Reoperative Abdominal Surgery
0039-6109/91 $0.00
+ .20
Abdominal Wall Considerations and
Complications in Reoperative Surgery Donald E. Fry, MD, * and Turner Osler, MDt
The abdominal wall represents the gateway for all operative procedures within the coelomic cavity and for most procedures within the abdominal retroperitoneal areas. When a patient is having an elective procedure within the abdomen, any number of incisions may be selected; and personal preference or optimization of exposure for a given location within the abdominal cavity usually governs the selection of a midline, transverse, or paramedian incision. However, when a patient has had a prior procedure within the abdomen, caution must be exercised when making the incision for a second intervention. Because the prior incision may have dense adherence of intestinal loops from the previous procedure, a separate incision may be desirable to reduce the risk of enterotomy and the tedious dissection of bowel from the site of entry into the abdomen. The second incision site must be selected with a full understanding of abdominal wall blood supply, because a poorly placed reoperative site may cause serious morbidity.
ABDOMINAL WALL ANATOMY The components of the abdominal wall are well known to general surgeons but are sometimes not seriously considered in terms of their clinical relevance. A generic enumeration of the abdominal wall anatomy in an anterior-to-posterior orientation would include the skin, subcutaneous fat of highly variable thickness, an anterior and posterior fascial envelope with one or more layers of muscle in between, preperitoneal fat, and finally the glistening mesenchymal layer of the peritoneal lining. The arterial blood supply is quantitatively different in the component parts of the abdominal wall. The skin and subcutaneous fat receive their *Professor and Chairman, Department of Surgery, University of New Mexico School of Medicine, Albuquerque, New Mexico tAssistant Professor, Department of Surgery, University of New Mexico School of Medicine, Albuquerque, New Mexico
Surgical Clinics of North America-Vol. 71, No.1, February 1991
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arterial supply from perforating vessels through the fascia from deeper sources. These various perforating sources form a random arcade of vascular intercommunications that make it difficult to cause ischemic necrosis by combinations of interdigitating incisions. The blood supply of the subcutaneous fat is the least among the abdominal wall components. Accordingly, bacterial contamination of the subcutaneous fat represents the anatomic focus for the development of most wound infections. The fascial blood supply arises from vascular branches via the rich arterial supply of the underlying or overlying muscle. This is best illustrated by the continued viability of the anterior fascia when full-thickness abdominal wall skin-subcutaneous flaps are developed for certain wound closures. However, dissection of the fascia from the underlying muscle results in fascial necrosis. Thus, incisions and combinations of incisions that compromise muscle blood supply will also reduce arterial perfusion of the associated fascia. The arterial blood supply of muscle usually parallels the course of the muscle fibers." The blood supply of the rectus muscle comes from the superior and inferior epigastric arteries, which form a rich anastomotic arcade across this muscle. The lateral abdominal muscles have a dermatomal blood supply, which comes from a lateral to a medial direction. There are anastomotic networks between each dermatomal artery so that muscle ischemia or necrosis requires division of numerous branches feeding a given area. The linea alba represents the midline fusion of the fascia from the anterior and posterior sheaths of the rectus muscle. It is a clearly developed structure in the upper midline but is much more poorly defined in the suprapubic area. The relatively avascular and midline location of the linea alba makes it popular for the fascial access site into the abdomen.
