AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

Urinary tract obstruction is a common problem encountered by urologists, primary care physicians, and emergency medicine physicians. Urinary tract obstruction can occur at any point in the urinary tract, from the kidneys to the urethral meatus. It can appear secondary to calculi, tumors, strictures, and anatomical abnormalities. Obstructive uropathy can result in pain, urinary tract infection, sepsis, and loss in renal function. Thus, the detection obstruction warrants a consultation with a urologist.

History of the Procedure

Relief of urinary tract obstruction dates back to the time of Hippocrates with the use of the urethral catheter. The first catheters were made of metal; by the Middle Ages, more flexible catheters were developed. Rubber catheters were developed in the 19th century. Today, various sizes, compositions (eg, latex, silicone), and tips (coude, straight, council tip) of catheters are available.

Suprapubic access to the bladder can be traced back to the 16th century. It was initially considered a procedure of last resort but was refined in the 20th century. Today, it is a fairly common mode for relief of urinary tract obstruction.

Problem

When urinary tract obstruction occurs, urine flow is impeded. This obstruction causes distention of the urinary tract proximal to the point of obstruction. The distention is caused by increased pressure. Distortion of the urinary tract and renal failure can develop; the severity depends on the degree and duration of obstruction. When the urinary tract is obstructed, urine stasis can occur. Thus, the urine can easily become infected.

Frequency

In an autopsy series of 59,064 patients aged 0-80 years, the frequency of hydronephrosis was 3.1%. In women with uterine prolapse, hydronephrosis occurs in approximately 5% with first-degree prolapse and in 40% with third-degree prolapse.

Etiology

Obstruction to urinary flow can occur anywhere from the kidneys to the urethral meatus. Certain points along this path are more susceptible to obstruction. The 3 points of narrowing along the ureter include the ureteropelvic junction (UPJ), the crossing of the ureter over the area of the pelvic brim (the iliac vessels), and the ureterovesical junction (UVJ).

In women, an additional area of ureteral narrowing can occur as the distal ureter crosses posterior to the pelvic blood vessels and the broad ligament in the posterior pelvis. Women can also experience urinary tract obstruction when the ureters become externally compressed by pelvic tumors or by advanced cervical or gynecologic malignancies.

More commonly in older women, prolapse of pelvic structures, such as the uterus and bladder, can lead to obstruction. In younger women, pregnancy can cause obstruction secondary to ureteral obstruction from the gravid uterus.

In men, the enlarged prostate (benign prostatic hypertrophy) can cause urinary tract obstruction by obstructing the urethra. Urethral stricture can also lead to urinary obstruction.

Both men and women can experience obstruction from calculi, strictures, or tumors (intrinsic or extrinsic). Obtaining a thorough history of present illness, medication history (eg, anticholinergics, narcotics), past medical history (diabetes, calculi, tumors, radiation, retroperitoneal fibrosis, neurologic disorders), and past surgical history (pelvic surgery, radiation) is helpful in identifying potential causes of obstruction. Individuals with neurogenic bladder or detrusor sphincter dyssynergia can also experience bladder outlet obstruction.

In children, obstruction may be more commonly due to UPJ or UVJ obstruction, ectopic ureter, ureterocele, megaureter, or posterior urethral valves. Prenatal screening with ultrasonography is important in early identification of obstruction. In addition, children with incontinence or urinary tract infection need a workup because they may also have some type of urinary tract obstruction.

Pathophysiology

Chronic urinary tract obstruction can lead to permanent damage to the urinary tract. Infravesical obstruction can lead to changes in the bladder, such as trabeculation, cellule formation, diverticula, bladder wall thickening, and, ultimately, detrusor muscle decompensation. Progressive back pressure on the ureters and kidneys can occur and can cause hydroureter and hydronephrosis. The ureter can then become dilated and tortuous, with the inability to adequately propel urine forward. Hydronephrosis can cause permanent nephron damage and renal failure. Urinary stasis along any portion of the urinary tract increases the risk of stone formation and infection, and, ultimately, upper urinary tract injury.

Clinical

The clinical presentation of urinary tract obstruction varies with the location, duration, and degree of obstruction. Thus, a thorough history and physical examination are key in the patient evaluation.

