1. General Surgery Department, National Hospital of Zinder, Zinder, Niger
2. Pediatric Surgery Department, National Hospital of Zinder, Zinder, Niger
3. Faculty of Health Sciences, University of Zinder, Zinder, Niger
4. General Surgery Department, Regional Hospital of Maradi, Maradi, Niger
5. Faculty of Health Sciences, University Dan Dicko Dankoulodo, Maradi, Niger
6. Pediatric Surgery Department, National Hospital of Lamordé, Niamey, Niger
7. Faculty of Health Sciences, Universite Abdou Moumouni, Niamey, Niger