BACKGROUND:

In obstetrics, ultrasonic artifactual mirror images are infrequent, but potentially dangerous since they can be mistakenly interpreted as heterotopic pregnancies, precluding diagnostic errors and iatrogenic interventions. These images require a reflection surface such as dilated bowl or plenty bladder to be generated.

OBJECTIVE:

We report a first trimester scan ghost twin, diagnosed since first trimester of pregnancy.

CLINICAL CASE:

39-year-old patient, with pregnancy due to in vitro fertilization, who attends ultrasound evaluation of the first trimester. Routine ultrasound at 11 weeks showed a mirror image and magnetic resonance imaging: a pregnant uterus with a hypoechoic retrouterine structure, with no fetus inside. The ultrasound mirror image reproduced again in the third trimester. The pregnancy came to an end and ended by abdominal route, without being able to demonstrate the structures that were noticed on the MRI.

CONCLUSION:

Very few reports of obstetric ultrasound mirror images have been reported. We hypothesize that the transient retrouterine hypoecogenic structure observed by MRI was the reflective surface that create the ghost twin image.