A first-time father is changing the diaper of his 1-day-old daughter. He asks the nurse, "What is this black, sticky stuff in her diaper?" The nurse's best response is:

Choice A) Newborns are abdominal breathers is incorrect because this is not a reason why the respiratory rate should be counted for a complete minute, but rather a characteristic of how newborns breathe. Abdominal breathing means that the diaphragm and the abdominal muscles are the main muscles used for breathing, rather than the chest muscles. Newborns are abdominal breathers because their chest wall is more compliant and less stable than adults, and their intercostal muscles are not fully developed. Abdominal breathing does not affect the accuracy or duration of measuring the respiratory rate, as long as the abdomen is visible and palpable. Therefore, this response is irrelevant and inaccurate.

Choice B) Activity will increase the respiratory rate is incorrect because this is not a reason why the respiratory rate should be counted for a complete minute, but rather a factor that can influence the respiratory rate. Activity means any physical or mental exertion that requires more oxygen and energy from the body. Activity can increase the respiratory rate, as well as the heart rate and blood pressure, to meet the increased oxygen demand and carbon dioxide removal. However, activity does not affect the accuracy or duration of measuring the respiratory rate, as long as the newborn is calm and resting during the measurement. Therefore, this response is irrelevant and inaccurate.

Choice C) The rate and rhythm of breath are irregular in newborns is correct because this is a reason why the respiratory rate should be counted for a complete minute. The rate and rhythm of breath refer to how fast and how regularly one breathes. Newborns have an irregular rate and rhythm of breath, which means that they breathe at different speeds and intervals, sometimes pausing for a few seconds between breaths. This is normal and harmless for newborns, as long as they do not stop breathing for more than 20 seconds or show signs of distress. However, it can make it difficult to measure the respiratory rate accurately, as counting for a shorter period may not reflect the true average rate. Therefore, counting for a complete minute can ensure a more reliable measurement. Therefore, this response is clear and accurate.

Choice D) Newborns do not expand their lungs fully with each respiration is incorrect because this is not a reason why the respiratory rate should be counted for a complete minute, but rather a feature of how newborns breathe.

Lung expansion means how much air one inhales and exhales with each breath. Newborns do not expand their lungs fully with each respiration, because they have smaller lung volumes and capacities than adults, and they breathe more shallowly and rapidly. However, lung expansion does not affect the accuracy or duration of measuring the respiratory rate, as long as the chest or abdomen movement is visible and palpable. Therefore, this response is irrelevant and inaccurate.

Choice A) Missed abortion: This is not the correct obstetric complication for methotrexate treatment. A missed abortion is a type of miscarriage in which the fetus has died but the products of conception are still retained in the uterus. Methotrexate is not used for this condition, as it can cause toxicity and bleeding. The usual treatment options for a missed abortion are expectant management, medical induction, or surgical evacuation.

Choice B) Abruptio placentae: This is not the correct obstetric complication for methotrexate treatment. Abruptio placentae is a condition in which the placenta separates from the uterine wall before delivery, causing bleeding and fetal distress. Methotrexate is not used for this condition, as it can worsen the bleeding and harm the fetus. The usual treatment options for abruptio placentae depend on the severity of the condition and the gestational age, but they may include fluid resuscitation, blood transfusion, tocolysis, or emergency delivery.

Choice C) Unruptured ectopic pregnancy: This is the correct obstetric complication for methotrexate treatment. An ectopic pregnancy is a pregnancy that implants outside of the uterine cavity, usually in the fallopian tube. An unruptured ectopic pregnancy is one that has not caused any bleeding or rupture of the tube. Methotrexate is used for this condition, as it can dissolve the pregnancy tissue and prevent further growth and complications.

Methotrexate is given as an injection and works by inhibiting folic acid metabolism, which is essential for cell division.

Methotrexate is only suitable for patients who have stable vital signs, low levels of human chorionic gonadotropin (hCG), and no fetal heartbeat or cardiac activity detected by ultrasound.

Choice D) Complete hydatidiform mole: This is not the correct obstetric complication for methotrexate treatment. A complete hydatidiform mole is a type of gestational trophoblastic disease in which there is an abnormal proliferation of placental tissue without any fetal development. Methotrexate is not used for this condition, as it can cause resistance and recurrence. The usual treatment option for a complete hydatidiform mole is suction curettage, which removes the molar tissue from the uterus.