Megalourethra - Everything You Should Know About It!

Introduction:

Mega means large, so it is evident that a megalourethra means a urethra that is larger than usual. This condition happens when there is a deficiency or any developmental defects associated with the erectile tissues of the penis. This anomaly is usually associated with other developmental malformations involving the organs such as kidneys and other genitourinary organs. Isolated megalourethra (megalourethra without the presence of any other developmental anomaly) is very rare. The megalourethra is not very life-threatening, but the presence of other developmental abnormalities can complicate the condition. Read further to know its types, causes, prevalence, pathophysiology, differential diagnosis, and management.

What Is a Megalourethra?

Megalourethra is an abnormal non-obstructive dilatation of the penile urethra due to the deficiency or failure in the development of the erectile tissues of the penis. The erectile tissues of the penis are the corpus cavernosum (two columns of spongy tissue that are present in the penis of males on either side of the ureter) and corpus spongiosum [a column of tissue that surrounds the urethra and runs along the shaft or the body of the penis, ends in its tip (also called glans penis)]. Megalourethra is also called megaurethra, megalomaniac urethra, or a macro penis. It can be identified at any age between 16 weeks of gestation and 24 years of age.

How Prevalent Is Megalourethra?

Megalourethra is an extremely rare condition with very few reported cases in the literature. Reports suggest that only 10 cases with prenatal megalourethra were reported before 2003. After which, further research has identified 100 cases of megalourethra post-natally in infants and 80 congenital cases, which concludes the total number of cases that have been reported so far in the history of the world population. The first case of congenital megalourethra was reported in the year 1955 by Nesbitt. It is more common in the anterior urethra but can affect the posterior urethra as well (the urethral valve is divided into anterior and posterior urethral valves).

What Are the Symptoms Associated With Megalourethra?

Megalourethra can result in various problems, including;

• Urinary retention (a situation wherein emptying the entire urinary bladder is not possible, leading to retention of the urine in the bladder).

• Incontinence (lack of control over urination).

• Enuresis or bedwetting.

• Spontaneous rupture of the urinary bladder is also a very serious problem that can occur with the megalourethra.

• Swelling under the penis.

• Penis ballooning before and after urination.

• Dribbling after urination.

What Is the Pathophysiology of Megalourethra?

Though the clear pathophysiology of megalourethra is yet to be identified, a theory on the pathophysiology of megalourethra states that it occurs when the ventral mesenchymal elements of the penis fail to fuse, leading to abnormal development of corpora cavernosum, or both corpus cavernosum and spongiosum together, ultimately leading to massive urethral dilatation.

What Are the Types of Megalourethra?

In 1963, Dorairajan and Stephen classified megalourethra into the two following types;

1. Scaphoid or focal megalourethra (also called deformity of the penis).

2. Fusiform or diffuse megalourethra (impotence).

Scaphoid Megalourethra:

It is the most common type of megalourethra among the cases that have been reported. This type has been spotted in around 80 % of the reported megalourethra cases. This type of megalourethra involves only the corpus spongiosum. The corpus spongiosum is deficient or absent in this type of megalourethra. This type is less serious and mild when compared to the fusiform type.

Fusiform Megalourethra:

This type has been spotted in fewer cases and only 20 % of the total cases. This type of megalourethra involves both the corpus cavernosum and corpus spongiosum. Both these structures are deficient or absent in this type. It is also found that this type of megalourethra has a very poor prognosis and is very serious comparatively.

What Are the Diagnostic Tests for Megalourethra?

Detailed investigation of the upper and lower urinary tract is required to identify megalourethra as early as possible to minimize the complications and morbidity rate. Following are the tests that are usually performed to identify and analyze megalourethra. The tests are selected based on the patient’s condition and the preference of the doctors.

• CT (computed tomography) scan.

• Ultrasound abdomen and pelvis.

• Urethrogram (examination of the male urethra by using X-rays).

• Cystoscopy (It is the endoscopy of the urinary bladder, which is accessed through the urethra).

• Serum urea and creatinine levels need to be monitored periodically.

What Are the Syndromes and Conditions Associated With Megalourethra?

Following are a few common syndromes which, along with other developmental anomalies, can be associated with megalourethra;

• Mega cystitis (very large urinary bladder compared to normal).

• Pyelectasis (extra fluid in kidneys prenatally).

• Distended bladder (retention of urine in the bladder).

• Oligohydramnios (very less amniotic fluid).

• Other urogenital abnormalities.

• Prune belly syndrome.

• VACTERL or VATER (vertebral anomalies, anal atresia, cardiac anomalies, tracheal anomalies, limb-related anomalies) syndrome.

• Potter syndrome.

What Are the Differential Diagnoses of Megalourethra?

Megalourethra is commonly mistaken for the below conditions that are associated with the urethra;

• Urethral webs.

• Urethral atresia.

• Urethral diverticulum.

• Urethral duplication.

How Is Megalourethra Treated?

• Reduction urethroplasty is the common surgical procedure performed to manage megalourethra. It is a major surgery that is performed in various stages depending upon the severity of the condition; as per reports, in cases of megalourethra, one or two stages of urethroplasty are indicated.

• Megalourethra requires a long-term follow-up to monitor if there are any complications associated with the penis function, like poor erection and fertility-related complications. Patients treated for fusiform megalourethra as babies or younger might require a prosthetic penis as adults.

• In prenatally diagnosed megalourethra, various tests are done to identify the intensity and severity of megalourethra along with other associated congenital anomalies.

• In cases with other severe developmental anomalies, termination of pregnancy is considered the best option.

• In milder forms, resolution of the condition spontaneously has also been noted.

Conclusion:

Megalourethra is a very rare condition. Hence, diagnosing it properly and seeking treatment at the earliest is necessary for a positive treatment outcome. It is also seen that prompt treatment has provided very pleasing functional and cosmetic results in the treatment of the scaphoid variant of megalourethra. Management of this condition entirely depends upon each individual’s condition and developmental anomalies associated with megalourethra.