Which of the following is a bacterial infection that spreads through any form of unprotected sex and by skin contact? Typically, it has stages of increasingly serious symptoms. If untreated, it may affect the heart, eyes, and brain. It can be treated with antibiotics.

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: CD4 counts are not used to detect HIV, but to monitor the progression of the infection and the immune system status. CD4 cells are a type of white blood cell that HIV targets and destroys. A normal CD4 count ranges from 500 to 1,500 cells per microliter of blood. A low CD4 count indicates a high risk of opportunistic infections and AIDS.

Choice B reason: Virus is a vague term that does not specify what kind of virus is being detected. HIV is a type of virus that belongs to the retrovirus family. It is difficult to detect the virus itself, as it hides inside the host cells and has a low concentration in the blood. Therefore, most laboratory tests focus on the antibodies that the body produces in response to the virus.

Choice C reason: HIV antibodies are the most common way to detect HIV, as they are produced by the immune system to fight the virus. Antibodies are proteins that bind to specific antigens (foreign substances) and mark them for destruction. HIV antibodies can be detected by a blood test, a saliva test, or a rapid test. However, antibodies may take several weeks to develop after exposure, so a negative test does not rule out the possibility of infection.

Choice D reason: CD8 counts are not used to detect HIV, but to monitor the immune system response and the viral load. CD8 cells are a type of white blood cell that kill infected cells and secrete antiviral substances. A high CD8 count indicates a strong immune response and a low viral load. A low CD8 count indicates a weak immune response and a high viral load.