Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) abdominal wall defect ?
    ### Response:
    An abdominal wall defect is an opening in the abdomen through which various abdominal organs can protrude. This opening varies in size and can usually be diagnosed early in fetal development, typically between the tenth and fourteenth weeks of pregnancy. There are two main types of abdominal wall defects: omphalocele and gastroschisis.
    