1. Department of Surgery , School of Medicine, , PO Box 65001, Dar es Salaam, Tanzania
2. Muhimbili University of Health and Allied Sciences , School of Medicine, , PO Box 65001, Dar es Salaam, Tanzania
3. Department of Surgery, Muhimbili National Hospital , PO Box 65000, Dar es Salaam, Tanzania
4. Department of Pathology , School of Diagnostic Medicine, , PO Box 65001, Dar es Salaam, Tanzania
5. Muhimbili University of Health and Allied Sciences , School of Diagnostic Medicine, , PO Box 65001, Dar es Salaam, Tanzania