Megalourethra

 

Recently, I got involved in the care of a newborn patient with a fusiform megalourethra. On examination, I was not able to palpate any corporal tissues. The penile skin was massive and the urethra had to be “milked” to get the urine out. At this point, it was clear to me the boy was destined to have issues voiding and with erectile function.

 

Etiology

A megalourethra is caused by a lack of corpus spongiosum and sometimes corpus cavernosa in the distal urethra which results in massive ballooning of the urethra. The glans and fossa navicularis are usually normal.

 

Types of Megalourethra

Scaphoid: ventral urethral dilation only, similar to a urethral diverticulum. The two corpora cavernosa are normal.

Fusiform: circumferential dilation due to deficiency of all 3 corporal bodies.

The patient I saw had a clear deficiency of all 3 corporas. The picture below is from an attempt at VCUG where the catheter got coiled inside the distal urethra:

 

Associations

Most case reports describe associations with anomalies in multiple organ systems such as VACTERL and Prune Belly syndrome.

Urinary Drainage

Some of the cases in the literature report issues with voiding and the need for vesicostomy or perineal urethrostomy. In some reports, the voiding problems developed over time — highlighting the need to closely monitor these patients.

 

Surgical Reconstruction

Scaphoid Megalourethra

The surgery to repair a scaphoid megalourethra is akin to a urethral diverticulum repair with good outcomes reported in case reports.

Fusiform Megalourethra

The repair of the fusiform megalourethra is a bigger challenge.

This article from 1996, mentioned that 11 patients with fusiform megalourethras had been described in the literature up to that point most of who had died or had renal failure. The article describes 2 cases of fusiform megalourethra: One of the patients died soon after birth and after a vesicostomy from urosepsis. The other patient underwent staged reconstruction but ended up losing the penis during the last surgery after extensive dissection of the neurovascular bundle.

Besides these 2 cases, I was not able to find any reports describing the surgical reconstruction of the fusiform megalourethra. After reading about the boy that lost the penis during attempted reconstruction with mobilization of the neurovascular bundle, I would err on the side of doing less rather than more for these patients. Maybe the best approach is to do a perineal urethrostomy if anatomically feasible or a vesicostomy if a urethrostomy would not work, and then just wait until puberty to do any major penile reconstruction. All the redundant tissues left alone may come in handy after puberty to create a more normal postpubertal phallus and possibly allow for the insertion of a penile prosthesis.

 

Conclusion

Megalourethras occur due to the distal deficiency of the corporas. The scaphoid type occurs when the 2 corpora cavernosa are intact and its repair is relatively straightforward. The fusiform type occurs with a deficiency of the 3 corporas, and poses and major reconstructive challenge.

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