Clinical Investigation

Normal distribution of humeral length in normal fetuses between 15-22 weeks of gestation

  • Ibrahim Kalelioglu
  • Recep Has
  • Atil Yüksel
  • Lem’i Ibrahimoglu
  • Esra Gilbaz
  • Hayri Ermis
  • Alkan Yildirim

Turk J Obstet Gynecol 2006;3(3):152-156

OBJECTIVE: To establish the normal distribution of humeral length in normal fetuses between 15-22 weeks of gestation, and describe the formula used in assessment of humeral shortness in our population. MATERIAL-METHODS: The 620 chromosomally and structurally normal fetuses of high risk pregnancies, which were referred to our clinic for karyotype analysis between January 2004 and April 2005, are enrolled into the study. The distribution of Humerus length (HL) is established according to gestational weeks and gestational days, and percentiles between 15 to 22 weeks are calculated. Regression analysis of HL to biparietal diameter (BPD) is also made and the formula to calculate expected humeral length according to BPD was symbolized. Weekly distribution of BPD/HL was constructed and the percentile values calculated. RESULTS: A linear increase in HL between 15-22 weeks was observed and median values of HL between 15-22 weeks were 20, 21, 24, 26, 29, 31, 32 and 35 mm, respectively. Formulas to calculate expected humeral length by means of gestational week and BPD were "(2.128x gestational week)-12.385" and “(0.699xBPD)-3.0880”, respectively. A linear decrease in BPD/HL was observed and median values of BPD/HL ratio between 15-22 weeks were 1.75, 1.70, 1.63, 1.61, 1.53, 1.53, 1.52 and 1.51, respectively. CONCLUSION: The formulas that we constructed can be used for the evaluation of humerus shortness between 15 to 22 weeks of gestation, in Down syndrome risk assessment with ultrasound.

Keywords: Down syndrome, Humerus shortness, nomogram, percentileDown\r\n