Esophageal atresia is a disorder in which the esophagus is obstructed by a segment that has complete obliteration of the lumen. It often occurs in conjunction with a tracheoesophageal fistula, typically connecting the trachea to the distal portion of the esophagus.

Esophageal atresia can occur on its own or in conjunction with other structural anomalies. One of the anomaly groupings that includes esophageal atresia is the VACTERL grouping.

The prognosis with esophageal atresia is variable, depending in part on the presence or absence of associated anomalies.

The sonographic findings of esophageal atresia are little or no fluid in the fetal stomach and polyhydramnios (Figure 12.1.1). If there is no tracheoesophageal fistula (and hence no route by which amniotic fluid can reach the fetal stomach), there will be complete absence of fluid in the fetal stomach and severe polyhydramnios. If there is a distal tracheoesophageal fistula, amniotic fluid can traverse this fistula to reach the fetal stomach. In these cases, the degree of polyhydramnios may be variable and there may be some fluid in the fetal stomach (Figure 12.1.2). Occasionally, the dilated proximal esophageal segment may be seen as a pouch of fluid behind the trachea (Figure 12.1.2).

The findings of polyhydramnios together with little or no fluid in the fetal stomach can also be present in fetuses with a facial or nuchal lesion that obstructs swallowing (e.g., lower facial teratoma). Hence, when the sonogram demonstrates polyhydramnios and little or no fluid in the fetal stomach, the fetal face should be examined before concluding that the diagnosis is esophageal atresia.

When the diagnosis of esophageal atresia is made, the entire fetus should be carefully assessed for the presence of associated anomalies.

Duodenal atresia is a disorder in which the duodenum is obstructed by a segment that has complete obliteration of the lumen. The atretic segment is usually just distal to the duodenal bulb, in the second portion of the duodenum.

Duodenal atresia may occur as an isolated anomaly or in association with other anomalies. Approximately one-third of fetuses with duodenal atresia have trisomy 21.

Duodenal atresia is the most common, but not the only, cause of duodenal obstruction. Other causes include annular pancreas, intestinal malrotation with Ladd’s bands, and duodenal web.

Sonographic diagnosis of duodenal obstruction is made when two findings are present: (i) dilation of the fetal stomach and duodenum (“double bubble”), appearing sonographically as two prominent fluid-filled structures in the upper abdomen and (ii) polyhydramnios (Figure 12.2.1). On a coronal or oblique view of the fetal abdomen, the dilated stomach and duodenum can sometimes be seen to be connected to one another (Figure 12.2.2).
The specific diagnosis of duodenal atresia can be suspected, but not established with certainty, because other causes of duodenal obstruction have similar sonographic findings (Figure 12.2.3).