STRATEGY FOR PLACEMENT OF THE REOPERATIVE INCISION The selection of an incision for reoperation within the abdomen is of considerable significance if one is to avoid serious morbidity during the patient's subsequent convalescence. For purposes of this discussion, reoperations will be subdivided into those that are acute and those that are remote from the previous procedure. Acute reoperations are those in which the original procedure has not resulted in a mature and fully healed primary operative site. Evidence of inflammation in the healing wound is still present. Reoperation for postoperative bleeding, intra-abdominal sepsis complicating a previous procedure, and reoperations for acute postoperative obstruction or anastomotic failure are acute reoperations. Remote reoperations are those procedures where the prior incision or incisions are fully mature. Commonly, the procedure in the remote reoperation group has an anatomic location and indications that are totally separate from the earlier procedure. Nevertheless, the site and configuration of the prior wound assume significance. In acute reoperations, the surgeon usually will operate through the previous incision. Because acute reoperations usually involve the anatomic
ABDOMINAL WALL CONSIDERATIONS AND COMPLICATIONS
3
structures and sites that were the focus of the original procedure, the exposure afforded by the original incision usually will prove adequate. Depending on the interval between the reoperation and the original procedure, the adhesive attachment of omentum and intestine usually will not be extensive nor difficult to disrupt when approached through the original incision. Finally, acute reoperation through the original incision will take advantage of the healing process that has already transpired." A 7-day-old surgical wound that is reopened and then reclosed remains a 7day wound at the time of reclosure. It does not revert to being a fresh wound. Because acute reoperation is commonly indicated because of intraabdominal infection or may be attended by significant contamination as suture lines are reconstructed or the intestinal tract is opened for any number of reasons, closure of the abdominal wound completely may not be desirable. Although definitive data are not currently available, it is felt that wounds reopened even for noninfectious indications are at increased risk for infection, dehiscence, evisceration, and perhaps even necrotizing fasciitis. Thus, delayed primary closure or even secondary closure may prove desirable for many acute reoperative wounds." Obviously, the advantages from prior days of the healing process that one may gain by using the same incisions are lost if the subcutaneous fat and skin are left open for delayed closure. Clinical judgment is important in weighing the merits of primary wound closure at the acute reoperation against the potential risks of contamination incurred at the reintervention. When remote reoperation is undertaken, opening the abdominal cavity through the previous incision commonly is less desirable. Old scar is less vascularized and is at least theoretically at greater risk for infection. Adhesions of omentum and intestine may make the old wound a difficult means for entrance into the abdominal cavity. Certainly, inadvertent enterotomy has been experienced by all surgeons reoperating through a remote incision. As noted previously, unlike the situation in acute reoperation, remote reoperations commonly are for indications different from those of the original procedure and may have distinct features thatnecessitate a separate incision for exposure. When patients have one or more previous mature incision sites on the abdominal wall, the following recommendations by the authors are thought to be justified. First, the surgeon should avoid the creation of a new incision that intercepts a prior incision at an acute angle. Rather, one should attempt to interdigitate new incision lines at right angles to old ones. The classic example where an angle less than 90 degrees is commonly created is the subcostal incision for cholecystectomy when the patient has had a prior midline incision. The 45-degree angle creates an ischemic area that may form the basis for a wound separation or infection or the delayed development of a ventral hernia. When a right subcostal incision is desirable, a less acute angle can be created by making the incision more transverse and less oblique. In selected cases, it may not be necessary to intercept the two incisions at all. Second, one should avoid parallel vertical incisions. Indeed, a corollary might well be to avoid vertical incisions altogether except for midline
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incisions. Parallel vertical incisions create a relative area of ischemia at the centralmost portion of their parallel extent. A midline and a paramedian incision create a high-risk area of acute (dehiscence) or delayed (ventral hernia) separation. Because the crossover of fascial and muscle blood supply across the linea alba is minimal, a paramedian incision, even without a prior midline incision, creates a relatively ischemic edge to the medial aspect of the wound. In the authors' opinion, a paramedian incision is generally to be avoided in all abdominal operations.
