By about 13 weeks, which organ is reliably seen in the left upper quadrant and indicates normal swallowing?

• A. Stomach
• B. Gallbladder
• C. Spleen
• D. Pancreas

Answer: (A)

Seeing a stomach bubble in the left upper quadrant by about 13 weeks is the best sign that the fetus is swallowing amniotic fluid, which reflects normal gastrointestinal function and coordination with swallowing. On ultrasound, the stomach appears as a fluid-filled, dark (anechoic) circle with a thin wall, and it sits on the left side of the fetal abdomen, so it shows up in the left upper quadrant in standard views. The presence of this stomach fluid indicates the fetus is taking in and processing amniotic fluid, an essential part of normal development.

Other organs listed aren’t as reliably seen this early or don’t specifically indicate swallowing at this gestational age. The gallbladder, for example, is harder to visualize this early and isn’t the go-to indicator of swallowing, while the pancreas and spleen aren’t as reliably identified and don’t serve as the best sign of normal swallowing at this time.