History and exam
Key diagnostic factors
common
signs of early organ dysfunction (tachypnea, tachycardia, hypotension, altered mental state) in a patient with suspected sepsis
In patients with fever or hypothermia, leukocytosis or leukopenia, tachypnoea, and tachycardia, a validated scoring system such as the quick Sequential [sepsis-related] Organ Failure Assessment (SOFA) score by the bedside can detect the risk of deterioration due to sepsis.[30] A patient is considered to be at high risk of an adverse outcome if at least two of the following three criteria are present: altered mental state (Glasgow Coma Scale <15), respiratory rate of 22 breaths per min or greater, or systolic blood pressure of 100 mmHg or less.
flank pain
Patients with acute obstruction will often present with flank pain, especially if the cause is unilateral.
The most common cause is urolithiasis, but uncommon causes such as cancer or ureteral strictures can also be responsible.
If a patient has fever, infection within an obstructed system must be excluded.
fever
Suggestive of urinary tract infection.
Infection in the setting of obstruction is a strong indicator for urgent intervention.
lower urinary tract symptoms
Symptoms such as frequency, urgency, decreased force of stream, and incomplete emptying are suggestive of disease at the level of the bladder or bladder outlet.
The most common cause is benign prostatic hyperplasia; other causes include neurogenic bladder, urethral stricture, and obstruction due to malignancy.
distended abdomen/palpable bladder
Distended abdomen may be due to an enlarged bladder that can often be palpated in the lower abdomen and is dull to percussion.
inability to urinate
In combination with a distended abdomen, this is virtually diagnostic of acute urinary retention.
enlarged or hard nodular prostate on rectal examination
Smooth enlargement with preserved median sulcus is consistent with benign prostatic hyperplasia.
A hard nodular mass, loss of median sulcus, or asymmetry may suggest prostate cancer.
costovertebral angle tenderness
Often present in patients with obstruction and infection.
uncommon
neurological disease (e.g., spinal cord injury, multiple sclerosis)
Bladder dysfunction is a common cause of chronic obstructive uropathy.
May have clinically silent retention.
Other diagnostic factors
common
haematuria
Obstructive uropathy does not cause haematuria, but many conditions that lead to obstruction may also cause haematuria (e.g., benign prostatic hyperplasia, urolithiasis, infection, malignancy within the urinary tract).
Haematuria can also cause clot retention.
increasing age
Older patients are more likely to have benign prostatic hyperplasia, malignancy, or bladder dysfunction due to neurological problems.
meatal narrowing
May be due to urethral mass, phimosis, or meatal stenosis.
uncommon
pelvic or abdominal malignancy
Ureteral or bladder outlet obstruction should be suspected in patients with a history of malignancy, especially gynaecological or pelvic cancer.
previous urethral instrumentation
urinary tract infection in a child
In infants, consider posterior urethral valves and other anatomical abnormalities, such as ureterocele, ureteropelvic junction obstruction, and vesicoureteral reflux.
pelvic mass on internal examination
May suggest malignancy or a pelvic organ prolapse.
weight loss and lymphadenopathy
May be found in association with obstructive uropathy if there is underlying malignancy.
recurrent urinary tract infections
This may suggest bladder outlet obstruction or poor detrusor function, resulting in urinary stasis, which can predispose to infection.
urinary incontinence
Overflow incontinence may result from urinary retention.
Risk factors
strong
benign prostatic hyperplasia (BPH)
Can cause both chronic and acute bilateral obstructive uropathy.
Men with untreated symptomatic BPH have a 2.4% incidence of acute urinary retention.[13] Risk factors for developing urinary retention in men with BPH include prostate volume >31 mL, prostate-specific antigen >1.6 microgram/L (>1.6 nanogram/mL), flow rate <10.6 mL/second, post-voiding residual volume >39 mL, and age >62 years.[1]
Similar risk factors exist for developing chronic kidney disease.[18]
constipation
Bowel dysfunction is often found in patients with urinary retention, particularly young women and children.[14]
It can worsen urinary retention in patients who already have other risk factors, such as neurogenic bladder from spinal cord injury.
medication (anticholinergic agents, opioid analgesics, alpha receptor agonists)
Side effects of many medications include urinary retention.[16]
It may be necessary to stop the medication or switch to an alternative drug, depending on the balance of risks and benefits.
urolithiasis (ureteric calculi)
Passing kidney stones can frequently cause acute unilateral obstructive uropathy. Stones 5 mm or smaller are more likely to pass spontaneously, with immediate resolution of the obstruction.[19] Larger stones are more likely to require intervention.
spinal cord injury, Parkinson's disease, or multiple sclerosis
Patients with injuries to the spinal cord or neurological disorders such as Parkinson's disease and multiple sclerosis often have involvement of the bladder. In many cases, the detrusor muscle fails to function properly, leading to urinary retention and obstructive uropathy. Abnormal detrusor function can also result in elevated storage pressures and subsequent upper tract compromise.
Progressive damage of the kidneys in multiple sclerosis is associated with duration of multiple sclerosis, presence of an indwelling catheter, high amplitude detrusor contractions, and permanently high detrusor pressure.[20]
malignancy
Though uncommon, malignancy in many locations may initially present as obstructive uropathy, or it may be a later effect as the disease spreads.[21]
The most common types of malignancy causing urinary tract obstruction are prostatic, bladder, cervical, and colon.
posterior urethral valves
A congenital anatomical abnormality occurring in males. The disorder can be diagnosed by characteristic findings on antenatal ultrasound or may be diagnosed after a child develops a urinary tract infection (UTI).
Newborns with hydronephrosis and UTIs should be evaluated by a urologist.
meatal stenosis
Patients with meatal stenosis may develop such severe disease that they develop urinary retention. This is diagnosed on physical examination or on attempted catheter placement.
weak
pregnancy
Pregnancy can be associated with obstruction of the kidneys. Obstruction in pregnancy is most often unilateral and is thought to be both physiological (related to the muscle relaxant effect of progesterone) and anatomical (due to uterine compression).[22]
In most cases, hydronephrosis of pregnancy is benign but may progress to become symptomatic, with associated increased risk of infection in <3% of cases.[22] Pregnant patients can also develop other disorders such as urolithiasis, and these causes should be considered when evaluating the pregnant patient with hydronephrosis.
haematuria
Rarely, bleeding from the urinary tract can lead to clot retention, when blood clots block the flow of urine.
Bleeding may arise from numerous causes including BPH, cancer, papillary necrosis, arteriovenous malformation, and trauma, or may be secondary to anticoagulation therapy.
bladder hernia
An uncommon cause of urinary tract obstruction is herniation of the bladder into the inguinal canal.[23]
cystocele
A cystocele may cause an anatomical restriction of the urethral outflow tract and result in obstructive uropathy.
iatrogenic injury
It is possible for one of the ureters to become damaged during abdominopelvic surgery because of the proximity of structures.[10]
urethral instrumentation
retroperitoneal fibrosis
An uncommon condition, but patients may present with bilateral obstructive uropathy due to extrinsic compression of the ureters.[26]
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