The Cornual Ectopic Pregnancy Ultrasound Guide
The Cornual Ectopic Pregnancy Ultrasound Guide A cornual ectopic pregnancy is a rare but potentially life-threatening condition where the fertilized egg implants in the interstitial part of the fallopian tube, located within the muscular wall of the uterus. Early and accurate diagnosis is critical to prevent serious complications such as rupture and hemorrhage. Ultrasound imaging remains the primary modality for diagnosing cornual ectopic pregnancies, and understanding the ultrasound features is essential for healthcare providers.
On ultrasound, one of the key features suggesting a cornual ectopic pregnancy is a gestational sac located high in the uterine fundus, separate from the endometrial cavity. The sac may be seen embedded within the myometrium, surrounded by a thin layer of myometrial tissue. In early cases, the gestational sac may appear as a small anechoic (dark) area with an echogenic (bright) ring, representing the trophoblastic tissue.
A hallmark ultrasound finding is the “interstitial line sign,” which appears as an echogenic line extending from the endometrial canal to the gestational sac. This sign indicates the tunnel through which the pregnancy has implanted, within the interstitial segment of the fallopian tube. Recognizing this feature is crucial because it helps distinguish a cornual pregnancy from other types of ectopic pregnancies or early intrauterine pregnancies.
Another important aspect is the myometrial mantle— the thickness of myometrial tissue surrounding the sac. In cornual pregnancies, this mantle is typically less than 5 mm, suggesting that the pregnancy is expanding within the muscular wall but not yet ruptured. Absence of an intrauterine pregnancy combined with an eccentrically located gestational sac near the uterine corner should raise suspicion.
Color Doppler ultrasound can contribute additional information by showing increased vascularity around the gestational sac, which is typical in ectopic pregnancies due to trophoblastic invasion. However, Doppler findings
alone are not definitive and should be interpreted in the context of other ultrasound features.
Differentiating a cornual ectopic pregnancy from a normal intrauterine pregnancy or a later-stage interstitial pregnancy is vital. For example, a normal intrauterine pregnancy will be centrally located within the endometrial cavity, and the gestational sac will be surrounded by a thick myometrial layer. Conversely, in interstitial pregnancies, the sac is more eccentrically located with a thin myometrial mantle and often a visible interstitial line.
Ultrasound assessments are complemented by clinical findings such as abdominal pain, vaginal bleeding, and elevated human chorionic gonadotropin (hCG) levels. If the ultrasound findings are inconclusive or suspicion remains high, serial hCG measurements and advanced imaging like MRI can be employed to confirm the diagnosis.
In summary, the ultrasound diagnosis of a cornual ectopic pregnancy relies on identifying a gestational sac located high and eccentrically in the uterus, surrounded by a thin myometrial layer, with the interstitial line sign often serving as a key marker. Early detection through these imaging features can guide appropriate management, which may range from conservative medical treatment with methotrexate to surgical intervention, thereby preserving future fertility and preventing life-threatening complications.
