Before 25 weeks the normal value of fetal rectal tube width is less than 7mm, after 37 weeks the normal value of fetal rectal width is less than 18mm, 18mm~20mm or more is considered abnormal. Generally do the examination before 25 weeks of pregnancy, go to know the width of the fetal rectum, the normal value is not more than 7mm, has been developed until the late pregnancy gestation, the normal value of the fetal rectum width after 37 weeks of fetal rectum width is within 15mm, generally not more than 18mm. Fetal ultrasound examination of the bowel slightly widening is not much effect, persistent widening or enlargement is considered abnormal, fetal rectal width 18~20cm and above is considered abnormal, greater than 30mm indicates that the fetus has the possibility of intestinal malformation. Mild dilatation of fetal intestine may be temporary dilatation caused by accumulation of fetal feces and amniotic fluid, persistent dilatation of more than 30mm is considered fetal intestinal malformation, such as intestinal obstruction, which requires further examination and diagnosis. Do a good maternity checkup after pregnancy and deal with any abnormality promptly.