Upper urinary tract obstruction (kidney, ureter) can manifest with flank pain, ipsilateral back pain, and ipsilateral groin pain. Nausea and vomiting are also common and usually occur in acute obstruction. Chronic obstruction is usually indolent and may be asymptomatic. When infection is present, the patient may experience fever, chills, and dysuria. Hematuria may also be present. When bilateral obstruction or unilateral obstruction in a solitary kidney is severe and renal failure is present, uremia can be present. Uremia symptoms include weakness, peripheral edema, mental status changes, and pallor.If hydronephrosis is severe, the kidney may be palpable on physical examination, especially in children. In cases that involve an infectious process, costovertebral angle tenderness can indicate pyelonephritis.

Lower urinary tract obstruction (bladder, urethra) can manifest with voiding dysfunction such as urgency, frequency, nocturia, incontinence, decreased stream, hesitancy, postvoid dribbling, and a sensation of inadequate emptying. Suprapubic pain or a palpable bladder indicates urinary retention. Infection may be present, and patients may experience dysuria. Hematuria may be present with or without infection.

Digital rectal examination can reveal prostatic enlargement, decreased rectal tone, or prostatitis. Urethral stricture often requires cytoscopy for diagnosis. Meatal stenosis is usually apparent on physical examination. Patients with urethral stricture may report a history of trauma, instrumentation, or sexually transmitted disease. Also, they may also experience split urinary stream. In women, the presence of uterine or bladder prolapse can be visualized on a pelvic examination. A urethral diverticulum can also be palpated on pelvic examination.

INDICATIONS

Section 3 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

A patient with complete urinary obstruction; any type of obstruction in a solitary kidney; obstruction with fever, infection, or both; or renal failure needs immediate attention by an urologist. If a patient has pain that is uncontrolled with oral medications or nausea and vomiting that causes dehydration, they also need immediate attention.

RELEVANT ANATOMY

Section 4 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

Obstruction to urinary flow can occur anywhere from the kidneys to the urethral meatus. Certain points along this path are more susceptible to obstruction. The 3 points of narrowing along the ureter include the UPJ, the crossing of the ureter over the area of the pelvic brim at the level of the iliac vessels, and the UVJ.

CONTRAINDICATIONS

Section 5 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

Different procedures carry different relative and absolute contraindications. Prior to any elective surgical intervention, the urine should be sterile and all coagulation parameters should be normal.

In the setting of pelvic trauma with possible urethral disruption, some urologists advocate placement of a suprapubic catheter instead of a Foley catheter because a Foley catheter can worsen the urethral disruption, introduce infection into a pelvic hematoma, and worsen pelvic bleeding.

When dealing with a pregnant woman with an obstructed urinary tract, some urologists place a ureteral stent, while others prefer placement of a percutaneous nephrostomy tube.

When patients have had previous abdominal or pelvic surgery, some urologists may prefer placing an open suprapubic tube instead of a percutaneously placed tube for fear of bowel injury.

WORKUP

Section 6 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

Lab Studies

• Urinalysis
• • Urinalysis can provide useful information in evaluating for infection or hematuria.
  • WBCs in the urine can indicate infection or inflammation.
  • Nitrite- or leukocyte esterase–positive urine indicates infection.
  • All urine that contains WBCs or is positive for nitrite or leukocyte esterase should be sent for culture analysis and antibiotic susceptibility.
  • RBCs in the urine can be present in infection, stones, or tumor. A urologist should evaluate all patients with microscopic or gross hematuria in order to assure that malignancy is not present. These patients require urine cytology and a full hematuria work-up (cystoscopy, upper urinary tract imaging).
  • Urine pH is useful in the evaluation and workup of stones.
• Basic metabolic panel
• • Renal insufficiency is detected on a basic metabolic panel based on elevated BUN and creatinine levels. This can result from bilateral renal obstructive processes or obstruction in a solitary kidney.
  • Other metabolic abnormalities can also be present in renal insufficiency. Hyperkalemia and acidosis may be present.
• Complete blood count
• • Leukocytosis is an indication of infection.
  • Anemia can be acute (eg, blood loss) or due to chronic processes (eg, chronic renal insufficiency, malignancy).

