There are many pathologic conditions that can affect the pregnant patient, some more concerning than others. Perhaps the most severe is ectopic pregnancy due to its associated morbidity and mortality if undiagnosed. Ultrasound is the standard imaging modality for the diagnosis of intrauterine pregnancy and evaluation of pregnancy-related complaints. A novice sonographer will need to understand how to accurately identify intrauterine pregnancy, determine gestation age and heart rate using specified measurements, and diagnose ectopic pregnancy. This chapter will focus on performing an obstetric ultrasound, basic pelvic anatomy, image acquisition using transvaginal and transabdominal techniques, and interpretation of pathology.
KeywordsIntrauterine pregnancy Biparietal diameter Crown-rump length Ectopic pregnancy Interstitial pregnancy Fetal demise Molar pregnancy
Transabdominal transverse gravid uterus. Using a transabdominal approach, the gravid uterus in visualized here in a transverse plane. The fetus, in this case, is lying in a more sagittal plane (MP4 2210 kb)
Transabdominal uterus in sagittal. Using a transabdominal approach, the gravid uterus is visualized here in a sagittal view. The fetal body is noted to be lying anterior to the placenta (MP4 1890 kb)
TVUS gravid uterus sagittal. Sagittal view of an anteverted uterus in long axis containing a gestational sac within the fundus using transvaginal ultrasound (MP4 2236 kb)
TVUS gravid uterus in transverse. Transverse view of a uterus in short axis containing a gestational sac with a yolk sac and developing fetus using transvaginal ultrasound. Note the fetal cardiac flicker (MP4 1981 kb)
Gestational sac with no yolk sac or fetal pole. Twin gestational pregnancy shown in the transabdominal approach with no obvious yolk sac or fetal pole. Upon further evaluation of this patient, a fetal pole was identified confirming intrauterine pregnancy using transvaginal ultrasound (MP4 3412 kb)
Double decidual sac. Double decidual sac is visualized as alternating hyperechoic rings separated by a thin hypoechoic layer of fluid surrounding a gestational sac (MP4 2245 kb)
Yolk sac. Confirmed intrauterine pregnancy within the fundus of the uterus. Not the double decidual sac containing a fetal pole attached to the yolk sac (MP4 3364 kb)
Fetal pole. Note the fetal pole with evidence of cardiac activity (MP4 3253 kb)
Small amount of free fluid in pouch of Douglas. Sagittal view of the uterus with a small early gestational sac vs. pseudogestational sac. Not the small amount of free fluid within the pouch of Douglas toward the end of the video clip (MP4 2278 kb)
Moderate to large amount free fluid in the pelvis. This transvaginal sagittal view shows an ectopic pregnancy posterior to the uterus, with a large amount of free fluid wrapping over the fundus of the uterus. There is also clotted blood, more echogenic, in the pouch of Douglas (MP4 2302 kb)
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Interstitial pregnancy. This is transvaginal view showing an interstitial pregnancy. Note the eccentrically located gestation sac with small amount of myometrium separating the sac from the external uterine wall (MP4 2417 kb)
Blighted ovum. An empty, irregular gestational sac greater than 2 cm representing a blighted ovum within the uterus in this sagittal transvaginal view (MP4 2168 kb)
Molar pregnancy. A molar pregnancy will often appear as tissue with variable echogenicity within which are scattered anechoic spaces, commonly referred to as a “cluster of grapes” (MP4 2342 kb)
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