Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study

Ayşe Ceren Duymuş; Nizamettin Bozbay; Özlem Polat Bozbay; Rrezearta Cungu; Osman Yıldırım; Aybike Tazegül Pekin

Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study

Abstract

Aims: To establish gestational age-specific reference centiles for fetal thymus transverse diameter between 18 and 25 weeks of gestation, corresponding to the routine mid-trimester anatomical survey. Methods: This retrospective cross-sectional study included singleton pregnancies that underwent detailed second-trimester ultrasonography between May 2023 and March 2025. Fetal thymus images were retrieved from the institutional Picture Archiving and Communication System (PACS). Cases with structural or chromosomal anomalies, maternal systemic disease, multiple gestations, incomplete thymus imaging, or absent postnatal follow-up were excluded. The transverse diameter of the fetal thymus was measured in the three-vessel and trachea view by two maternal-fetal medicine specialists. Intraclass correlation coefficient (ICC) analysis was performed to assess interobserver agreement. The relationship between gestational age and thymus size was evaluated using Pearson correlation and linear regression. Gestational age-specific centiles were constructed. Results: A total of 407 fetuses between 18 and 25 weeks of gestation were included. Fetal thymus transverse diameter demonstrated a significant positive correlation with gestational age (r=0.567, p<0.001). Linear regression analysis showed that gestational age independently predicted thymus size (B=0.90 mm/week, p<0.001), explaining 32.1% of the variability (R²=0.321). Conclusion: We present gestational age-specific reference centiles for fetal thymus transverse diameter during routine mid trimester anatomical screening. These data may facilitate standardized assessment of fetal thymus size, potentially contributing to the identification of fetuses at risk for genetic, inflammatory, or stress-related conditions.

Keywords

Supporting Institution

None

Ethical Statement

The study protocol complied with the principles of the Declaration of Helsinki and later revisions governing ethical conduct in human research. Approval for the study was obtained from the Selçuk University Rectorate Ethics Committee

Thanks

None

References

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Details

Primary Language

English

Subjects

Obstetrics and Gynaecology

Journal Section

Research Article

Authors

Ayşe Ceren Duymuş ^*
0000-0002-8760-3781
Türkiye

Nizamettin Bozbay
0000-0001-9632-5093
Türkiye

Özlem Polat Bozbay
0000-0003-1975-6687
Türkiye

Rrezearta Cungu
0009-0004-4299-1321
Türkiye

Osman Yıldırım
0009-0001-3082-9704
Türkiye

Aybike Tazegül Pekin
0000-0002-6399-0166
Türkiye

Publication Date

September 11, 2026

Submission Date

March 8, 2026

Acceptance Date

July 29, 2026

Published in Issue

Year 2026 Volume: 8 Number: 5

IZ

https://izlik.org/JA67WK46FR

Cite

RIS / Bibtex

APA

Duymuş, A. C., Bozbay, N., Polat Bozbay, Ö., Cungu, R., Yıldırım, O., & Tazegül Pekin, A. (2026). Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study. Anatolian Current Medical Journal, 8(5), 946-951. https://izlik.org/JA67WK46FR

AMA

1.Duymuş AC, Bozbay N, Polat Bozbay Ö, Cungu R, Yıldırım O, Tazegül Pekin A. Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study. Anatolian Curr Med J / ACMJ / acmj. 2026;8(5):946-951. https://izlik.org/JA67WK46FR

Chicago

Duymuş, Ayşe Ceren, Nizamettin Bozbay, Özlem Polat Bozbay, Rrezearta Cungu, Osman Yıldırım, and Aybike Tazegül Pekin. 2026. “Reference Centiles for Fetal Thymus Transverse Diameter at 18-25 Weeks of Gestation: A Cross-Sectional Ultrasound Study”. Anatolian Current Medical Journal 8 (5): 946-51. https://izlik.org/JA67WK46FR.

EndNote

Duymuş AC, Bozbay N, Polat Bozbay Ö, Cungu R, Yıldırım O, Tazegül Pekin A (September 1, 2026) Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study. Anatolian Current Medical Journal 8 5 946–951.

IEEE

[1]A. C. Duymuş, N. Bozbay, Ö. Polat Bozbay, R. Cungu, O. Yıldırım, and A. Tazegül Pekin, “Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study”, Anatolian Curr Med J / ACMJ / acmj, vol. 8, no. 5, pp. 946–951, Sept. 2026, [Online]. Available: https://izlik.org/JA67WK46FR

ISNAD

Duymuş, Ayşe Ceren - Bozbay, Nizamettin - Polat Bozbay, Özlem - Cungu, Rrezearta - Yıldırım, Osman - Tazegül Pekin, Aybike. “Reference Centiles for Fetal Thymus Transverse Diameter at 18-25 Weeks of Gestation: A Cross-Sectional Ultrasound Study”. Anatolian Current Medical Journal 8/5 (September 1, 2026): 946-951. https://izlik.org/JA67WK46FR.

JAMA

1.Duymuş AC, Bozbay N, Polat Bozbay Ö, Cungu R, Yıldırım O, Tazegül Pekin A. Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study. Anatolian Curr Med J / ACMJ / acmj. 2026;8:946–951.

MLA

Duymuş, Ayşe Ceren, et al. “Reference Centiles for Fetal Thymus Transverse Diameter at 18-25 Weeks of Gestation: A Cross-Sectional Ultrasound Study”. Anatolian Current Medical Journal, vol. 8, no. 5, Sept. 2026, pp. 946-51, https://izlik.org/JA67WK46FR.

Vancouver

1.Ayşe Ceren Duymuş, Nizamettin Bozbay, Özlem Polat Bozbay, Rrezearta Cungu, Osman Yıldırım, Aybike Tazegül Pekin. Reference centiles for fetal thymus transverse diameter at 18-25 weeks of gestation: a cross-sectional ultrasound study. Anatolian Curr Med J / ACMJ / acmj [Internet]. 2026 Sep. 1;8(5):946-51. Available from: https://izlik.org/JA67WK46FR