**3. Diagnosis**

In most cases, the diagnosis of duodenal obstruction can be established prenatally. Duodenal obstruction develops approximately by 12–14 weeks of fetal development, so there is no possibility of earlier detection of this anomaly. Ultrasound is used to define the "double bubble sign." These are two fluid levels, one in the distended stomach, and the other one in the duodenum (**Figure 1**). Polyhydramnios develops in pregnancies complicated by duodenal obstruction.

Postnatally, the diagnosis of duodenal obstruction is confirmed in an abdominal X-ray, showing the "double bubble" sign described above (**Figure 2**). Abdominal ultrasound is necessary to detect not only duodenal atresia (**Figure 3**), but also to find concomitant anomalies and rare forms of situs inversus. These findings can necessitate alternative port placement during laparoscopy.

**Figure 1.** *"Double-bubble" sign of duodenal obstruction on a prenatal ultrasound.*

**Figure 2.** *Postnatal X-ray showing the "double-bubble" sign of duodenal obstruction.*

**Figure 3.**

*Postnatal ultrasound showing the "double-bubble" sign of duodenal obstruction. 1 – Stomach, 2 – Duodenum.*
