A nurse is caring for a client who is 6 hr postpartum. The client is Rh-negative and her newborn is Rh-positive. The client asks why an indirect Coombs test was ordered by the provider. Which of the following is an appropriate response by the nurse?

Choice A reason: Physiological jaundice is not the correct answer, as it is a normal and benign condition that occurs in about 60% of term newborns, and usually appears after the first 24 hours of life. Physiological jaundice is caused by the breakdown of fetal hemoglobin and the immature liver function, and resolves within a few days.

Choice B reason: Maternal cocaine abuse is not the correct answer, as it is a maternal risk factor that can cause various complications in the newborn, such as low birth weight, prematurity, intrauterine growth restriction, or congenital anomalies. Maternal cocaine abuse does not cause jaundice in the newborn, unless it leads to hepatic or renal dysfunction.

Choice C reason: Maternal/newborn blood group incompatibility is the correct answer, as it is a maternal-fetal condition that can cause hemolytic disease of the newborn, which is a severe form of jaundice that can appear within the first 24 hours of life. Maternal/newborn blood group incompatibility occurs when the mother's blood type is Rh negative and the newborn's blood type is Rh positive, or when the mother's blood type is O and the newborn's blood type is A or B. The maternal antibodies cross the placenta and attack the newborn's red blood cells, causing hemolysis, anemia, and hyperbilirubinemia.

Choice D reason: Absence of vitamin K is not the correct answer, as it is a nutritional deficiency that can cause hemorrhagic disease of the newborn, which is a bleeding disorder that can occur within the first week of life. Absence of vitamin K is due to the lack of intestinal flora and the low vitamin K content in breast milk, and can cause bleeding in the skin, mucous membranes, or internal organs. Absence of vitamin K does not cause jaundice in the newborn, unless it leads to hepatic or biliary dysfunction.

Choice A reason: Orthostatic hypotension is a normal finding in the postpartum period, because the client has a sudden decrease in blood volume after delivery. The nurse should instruct the client to change positions slowly and drink plenty of fluids.

Choice B reason: Urine output of 3,000 mL in 12 hr is a normal finding in the postpartum period, because the client has increased renal perfusion and diuresis after delivery. The nurse should encourage the client to empty the bladder frequently and monitor the intake and output.

Choice C reason: Heart rate 160/min is an abnormal finding in the postpartum period, because it indicates tachycardia, which can be a sign of infection, dehydration, hemorrhage, or cardiac complications. The nurse should assess the client's temperature, blood pressure, pulse, respirations, skin color, lochia, and pain level, and report any abnormal findings to the provider.

Choice D reason: Fundus palpable at the umbilicus is a normal finding in the postpartum period, because the uterus gradually involutes and descends into the pelvis after delivery. The nurse should palpate the fundus and check for firmness, position, and height. The fundus should be at the level of the umbilicus immediately after delivery, and descend about one fingerbreadth per day.