Urinary Tract Obstructions Midterm Notes PDF

**URINARY AND RENAL DISORDERS -- *Urinary Tract Obstructions*** **Urinary Tract Obstructions** Urinary tract obstructions are **blockages or restrictions** that impede the flow of urine through the urinary tract. These obstructions can occur at various points along the urinary tract, from the rena...

**URINARY AND RENAL DISORDERS -- *Urinary Tract Obstructions*** **Urinary Tract Obstructions** Urinary tract obstructions are **blockages or restrictions** that impede the flow of urine through the urinary tract. These obstructions can occur at various points along the urinary tract, from the renal pelvis to the urethra, and can be classified as **upper or lower urinary tract obstruction.** **1. Most Likely Cause** - **Causes of Upper Urinary Tract Obstruction**: - **Nephrolithiasis (Kidney Stones)**: Formation of **crystals, proteins, or other substances** (like **calcium oxalate, calcium phosphate, uric acid, or struvite stones**) within the kidneys or ureters. - **Congenital Anomalies**: Structural abnormalities in the urinary tract that obstruct urine flow. - **Compression of the Urinary Tract**: Can be caused by **tumors**, **pregnancy**, or **fibrosis** surrounding the ureters. - **Causes of Lower Urinary Tract Obstruction**: - **Prostate Enlargement**: Common cause in older males due to **benign prostatic hyperplasia (BPH)**. - **Urethral Stricture**: Narrowing of the urethra, often due to **infection, trauma, or scar tissue**. - **Pelvic Organ Prolapse**: In females, organs such as the bladder, rectum, or uterus may prolapse, leading to bladder obstruction. - **Bladder Dysfunction (Neurogenic Bladder)**: Neurological conditions such as **spinal cord injuries** can impair the bladder\'s ability to contract properly. **2. Pathophysiology** The pathophysiology of urinary tract obstructions depends on the **location, duration, and extent of the blockage**. 1. **Blockage and Pressure Increase**: - Obstruction of the urinary tract causes **urine to accumulate upstream** of the blockage. - This increases **intraluminal pressure** in the affected region, especially in **Bowman\'s capsule**, which **reduces the glomerular filtration rate (GFR)**, thereby decreasing kidney function. - The longer the obstruction persists, the greater the likelihood of structural damage, including **hydronephrosis** (swelling of the kidneys). 2. **Hydronephrosis**: - Urine backs up into the kidneys, causing **dilation of the renal pelvis and calyces**, leading to kidney damage over time. - Compression of the renal cortex and medulla may lead to **renal atrophy** and loss of nephrons. 3. **Infection and Urinary Stasis**: - Urine stasis increases the risk of **urinary tract infection (UTI)** because stagnant urine is an ideal environment for bacterial growth. 4. **Compensatory Changes**: - If only one kidney is affected (unilateral obstruction), the **unaffected kidney undergoes compensatory hypertrophy**, increasing its filtration rate to maintain renal function. - Long-term obstructions may lead to **renal fibrosis** and **irreversible kidney damage**. **3. Disease Transmission** - **Transmission:** - **Not transmissible**. Urinary tract obstructions are mechanical or anatomical problems, not infectious diseases. - However, **infections secondary to obstruction (like pyelonephritis or cystitis)** may be caused by bacteria such as **E. coli**, which can be transmitted through contaminated water or direct contact. **4. Risk Factors** Risk factors for urinary tract obstructions are related to the development of **structural abnormalities**, **infections**, and **neurological dysfunctions**. **Risk Factors for Upper Urinary Tract Obstruction** - **Nephrolithiasis (Kidney Stones)**: - **Age, Gender, and Race**: Men are at higher risk than women for kidney stones, with **middle-aged adults** being the most affected. - **Geographic Location and Climate**: Warm climates promote **dehydration**, which increases the risk of stone formation. - **Dietary Factors**: High intake of **sodium, oxalate, or animal protein** increases stone risk, while adequate hydration reduces it. - **Medical Conditions**: Conditions such as **hyperparathyroidism** or **metabolic disorders** can increase the levels of calcium, uric acid, or oxalate in the urine, promoting stone formation. **Risk Factors for Lower Urinary Tract Obstruction** - **Prostate Enlargement**: Affects men aged **\>50 years**, particularly those with **benign prostatic hyperplasia (BPH)**. - **Pelvic Organ Prolapse**: Risk is higher in women who have had **multiple pregnancies** or **pelvic surgeries**. - **Urethral Stricture**: Occurs due to **scar tissue** from trauma, infection, or surgical procedures on the urinary tract. - **Neurogenic Bladder**: Neurological conditions, such as **spinal cord injuries, multiple sclerosis (MS), or stroke**, may impair bladder control and increase the risk of obstruction. **Summary Table** **Criteria** **Urinary Tract Obstructions** ----------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Most Likely Cause** Upper tract: **Kidney stones, congenital anomalies, tumors, fibrosis**. Lower tract: **Prostate enlargement, pelvic organ prolapse, urethral stricture, neurogenic bladder**. **Pathophysiology** Obstruction increases pressure in urinary tract → **hydronephrosis** → **renal dysfunction**. **Urinary stasis** increases UTI risk. **Transmission** **Not transmissible**, but infections resulting from obstruction (e.g., UTI) may be caused by **E. coli**. **Risk Factors** Upper tract: **Age, gender, race, dehydration, dietary factors, metabolic disorders**. Lower tract: **BPH, pelvic prolapse, urethral stricture, neurological conditions (MS, stroke, spinal cord injury)**.