Final answer:
Prenatally, the diagnosis of congenital diaphragmatic hernia is made through fetal ultrasound.
Step-by-step explanation:
The diagnosis of congenital diaphragmatic hernia can be made prenatally through fetal ultrasound. This imaging technique uses sound waves to create images of the developing fetus. It can help identify the abnormal herniation of abdominal organs into the chest cavity, which is characteristic of congenital diaphragmatic hernia. Other imaging studies such as amniocentesis and MRI may be used to assess other aspects of the fetus's health, but fetal ultrasound is the primary diagnostic tool for congenital diaphragmatic hernia.