A nurse is teaching a newly licensed nurse about the uses of ultrasonography in the first trimester of pregnancy. Which of the following statements by the newly licensed nurse indicates an understanding of the teaching?

Ultrasonography is a diagnostic imaging technique that uses high-frequency sound waves to create images of the internal structures of the body. It is a safe and noninvasive method that can provide valuable information about the pregnancy, such as the number, size, location, and health of the fetus(es), the placenta, the amniotic fluid, and the uterus.
Ultrasonography can be performed at any time during pregnancy, but it is especially useful in the first trimester (the first 12 weeks of pregnancy) for several reasons, such as:
 
-    To confirm the pregnancy and rule out ectopic pregnancy (a pregnancy that occurs outside the uterus) or molar pregnancy (a pregnancy that develops into an abnormal mass of tissue)
-    To determine gestational age (the length of time since the first day of the last menstrual period) and estimate due date (the expected date of delivery)
-    To screen for chromosomal abnormalities (such as Down syndrome) or structural defects (such as spina bifida) in the fetus
-    To identify multiple gestations (such as twins or triplets) or complications (such as miscarriage or
bleeding)
One of the main uses of ultrasonography in the first trimester is to determine gestational age. This is important because it can affect many aspects of prenatal care and delivery, such as:
-    The timing and accuracy of other tests and procedures
-    The monitoring and evaluation of fetal growth and development
-    The identification and management of potential problems or complications
-    The planning and preparation for labor and delivery
Gestational age can be determined by measuring the crown-rump length (CRL) of the fetus, which is the distance from the top of the head to the bottom of the spine. The CRL can be measured by using a transvaginal ultrasound (an ultrasound probe that is inserted into the vagina) or a transabdominal ultrasound (an ultrasound probe that is moved over the abdomen). The CRL can be compared to a standard growth chart to estimate gestational age. The CRL measurement is most accurate between 7 and 13 weeks of pregnancy .
Therefore, the newly licensed nurse who says that ultrasound is used to determine gestational age in the first trimester indicates an understanding of the teaching.

The other statements show a lack of knowledge or misunderstanding of the uses of ultrasonography in the first trimester:
-    a) "Ultrasound is used to observe for placental maturity in the first trimester." This is not correct because placental maturity is not assessed in the first trimester. Placental maturity refers to the changes that occur in the placenta as it ages and prepares for delivery. Placental maturity can be evaluated by using a grading system that ranges from 0 to 3, based on the appearance of calcifications (deposits of calcium) in the placenta. Placental maturity can be assessed by using a transabdominal ultrasound in the third trimester (after 28 weeks of pregnancy).
-    b) "Ultrasound is used to detect intrauterine growth restriction in the first trimester." This is not correct because intrauterine growth restriction (IUGR) is not detected in the first trimester. IUGR is a condition in which the fetus does not grow as expected and has a low birth weight for its gestational age. IUGR can be caused by various factors, such as placental insufficiency, maternal malnutrition, infection, or chronic disease. IUGR can affect fetal development and increase the risk of complications, such as hypoxia, hypoglycemia, or stillbirth. IUGR can be diagnosed by measuring fetal growth parameters, such as abdominal circumference, head circumference, femur length, and estimated fetal weight. These measurements can be obtained by using a transabdominal ultrasound in the second or third trimester (after 20 weeks of pregnancy).
 
-    d) "Ultrasound is used to perform a biophysical profile in the first trimester." This is not correct because a biophysical profile (BPP) is not performed in the first trimester. A BPP is a test that evaluates fetal well-being by assessing five parameters: fetal movement, fetal tone, fetal breathing, amniotic fluid volume, and fetal heart rate. A BPP can help detect fetal distress or hypoxia and guide management decisions. A BPP can be performed by using a combination of transabdominal ultrasound and nonstress test (NST) in the third trimester (after 32 weeks of pregnancy).