

• The absence of a yolk sac in a gestational sac > 8 mm MSD or the absence of an embryo in a gestational sac > 16 mm MSD is worrisome for a nonviable IUP, but these cutoffs are not sufficient to make a definitive diagnosis of a nonviable IUP 1.
• The most important feature to assess in an extrauterine mass is whether it is inside the ovary or outside the ovary, as this can help distinguish between a corpus luteum and a tubal pregnancy 1.

From the Research

Ectopic Pregnancy with Gestational Sac in the Uterus

• An ectopic pregnancy can occur even if a gestational sac is visible in the uterus, but no viable intrauterine pregnancy (IUP) is present 2.
• This situation is often referred to as a pseudogestational sac, which can delay the diagnosis of an ectopic pregnancy 2.
• A pseudogestational sac is a fluid collection within the uterine cavity that can be mistaken for a true gestational sac, but it does not contain an embryo 2.

Diagnosis of Ectopic Pregnancy

• The diagnosis of an ectopic pregnancy can be made using a combination of clinical presentation, laboratory tests, and imaging studies 3, 4, 5.
• Transvaginal ultrasonography can be used to visualize the adnexa and detect an ectopic pregnancy, but it may not always be possible to see the ectopic pregnancy, especially in early gestations 3, 6.
• Serial beta human chorionic gonadotropin (β-hCG) levels and trends can be used to help diagnose an ectopic pregnancy, but β-hCG levels can be variable and may not always be reliable 3, 4, 5.

Risk Factors and Presentation

• Ectopic pregnancy can occur in any woman of reproductive age, but certain risk factors increase the likelihood of an ectopic pregnancy, such as a history of pelvic inflammatory disease, previous ectopic pregnancy, and infertility 3, 4.
• The presentation of an ectopic pregnancy can be variable, but common symptoms include vaginal bleeding, lower abdominal pain, and pelvic tenderness 3, 6, 5.
• Emergency physicians should be aware of the subtleties of radiographic identification of intrauterine pregnancies and the need for clinical correlation to diagnose an ectopic pregnancy 2, 5.