Congenital anomalies usually result in voiding dysfunction early in life and are usually partially or completely surgically corrected. When voiding dysfunction occurs in adults, it may affect only the lower urinary system (eg, the bladder and urethra); when voiding dysfunction occurs in children, it commonly involves damage to the upper urinary system (ie, the ureters and kidneys) as well. Many congenital anomalies are discovered early in utero because of prenatal care measures such as ultrasound. The urinary system begins developing days after conception, and anomalies can be seen on a sonogram as early as 20 weeks. Depending on the anomaly, intrauterine surgery may be performed on the fetus. Be-cause the urinary system may be only one of several organ systems that are abnormal due to genetic disorders, any defects not noted during gestation should be immediately apparent at birth. Such anomalies include renal agenesis (complete absence of one or both kidneys), ectopic ureter, and Eagle-Barrett syndrome (also known as prune-belly syndrome), with exstrophy of the bladder. On the other hand, voiding dysfunction can be discovered insid-iously (for example, during toilet training). At times congenital anomalies, such as posterior urethral valves, typically seen only in males, may escape detection until early adolescence or adulthood, when the voiding dysfunction or its sequelae cause the individual to seek a urologic evaluation. Although pediatric in nature, these disorders may affect urinary tract function when the patient be-comes an adult.
Both neurogenic and non-neurogenic disorders can cause adult voiding dysfunction (Table 44-2). The micturition (voiding) process involves several highly coordinated neurologic responses that mediate bladder function. A functional urinary system allows for appropriate bladder filling and complete bladder emptying. If voiding dysfunction goes undetected and untreated, the upper urinary system may be compromised.
Chronic incomplete bladder emptying from poor detrusor pressure results in recurrent bladder infection. Incomplete bladder emptying due to bladder outlet obstruction (such as benign prostatic hyperplasia), causing high-pressure detrusor contractions, can result in hydro-nephrosis from the high detrusor pressure that radiates up the ureters to the renal pelves.