Imaging Studies

• Ultrasonography
• • Ultrasonography of the kidneys and bladder is a useful imaging modality as an initial study. It is a noninvasive inexpensive study that does not involve radiation exposure or depend on renal function.
  • In patients with intravenous pyelography (IVP) dye allergies or elevated creatinine levels, this is a useful source of imaging.
  • In children, this is often part of the initial workup for obstructive processes.
  • Ultrasonography is sensitive in revealing renal parenchymal masses, hydronephrosis, distended bladder, and renal calculi.
  • The accuracy of this imaging modality heavily depends on the experience of the ultrasonographer.
  • In adults, if the ultrasonography findings are abnormal in any way, additional imaging is usually recommended.
• Computerized tomography scan
• • A CT scan is very useful in providing anatomic detail and is often a first-line test in the evaluation of a patient.
  • A CT scan provides information regarding the urinary tract, as well as any possible retroperitoneal or pelvic pathologic condition that can affect the urinary tract via direct extension or external compression.
  • A noncontrast CT scan should be obtained to assess for calculi.
  • A contrasted CT scan is needed to provide information on renal pathology.
  • If delayed contrast images are obtained, a CT urogram with 3-dimensional reconstruction can provide excellent visualization of the entire upper urinary tracts. A CT scan can be used to identify or rule out any other intra-abdominal processes that can cause presenting symptoms (eg, appendicitis, cholecystitis, diverticulitis, abdominal aneurysms, ovarian cysts).
• Intravenous pyelography
• • An IVP involves the injection of dye into the venous system and a series of kidneys, ureters, and bladder (KUB) radiographs over time.
  • It can be performed in patients with a normal creatinine value (<1.5 mg/dL) for visualization of the upper urinary tract.
  • It provides both anatomical and functional information.
  • Delayed calyceal filling, delayed contrast excretion, prolonged nephrogram results, and dilation of the urinary tract proximal to the point of obstruction characterize obstruction.
  • IVP is superior to CT scan in revealing small urothelial upper tract lesions.
  • If an IVP is inadequate, retrograde pyelography can be performed to completely visualize the renal pelvis or ureter.
  • Patients with IVP dye allergy can not undergo this test.
  • A combination CT scan and IVP (CT/IVP) test is commonplace. With this combined technique, both modalities can be used. The CT urogram, as mentioned above (see Computerized tomography scan), is also an excellent modality.
• Radionucleotide studies: A renal scan can be performed to determine the differential function of the kidneys, as well as to demonstrate the concentrating ability, excretion, and drainage of the urinary tract. Lasix can be administered with the renal scan to verify delayed excretion and the presence of obstruction.
• Magnetic resonance imaging
• • MRI is not a first-line test used to evaluate the urinary tract.
  • In patients who cannot tolerate a CT scan with contrast, an MRI with gadolinium can be performed to reveal any enhancing renal lesions.
  • MRI is useful in delineating specific tissue planes for surgical planning, as well as in evaluating the presence or extent of a renal vein or inferior vena cava thrombus in cases of renal tumors.
  • MRI does not reveal urinary stones so is not often used as a first-line test.
• Retrograde urethrography: Radiographic dye is injected into the urethral meatus via Foley catheter at the distal urethra. Fluoroscopy is used to visualize the entire urethra for stricture or any abnormalities. This test can be particularly useful in working up lower urinary tract trauma.
• Retrograde pyelography: See Cystoscopy with retrograde pyelogram.
• Nephrostography: This can be performed in patients who have a nephrostomy tube in place. Radiographic dye is injected antegrade through the nephrostomy tube. With fluoroscopy, any abnormalities or filling defects in the renal pelvis or ureter are visible. This can be performed in patients with IVP contrast allergies.

