What causes blockade in ureter
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A ureteric blockage (ureteral obstruction) occurs when urine cannot pass normally from the kidney to the bladder. Causes include:
- Ureteric stone: the most common acute cause.
- Narrowing or scar tissue (stricture): after surgery, radiation, infection such as tuberculosis, injury, or previous stone procedures.
- Tumors: cancer arising in the ureter, kidney, bladder, cervix, uterus, prostate, colon, or retroperitoneum may block or compress the ureter.
- External compression: enlarged prostate indirectly causing urinary obstruction, pregnancy, pelvic masses/fibroids, enlarged lymph nodes, or retroperitoneal fibrosis.
- Blood clot, sloughed papilla, or fungal ball within the ureter.
- Congenital abnormalities: especially ureteropelvic-junction obstruction, abnormal ureter insertion, or a crossing blood vessel.
- Inflammation/infection: swelling from severe ureteritis or adjacent inflammatory disease.
- Bladder outlet obstruction or reflux-related high pressure, which can impair drainage from one or both ureters.
A blockage can lead to hydroureter and hydronephrosis, pain, infection, and reduced kidney function if prolonged.
Urgent assessment is needed if there is fever or chills, severe flank pain, vomiting, very little/no urine, a single functioning kidney, or known kidney disease, because an infected obstructed kidney requires emergency drainage.
How is ureteric obstruction like hydroureteronephrosis diagnosed and treated?
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https://www.nhs.uk/conditions/hydronephrosis
Hydroureteronephrosis means dilatation of the ureter and kidney collecting system due to impaired urine drainage. It may be unilateral or bilateral. It is often due to an obstruction, but dilatation alone does not always prove a fixed blockage, such as in pregnancy or vesicoureteric reflux.
Diagnosis
1. Clinical assessment
A clinician asks about:
- Colicky flank pain, nausea/vomiting, blood in urine, fever or urinary symptoms
- Reduced urine output, urinary retention, prior stones or urinary procedures
- Cancer, pelvic surgery/radiotherapy, pregnancy, neurological bladder disease, or medications
- In men, symptoms of prostatic obstruction
Examination may look for fever/sepsis, bladder distension, abdominal or pelvic mass, and prostate enlargement.
2. Laboratory tests
- Urinalysis and urine culture: blood, infection, crystals.
- Blood tests: serum creatinine/eGFR, urea, electrolytes, complete blood count, inflammatory markers when infection is suspected.
- Pregnancy test where relevant.
3. Imaging
- Ultrasound is generally the first test. It shows hydronephrosis/hydroureter, kidney size, bladder residual urine, and sometimes the obstruction.
- Non-contrast CT of kidneys, ureters and bladder (CT KUB) is the most accurate test for suspected ureteric stones.
- Contrast CT urography may be used to define a stricture, mass, injury, or level/cause of obstruction when kidney function permits.
- MRI/MR urography is useful when radiation or iodinated contrast should be avoided, particularly in pregnancy.
- Cystoscopy with retrograde pyelography can directly assess the bladder, ureteric opening, and narrowing, and may allow stent insertion.
- Diuretic renography assesses drainage and split renal function when obstruction is uncertain or chronic, for example in suspected UPJ obstruction.
A history, urine testing, kidney-function testing, and ultrasound are core initial investigations; CT is particularly useful when calculi are suspected. This is consistent with Comprehensive Clinical Nephrology, which describes ultrasound as first-line and CT as preferred for suspected stones.
Treatment
Treatment has two goals:
- Urgently decompress the kidney when needed
- Treat the cause of obstruction
Immediate management
- Pain relief and antiemetics.
- IV fluids only when clinically needed, not forced excessive fluids.
- Antibiotics if urinary infection is suspected, guided by urine and blood cultures.
- Monitor urine output, renal function, and electrolytes.
Urgent drainage
Urgent urology intervention is needed for:
- Obstruction plus fever/sepsis or pyonephrosis
- Acute kidney injury, rising creatinine, or high potassium
- Bilateral obstruction or obstruction in a solitary functioning kidney
- Severe persistent pain/vomiting despite treatment
- Complete obstruction or anuria
Drainage is achieved by either:
- Retrograde ureteric stent (double-J stent): inserted through the bladder into the ureter to bypass the obstruction.
- Percutaneous nephrostomy: a tube placed through the back directly into the renal pelvis, especially if stenting fails or cannot be performed.
An infected obstructed kidney is an emergency: antibiotics alone are not enough without prompt drainage.
Definitive treatment by cause
| Cause | Typical definitive treatment |
|---|---|
| Ureteric stone | Observation for selected small stones, medical expulsive therapy in appropriate patients, ureteroscopy with laser lithotripsy, shock-wave lithotripsy, or percutaneous stone removal for large/complex stones |
| Ureteric stricture | Temporary stent or nephrostomy, balloon dilatation/endoureterotomy in selected cases, or surgical ureteric reconstruction/reimplantation |
| UPJ obstruction | Observation if mild with preserved function, otherwise pyeloplasty |
| Tumor or external compression | Stent or nephrostomy for drainage, plus treatment of the underlying cancer or pelvic/retroperitoneal disease |
| Bladder outlet obstruction | Bladder catheter first, then treatment such as medicines or surgery for an enlarged prostate; other causes need tailored management |
| Pregnancy-related obstruction | Usually conservative treatment and monitoring; stent or nephrostomy if severe pain, infection, renal impairment, or persistent obstruction |
| Reflux/congenital abnormality in children | Pediatric urology follow-up, serial ultrasound and functional testing; selected cases need reconstructive surgery |
After drainage or correction, repeat kidney-function tests and imaging are used to ensure recovery and confirm that the dilatation is improving. Long-standing obstruction can leave permanent loss of renal function even after it is relieved.
Hydronephrosis is generally investigated with urine/blood tests and imaging, and treatment depends on cause and severity, as summarized by the NHS hydronephrosis guidance. Recent systematic reviews address drainage choices particularly in malignant obstruction and stone obstruction during pregnancy (PMIDs 38830555 and 39356029); they do not replace individualized urology assessment.
Seek emergency care now for fever or chills with flank pain, confusion, inability to pass urine, severe vomiting, or markedly reduced urine output.
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