PREVENTION OF ABDOMINAL WALL COMPLICATIONS Whether for acute or remote reoperations, the abdominal wall subjected to reoperation is thought to be at increased risk for infection, dehiscence, or ventral herniation. Wound ischemia, tension, postoperative infection, and technical failures of wound closure become interrelated variables that are commonly impossible to separate when one attempts to analyze a bad outcome in a given patient. Wound ischemia begets infections, which commonly are identified as dissolution of the fascia and an apparent pullthrough of suture material. Tension creates ischemia, and certainly, infection of tissues can create ischemia as well. Wound edge ischemia from strangulating fascial sutures may result in fascial necrosis, infection, or both. In general, preventive systemic antibiotics would appear to be a prudent choice whether for acute or remote reoperations. The antibiotic should be administered preoperatively, should have activity against the likely contaminants identified, and should have a pharmacokinetic profile that will ensure its presence in the tissues throughout the procedure. 8, 9 In the acute reoperation, the choice of drug should be tempered by the patient's history before the reoperative event. If a patient has already had a course of antibiotic therapy during the postoperative period of the initial procedure, then conventional antimicrobial prophylaxis with commonly used antibiotics may not prove adequate. For example, if a patient has already had a 7-day course of broad-spectrum antibiotics for peritonitis, it is unlikely that a first-generation cephalosporin will be of great utility as a preventive antibiotic. On the other hand, in the absence of prior antibiotic administration, an early-generation cephalosporin may be useful for prophylaxis. Because no data are really available to guide antibiotic selection for infection prevention in the acute reoperative patient, the decision is an empiric one that is predicated on which drugs have previously been used and what culture data are available to identify current colonization of the patient. In remote reoperations, use of the oral antibiotic bowel preparation in conjunction with mechanical colon preparation may offer some advantages. 3 Reoperation into the upper abdomen is associated with the risks of inadvertent enterotomy into the transverse colon. The preoperative mechanical preparation of the colon and use of neomycin-erythromycin will allow a safe primary closure for these colonic enterotomies. Although it has not been proved to be beneficial, the simultaneous use of systemic antibiotics
ABDOMINAL WALL CONSIDERATIONS AND COMPLICATIONS
5
together with the oral intestinal antibiotic preparation probably will provide additional protection against infectious morbidity in these complex cases. At the time of reoperation, the edges of the incision may be suboptimal for wound closure. In acute reoperation, particularly in infected or trauma patients, the subcutaneous fat and fascial edges of the wound commonly will require debridement before reapproximation. Tenuously viable wound margins, particularly when increased intra-abdominal pressure is present from distended and edematous intestine, certainly will set the stage for dehiscence or subsequent ventral herniation. In some cases, intestinal decompression with a long intestinal tube may prove desirable in reducing intra-abdominal pressure and abdominal wall tension for primary closure. In some complex cases, the use of synthetic polypropylene mesh will obviate attempted closure of the fascia under conditions of increased abdominal wall tension. The wound edges are simply allowed to retract to a resting position, and the mesh is sewn in place. Commonly, the resolution of gastrointestinal ileus and bowel wall edema will allow primary fascial closure later. If not, a more complicated reconstruction may be necessary. In remote reoperation, broad splayed or attenuated segments of the prior surgical wound may be undesirable for wound closure. Primary closure of scar may increase infection rates by virtue of its avascular nature and may also be undesirable from a cosmetic perspective. Thus, excision of the prior wound scar may be useful.
REOPERATION FOR ABDOMINAL WALL COMPLICATIONS Unfortunately, the abdominal wall incision and its associated complications may itself be the focus of the reoperation. The continuum of postoperative abdominal wall complications may range from simple wound infection to necrotizing fasciitis. Simple wound infections commonly are managed by removing the skin sutures and separating the subcutaneous fat. The adjuvant effects of dermal sutures are thus eliminated. Pus is evacuated, and the fibrinous debris can be removed mechanically. With local care, these wound infections will heal uneventfully by secondary intention. Antibiotics are rarely indicated and should be employed only when either cellulitis or tissue necrosis is present. Thus, routine cultures for every wound infection hardly seem justified, and culture should be reserved for the more complex complications. Fascial separations may occur with or without infection and with or without evisceration. One or two broken sutures may create a small area of dehiscence secondary to purely technical error. TJnraveled knots or "scored" monofilament sutures that subsequently break are common causes for these complications. In complex cases, the small area of dehiscence without evisceration can be handled without reoperation. However, in general, localized fascial separations are certain to result in ventral hernia and are best managed by a return to the operating room and appropriate repair. With the increased popularity of running fascial repairs, the localized fascial dehiscence means that total wound separation and evisceration are eminent, and repair should be undertaken immediately.
