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Saturday, July 08, 2006

Concepts of PelvicOrganReconstructive Surgery

Whether to use a biomaterial:
Until very recently, gynaecologists had not kept pace with the concept of either bolstering a sutured repair or of bridging a fascial defect with mesh. However, the potential benefit of reinforcing pelvic floor defects using a biomaterial implant is self evident, particularly given the poor performance of ‘suture-only’ repair techniques. The advantages given by the biomeshes can put the pelvic organ reconstructive surgeon ahead of the pack - my prediction is that the general surgeons will not be long in realising that to correct the collagen deficit can form the basis of a scientific repair of the hernia.
The choice of the type of mesh or biomesh must greatly be influenced by the defective collagen structures surrounding the herniated vaginal wall: rectifying the “wrong” in the tissue defects must clearly include improving the collagen content of the surrounding tissues.
Winds of change are blowing, but not always in the right direction!
The trend began with laparoscopic mesh sacrocolpopexy, but has been greatly extended by heavy marketing of commercially available minimal access devices (“kits”). Current surgical practice in many pelvic floor clinics around the world now amounts to little more than implanting quite large sheets of polypropylene mesh, either with a laparoscope or with a trans-gluteal or trans-obturator needle device ─ despite a the lack of clinical safety data, and the absence of any compelling clinical evidence that the use of synthetic mesh improves either anatomic or functional outcome.
This paradigm shift has been fuelled largely by two arguments: the well recognized superiority of prosthetic hernioplasty over non-augmented suture repairs, and the stellar track record of “tension free” mid-urethral tapes. Nonetheless, it is surprising that there has been such a pronounced swing to an unproven method, particularly given the worrisome anecdotes of mesh misadventure, which now seem to abound.
It has been said that “the regional gynaecological clinics specialise in putting in these mesh buttresses, while tertiary referral units now specialise in the enormously difficult task of taking them out”.

The basis of the synthetic meshes’ success is dependent on the permanent presence of “supporting” material and the inflammatory reaction it gives, with resultant scar tissue formation- both reasons not to use it in the tissue layers surrounded by hollow viscus!
This alone is enough reason not to use synthetic meshes and to use second generation biomeshes.

How best to insert the biomaterial:
It is a long established surgical principle that placing alloplastic material in close approximation to a hollow viscus (bladder, rectum) is hazardous. Surgical prudence might also question the wisdom of having relatively inexperienced gynaecologists insert mesh into the pelvic sidewall with needle devices, when they have not been trained to dissect these areas at open surgery. Given the limited safety data relating to trans-gluteal or trans-obturator mesh insertion, there is justified concern that these ‘minimally invasive’ techniques may not be ‘minimally harmful’ ones!

The other question is whether to operate via the vaginal or the abdominal route. For the surgeon with advanced vaginal skills, exposure of the fascial defects and access to the retroperitoneal spaces is easily accomplished from below. The hernia can be corrected from the side of the herniation on the site of the herniation.
Despite the trend towards endoscopic surgery in recent years, there is also little justification for repairing prolapse via a laparoscopic approach.

The Need for Change in Treatment Strategies
The basis of traditional anterior and posterior “repairs” is to remove a central diamond of vaginal wall overlying the central bulge, and then plicate the medial “fascia” (which is, in reality, just the muscularis layer of the vagina). This process inevitably creates a central plate of non-specific scar tissue, which generally relieves symptoms and hides the bulge for a time.
From the biomechanical perspective, midline fascial plication makes no attempt to define or repair the true fascial defect. Rather, plicating the loose tissue towards the midline actually increases the strain on the un-repaired paravaginal defects, or if done with the VPVR, on the repaired defects[7]. Hence, it should surprise no-one that anatomic failure rates are high and that durability of symptomatic bulge control is unreliable.
Given the enormous economic costs of pelvic floor surgery, gynaecologists must come up with a more mechanically appropriate method of prolapse repair, or face cost controls from third party payers.

‘Suture-only’ vaginal paravaginal repair or uterosacral colpopexy repairs the true fascial defects, using connective tissue that is often beginning to weaken secondary to an acquired collagen defect. Results can be better than with plication-type repairs, but failure to address the collagen defect is an unremedied source of failure.

