When evaluating a patient for sexually transmitted infections (STIs), the nurse should be aware that the most common bacterial STI is:

Choice A reason: Infection is not the greatest risk for a woman with marginal placenta previa, as it is not directly related to the condition. Marginal placenta previa is a type of placenta previa where the edge of the placenta is near the cervical os but does not cover it. It can cause painless bleeding during pregnancy or labor, but it does not increase the risk of infection.

Choice B reason: Hemorrhage is the greatest risk for a woman with marginal placenta previa, as it can occur due to the separation of the placenta from the uterine wall during labor or delivery. The bleeding can be profuse and life-threatening, and it requires prompt intervention and monitoring.

Choice C reason: Urinary retention is not the greatest risk for a woman with marginal placenta previa, as it is not directly related to the condition. Urinary retention is the inability to empty the bladder completely, and it can occur due to various factors such as anesthesia, trauma, or medication. It can cause discomfort, infection, or bladder distension, but it is not as serious as hemorrhage.

Choice D reason: Thrombophlebitis is not the greatest risk for a woman with marginal placenta previa, as it is not directly related to the condition. Thrombophlebitis is the inflammation of a vein due to a blood clot, and it can occur due to prolonged bed rest, dehydration, or injury. It can cause pain, swelling, or redness in the affected area, and it can lead to pulmonary embolism if the clot dislodges and travels to the lungs. However, it is not as common or as severe as hemorrhage.

Choice A reason: The NST has no known contraindications, as it is a non-invasive and safe test that does not stimulate uterine contractions or cause fetal distress. It is the most widely used method of antepartum fetal surveillance.

Choice B reason: The NST is not slightly more expensive than the CST, as it requires less time and equipment. The NST usually takes 20 to 40 minutes, while the CST may take up to 2 hours. The NST only needs a fetal monitor, while the CST also needs an intravenous line and oxytocin infusion.

Choice C reason: The NST does not have fewer false-positive results than the CST, as it has a higher rate of nonreactive results that may indicate fetal compromise when there is none. A nonreactive NST is one that does not show at least two accelerations of the fetal heart rate of 15 beats per minute or more lasting 15 seconds or more in a 20-minute period.

Choice D reason: The NST is not more sensitive in detecting fetal compromise than the CST, as it has a lower predictive value for fetal well-being. A reactive NST is one that shows at least two accelerations of the fetal heart rate of 15 beats per minute or more lasting 15 seconds or more in a 20-minute period. However, a reactive NST does not rule out the possibility of fetal hypoxia or acidosis.