Urethral Duplication - An Intriguing Anomaly

Introduction

Urethral duplication is a complex congenital abnormality that occurs more frequently in boys and rarely occurs in girls. Urethral duplication, also called the accessory urethra, is an abnormality present from birth. This condition is characterized by two urethral channels, which are either partial or complete. Urethral duplication has a complex clinical presentation that is either symptomatic or asymptomatic. Management of urethral duplication is often necessary for patients with symptomatic clinical presentation. Surgical repair of the urethra is considered in patients with symptoms and for cosmetic deformity. In this article, we will explore the nature of urethral duplication, its potential symptoms and complications, and the treatment options available to address this condition. It is important to consult with a qualified healthcare professional for a proper diagnosis and individualized care plan tailored to your specific needs.

What Is Urethral Duplication?

Urethral duplication is an uncommon congenital anomaly seen more commonly in males, and they are often associated with other urogenital abnormalities like bladder duplication or bladder dystrophy. Urethral duplication commonly occurs in the sagittal plane, with the additional urethra located dorsally to the normal urethra. The diversity of clinical symptoms depends on the anatomical abnormality during birth.

What Is Embryogenesis of Urethral Duplication?

The embryogenesis of urethral duplication is still unclear, even though there are various theories explaining the embryogenesis of urethral duplication. Typically in males, the components of the external genitalia are formed from labioscrotal swelling, cloacal folds, preputial swelling, and urogenital sinus. They are developed from all three germ layers with the timely communication of hox genes, fibroblast growth factors, sonic hedgehog signal, and bone morphogenic protein signals. According to most histological studies, the urethra evolves entirely or partially from the endoderm of the urogenital sinus. The distal-most granular part is formed from the ectoderm layer. The migration and fusion of paramedian folds of the mesodermal layer form the entire urethra.

The theory of Patten and Barry is the most commonly quoted and accepted theory explaining the hypothesis of complete urethral duplication. Still, it needs to explain the reasons for other types. It results from the abnormal connection between the ventral end of the cloacal membrane and the lateral folds of the genital tubercle.

What Are the Types of Urethral Duplication?

Urethral duplication is classified into various types and classification. But the most accepted classification is the classification of Effman et al. He proposed this classification based on the radiological findings. Urethral duplication is classified into three types.

1. Incomplete Duplication:

• Type 1A-Distal Incomplete Duplication: The opening is on the dorsal or ventral surface and does not communicate with the bladder or urethra.

• Type 1B-Proximal Incomplete Duplication: The additional urethra develops from the normal urethra and ends blindly.

2. Complete Urethral Duplication:

• Type 2A-Complete urethral duplication with two external openings.

• Type 2B-Complete urethral duplication with one external opening; two urethras arise from the bladder and reunite in the standard channel distally.

• The type 2A duplication with two meatuses is further classified into: Type 2A1 that is two non-communicating urethras arising independently from the bladder and type 2A2 that is when there is a second urethral channel arising from the first, that independently courses into the second channel opening.

• Type 3 Urethral duplication is a component of duplicated or septate bladders.

What Are the Clinical Manifestations of Urethral Duplication?

The variation in the clinical manifestations of urethral duplication depends on the congenital malformation in the anatomical structures. The clinical presentation of urethral duplication based on the Effman et al. classification is as follows:

• Type 1A causes only a few symptoms, like the elimination of pus, and sometimes is asymptomatic.

• Complete duplication of the urethra in types 2A1 and 2A2 causes urinary obstruction, urinary tract infections, and double urinary stream. Type 2A2, or duplication in Y or H, can result in a functional ventral urethra.

• In children, this type can result in the excretion of urine and stools.

• The other most common symptom in patients with complete duplication is the loss of bladder control (urinary incontinence)

• Double urine flow is a common clinical manifestation in patients with collateral urethral depletion.

• Urethral duplication can even result in renal failure in severe cases.

• Patients with type 1B and 2B urethral duplication are primarily asymptomatic.

How Is Urethral Duplication Diagnosed?

The diagnosis of this condition is established by taking a detailed clinical history, conducting a comprehensive physical examination, and utilizing additional imaging studies.

• The radiological investigation is a mandatory diagnostic tool in diagnosing urethral duplication and ruling out other differential diagnoses. The most commonly used imaging technique is voiding cystourethrography (A type of X-ray that uses fluoroscopy to study the urethra and bladder). But the definitive imaging study for the initial diagnosis of urethral duplication is the retrograde urethrogram (RUG) which is less invasive with minimal radiation exposure.

• Suppose two urethral openings are identified along the perineum or rectum. In that case,type2A2 Y duplication is mostly suspected, and RUG is performed to confirm the diagnosis and to rule the urethral opening is not of a fistulous origin.

• The presence of a blindly ending urethra in the longitudinal plane of the penis is suggestive of type 1A. Ultrasound radiography of the kidney and bladder is necessary to investigate the other associated anomalies.

• For surgical treatment planning, cystoscopy is essential. Currently, the use of sono-urethrogram and MR urethrography is increasing.

How Is Urethral Duplication Treated?

The treatment of urethral duplication depends on its type and the extent of symptoms in the condition. Identifying the functional urethra is necessary before initiating the treatment plan. The patients with incomplete urethral duplication of type 1A and 1B are primarily asymptomatic and don't require surgical intervention. In case of infection or pus discharge, the accessory urethra is removed.

In patients with urethral duplication of type 2A2, there is a normal dorsal urethra and a ventral accessory urethra. The surgical approach involves an initial opening of the ventral urethra through the perineum and preserving the normal dorsal urethra. Later surgical repair of the urethra is performed using grafts or flaps. In patients with type 2A2 with a ventral urethra being functional is challenging to perform a surgical correction.

What Are the Complications of Urethral Duplication?

Potential complications associated with urethral duplication:

• Urinary Tract Infections (UTIs): The presence of two urethral openings can increase the risk of UTIs. Bacteria can enter either urethra, leading to recurring infections.

• Voiding Dysfunction: Urethral duplication can cause difficulties with urination, including weak urine stream, urinary retention (inability to completely empty the bladder), or urinary incontinence (involuntary leakage of urine).

• Urinary Reflux: In some cases, one urethra may have an abnormal connection with the bladder, causing urinary reflux. This means urine can flow back into the ureter and potentially reach the kidneys, leading to urinary tract infections and kidney damage.

• Sexual Dysfunction: Urethral duplication can impact sexual function, particularly in cases where the duplication affects the portion of the urethra responsible for semen ejaculation.

• Obstruction: Duplication of the urethra can result in obstructions or strictures, causing difficulties with urine flow and potentially requiring additional surgical interventions to correct.

• Psychological and Emotional Impact: Dealing with a complex congenital condition like urethral duplication can cause emotional stress and affect quality of life.

Conclusion

Urethral duplication is a rare anomaly characterized by two urethra channels. It occurs mainly in males. It has a diverse variety of clinical presentations and is primarily accompanied by other associated anomalies making it difficult to be diagnosed. This condition requires radiographic and endoscopic workup to analyze anatomical considerations and derive a proper treatment plan. Mostly they are asymptomatic, and the surgical plan depends on the patient's clinical presentation. Studies show that surgical correction of the Y-type urethral duplication is the most challenging.