Abstract. Congenital absence of gallbladder and atrial septal defect (ASD) are clinically rare congenital organ malformations, and the simultaneous occurrence of the two is even more rare. The present study reported a case of gallbladder agenesis combined with congenital ASD. A 38-year-old male patient presented with a 3-year history of recurring upper right abdominal pain. The pain had no evident cause and was accompanied by dyspepsia and gasteremphraxis with indigestion. Several color Doppler ultrasonography scans revealed cholecystitis and gallbladder stones. A physical examination revealed cardiac murmur. A color Doppler ultrasonography of the heart was indicative of congenital heart disease. A corrective surgery for ASD was performed. Subsequently, a mini-incision cholecystectomy was performed as explorative surgery. A magnetic resonance cholangiopancreatography scan of the abdomen was performed in order to confirm the diagnosis of gallbladder disorder and cystic duct hypoplasia. A final definite diagnosis of gallbladder agenesis was confirmed. In conclusion, atrophy and gallbladder full of stones are frequently misdiagnosed, and establishing a definitive preoperative diagnosis is difficult. Awareness of this congenital malformation may assist physicians in distinguishing cases with unclear manifestation and avoiding unnecessary surgical interventions. IntroductionConcurrent manifestation of congenital absence of gallbladder and atrial septal defect (ASD) is a rare congenital organ malformation in clinical practice (1). No apparent association has been identified between these two congenital organ malformations. Sufficient attention must be paid to these disorders as they are often misdiagnosed or overlooked during diagnosis. The incidence of gallbladder agenesis in the general population is reported to be 13-65/100,000 (2). In clinical practice, the incidence is 0.007-0.0027%, while in autopsy series it is 0.04-0.13% (3). Females are more commonly affected (ratio, 3:1), and >50% of patients with gallbladder agenesis are symptomatic and require surgical intervention (4,5). It is crucial that clinicians consider gallbladder agenesis in cases where the gallbladder appears abnormal on preoperative imaging studies and cannot be identified using laparoscopy (6). Preoperative diagnostic imaging such asmagnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasound should be considered. If such a condition is encountered during surgery, intraoperative cholangiography and intraoperative ultrasound may be performed to rule-out agenesis and ectopic gallbladder (7). In the present case report, the diagnosis and surgical intervention of gallbladder agenesis and ASD is described. Case reportA 38-year-old male visited the Affiliated Hospital of Inner Mongolia Medical University (Hohhot, China) in December 2010 with a 3-year history of recurring upper right abdominal pain, which had deteriorated in the last week. The pain had no evident cause. It was accompanied by dyspepsia and gasteremphraxis with indigesti...