Hello my friend. LAminectomy at level of lumbar vertebra may lead to temporary or permanent urination difficulties because nerves which are responsible for bladder function may have been damaged or oedema caused compression of these nerves. Usually this is just temporary disorder. At this point it is important to recover from the surgery in next 4 weeks, and if necessary, he should wear a catheter for this time. Then follow up MRI scan should be done to see the spinal canal, if there is some nerve injury. Till that, he should be patient and follow urologist instructions. Also, ENMG test may be done, but only if MRI scan is fine. WIsh you good health. Kindly regards