In late pregnancy, the fetus has basically developed and is less likely to have malformations, but some fetuses may have digestive system malformations due to pollution, drugs and external stimuli. Therefore, pregnant women should strictly follow the doctor’s instructions for maternity checkups to understand the development of the fetus. In the ultrasound examination, if the fetus shows the following symptoms, it is necessary to consider the possibility that the fetus has digestive system malformation: 1. increased amniotic fluid: due to abnormal development of the digestive system, the fetus is unable to swallow amniotic fluid, resulting in high amniotic fluid volume; 2. duodenal double bubble sign: if there is duodenal atresia, due to the expansion of the gastric vesicles as well as the duodenal stump, the duodenal double bubble sign can appear; 3. digestive tract bulge: it can be seen that the abdominal wall defect as well as the presence of visceral floaters in the amniotic fluid. If a patient has one or more of these conditions, a 4D ultrasound should be performed immediately to confirm the diagnosis and, if necessary, prenatal diagnosis. If the symptoms of malformation are not serious, treatment can wait until after delivery; if the symptoms are more serious, the pregnancy should be terminated at the right time under the guidance of the doctor and early treatment, such as laparoscopic surgery, should be done according to the condition of fetal malformation.