Hi there, welcome to HCM.Thank you for your question. Regarding the first part of your question. RetroListhesis and disc bulge are radiological terms reported in an MRI which would require correlation with how your doing clinically.Retrolisthesis describes the relative position of one bone over the other where one of the bones as slipped in relation to the other.Mild retrolisthesis is a normal variant at L5/S1 level and should not be a cause for Concern. Annulus is the outer envelop or covering of disc (which is the cushion between your bones). With degeneration of the disc s some times the material bulges through its covering which presents as an annulus bulge. When the bulge goes backwards it can impinge on the nerves decreasing the space available for them which can also be termed as stenosis or narrowing of the space available for the nerves. If the bulge is not symmetrical it can affect one side more than the other as seen in your question (left more than right).These information is useful if the pain distribution matches the MRI, that is side of pain matching the side of narrowing seen in MRI. Conservative treatment with the combination of medications, physical therapy,exercises with strengthening of core muscles, spinal injections and life style modification should be tried before surgery is considered.Lifiting heavy weights, bending forwards and twisting movements have been associated with progression of back pain and should be avoided during exacerbations. However, surgery will be absolutely Indicated if there is new onset weakness or numbness, loss of urine or motions control related to your spinal ailment.Unrelenting pain affecting your life style would be a relative Indication. Hope this answers your question. All the best With best regards DR . SBK