This prospective study was carried out at Bursa Uludag University Hospital between January 2021 and January 2022, following the approval of the local ethical committee (2021-7/26). Eighty-four ASA class I-III patients aged 4-11 years who were scheduled for elective urogenital surgery were included in the study. The parents were informed about the research, both verbally and in writing, and their consent was obtained. Patients with a pathology that prevents emptying in the upper gastrointestinal system, who have motility disorders in the gastrointestinal system, who are under follow-up due to diabetes mellitus (DM), who can-not cooperate, refuse to drink fluids or USG, do not provide consent from their families, have a history of lower esophagus or gastric operation, have a history of upper gastrointestinal bleeding in the last month, clinically significant hepatic or renal failure, and a BMI \> 35 kg m2 were excluded from the study.During the preoperative visit, the child's physical characteristics (sex, age, weight, height, and body mass index) and initial vital parameters (heart rate and noninvasive blood presure) were recorded. Oral intake was discontinued in all children according to our common protocol (two hours for clear liquids; six hours for semi-solid and solid foods)All patients were randomized according to a table created on a computer using the closed-envelope method. It was planned such that only the surgeons knew which group the randomized patients were in. The anesthesiologist who performed the USG measurements did would not know which group the patient belonged to. Informed consent was obtained after the study protocol was properly explained to the children in accordance with their parents and age. In the clinic, clear liquids (water or apple juice) at room temperature (22°C) were administered to the patients by a second anesthesiologist and clinic nurse, in accordance with the group. The gastric antral area (GAA) was measured with USG just before the intake of liquid (T0), at the 5th minute (T5), 10th minute (T10), 30th minute (T30), 60th minute (T60), 90th minute (T90) by the anesthesiologist. This planned procedure was performed on the morning of the day of the operation, at least two hours before the induction of anesthesiaThe patients were grouped according to the kind of liquid (water or apple juice) and physical activity (resting or mobilization). \[Group WR \[water+rest (n:19)\], Group WM \[water+mobilization (n:21)\], Group AR \[apple juice (49.6kcal/100 ml + rest (n:23)\] and Group AM \[apple juice (49.6kcal/100 ml) + mobilization (n:21)\]\]. All the clear liquids were administered at a dose of 5 ml/kg. Patients in the resting groups (WR and AR); sat between ultrasound examinations and watched the age-appropriate animation of their choice. Age-appropriate audiovisual interventions such as cartoons and interactive games are effective in reducing preoperative anxiety in children. However, the selection of audiovisual interventions according to the age of the child is crucial. Patients in the mobilized group (WM and AM) were encouraged to walk into the clinic and their rooms between the ultrasound examinations.During USG imaging, patients were placed in a 45° semi-recumbent, right lateral decubitus (RLD) position. A portable ultrasound device (Logic E® GE, Boston, MA, USA) equipped with a high-frequency linear array transducer (probe 8-12 MHz) was used to obtain a cross-sectional image of the gastric antrum. The gastric antrum was identified in the sagittal or sagittal oblique plane in the epigastrium, along the edge of the left lobe of the liver, and anterior to either the aorta or the inferior vena cava, according to the standard protocol. Gastric emptying is influenced by gravity and should be faster in an upright positionGAA, craniocaudal (D1) (cm) and anteroposterior (D2) (cm) of the antrum, including stomach wall, in the RLD position werw calculated using real-time USG (Logic E® GE, Boston, USA) linear probe (8-12 MHz) diameters. A single cross-section of the antrum was obtained in the sagittal plane containing the left lobe of the liver and the aorta or inferior vena cava and was considered a standard level for measuring craniocaudal and anteroposterior diameters. The values of these diameters were inserted into the formula below to calculate the antral GAA, which correlates with gastric volume (GAA = π × D1 × D2/4).

A single investigator evaluated the hunger and thirst ratings of all children before drinking the beverages (0 min), and at 10, 15, 30, 60, and 90 min after drinking.