Reconstructive surgery of the urethra is based on the concept of tissue transfer.
It comes to moving tissue from a source member to the receiver member with a medical condition requires reconstructive surgery.
Each fabric has physical characteristics of its own:
- internal tension
which are a function of the arrangement between them of collagen fibers and elastin.
Two tissue transfer types are available.
1) Free flap “graft”
It is totally free from the source body in his collection and he is transferred to the body to rebuild. Then develops this flap to a new vascular supply within 96 hours, which occurs in two phases:
- The initial phase, imbibition, during the first 48 hours
- The second phase of inoculation for 48 hours which is also the year in which establishes a real microcirculation vascularizing graft flap.
One can opt for a levy in total thickness – all the epidermis and superficial dermis and deep “FTSG full thickness” – or partial – the epidermis and superficial dermis “STSG split thickness” – the tissue to be sampled.
Free flaps which have been successfully used to reconstruct the urethra are flaps in total thickness of:
- skin of the genital area or extra-genital anatomical regions,
- bladder urothelium: favorable properties of vascular perspective,
- buccal mucosa: excellent and optimal properties of the vascular viewpoint. Used the inner lining of the cheek, the inner lining of the lips or mucous membrane of the tongue.
- rectal mucosa,
- More anecdotally: ureter, vaginal scrotal.
2) Pedicle flap “flap”
The tissue is removed from the organ source and transferred to the receiver member with its vascular pedicle. The arterial and venous pedicle vascularizing the graft was preserved intact by dissection, or it was braided by microsurgery on the recipient site.
In reconstructive surgery of the anterior urethra, a meta analysis showed that the results of free flaps were equivalent to those pedicle flaps.
The oral mucosa has a thick epithelium squamous non keratinized, covering a thin lamina propria. It houses a large number of microorganisms and thus the inflammatory response that develops vis-vis bacteria, in particular is minimal. There are many immunological processes intrinsic to the oral mucosa that make insensitive and impervious to the normal bacterial flora of the mouth.
Histological studies have shown that the oral mucosa was highly compatible with urethral tissues. Over time, the tissues of the oral graft can not be distinguished from surrounding urethral tissue. The architecture of the oral mucosa tissue is very close to the stratified squamous epithelium of the multi penile urethra and bulbar.
Better to avoid sampling at the lip as this can cause difficulty in chewing or smile or even peri-odontales consequences.
Hence largely preferable to sample at the internal face of the cheek, or to the right or to the left, or on both sides according to the needs of the urethral reconstruction.
The surgeon must ensure that the tissue from which the flap is raised is healthy and there is no pathology at the mouth.
It must also have anatomical landmarks and must respect, both at the time of the incision at the time of wound closure after removal of the flap, the parotid duct that drains the parotid gland.
The underside of the tongue is another excellent alternative tissue sampling at the oral cavity.
The advantages of tissue samples in the oral cavity are:
- ease of access, lack of hair or hair,
- rich vascularity at the mouth, which facilitated the rapid revascularization of the graft in its new location,
- the excellent cosmetic results at the sampling site in the mouth,
- the flap is very elastic and shrinks little,
- it retains after the transfer the elasticity properties of the original tissue,
- do not occur at the urethral meatus excoriations problems, inlays or uncontrolled proliferation as was seen frequently with the use of the bladder mucosa,
- the oral mucosal flap has a high resistance to infection and trauma, and high power of regeneration,
- the architecture of the oral mucosa is characterized by a thick stratified epithelium and a thin lamina propria, which gives consistency to the flap and allows it easy to handle for the purposes of surgery; Moreover it also allows rapid revascularization of the flap.
The disadvantages are:
- amount of tissue obtained by sampling in the oral cavity is sufficient to reconstruct a long tube could replace the urethra,
- there may be unsightly contracture at the corner of the mouth if the flap was taken too close to this angle
the superficial branch of the facial nerve are exposed to injury during the dissection for taking the flap,
- recurrence of stenosis and fistulas are likely to be observed with the use of free flaps of oral mucosa and with all kinds of free or pedicle flaps.
It remains objectively and subjectively, the oral mucosa is a very satisfactory material for the reconstruction of the urethra. This is probably due to the presence of growth factors in the oral mucosa that promote rapid healing and rapid revascularization of the flap.
Some bibliographic references:
1) Surgery of the penis and urethra
Ch. Reading . By Dr Ali Al Amiri R2 Academic Day
2) Oral Mucosa Harvest: An Overview of Anatomic and Biologic Considerations
Michael R. Markiewicz a,*, Joseph E. Margarone IIIb, Guido Barbagli c, Frank A. Scannapieco d eau-ebu update series 5 (2007) 179–187
3) Oral Mucosa Graft: An Ideal Substitute for Urethroplasty
Maged Ragab and Hossam Haroun
Tanta University, Tanta EGYPT
4) The First Oral Mucosal Graft Urethroplasty Was Carried
Out in the 19th Century: The Pioneering Experience of Kirill Sapezhko (1857–1928)
Igor Korneyev a,*, Dmitry Ilyin a, Dirk Schultheiss b, Christopher Chapple c
EUROPEAN UROLOGY 62 (2012) 624–627