Akyva First In Human

List of Eligibility Criteria apply to both Non-neurogenic and Spinal Cord Injury (SCI) Neurogenic underactive bladder study participants unless otherwise noted. Inclusion Criteria: * Are male or female, as assigned at birth, aged ≥ 22 years of age. (SCI Only: 22 to 70 years of age) * Able to initiate at least three (3) volitional voiding episodes over the 7-day period based on review of their 7-day bladder diary collected between day of consent and before the implant procedure. * Currently performing clean intermittent catheterization (CIC) for urinary retention at a rate of ≥7 catheterization episodes over the 7-day period, as reflected in a 7-day bladder diary collected between day of consent and before the implant procedure. * Are medically fit to withstand abdominal-pelvic surgery under general anesthesia, as evaluated by standard-of-care pre-operative surgical clearance. * Females of childbearing potential must agree to the use of contraception for the duration of the study * Are able to understand the risks associated with the study, are willing and able to provide written informed consent prior to any study-related activity, willing and capable of participating in all follow up assessments and willing to undergo all study assessments as described at an approved clinical investigator site. * No neurologic cause * SCI Only: Chronic spinal cord injury (\>= 6 months post-injury) with sacral/infrasacral (L1 or below) lesions, or mixed lesions associated with neurogenic lo…