Diagnostic Procedures

• Cystoscopy: Cystoscopy is the placement of a small camera called a cystoscope through the urethral meatus and passing through the urethra into the bladder. Any abnormalities in the urethra, prostatic urethra, bladder neck, and bladder can be visualized. This can be performed in the office or in the operating room.
• Cystoscopy with retrograde pyelogram: Retrograde pyelography is performed in the operating room with a cystoscope in the bladder. Radiographic dye is injected into each ureteral orifice. Then, with the use of fluoroscopy, any ureteral or renal pelvis filling defects or abnormalities can be visualized. The contrast load does not interfere with renal function and can be used in patients with elevated creatinine levels. It can also be used in patients with an IVP dye allergy because the contrast remains extravascular.

Histologic Findings

When upper urinary tract obstruction occurs, the kidney undergoes interstitial fibrosis, with the accumulation of collagens and other extracellular matrix components.

Staging

No staging system exists for urinary tract obstruction.

TREATMENT

Section 7 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

Medical therapy

A consultation with a urologist should be obtained in patients with urinary tract obstruction, as in hydronephrosis or urinary retention. A patient with complete urinary obstruction; any type of obstruction in a solitary kidney; obstruction with fever, infection, or both; or renal failure needs immediate attention by an urologist. Patients with pain that is uncontrolled with oral medications or nausea and vomiting that causes dehydration also need immediate attention.

A partial urinary tract obstruction in the absence of infection can be initially managed with analgesics and prophylactic antibiotics until a complete urologic evaluation is performed and definitive management is completed.

Antibiotics are often given for prophylaxis and should cover common urinary tract pathogens. Commonly used antibiotics include trimethoprim- sulfamethoxazole, nitrofurantoin, cephalosporins, and fluoroquinolones.

Pain secondary to urinary tract obstruction is often managed with oxycodone, hydrocodone, acetaminophen, and nonsteroidal anti-inflammatory medications.

Surgical therapy

The goal of surgical intervention is to completely relieve the urinary tract obstruction. This can evaluated with reimaging to ensure that the obstruction is resolved, as well as renal function monitoring with a creatinine laboratory test. The recovery of renal function depends on the severity and duration of obstruction.

Different interventions can be performed to temporarily relieve the point of obstruction. Surgical intervention is usually obtained once the point of obstruction is identified with radiographic imaging.

Lower urinary tract obstruction (bladder, urethra) can be relieved with the following:

• Urethral catheter
• • A urethral catheter is a flexible external catheter that extends from the bladder through the urethra.
  • A physician or nurse can place it. If catheter placement is difficult, a urologist may be needed to avoid urethral trauma. The urologist may need to perform urethral dilation, cystoscopy, or both to pass the catheter.
  • The catheter can be left indwelling, or, as an alternative, the patient can perform clean intermittent catheterization.
  • If blood is present at the urethral meatus after pelvic trauma and suspicion of urethral injury exists, a urologist should be consulted prior to catheter placement. Retrograde urethrography needs to be performed to rule out urethral injury.
• Suprapubic tube or catheter: If a Foley catheter cannot be passed, a suprapubic tube can be placed percutaneously (at the bedside) or in an open fashion (in the operating room). A suprapubic tube is placed on the lower anterior abdominal wall, approximately 2 finger-breadths above the pubic symphysis.

Upper urinary tract obstruction (ureter, kidney) can be relieved with the following:

• Ureteral stent: A ureteral stent is a flexible tube that extends from the renal pelvis to the bladder. It can be placed during cystoscopy to relieve obstruction along any point in the ureter. A ureteral stent generally needs to be changed every 3 months.
• Nephrostomy tube: A nephrostomy tube is a flexible tube that is placed through the back into the renal pelvis. If a ureteral stent cannot be placed cystoscopically in a retrograde fashion, a percutaneous nephrostomy tube can be inserted for relief of hydronephrosis. If needed, a ureteral stent can then be passed in an antegrade fashion through the nephrostomy tube tract.

The following are urologic emergencies that require immediate attention and intervention:

• Complete urinary tract obstruction
• Any type of obstruction in a solitary kidney
• Obstruction with fever, infection, or both
• Renal failure
• Pain that is uncontrolled with oral medications
• Nausea and vomiting that causes dehydration

Preoperative details

Before any surgical intervention or any manipulation of the urinary tract, broad-spectrum antibiotics should be initiated to prevent infection or urosepsis. Ideally, before any manipulation is performed, the urine should be sterile. However, this may not be possible in cases of emergent surgical intervention. Urine culture along with the administration of broad-spectrum antibiotics is important.

