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The Speed of Sound

The Speed of Sound

Symptom: Vaginal Bleeding in Early Pregnancy

Butts, Christine MD

Author Information
doi: 10.1097/01.EEM.0000544437.37322.6b
    pregnancy, vaginal bleeding
    pregnancy, vaginal bleeding:
    Image 1. A transvaginal ultrasound demonstrated a fetal pole within a small gestational sac. Watch of a video of this at http://bit.ly/VideosSound.
    Figure
    Figure

    A 38-year-old woman presented to the emergency department with vaginal bleeding and cramping. She reported that she had taken several home pregnancy tests, which were positive. A urine pregnancy test at triage was also positive. Her last normal period was approximately two months earlier. She had three prior pregnancies and births with no complications and no other medical problems.

    Her exam was unremarkable except for her pelvic exam, which demonstrated a moderate amount of dark blood in the vagina with no active bleeding from the cervical os. The os was closed, and no cervical motion tenderness, uterine tenderness, or adnexal mass or tenderness was found. The patient's workup was significant for a β-Hcg of 1,008 mIU/mL. Hemoglobin and hematocrit were within normal limits. A transvaginal ultrasound was performed at the bedside. What is concerning about this image?

    Find the diagnosis and case discussion on p. 22.

    Diagnosis: Spontaneous Abortion

    Vaginal bleeding in the first trimester of pregnancy is a common presenting complaint in the emergency department. The first task in these patients is to rule out an ectopic pregnancy. Bedside ultrasound is typically sufficient to achieve this goal because identifying an intrauterine pregnancy virtually rules out an ectopic pregnancy in patients who are not receiving follicle-stimulating medications. (J Clin Ultrasound 2002;30[3]:161.) Intrauterine pregnancy is defined as the presence of a yolk sac or fetal pole (plus or minus a heartbeat) within the endometrium of the uterus.

    In this case, an intrauterine pregnancy was identified: A fetal pole with a heartbeat was seen within the uterus. (Image 1; video available at http://bit.ly/VideosSound.) Some signs point to the fact that this pregnancy is not proceeding normally. A number of findings are conclusive of pregnancy failure when evaluating a first trimester pregnancy with ultrasound. (N Engl J Med 2013;369[15]:1443.) These include the absence of a fetal heartbeat in comparison with the crown rump length and the overall gestational sac size. Several other factors suggest (if not confirm) pregnancy failure, including lack of progression of the gestational sac or yolk sac and structural abnormalities, such as an abnormal-appearing yolk sac.

    The mean sac diameter (MSD) of the gestational sac is determined by measuring the sac in three planes (transverse, longitudinal, and coronal), and can be calculated by most ultrasound machines. The MSD should enlarge as the pregnancy progresses. A difference of less than 5 mm between the MSD and the crown rump length is an ominous sign that pregnancy failure is likely. The gestational sac in this patient looked small compared with the fetal pole. This finding, even with the presence of a fetal heartbeat, is concerning. A normal-sized gestational sac relative to the fetal pole is shown in Image 2. (Video available at http://bit.ly/VideosSound.)

    Figure
    Figure:
    Image 2. Transvaginal ultrasound demonstrating a fetal pole within a normal gestational sac. Watch of a video of this at http://bit.ly/VideosSound.

    This patient was discharged with precautions and follow-up. Unfortunately, she returned two days later with increased bleeding. A repeat ultrasound at that time demonstrated loss of fetal heart tones, and the patient underwent an uncomplicated spontaneous abortion.

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