Rigi10™ Malleable Penile Prosthesis
Also Known As
Opening, passage, canal, orifice, foramen. For urethral meatus: External urethral orifice, urinary meatus, urethral opening. For auditory meatus: Ear canal, acoustic meatus, external acoustic meatus.
Definition
A meatus is a natural opening or passage within the body. Anatomically, it refers to an orifice or canal-like structure. For example, the external auditory meatus is the passage leading from the outer ear to the eardrum. In urology, a significant meatus is the urethral meatus (also known as the external urethral orifice), which is the external opening of the urethra through which urine is expelled from the body during urination.¹ It is located at the tip of the penis in males and in the anterior part of the vulva in females. The proper functioning and structure of the urethral meatus are crucial for normal urinary function. The meatus itself is typically lined with stratified squamous epithelium, providing a protective barrier.
How it works and its purpose:
The primary purpose of any meatus is to serve as an opening for a passage, allowing for the entry or exit of substances or structures. The urethral meatus, specifically, allows for the controlled expulsion of urine from the bladder. Its structure, including its size and shape, can impact urinary flow. For instance, a narrow meatus (meatal stenosis) can obstruct urine flow, leading to various urinary complications.¹ The morphology of the urethral meatus can vary, with classifications including typical, slit-like, point-like, horseshoe, and megameatus, each potentially influencing surgical approaches or susceptibility to certain conditions.²
Clinical Context
The urethral meatus is of significant clinical importance in urology. It is the site of various congenital and acquired conditions and is a key anatomical landmark for urological procedures.
Relevant Medical Conditions:
- Meatal Stenosis: An abnormal narrowing of the urethral meatus, more common in circumcised males. It can cause obstructive voiding symptoms such as a deflected or thin urinary stream, dysuria (painful urination), and incomplete bladder emptying.¹ This condition may require surgical correction (meatotomy or meatoplasty).²
- Hypospadias: A congenital condition in males where the urethral meatus is located on the underside of the penis, rather than at the tip. The severity varies depending on the meatal position. Surgical correction is often performed in childhood. AI and machine learning models are being explored to predict hypospadias severity based on meatal location and other factors.³
- Epispadias: A rare congenital anomaly where the meatus is on the upper aspect (dorsum) of the penis.
- Urethritis: Inflammation of the urethra, often caused by sexually transmitted infections (e.g., gonorrhea, chlamydia), can cause discharge from the meatus and dysuria.¹
- Urethral Strictures: Scarring that narrows the urethra can occur near the meatus or elsewhere along the urethra, impacting urine flow.¹
- Urethral Trauma: Injuries to the penis or perineum can damage the meatus or urethra.¹
- Urethral Cancer: Though rare, cancer can affect the urethra, including the meatus.¹
Patient Selection Criteria & Surgical Procedures:
- Meatotomy/Meatoplasty: Surgical procedures to widen a stenotic urethral meatus. Meatotomy involves a simple incision, while meatoplasty is a more formal reconstruction. These are indicated when meatal stenosis causes significant symptoms or obstruction.² The morphology of the meatus (e.g., point-like or slit-shaped) can influence the need for intervention during transurethral surgeries.²
- Hypospadias Repair: Various surgical techniques are used to reconstruct the urethra and correctly position the meatus at the tip of the penis.
- Urethral Catheterization: The meatus is the entry point for urethral catheters used for bladder drainage, urine sampling, or instilling medications. Proper technique is crucial to avoid meatal or urethral injury.¹
- Cystoscopy: A diagnostic procedure where a thin tube with a camera (cystoscope) is inserted through the meatus to visualize the urethra and bladder.¹
- Transurethral Resection of the Prostate (TURP) / Transurethral Resection of Bladder Tumor (TURBT): The size and morphology of the urethral meatus are critical factors when introducing the resectoscope. A narrow meatus may require dilatation or meatoplasty to allow passage of the instrument and prevent urethral injury.²
Expected Outcomes:
Outcomes vary depending on the condition and procedure. Successful meatotomy/meatoplasty for meatal stenosis typically results in improved urinary flow and relief of symptoms. Hypospadias repair aims for a functional and cosmetically normal penis. For infections, appropriate antibiotic treatment usually resolves urethritis. Outcomes for urethral cancer depend on the stage and grade of the tumor.