33 Urinary tract obstruction

Overview/pathophysiology

Urinary tract obstruction usually is the result of blockage from pelvic tumors, calculi, and urethral strictures. Additional causes include neoplasms, benign prostatic hypertrophy, ureteral or urethral trauma, inflammation of the urinary tract, pregnancy, and pelvic or colonic surgery in which ureteral damage has occurred. Obstructions can occur suddenly or slowly, over weeks to months. They can occur anywhere along the urinary tract, but the most common sites are the ureteropelvic and ureterovesical junctions, bladder neck, and urethral meatus. The obstruction acts like a dam, blocking passage of urine. Muscles in the area contract to push urine around the obstruction, and structures behind the obstruction begin to dilate. The smaller the site of obstruction, the greater the damage. Obstructions in the lower urinary structures, such as the bladder neck or urethra, can lead to urinary retention and urinary tract infection (UTI). Obstructions in the upper urinary tract can lead to bilateral involvement of the ureters and kidneys, leading to hydronephrosis, renal insufficiency, and kidney destruction. Hydrostatic pressure increases, and filtration and concentration processes in the tubules and glomerulus are compromised.

Health care setting

Primary care and acute care

Assessment

Signs and symptoms:

Anuria, nausea, vomiting, local abdominal tenderness, hesitancy, straining to start a stream, dribbling, decreased caliber and force of urinary stream, hematuria, oliguria, and uremia. Pain may be sharp and intense or dull and aching; localized or referred (e.g., flank, low back, buttock, scrotal, labial pain).

Physical assessment:

Bladder distention and “kettle drum” sound over bladder with percussion (absent if obstruction is above the bladder) and mass in flank area, abdomen, pelvis, or rectum.

History of:

Recent fever (possibly caused by the obstruction), hypertensive episodes (caused by increased renin production from the body’s attempt to increase renal blood flow).

Diagnostic tests

Serum k⁺ and na⁺ levels:

To determine renal function. Normal range for K⁺ is 3.5-5.0 mEq/L; normal range for Na⁺ is 137-147 mEq/L.

Blood urea nitrogen (BUN) and creatinine:

To evaluate renal-urinary status. Normally, their values are elevated with decreased renal-urinary function. Note: These values must be considered based on patient’s age and hydration status. For the older adult, serum creatinine level may not be a reliable indicator because of decreased muscle mass and a decreased glomerular filtration rate. Hydration status can affect BUN: fluid volume excess can result in reduced values, whereas volume deficit can cause higher values.

Urinalysis:

To provide baseline data on functioning of the urinary system, detect metabolic disease, and assess for presence of UTI. A cloudy, hazy appearance; foul odor; pH greater than 8.0; and presence of red blood cells, leukocyte esterase, white blood cells (WBCs), and WBC casts are signals of UTI.

Urine culture:

To determine type of bacteria present in the genitourinary tract. To minimize contamination, a sample should be obtained from midstream collection.

Hemoglobin (HB) and hematocrit (HCT):

To assess for anemia, which may be related to decreased renal secretion of erythropoietin.

Kidneys, ureters, and bladder (KUB) radiography:

To identify size, shape, and position of the KUB and abnormalities such as tumors, calculi, or malformations.

Imaging studies:

A variety of imaging studies may be used to identify area and cause of obstructions:

• Excretory urography/intravenous pyelography: To evaluate cause of urinary dysfunction by visualizing the kidneys, renal pelvis, ureters, and bladder.

• Antegrade urography: Involves placement of percutaneous needle or nephrostomy tube through which radiopaque contrast is injected. Antegrade urography is indicated when the kidney does not concentrate or excrete intravenous (IV) dye.

< div class='tao-gold-member'>

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Psychosocial support
2. Care of the renal transplant recipient
3. Pneumothorax/hemothorax
4. Bronchiolitis

Stay updated, free articles. Join our Telegram channel

Join

Full access? Get Clinical Tree