Growth of the normal human lower urinary tract from 12 to 21 weeks gestation

Normal development of the human lower urinary tract was studied between the 14th and 20th week of gestation using 3 modes of fixation. Fixation by direct distension provides a high degree of reproducibility of parameters used to study the growth of the fetal bladder. Using this method, fetuses ranging from 12 to 21 weeks gestation were studied. Results obtained demonstrate that the length of the bladder, the inter-ureteric distance, and the distance between the apex of the trigone and the distal tip of the urethra occur in a linear mode. Furthermore, the rate of growth of the male urethra was evidently higher when compared to that of the female from the 12th week of gestation. Data from this work can be used for a more accurate assessment of cases with abnormal lower urinary tract development.