Which of the following is transmitted through direct contact with the blood or body fluid of someone who is infected (usually through unprotected sex, sharing needles, or passed from a mother to a baby at birth)? Symptoms may take 10 years or more to show. Once they appear, the person is susceptible to life-threatening infections.

Choice A reason: This is not an appropriate response by the nurse, as an ultrasound is not a screening tool for spina bifida. Spina bifida is a birth defect that occurs when the spine and spinal cord do not form properly. It can be detected by a blood test that measures the level of alpha-fetoprotein (AFP) or by a detailed ultrasound that shows the spine and the brain.

Choice B reason: This is not an appropriate response by the nurse, as an ultrasound is not necessary to determine if there is more than one fetus. Multiple fetuses can be detected by other methods, such as listening to the fetal heartbeats, measuring the fundal height, or feeling the fetal movements.

Choice C reason: This is an appropriate response by the nurse, as an ultrasound assists in identifying the location of the placenta and fetus. This is important for an amniocentesis, which is a procedure that involves inserting a needle through the abdomen and the uterus to collect a sample of amniotic fluid. The ultrasound helps to guide the needle and avoid injuring the placenta or the fetus.

Choice D reason: This is not an appropriate response by the nurse, as an ultrasound is not useful for estimating fetal age at 36 weeks of gestation. Fetal age can be estimated by an ultrasound in the first trimester, when the fetus is growing at a predictable rate and has distinct features. However, in the third trimester, the fetus grows at different rates and has more variations in size and shape. Therefore, an ultrasound is less accurate and reliable for estimating fetal age at this stage.

Choice A reason: Infection is not a common cause of IUGR, as most infections do not cross the placenta and affect the fetal growth. However, some infections such as cytomegalovirus, rubella, or toxoplasmosis can cause congenital anomalies and IUGR.

Choice B reason: Previous preterm birth is not a direct cause of IUGR, as it does not affect the current pregnancy. However, it may indicate an underlying maternal or fetal condition that could increase the risk of IUGR, such as cervical incompetence, placental abruption, or preeclampsia.

Choice C reason: Utero-placental insufficiency is the most common cause of IUGR, as it reduces the blood flow and oxygen delivery to the fetus. It can result from maternal factors such as hypertension, diabetes, smoking, or drug abuse, or from placental factors such as placenta previa, placental infarction, or cord compression.

Choice D reason: Chronic hypertension is a risk factor for IUGR, as it can lead to utero-placental insufficiency and fetal hypoxia. However, it is not the only cause of IUGR, as other factors can also affect the placental function and fetal growth.