ABSTRACT
The fetal bladder can be easily visualized in all stages of pregnancy. Although the dimensions of the bladder are variable throughout the pregnancy, a longitudinal measurement of more than 7 mm in the first trimester is considered abnormal. The bladder should always be assessed in combination with the liquor volume and the kidneys. The majority of the fetuses with normal karyotype show spontaneous resolution of the bladder enlargement and have a normal outcome. The finding of an enlarged bladder in the second trimester is usually due to bladder outlet obstruction. The presence of normal kidneys suggests that the renal function is likely to be preserved and is usually confirmed with the additional finding of normal liquor volume. The combination of an enlarged bladder with abnormal kidneys and reduced or absent liquor volume is indicative of poor renal function and is generally indicative of a guarded prognosis.
