Obesity Obsessive compulsive disorder (OCD) Obstipation Obstruction of duodenum Occlusive arterial disease Oligomenorrhoea Oligospermia Oophoritis Ophthalmoplegia, progressive external Optic atrophy Oral aphthae, recurrent Oral candidiasis Oral cavity cancer Oral leukoplakia Oral lichen planus Orchitis Orthostatic hypotension Osteoarthritis
Osteoarthritis of lumbar disk Osteoarthritis of the knee Osteochondromas Osteoclastoma Osteomalacia Osteomyelitis Osteonecrosis of femur Osteoporosis Osteosarcoma Otitis media, chronic secretory Ototoxic hearing loss Ovarian cancer Ovarian pregnancy Ovarian tumor, benign Overlap syndrome Overweight Ovulation bleeding Ozostomia