ABSTRACT
The main differential feature of the gastrointestinal (GI) tract in comparison with other organ systems is that its ultrasound (US) appearance varies significantly during pregnancy and also, for some sites, in the course of the same US examination, due to the physiology of swallowing, stomach emptying and intestinal peristalsis. It is therefore necessary to become acquainted with the whole range of anatomic correlates. It should be underlined that the detection of an intra-abdominal abnormality can become particularly challenging due to the variety of systems and organs that could be involved, including the GI tract, genitourinary system, adrenal glands, spleen, liver, pancreas, and lungs. Many of these abnormalities do not give a direct sono-graphic sign, but they may be suspected on the basis of the observation of indirect abnormal findings. Topography of the observed abnormality, fetal sex, and gestational age are significantly useful to determine their possible origin [1]. Another feature of the GI tract pathologies that renders their antenatal diagnosis a difficult task is the frequent absence of any sono-graphic evidence before the third trimester. Furthermore, some abnormalities may not give any sonographic sign during the whole pregnancy, such as an esophageal atresia (EA) with tracheal fistula; in this case, there is usually an almost normally fluid-filled stomach.
