Preheat the oven to 350 degrees F (175 degrees C). Grease an 8x8-inch baking dish.

Beat egg in a mixing bowl. Whisk in onion, pickle juice, salt, and pepper. Stir in bread until soggy, then mix in ground beef until evenly combined. Form into a loaf and place into the prepared pan.

Stir together chopped pickles, ketchup, water, sugar, and Worcestershire sauce; pour over the meatloaf.

Bake in the preheated oven until no longer pink in the center, about 1 hour. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C).