BLADDER DISTENSION AND PYELECTASIS IN THE MALE FETUS - CAUSES, COMPARISONS, AND CONTRASTS

The objective of this paper was to determine if prenatal sonographic f indings can accurately differentiate between the causes of bladder dis tention and pyelectasis in the male fetus. Twenty-one cases were evalu ated for the presence of oligohydramnios, posterior urethral dilation, bladder wall thickening, urachal patency, cortical thinning, cortical cysts, an;Li increased renal echogenicity. Postnatal diagnosis Includ ed posterior urethral valves (10 cases), prune belly syndrome (four ca ses), vesicoureteral reflux (four cases), left ureterovesical junction obstruction tone case), and nonrefluxing, nonobstructive megacystis-m egaureter (two cases). Oligohydramnios was present in eight of 10 case s of posterior urethral valves and in one of four cases of prune belly syndrome. A dilated posterior urethra was noted in seven of 10 cases of posterior urethral valves and transiently in two of four cases of p rune belly syndrome. Bladder wall thickening developed in all cases of posterior urethral valves and was noted in two of four patients with prune belly syndrome. A patent urachus likewise was identified in two of four cases of prune belly syndrome. The presence of oligohydramnios , progressive bladder wall thickening, and dilated posterior urethra w as most suggestive of posterior urethral valves, whereas the presence of a patent urachus was most suggestive of prune belly syndrome. The p resence of pyelectasis and megacystis without additional amniotic flui d, bladder, urethral, or renal abnormalities was most suggestive of ve sicoureteral reflux, ureterovesical junction obstruction, or nonreflux ing, nonobstructive megacystis-megaureter. Owing to the overlap and ev olution of these findings, close follow-up evaluation is recommended.