Introduction
Urinary calculi are calcified particles found in the urinary tract. Urolithiasis is a condition in which calculi is present in the kidneys, ureter, or urinary bladder. Urethra is an uncommon site for urolithiasis. Nausea, abdominal pain, vomiting, and hematuria (blood in urine) are usually seen in this condition. Fever and chills can be present in case of a secondary infection. The calculi may vary from microscopic crystalline to a few centimeters in diameter.
What Is Urethral Calculi?
When calculus is present in the urethra, the condition is called urethral calculi. Urethra is the tube from the urinary bladder that takes the urine outside the body. Calculus is a hard stone made up of minerals and salts from the body. Urethral calculi are rare, accounting for approximately one percent of reported cases. The size and location of the stone determine its passage through the tract. Stones lesser than 5mm are likely to pass spontaneously, while the bigger ones (i.e., bigger than 10mm) are unlikely to pass spontaneously. Recent studies show an increase in female prevalence in the condition, which previously was thought to be a dominant male disease.
What Are the Signs and Symptoms Of Urethral Calculi?
Large calculi in the kidneys are usually asymptomatic until they cause an obstruction or an infection.
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Severe pain is usually associated with nausea and vomiting as the calculi pass to the ureter and cause an obstruction.
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Hematuria (blood in the urine) can also be seen.
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Renal colic is the pain when a stone gets obstructed in any part of the urinary system. Renal colic in urethral calculi can be excruciating and intermittent; It is usually cyclic and intermittent and may last about 20 minutes to an hour.
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Flank pain ( the area below the ribs and above the hips is called the flank). Ureteral or pelvic obstruction can cause pain that spreads over the abdomen. If the pain radiates along the course of the ureter, it can be a lower ureteral obstruction. Suprapubic pain(pain in the lower abdomen) and urinary urgency can indicate a distal ureteral or bladder calculi.
What Is the Pathophysiology Behind Urethral Calculi?
Eighty-five percent of the urethral calculi comprises calcium oxalate. The mechanism of calculi formation is still a topic of dispute among researchers. The calculi are generally classified into two types; primary and secondary calculi. Primary calculi occur independently secondary to other pathologies like diverticula(a small bulge that forms in the lining of the digestive system), strictures, neurogenic bladder(nerves that carry signals to and fro the bladder are impaired), etc. Secondary calculi are more common and occur in the upper urinary tract.
How Is Urethral Calculi Diagnosed?
The diagnosis of urethral calculi is mainly based on clinical signs and presentations, in addition to the cystoscopic evaluation in addition to the clinical examination, the history of the patient, etc. Investigations like urine analysis, urine culture sensitivity, complete blood count, blood urea, serum creatinine, and serum uric acid are done. Radiologic studies include plain abdominal film intravenous urography, abdominal ultrasound, and retrograde urethrography. Retrograde urethrography(RUG) is usually the standard modality for the evaluation of the condition of the urethra. The process is simple and can be done bedside. It involves injecting 20-30ml of water-soluble dye into the urethral meatus and taking an X-ray. Imaging studies like non-contrast CT can help find the calculi's anatomical location and size.
How Is Urethral Calculi Treated?
The mode of treatment depends on the size and location of the calculi, as explained below:
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Analgesia: Painkillers are used to relieve the pain associated with urethral calculi. The vomiting usually resolves with the reduction of pain. But if vomiting persists, the doctor would suggest an anti-emetic as well.
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Expulsive Therapy: Although increased fluid consumption is recommended, it is not scientifically proven. This is considered useful in the passage of the calculi through the bladder. Patients with less than 1mm calculi can be managed with analgesics, increased fluid administration, and alpha-blockers that can help the calculus pass easily. Calculi that are not removed within six to eight weeks might require surgical removal. Patients with suspected infections can be treated to resolve the infection first, then remove the calculi.
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Calculi Removal: The size and anatomical location of the calculus determine the removal of the calculus. The technique to remove calculus includes extracorporeal waves lithotripsy and endoscopy techniques to ensure the complete removal of the calculi. Endoscopic procedures can be rigid or flexible. Smaller calculi are removed as such, while larger ones might require to be fragmented.
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Calculi Dissolution: Uric acid calculi can be dissolved using potassium citrate. This alkalizes the urine, dissolving the crystal gradually. Calcium and oxalate crystals cannot be dissolved easily using this technique.
What Are the Differential Diagnosis of Urethral Calculi?
The differential diagnoses of urethral calculi include:
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Pelvic Phlebolith: Phleboliths are tiny masses of calcium deposits in the vein. It is called pelvic phlebolith when they are found in the pelvic area.
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Prostatic Calcification: When calcification occurs in the prostate gland, the condition is called prostatic calcification. This blocks the small sacs that secrete fluid into the urethra resulting in infection and precipitation of lime. Transrectal ultrasound can help differentiate prostatic calcification from urethral calculi.
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Coaptite Injection: This is used to treat urinary incontinence. Coaptite injection is used to close the bladder to the middle of the urethra.
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Peritonitis: Inflammation of the abdominal wall is called peritonitis. Severe abdominal pain can be seen, which increases even with slight movement.
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Cholecystitis: The patient will have colicky pain in the abdomen.
Conclusion
Urethral calculi are the rarest form of urinary tract calculi with no established prevalence and no standard management or treatment. The passage of the stone depends on the size and location of the stone. Stones smaller than 5 mm can easily pass spontaneously, while the bigger ones (bigger than 10 mm) are unlikely to pass spontaneously. The calculi's size and location in the urethra determine the treatment.
