Many patients are initially reluctant to seek treatment for pelvic organ prolapse and will later cite that it was a change in their bladder function, including difficulty emptying, suprapubic pressure, nocturia, new-onset urgency, or urinary incontinence, that prompted them to consult a specialist. Although pelvic floor disorders can cause these symptoms, there are other pathologies, such as pelvic or bladder wall carcinoma, that may present with similar symptoms. In this chapter, we will briefly review the pertinent anatomy, physiology, and diagnostic tools that are utilized when evaluating bladder function. Our discussion will focus primarily on the lower urinary tract.
LOWER URINARY TRACT STRUCTURE AND FUNCTION
The genitourinary system is divided into upper and lower tracts. The upper urinary tract (UUT) consists of the renal parenchyma and the collecting system components (renal pelvis and ureters). The bladder and urethra compose the lower urinary tract (LUT). The kidneys lie in the retroperitoneum and weigh approximately 135 g in women. The superior margin of the left kidney is located at the level of the 12th thoracic vertebral body and the right kidney is 1 to 2 cm lower due to displacement by the liver.1
The ureters are also located in the retroperitoneum. They vary in length from 22 to 26 cm and travel from the renal pelvis located at the level of the 1st to 2nd lumbar vertebral body to the posterior bladder base.1 There are three distinct regions where the ureteral lumen narrows: the ureteropelvic junction, where the ureter crosses over the iliac vessels and also upon entering the bladder, or ureterovesical junction. The distal ureter traverses obliquely through the muscular layers of the bladder base and terminates at the ureteral orifice on the trigone. This results in distal ureter constriction when the bladder contracts. For this reason, ectopic ureteral orifices that are positioned lateral to the trigone are at risk for urinary reflux. Ureteral orifices that are medial to the normal placement on the trigone traverse thicker muscular layers that surround the bladder neck and proximal urethra and are more susceptable to ureteral obstruction.2
The bladder is located in the lower pelvis and the superior surface of the bladder (located at the level of the pubic bone) has an apex where a fibrous remnant of the allantois, the urachus, once drained the fetal bladder. The posterior-inferior surface of the bladder including the trigone is called the base. The remaining two bladder surfaces on the left and right are described as being positioned inferior-lateral.
The internal surface of the bladder, ureters, and renal pelvis are lined with transitional epithelium called the “urothelium.” This layer is usually six to seven cells thick and rests on the lamina propria, a supporting structure (Figure 7-1).1 The urothelium is smooth when the bladder is full and contracts ...