If cystoscopy and stent are needed emergently, coagulation is not a concern. If percutaneous drainage is necessary, coagulopathies should be corrected.

Intraoperative details

Different interventions can be performed to temporarily relieve the point of obstruction. If the planned procedure cannot be performed safely or is not adequate in relieving urinary tract obstruction, other modes of urinary tract decompression can be tried.

Postoperative details

When a patient has long-standing urinary obstruction that has been relieved, they may experience postobstructive diuresis. This physiologic diuresis is usually a self-limiting diuresis that can be managed conservatively with fluid replacement and, if needed, electrolyte replacement.

Follow-up

Definitive treatment at the point of obstruction is needed after the acute obstruction is resolved. Adults and children often have different etiologies of urinary tract obstruction. Thus, various definitive surgical treatment options are available for each condition. After definitive treatment is achieved, a final imaging study is obtained to verify complete relief of the obstruction. The type of study performed, as well as the timing of the study, is left to the discretion of the urologist.

For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center. Also, see eMedicine's patient education articles Intravenous Pyelogram, Cystoscopy, Magnetic Resonance Imaging (MRI), and CT Scan.

COMPLICATIONS

Section 8 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

A patient with urinary tract obstruction should see a urologist promptly because of the serious complications that the obstruction can impose. The following are complications of obstructive uropathy:

• Infection, including cystitis (bladder infection), pyelonephritis (kidney infection), abscess formation, and urosepsis
• Urinary extravasation with urinoma formation
• Urinary fistula formation
• Renal insufficiency or failure
• Bladder dysfunction secondary to a defunctionalized bladder
• Pain

OUTCOME AND PROGNOSIS

Section 9 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

Prognosis depends on the cause, location, degree, and duration of obstruction, as well as the presence of a urinary tract infection. The longer the duration of obstruction, the greater the severity of obstruction, and the presence of a concomitant infection can lead to a worse prognosis. The prognosis is favorable if the renal function is normal, the infection is cleared, and the obstruction is relieved in a timely manner.

FUTURE AND CONTROVERSIES

Section 10 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

As time goes on, new procedures emerge and old procedures are modified to relieve urinary tract obstruction. In addition, with newer cameras and equipment and the use of laparoscopy, surgical intervention is becoming more advanced.

ACKNOWLEDGMENTS

Section 11 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthor Martin I Resnick, MD, to the development and writing of this article.

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• Acknowledgments
• References

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• Kabalin JN. Surgical anatomy of the retroperitoneum, kidneys, andureters. In: Walsh PC, Retik AB, eds. Campbell's Urology. 7th ed. Philadelphia, Pa:. WB Saunders and Co;1998.
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• Macfarlane MT. Obstructive uropathy. In: Urology. 2nd ed. Philadelphia, Pa:. Williams & Wilkins;1995:97-102.
• McNaughton-Collins M, Barry MJ. Managing patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia. Am J Med. Dec 2005;118(12):1331-9.
• Resnick MI, Kursh ED. Extrinsic obstruction of the ureter. In: Walsh PC, Retik AB, eds. Campbell's Urology. Vol 1. Philadelphia, Pa:. WB Saunders and Co;1998:387-422.
• Sty JR, Pan CG. Genitourinary imaging techniques. Pediatr Clin North Am. Jun 2006;53(3):339-61.
• Tanagho EA. Urinary obstruction and stasis. In: Tanagho EA, McAninch JW, eds. Smith's General Urology. New York, NY:. McGraw-Hill;1995:172-185.
• Thomas AW, Cannon A, Bartlett E, et al. The natural history of lower urinary tract dysfunction in men: minimum 10-year urodynamic follow-up of untreated bladder outlet obstruction. BJU Int. Dec 2005;96(9):1301-6.
• Thomas AW, Cannon A, Bartlett E, et al. The natural history of lower urinary tract dysfunction in men: minimum 10-year urodynamic followup of transurethral resection of prostate for bladder outlet obstruction. J Urol. Nov 2005;174(5):1887-91.

Article Last Updated: Jun 12, 2006