Augmentation materials, used in a tension-free manner, would thus appear to be as appropriate for prolapse repair as for hernia surgery. However, one should be wary of placing a permanent mesh and inducing inflammatory scarring in close proximity to a hollow viscus. Synthetic mesh that works well for TVT mid-urethral slings or abdominal sacrocolpopexies may be erosive and painful if placed in a more dynamic part of the vaginal wall.

The limitations of operating with surgical kits should also be kept in mind. Optimal paravaginal repair requires the ability to individualise (according to each patient’s defects and age) and to tension the suspensory hammock in all directions. Conversely, mesh placed with “surgical kits” has a limited range of adjustment, and can only be tensioned in a side-to-side direction.
Hence, bulge recurrence can occur above or below the transverse margins of the synthetic implants, or creating a phenomenon called a meshoma by Amid [8]; nonfixation, insufficient fixation, or insufficient dissection to make adequate room for the prosthesis can lead to folding and wrinkling of the mesh, a process that continues until the mesh is wadded up into a ball, causing pain or bulging on both sides of the ball.
In my own series of Prolift implants this happened with especially the anterior prolifts after 12 months. This shrinkage of polypropoline meshes can be as much as 30-50% of their original size as soon as after four weeks![9].

If tissue augmentation is needed, use of a remodelling second generation biomesh (SIS or InteXen) offers excellent repair strength and is virtually morbidity-free.

In summary, what can be achieved at surgery ranges from reliable anatomic restoration, to non-physiological distortion. Pelvic reconstructive surgery is presently undergoing a revolutionary change.

What course you take is up to you:
· You can either stay in the “comfort” of what you are doing with POP surgery or you can step into the future.
· You can treat the prolapsed vaginal wall as a bulge that is in need of camouflage, or you can visualise it as a herniation needing a ‘site-specific’ repair.
· You can try to strengthen this support defect use weakened, collagen-deficient tissue, or you can utilise an appropriate augmentation material.
· You can augment with synthetic mesh, applied with a “one-size-fits-all” surgical kit, or you can individualise your repair depending on the type of prolapsed and the patient’s age.
· You can implant synthetic meshes which can be morbid and difficult to remove, or you can essentially avoid such problems with modern tissue engineering technology.

Further reading:

1. Robinson Dudley, Anders Kate, Cardoso Linda, Bidmead John(2007). Outcome measures in urogynecology: The clinicians’perspective. Int Urologynecol J 18: 273-279
2. Pelusi G, busacchi P,demaria F and Rinaldi AM(1990).The use of the kelly plication for the prevention and treatment of genuine stress urinary incontinence in patients undergoing surgery for genital prolapse. Int Urogynecol J 1 196-199
3. Weber AM,Walters MD,Piedmonte MR. Ballard LA (2001). Anterior Colporrhaphy: a randomized trail of three surgical techniques.. Am J of Obstet 7 gynecol 185(6): 1299-1306.
4. H D E Atkinson, S G Nicol, S Purkayastha, and S Paterson-Brown,(2004) Surgical management of inguinal hernia: retrospective cohort study in southeastern Scotland, 1985-2001. BMJ. 2004 December 4; 329(7478): 1315–1316.
5. Raphael Rosch, Uwe Klinge, Zhongyi Si, Karsten Junge, Bernd Klosterhalfen and Volker Schumpelick .(2002) A role for the collagen I/III and MMP-1/-13 genes in primary inguinal hernia? BMC Medical Genetics 2002, 3:2
6. Lin et al, (2007). Changes in the extracellular matrix in the anterior vagina of women with or without prolapsed. Int Urogynecol J 18:43-48
7. Morse N,O’Dell KK,Howard AF, Baker SP, Aronson MP, Young SB (2007). Midline anterior repairs alone vs anterior repair plus vaginal paravaginal repair: a comparison of anatomic and quality of life outcomes. Int Urogynecol J (2007) 18:245-249.
8. Parviz K. Amid (2004). New Phenomenon Causing Chronic Pain After Prosthetic Repair of Abdominal Wall Hernias Arch Surg. 2004;139:1297-1298
9. Klinge U,Klosterhalfen B, Muller M ottinger AP, Schumpelick V.(1998)Shrinking of polypropylene mesh in vivo: an experimental study in dogs.
Eur J Surg. 1998 Dec;164(12):965
edited by R Reid

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