The optimal approach to the management of NLDO in the first year of life remains uncertain. Our prospective observational data suggest a slightly reduced chance of success with immediate office probing (75% for office probing, 80% for facility probing), however, immediate office probing may be more cost-effective even if the proportion with success is lower. For a subject undergoing a single operation, immediate office probing is less expensive than deferred probing in a facility because there is no fee for anesthesia, the facility, or for medications prescribed during the pre-operative observation period. Some portion of this lower cost would be offset however by the additional cost of a second procedure if the initial office probing is not successful. Deferred facility probing is more expensive per procedure; however, the overall costs are reduced by the number of children whose NLDO spontaneously resolves while waiting to perform the procedure in a facility.