Hydronephrosis
From Medical-Wiki
Hydronephrosis is dilation of the renal pelvis and calyces. Hydroureter is dilation of the ureter. While both conditions are usually in response to obstruction, this is not always the case.
When obstruction occurs, it may occur at any point from the kidneys to the urethral meatus. The pathological response to an increase in backflow pressure is immediate. Glomerular filtration rates (GFR) decline within hours. Tubular transport becomes concomitantly impaired. GFR may remain decreased for weeks following the event. In the case of chronic flow disruption, profound tubular atrophy may occur. Chronic hydronephrosis also produces anatomic change. If this process continues long enough, the kidney may be left with only a thin rim of parenchyma. [1]
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Points of obstruction
The most common points for obstruction to occur are the ureteropelvic junction (UPJ), the crossing of the ureter over the area of the pelvic brim (the iliac vessels), and the ureterovesical junction (UVJ).
Women may additionally be obstructed at the point where the ureter crosses posterior to the pelvic blood vessels and the broad ligament in the posterior pelvis, and the ureter may be flattened by pelvic tumors and GYN malignancies. Pregnancy may also result in obstruction from the gravid uterus.
In men, an enlarged prostate from benign prostatic hypertrophy (BPH) and urethral stricture can both lead to urinary obstruction.
Men and women may both be obstructed by calculi, strictures, and intrinsic and extrinsic tumors.
In the pediatric population, UPJ or UVJ obstruction, ectopic ureter, ureterocele, megaureter, and posterior urethral valves can all cause obstruction.
Clinical presentation
Clinically, acute upper tract obstruction may present with flank pain, ipsilateral back pain, groin pain, nausea and vomiting. If infection is present, patients may experience fever, chills, and dysuria. Hematuria may also occur. In the presence of bilateral obstruction, uremia may occur. Uremia may produce weakness, peripheral edema, mental status changes, and pallor. With severe hydronephrosis, an abdominal mass may be palpable. With infection, costovertebral angle (CVA) tenderness may be present.
Lower tract obstruction—at the level of the bladder and urethra—may be expressed as urgency and voiding dysfunction. Associated symptoms are urgency, frequency, nocturia, incontinence, decreased stream, hesitancy, post-voiding dribbling, and a sensation of inadequate emptying.
Causes
Of all the causes of obstruction, an impacted renal calculus is the most common pathology. Intraluminal obstruction may also be caused by blood clots and mucosal edema because of calculus passage or following instrumentation of the ureter, trauma, or anticoagulant therapy.
Morbidity & mortality
Surgical errors causing ureteral ligation are a common complication of abdominal and pelvic procedures. Blunt and penetrating pelvic trauma can cause rupture of the ureter or compression from a retroperitoneal hematoma that can also lead to obstruction. Rarely, extrinsic compression from an abscess or inflammatory mass from appendicitis, pancreatitis, or Crohn disease can occur mild or complete obstruction. [2]
Diagnosis
Clinical findings
On physical examination, a digital exam may reveal prostatic enlargement, decreased rectal tone, or prostatitis. In the case of a kidney stone, imaging or cystoscopy may be needed to confirm a diagnosis. Physical exam will usually reveal meatal stenosis. In women, uterine or bladder prolapse may be visualized on pelvic examination. [3]
Radiological findings
The type of appropriate imaging is contingent upon the nature of the primary problem. The algorithm for a renal calculus, for example, include plain radiographs, helical CT scans, and in some cases cystoscopy. For pelvic pathology, however, pelvic ultrasonography is the most appropriate technique.
Treatment
Treatment is contingent upon treating whatever is the primary pathology.
