GastroplastyObesity, MorbidJejunoileal BypassBariatric SurgeryGastric BypassObesityAnastomosis, Roux-en-YPirinitramideSurgical StaplersStomachHernia, HiatalWeight LossEsophageal StenosisPostoperative ComplicationsFundoplicationLaparoscopyEsophagusPostoperative PeriodReoperationObesity, AbdominalFollow-Up StudiesGastroesophageal RefluxBody WeightPediatric ObesityBody Mass IndexMethods