Determining of gestational age and identification of term fetuses by Ultrasonic colon diameter measurement

Document Type : Original Article


1 Assistant Professor, Department of Radiology, School of Medicine, Mashhad Branch Islamic Azad University, Mashhad, Iran.

2 Assistant Professor, Department of Obstetrics and Genecology, Women's Health Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

3 General Physician, School of Medicine, Mashhad Branch Islamic Azad University, Mashhad, Iran.


Introduction: Determining of gestational age is of great importance in prenatal care. Nowadays, sonography is accepted as the best method of calculation of gestational age. But as pregnancy enters into the third trimester, the accuracy of parameters determining the gestational age by ultrasound decreases. Therefore, there is a need to new ultrasonic parameters. This study was performed with the aim to evaluate the correlation between gestational age and fetal colon diameter; and finally establishing a normal range of colon diameter in Iranian fetuses.
Methods: This cross-sectional study was performed on 100 pregnant women who had referred to the hospitals of Islamic Azad University of Mashhad for routine ultrasound assessment at third trimester in 2013-14. The patients underwent sonography. The maximum diameter of fetal descending colon was measured in transverse section, then its correlation with gestational age was assessed by Pearson correlation test. Data was analyzed by SPSS software (Version 16).
Results: From 100 screened fetuses, 60 fetuses aged 38 weeks or more, and 40 fetuses aged less than 38 weeks. The minimum and maximum of measured colon diameter in preterm fetuses were 10.9, 13.4, respectively and in term fetuses were 13.5, 17.9 millimeter, respectively. Statistical analysis showed a significant relationship between gestational age and colon diameter(P=0/98).
Conclusion: there is a good linear relationship between gestational age and fetal colon diameter; therefore, it can be used as an independent biometry for determining of gestational age. Also, colon diameter seems to be a good marker for identifying term fetuses.


  1. Dilmen G, Turhan NO, Toppare MF, Seckin N, Oztark M, Goksin E. Scapula length measurement for assessment of fetal growth and development. Ultrasound Med Biol 1995; 21(2): 139-42.
  2. Callen P. Ultrasonography Obstetrics and Gynecology. 5th ed. Philadelphia: Saunders Elsevier; 2008. P. 225-47.
  3. Okland I. Biases in second trimester ultrasound dating related to prediction models and fetal measurements [PhD thesis]. Norway: University of Science and Technology Faculty of Medicine; 2012.
  4.  Kimberly B ,  Ken L. Determination of Gestational Age by Ultrasound. J Obstet Gynaecol Can 2014; 36(2):171-81.
  5. Priestly Shan B. Madheswaran M. Revised Estimates of Ultrasonographic Markers for Gestational Age Assessment of Singleton Pregnancies among Indian Population. International Journal of Advanced Science and Technology 2010; 17:1-12.
  6. Fahimi F. Estimation of Gestational Age According to Sonography Parameters , Comparing Mono - and Multivariate Models. Hamedan medicine university journal. 2004; 11(3) : 24-27.
  7. Sahebghalam H, Panahi GH, Dadgar S, Afzali N, Shaban M. The Comparison of the Diagnostic Value of Fetal Foot length Measurement with the length of Femur and Fetal biparietal Diameter in Determining the Gestational Age. Iranian obstetrics and gynecology journal. 2009; 11(4): 9-13.
  8. Zalel Y, Perlitz Y, GamzuA R, Peleg D,  Ben-ami M. In-utero development of the fetal colon and rectum. sonographic evaluation. Ultrasound Obstet Gynecol  2003; 21(2):161-4.
  9. Zilianti M, Fernández S. Correlation of ultrasonic images of fetal intestine with gestational age and fetal maturity. Obstet Gynecol 1983;62(5):569–73.
  10. Nyberg DA, Mack LA, Patten RM, Cyr DR. Fetal bowel. Normal sonographic findings. J Ultrasound Med 1987; 6(1):3-6.
  11. Goldstein I ,Lockwood C, Hobbins JC. Ultrasound assessment of fetal intestinal development in the evaluation of gestational age. Obstet Gynecol. 1987; 70(5): 682-6.
  12. Malas MA, Aslankoç R, Ungör B, Sulak O, Candir O. The development of large intestine during the fetal period. Early Hum Dev 2004;78(1):1-13.
  13. Parulekar SG . Sonography of normal fetal bowel. J Ultrasound Med 1991; 10(4):211-20.
  14. Ana A. Carvalho V, Marchiori E, Carvalho J, Figueiredo I, Velarde L. Use of fetal colon thickness for auxiliary term dating of pregnancy. International Journal of  Gynecology and Obstetrics. 2011; 112: 216-219.
  15. Akram W, Yousif Sh , Falih M. Use of colon caliber diameter as auxiliary method in pregnancy dating between 34-40 weeks of gestation. Mustansiriya Medical Journal. 2013; 12(2) 57-52.