A frequency/volume bladder chart provides vital information about bladder function that is not provided by formal urodynamics studies: 24-hour urinary output, the total number of daily voids, number of nighttime voids, the average voided volume, and the functional bladder capacity (largest volume voided in normal daily life). This information allows the clinician to confirm reports of urinary frequency with objective data and to determine whether part of the patient’s problem is an abnormally high (or low) urinary output. The chart can be used to calculate the volume of urine generated in nighttime hours versus daytime hours. Nighttime volume is calculated by adding output from voids that occur after the woman has fallen asleep for the night and the first morning void on awakening for the day. Older women sometimes have a marked shift in urine production, with more than half of their urine output generated during sleeping hours (Fig. 26.4). Demonstrating this on the voiding diary may lead to further treatment options.
Urinalysis Examination of the urine by dipstick testing and microscopy is done to exclude infection, hematuria, and metabolic abnormalities. Hematuria cannot be diagnosed on the results of a dipstick test alone; confirmation by microscopic evaluation is mandatory.
Figure 26.4 Voiding diary (also called bladder chart). Daytime frequency is seven. The patient has nocturia (gets up to void two times during sleeping hours) and also has nocturnal polyuria (an increased proportion of the 24-hour output occurs at night; note that nighttime urine output excludes the last void before sleep but includes the first void of the morning). She has urge incontinence, likely caused by the relatively larger bladder volumes voided at night, which in turn may be related to her greater ﬂuid, caffeine, and alcohol consumption in the evening.
If a urinary tract infection is documented by microscopy or culture, it is reasonable to see whether urinary tract symptoms improved with eradication of bacteriuria. Occasionally, a simple urinary tract infection causes the onset or exacerbation of urinary incontinence. Some women, particularly older ones, have asymptomatic bacteriuria that truly is asymptomatic; thus, if attempted treatment of a woman with bacteriuria but without classic urinary tract infection symptoms (such as dysuria, urgency, or frequency) does not improve incontinence, further antibacterial treatment is generally unnecessary.
If hematuria and bacteriuria are found, the urine should be rechecked after eradication of the bacteriuria. Hematuria found in the absence of bacteriuria may need further evaluation to rule out kidney or bladder tumors; the necessity for and extent of the evaluation depends on concomitant risk factors and the clinical presentation. If malignancy is suspected, bladder biopsy should be performed by the surgeon who would treat the patient in the event a malignancy is discovered.
Routine urinary cytology is not helpful, but testing may be of value in women older than 50 years with irritative urinary tract symptoms, particularly if those symptoms are of sudden onset.
Postvoid Residual Volume Incomplete bladder emptying may cause incontinence. Patients with a large postvoid residual (PVR) urine volume have a diminished functional bladder capacity because of the dead space occupied in the bladder by retained urine. This stagnant pool of urine is a source of urinary tract infections because the major defense of the bladder against infection is frequent, nearly complete emptying.
A large PVR volume can contribute to urinary incontinence in two ways. If the bladder is overdistended, increases in intra-abdominal pressure can force urine past the urethral sphincter, causing stress incontinence (sometimes termed “overﬂow incontinence” in the context of a large PVR volume). In some cases, bladder overdistention may provoke an uninhibited contraction of the detrusor muscle, leading to incontinence. These conditions may coexist, further complicating the problem.