Defining Umbilical Norms in Kenya: A Morphometric Analysis of 411 Adults

The umbilicus is a defining landmark of the abdomen, yet limited data exist for normal umbilical position and shape in African populations, particularly in Kenya. This study examined morphometric references among 411 Kenyan adults, emphasizing whether the "golden ratio" (1.62) holds true in this context.

We conducted a cross-sectional study at a Kenyan referral hospital, enrolling adults aged 18-65 years without recent pregnancy, hernias, or prior abdominal surgery. Supine measurements determined 4 anatomical ratios, with the X:U ratio (distance from xiphoid to umbilicus over distance from umbilicus to the anterior superior iliac spine line) as the primary variable. We compared the mean X:U to 1.62, examined sex differences, and classified umbilical shape using the Craig system.

The mean participant age was 33.8 ± 13.2 years, with men comprising 62.8% of the sample. The average X:U ratio was 1.69 ± 0.46 (95% confidence interval [CI], 1.65-1.74), significantly higher than 1.62 (P < 0.001; Cohen d = 0.17, 95% CI, 0.07-0.27). Men showed a higher ratio than women (1.74 versus 1.62, P = 0.01; Cohen d = -0.26; 95% CI, -0.46 to -0.06). Oval shape was predominant (49.6%). Secondary analysis showed a small negative correlation between body mass index and the X:U ratio (r = -0.22; 95% CI, -0.31 to -0.12; r² ≈ 0.05; P < 0.001).

Kenyan adults have a mean X:U ratio of 1.69, modified independently by sex and body mass index. This umbilical ratio departs from the golden ratio, underscoring the need for population-specific morphometric references.