Ultrasonographic Imaging of the Fetal Duodenal Tract

Ultrasonographic Imaging of the Fetal Pyloric Sphincter

OBJECTIVES

In this study, we hypothesized that the pyloric sphincter can be directly visualized by ultrasonography in the prenatal period.

METHODS

This study was designed as a cross-section. Single, healthy pregnancies between 18 and 22 weeks of gestation who applied to the Perinatology outpatient clinic for second-level ultrasonography were included in the study. In addition to the demographic characteristics of the participants, fetal pyloric mucosa, fetal pyloric sphincter length, and fetal pyloric sphincter thickness were measured by ultrasonography. Intrarater variability was calculated.

RESULTS

A total of 93 eligible patients were evaluated in the study. The mean age of the participants was 27.25 ± 6.23, and the gestational age was 21.18 ± 0.98. Pylorus imaging and measurements were possible in all fetuses that were in the optimal position. Mean pyloric sphincter length (mm) was 5.32 ± 0.93, pyloric sphincter thickness (mm) was 2.13 ± 0.44, and sphincter muscle thickness (mm) was 1.05 ± 0.24.

CONCLUSIONS

The pyloric sphincter can be easily visualized on a second-trimester ultrasound scan when the appropriate technique is used. This may make an additional contribution to the diagnosis of fetal gastrointestinal tract pathologies.

Ultrasound examination of the normal fetal duodenum

Objective

To use the fetal pylorus as a reference point to conveniently display the normal fetal duodenum by ultrasound.

Methods

This study was designed in cross-section. A total of 450 healthy singleton pregnant women at 19-39 weeks of gestation who underwent prenatal screening at our hospital from January 2019 to February 2020 were selected. They were divided into three groups according to gestational weeks: the 19-23 gestational weeks group, 29-32 gestational weeks group, and 34-39 gestational weeks group. The duodenal bulb was identified. Its movement and course were continuously and dynamically observed. The descending part of the duodenum was identified, and the duodenal course was traced.

Results

The fluid-filled in the fetal duodenum was discontinuous. The overall detection rates of the duodenum in the 19-23 gestational weeks group, 29-32 gestational weeks group, and the 34-39 gestational weeks group were 82.2%, 26.2%, and 13.8%, respectively. The detection rates of the bulbar, descending, horizontal, and ascending parts of the duodenum were 94.4%, 58.2%, 58.0%, and 52.0%, respectively. The anatomical structures of the duodenum as a whole and the pancreas were most easily recognized in the 19-23 gestational weeks group; while in the 34-39 gestational weeks group, the bulbar part had a maximum detection rate of 98.8%, and it had the longest filling time and the shortest examination time.

Conclusion

The pylorus is an ideal starting point for tracing the fetal duodenum. The overall detection rate of the fetal duodenum decreases with gestational age. The duodenal bulb is the most easily detected site.