This section looks at the bladder and urethral sphincters starting with the male urethra. There is a significant difference in the length of the male and female urethra and we are going to look at this in more detail.
The male urethra has a length of 18-20cm and is S shaped. It has two functions:
- Passage of semen at time of ejaculation
Figure 2.2: The four different parts of the male urethra.
The male urethra consists of:
Prostatic urethra (3-4 cm), the section of the urethra closest to the bladder, it passes through the prostate gland and receives ducts from the prostate.
Membranous urethra (2cm) passes through the pelvic floor and includes the area of the external sphincter - this is the narrowest and least dilatable section of the male urethra, with the exception of the urinary meatus. The membranous urethra is the section of the urethra that is most commonly damaged when the pelvis is fractured or crushed.
The prostatic and membranous urethra are together called the posterior urethra.
Bulbar urethra (1.5cm), is the next section of the urethra, it descends with slight concavity to the bulb of the penis, the bulbar urethra is the section of the urethra between the sphincter and the base of the penis. This is the section of the urethra that is damaged by a straddle injury, as it is close to the skin surface.
Penile urethra (15cm) extends from the bulb of the penis to external meatus. It has a number of lacunae (small recesses) along its length.
The bulbar urethra, penile urethra and meatus are together known as the anterior urethra.
Clinical practice point. Insertion of a catheter
Did you know? A lubricant which dilates and anaesthetises the urethra will aid the insertion of a catheter and can reduce the risk of urethral trauma.
To get the most benefit from the gel you need to hold the penis upright, get a good seal around the meatus, insert the full 11ml slowly, gently massage along the penis, continue to hold the tip of the penis in an upright position and wait to allow the product to work (check the manufacturers instructions).
The urethra can easily hold 11ml of lubricant. If the catheterisation is expected to be difficult or complex, two tubes can be used and the advice would be to wait longer eg 10-15 minutes, to allow for dilation. The urethra can accommodate this volume of lubricant.
- If the catheter cannot be inserted the practitioner needs to be able to identify what section of the urethra the obstruction is sited.
A standard-length, not short-length, catheter must always be used and inserted up to the hilt before inflating the balloon, to ensure the balloon is not inflated in the urethra and is fully inside the bladder.
If this practice is not followed and the catheter balloon was inflated in the urethra, this would cause damage and potential haemorrhage in the prostatic urethra.
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