Diagnostic ultrasound ( PDFDrive )

CHAPTER
38
The Fetal Gastrointestinal Tract and
Abdominal Wall
Nir Melamed, Anne Kennedy, and Phyllis Glanc
SUMMARY OF KEY POINTS
• The gastrointestinal (GI) tract and abdominal wall
anomalies are diverse. Although they may occur in
isolation, many are associated with syndromic or karyotype
abnormalities; thus it is important to search for associated
anomalies.
• Familiarity with normal development is needed to
recognize the varying appearances during gestation of
structures such as the abdominal wall with physiologic
midgut herniation, the identiication of the gallbladder in
the latter half of pregnancy, or the appearance of
meconium at different stages of gestation.
• The prognosis and presentation of a GI tract or abdominal
wall anomaly may vary with the stage of gestation.
• Anomalies of the GI tract may be diagnosed as part of the
evaluation of indirect clues such as polyhydramnios.
• Early prenatal diagnosis, in particular of abdominal wall
anomalies, may be performed by late irst trimester, in
conjunction with a nuchal translucency evaluation.
• Abnormalities of the GI tract may not be clinically
apparent in the newborn; thus prenatal diagnosis
facilitates appropriate triage to a center that can provide
treatment.
CHAPTER OUTLINE
THE GASTROINTESTINAL TRACT
Embryology of the Digestive Tube
Esophagus
Esophageal Atresia
Stomach
Small or Absent Fetal Stomach
Dilated Fetal Stomach
Midline or Right-Sided Stomach
Intraluminal Gastric Masses
Small Bowel and Colon
Bowel Obstruction
Meconium Ileus
Anorectal Malformations
Hirschsprung Disease
Enteric Duplication Cysts
Meconium Peritonitis and
Pseudocyst
Echogenic Bowel
Liver
Hepatomegaly
Hepatic Calciications
Hepatic Cysts and Masses
Gallbladder and Biliary System
Nonvisualization of the Gallbladder
Fetal Gallstones
Choledochal Cyst
Pancreas
Annular Pancreas
Pancreatic Cysts
Spleen
Splenomegaly
Splenic Cysts
ABDOMINAL WALL
Embryology
Gastroschisis
Epidemiology
Pathogenesis
Prenatal Diagnosis
Associated Conditions
Management
Omphalocele
Epidemiology
Prenatal Diagnosis
Associated Conditions
Management
Bladder Exstrophy
Cloacal Exstrophy
Ectopia Cordis
Other Complex Body Wall Defects
Pentalogy of Cantrell
Body Stalk Anomaly
Amniotic Band Syndrome
Systematic and thorough evaluation of the fetal gastrointestinal
(GI) tract and abdominal wall is critical to ascertain the
risk of isolated and multiple fetal abnormalities. Anomalies of
the fetal abdomen may be the only sonographic evidence of
multisystem organ derangement secondary to conditions such
as genetic disorders or fetal infection. Furthermore, detection
of fetal intraabdominal masses or abnormalities is important
because these conditions may not be detected on the routine
newborn examination. In some cases, anomalies of the GI tract
may be diagnosed as part of the evaluation of indirect clues such
as polyhydramnios.
THE GASTROINTESTINAL TRACT
Embryology of the Digestive Tube
he GI tract begins to develop in the third and fourth weeks of
life. he primitive gut tube is formed by incorporation of the
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