To determine the effectiveness of using the ICD-9-CM procedure code 54.71 for case ascertainment of gastroschisis.Using procedure code 54.71, we queried a statewide hospital discharge database to identify all cases coded as undergoing surgical repair of gastroschisis. Each retrieved case was verified as having gastroschisis by review of the hospital record. All gastroschisis cases were then matched to the Florida Birth Defect Registry (FBDR) dataset. This registry uses a passive system of multiple data sources and employs the ICD-9-CM diagnostic code 756.79 to identify gastroschisis and other abdominal wall defects.Of 93 cases identified by using code 54.71, 92 were confirmed by record review to have gastroschisis. The FBDR identified 87 of the 92 cases (95%). The FBDR missed three of the remaining five cases because of linkage difficulties between inconsistent data elements in the respective data files. The other two cases were not identified by the FBDR because the source database (AHCA discharge) truncates the entry of ICD-9-CM diagnostic codes when more than 10 of them are listed in the medical record.Use of the surgical procedure code was demonstrated to be superior to the diagnostic code as a method for identification of gastroschisis cases. The same approach may be useful in the detection of malformations other than gastroschisis.