Prenatal diagnosis of midgut volvulus using two-dimensional and three-dimensional ultrasound

Objective: Fetal midgut volvulus is rare and fatal, which can be easily missed on prenatal two-dimensional (2D) ultrasonography. The purpose of this study was to review our experience in prenatal diagnosis of midgut volvulus using 2D and three-dimensional (3D) ultrasound, so as to assess the diagnostic value of the two ultrasonic methods in fetal midgut volvulus. Methods: The retrospective study was conducted on 355 fetuses with intestinal dilatation diagnosed with 2D ultrasonography in the First Affiliated Hospital of Anhui Medical University from January 2017 to December 2019. All cases underwent 3D volume-rendered imaging. The diagnostic value of the two ultrasonic methods in fetal midgut volvulus was assessed. Results: Twelve cases of midgut volvulus were confirmed during postnatal surgery, 11 of which were correctly identified by prenatal imaging. On 2D ultrasound images, the whirlpool sign was observed in 5/12 (41%) fetuses, and of these 5 fetuses, one case also showed the coffee-bean sign. Two weeks later, another fetus showed the coffee-bean sign on ultrasound. The coffee-bean sign without the whirlpool sign was observed in two fetuses. The spiral sign was observed in 9 of the 12 cases (75%) with 3D imaging using the inversion mode. The sensitivity, specificity and accuracy of 2D ultrasound diagnosis were 83.3%, 93.3% and 93.0%, respectively. The sensitivity, specificity and accuracy of 3D ultrasound diagnosis were 91.7%, 98.3% and 98.0%, respectively. Conclusion: Midgut volvulus should be highly suspected in the presence of intestinal dilatation and positive spiral sign on 3D volume-rendered images. Absent or decreased intestine wall echo on 2D and 3D images may be indicative of intestinal necrosis.