The corpus spongiosum is a column of spongy, vascular tissue located along the underside of the penis. This tissue surrounds the entire length of the urethra, the tube through which both urine and semen exit the body. During an erection, the corpus spongiosum fills with blood but remains relatively flexible compared to the paired corpora cavernosa. This flexibility prevents the urethra from becoming compressed as the penis stiffens, ensuring the channel remains open for ejaculation. Damage to this spongy layer is considered a serious urological injury due to its connection with the urinary tract.
Mechanisms Leading to Injury
Damage to the corpus spongiosum most commonly results from significant external forces applied to the erect or semi-erect penis. The most frequent cause involves blunt force trauma during sexual activity, often referred to as a “false step of coitus.” This occurs when the erect penis forcefully strikes the partner’s pubic bone or perineum. This sudden, forceful bending can tear the delicate tissue and the surrounding sheath, resulting in a rupture.
Non-sexual blunt trauma can also cause injury, such as a straddle injury where the perineum is crushed against a narrow object like a bicycle crossbar. This mechanism typically compresses the bulbous portion of the corpus spongiosum, which is fixed against the pubic arch, leading to localized injury. Trauma can also occur from penetrating injuries, such as stab or gunshot wounds, or from iatrogenic causes.
Iatrogenic injury refers to damage caused inadvertently during a medical procedure, such as difficult urethral catheterization or endoscopic surgery. For instance, the forceful insertion of a catheter can create a false passage through the urethral wall and tear the supporting spongiosum tissue. This damage can be subtle but initiates a scarring process within the urethral tract.
Recognizing the Symptoms of Damage
The most immediate physical sign of corpus spongiosum damage is the presence of blood at the external urethral opening, known as blood at the meatus. This symptom suggests a tear in the urethra itself, which is encased by the corpus spongiosum. The bleeding can range from a few drops to a continuous flow depending on the extent of the tear.
Following the traumatic event, the injured area will develop localized swelling and bruising as blood leaks from damaged vessels, forming a hematoma. The penis may become noticeably discolored, often presenting with a dark, rapidly expanding bruise. Patients will also experience acute pain, which worsens with any attempt at urination or erection.
A primary concern is the inability or difficulty to pass urine, which can progress to acute urinary retention. This occurs when swelling and hematoma severely compress the urethra or when the tear is extensive enough to impede flow. Any combination of these symptoms following trauma indicates a urological emergency requiring immediate medical attention.
Medical Assessment and Immediate Care
Upon arrival at a medical facility, a thorough physical examination assesses the extent of bruising, swelling, and any penile deformity. The physician looks for blood at the meatus and determines if the patient can pass urine. Retrograde urethrography (RUG) is the standard initial imaging technique used to diagnose and characterize a suspected urethral injury.
During a RUG, a contrast dye is gently injected into the urethra through the meatus, and X-ray images are taken as the dye flows toward the bladder. If there is a tear in the urethra and the corpus spongiosum, the contrast material will leak out of the normal channel, confirming the location and severity of the rupture. Further imaging, such as penile ultrasound or magnetic resonance imaging (MRI), may be used to evaluate the depth of the hematoma and confirm that the paired corpora cavernosa are intact.
Immediate care focuses on achieving urinary diversion to prevent urine from leaking into damaged tissues, which could worsen infection and scarring. Since inserting a standard Foley catheter through a torn urethra can cause further damage, a suprapubic catheter is placed directly into the bladder through the lower abdominal wall. This method effectively bypasses the injured segment of the urethra, allowing the area to rest and begin healing.
The definitive treatment involves surgical exploration and repair, particularly for significant lacerations or crush injuries. During surgery, the hematoma is evacuated, and the tear in the corpus spongiosum and the underlying urethra is repaired with fine, dissolvable sutures. Minor, non-displaced tears may be managed conservatively with only urinary diversion. However, immediate surgical repair is preferred to minimize the risk of long-term complications.
Potential Long-Term Complications
The most common long-term consequence of corpus spongiosum damage is the development of a urethral stricture. This complication results from the body’s healing process, where the injury triggers the formation of scar tissue, or fibrosis, within the spongy tissue. The contracting scar tissue narrows the urethral lumen, obstructing the flow of urine.
A stricture may not become apparent for months or even years after the initial trauma. Patients with a stricture present with a weak urinary stream, the sensation of incomplete bladder emptying, and recurrent urinary tract infections. The resistance created by the narrowed urethra can cause secondary issues like bladder wall thickening and, in severe cases, damage to the kidneys.
The treatment for a significant urethral stricture requires reconstructive surgery called urethroplasty. This procedure aims to remove the scarred segment and rejoin the healthy ends or use tissue grafts to widen the narrowed area. Urethroplasty is necessary to restore the full caliber of the urinary channel and prevent recurrent obstruction. The potential for stricture formation underscores the lasting impact of corpus spongiosum injuries.