Final answer:
The necessary nursing intervention before a second-trimester transabdominal ultrasound is to instruct the woman to drink 1 to 2 quarts of water.
Step-by-step explanation:
Before a second-trimester transabdominal ultrasound, the necessary nursing intervention is to instruct the woman to drink 1 to 2 quarts of water. This is done to ensure that the bladder is full before the ultrasound procedure. A full bladder helps to provide better visualization of the fetus and the surrounding structures during the ultrasound.