1st Trimester Obstetrical Ultrasound

First trimester ultrasound is performed for

• pregnancy dating
• assessment of fetal viability
• identification of twins
• Nuchal Translucency (NT) screening for Down syndrome
• Integrated and Sequential screening
• ectopic pregnancy

How is the exam performed:
First trimester sonogram usually begins with a transabdominal sonogram performed with a full bladder. The distended bladder displaces small bowel loops out of the pelvis and allows visualization of the uterus and ovaries. If adequate visualization of the pregnancy is accomplished transabdominally and no ovarian abnormalities are noted, then the examination is considered complete. If a more detailed assessment of the pregnancy or of the uterus or the ovaries is indicated, then a transvaginal sonogram is performed following emptying of the bladder.