A person undergoing a routine mammogram is an example of what type of prevention?

Rationale:

A. Also called cordocentesis, this is an invasive diagnostic test used to detect fetal blood disorders or infections. It is not typically used for routine Down syndrome screening because it carries higher risks and is done later in pregnancy.

B. Alpha-fetoprotein (AFP) analysis is part of the maternal serum screening (quad or triple screen) performed during the second trimester. Abnormal levels of AFP, along with other markers such as human chorionic gonadotropin (hCG) and unconjugated estriol, can indicate an increased risk for Down syndrome, neural tube defects, or other fetal abnormalities. AFP screening is noninvasive and widely used for early detection of chromosomal anomalies.

C. Amniocentesis is a diagnostic test, not a screening test. It involves sampling amniotic fluid to detect chromosomal abnormalities, genetic disorders, or infections. While highly accurate for Down syndrome, it is invasive and carries a small risk of miscarriage, so it is typically offered after an abnormal screening test or for high-risk pregnancies.

D. Chorionic villus sampling (CVS) is also a diagnostic procedure, performed in the first trimester by sampling placental tissue. Like amniocentesis, it confirms genetic conditions such as Down syndrome but is not a routine screening test.

Rationale:

A. HIV is present in very low concentrations in saliva, and normal, closed-mouth kissing does not transmit the virus. Transmission is only theoretically possible if both partners have open sores or bleeding gums, allowing blood-to-blood contact, but this is extremely rare. Therefore, casual kissing is considered a very low-risk activity.

B. The primary route of HIV transmission worldwide is sexual contact. HIV is present in semen, vaginal fluids, and rectal secretions, and can enter the body through mucous membranes, microtears, or abrasions in the genital, anal, or oral areas. Unprotected sexual intercourse (without condoms or pre-exposure prophylaxis) carries a high risk of transmission. Factors that increase risk include multiple sexual partners, presence of other sexually transmitted infections, and high viral load in the infected partner.

C. HIV is not transmitted through intact skin, so casual contact such as shaking hands, hugging, or touching surfaces does not pose any risk. The virus is fragile outside the human body and cannot survive long on environmental surfaces, making casual contact safe.

D. HIV is not transmitted through saliva in sufficient quantities to infect another person. Sharing food or utensils does not provide the virus with access to the bloodstream or mucous membranes in a way that would allow infection, so this is considered safe.