RIU 435 Lecture Notes - Lecture 11: Ductus Venosus, Umbilical Vein, Abdominal Cavity
11 Dec 2020
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Document Summary
Fetal abdominal organs well formed by second trimester. Stomach, liver, vascular structures, cord insertion, small bowel, and colon should be clearly identi ed by sonographer. Umbilical arteries and vein provide important anatomic landmarks for fetal abdominal anatomy and measurements. Ductus venosus is patent; serves as conduit between portal veins and systemic veins. Proportions of fetal body differ from adult: Fetal abdomen larger relative to body length. Liver occupies larger volume of fetal abdomen. Urinary bladder, ovaries, uterus lie in abdominal cavity. Therefore, fetal ascites may separate omental leaves. Usually by the 10th or 11th week, midgut herniation returns to abdomen. Undergoes further rotation resulting from decrease in size of liver and kidneys and growth of abdominal cavity. After intestines return to abdominal cavity, they enlarge, lengthen, and assume nal positions. Defects that occur when midgut fails to return to abdominal cavity from umbilical cord during 10th week.
