I came across the term "водно-сифонная проба" in a Russian case report in which a child undergoes medical investigation for his symptoms. Multitran says that it's "aqueous-siphon test" in English, but I highly doubt that.
According to Russian descriptions I've found online, during this test the patient is asked to drink a glass of water or juice while lying on their back, and the technician assesses the workings of the GI tract by observing how this liquid passes into the stomach and further on.
What could be the proper English term for this?
Googling for "aqueous-siphon" ultrasound in English, I came across a text that was clearly translated from Russian:
Ultrasonography (US) of the stomach with an aqueous-siphon test (intake of 200 ml of water). Trendelenburg positioning for five minutes did not show the presence of gastroesophageal reflux (GR). However, signs of GR complicated by esophagitis with spontaneous reopening of esophageal hiatus were revealed during a fibrogastroduodenoscopy (EGD).