Clinical Analysis of Congenital Duodenal Obstruction and the Role of Annular Pancreas

Background and Objectives: Congenital duodenal obstruction (CDO) is a very rare anomaly with an incidence of 1 in 5000-10,000 live births. Annular pancreas is one of the reasons for CDO and is defined as the pancreatic tissue encircling the duodenum. The exact cause of annular pancreas remains unclear. Materials and Methods: A retrospective study was conducted on all prenatally diagnosed cases of CDO, with the diagnoses and ethiology confirmed by surgery after birth from 1 January 2018 to 1 January 2024. The cases suspected of having CDO in their fetuses underwent ultrasound evaluations on a weekly or biweekly basis. The cohort was divided into two groups, "CDO with annular pancreas" and "CDO without annular pancreas", in order to compare the clinical characteristics and outcomes. Results: A total of 34 cases of CDO were detected prenatally, with 30 of these cases being confirmed through postnatal surgical interventions. The underlying ethiology was duodenal atresia in 15 cases (50%), duodenal web in 2 cases (6.6%) and annular pancreas in 13 cases (43.3%). All cases had a dilated stomach and double bubble sign. Polyhydramnios was identified in all cases except for one. Three cases were terminated and intrauterine demise was observed in one case. Nine of the cases (33%) died in the postnatal period. In 19 cases (55.9%), CDO was associated with chromosomal abnormalities. Chromosomal abnormalities were significantly more common in the cases of CDO with annular pancreas (p = 0.033). Conclusions: The prenatal diagnosis of CDO is mostly based on findings of double bubble and polyhydramnios. An annular pancreas, although rare, is an important cause of neonatal duodenal obstruction. An accurate diagnosis is usually performed during a laparotomy. Given the higher rates of chromosomal abnormalities in cases of annular pancreas, it is clear that more reliable markers or imaging techniques are needed to detect the ethiology of CDO in the prenatal period.