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When repairing dehiscence or evisceration, the surgeon must take into consideration those variables that were responsible for the complication. If a purely technical error was indeed the cause of the fascial separation, then suture repair alone will be sufficient. If fascial infection and necrosis were responsible, then appropriate debridement of the fascial layer back to viable, bleeding tissue is essential. Debridement should not be abbreviated in the interest of trying to bring the fascia back together for closure. Such short cuts invariably lead to reseparation of the fascia and further reoperations. Intestinal intubation may reduce the intra-abdominal pressure in selected cases and allow primary closure after dehiscence. In general, the use of retention sutures, with or without all the different bridge devices that are employed, may prevent evisceration of the abdominal contents, but they do not prevent dehiscence events. Necrotizing fasciitis of the abdominal wound is a complication that must be promptly appreciated and managed. 10, 12 These infections usually are polymicrobial and can have a fulminant course." In many patients, dehiscence is the event that leads to the diagnosis, although fever, leukocytosis, and other evidence of clinical infection usually are present. Wide and appropriate debridement requires removal of considerable fascia and muscle to eradicate the infection. The overlying subcutaneous tissue may remain viable and should be preserved in the interest of subsequent reconstruction.
POLYPROPYLENE RECONSTRUCTION OF THE ABDOMINAL WALL Synthetic material has become somewhat popular as a replacement for lost fascia. 1, 5, 11, 13-15 The availability of these synthetic meshes has allowed the surgeon to debride the abdominal wall with necrotizing infection fully without worry about closure of the wound at the time of the procedure. In selected difficult trauma cases, when shock, extensive resuscitation, and edema of the intestinal contents make closure of the abdominal fascia difficult, a temporary mesh interposition can permit immediate closure. As noted above, when the distended and edematous state of the intestine has resolved, primary closure of the fascia can be achieved. Polypropylene mesh has been extensively used for fascial replacement. The polypropylene itself is relatively inert and does not appear to foster infection with the same degree of efficiency as is seen with braided materials. The coarse weave of the mesh allows effective drainage between the interstices and permits drainage to the exterior. The relatively inert character of polypropylene combined with the coarse weave has allowed this synthetic material to be used as a fascial substitute even when infection has been active within the abdomen or in the abdominal wall. As in other clinical circumstances, the mesh will become infected itself if necrotic elements of fascia and soft tissue are sewn into the mesh or if the mesh is covered prematurely with grafts or flaps when large concentrations of bacteria have colonized the mesh surface. The technique for mesh placement is relatively simple." After complete
7
ABDOMINAL WALL CONSIDERATIONS AND COMPLICATIONS
wound debridement, the fascial edges are allowed to retract to a resting position. A large sheet of polypropylene mesh is contoured to fill the defect. The mesh is then cut so that a l-cm excess is present all around the wound for suturing. When contouring the mesh, it is always best to err in favor of cutting the sheet too large rather than too small. The redundency can be corrected by the placement of sutures as the mesh is sewn in place. The contoured piece of mesh is then placed in the wound and sutured to the fascia with 0 polypropylene suture. The mesh edge is placed beneath the native fascia and peritoneum. Horizontal mattress suturing is then used to sew the mesh to the posterior surface of the fascia and peritoneum. The stitch is passed anterior to posterior through both the anterior and the posterior fascial layers, then passed down through the mesh and back up through the mesh with a l-cm gap between the entering and exiting sites on the mesh. Thus, the polypropylene suture will have a l-cm bite on the mesh that is 1 em from the edge. Sutures are placed in an interrupted fashion, 1 em apart, about the perimeter of the inlaid mesh (Fig. 1). It generally is desirable to employ interrupted sutures when mesh is used for infection or necrotizing fasciitis, because persistent local infection or necrosis may result in the failure of several sutures. If a running technique is employed, a failed suture that pulls through subsequently necrotic fascia may result in separation of the entire segment. In elective repair of large ventral hernia defects or in the placement of mesh in uninfected but difficult-to-close abdominal walls, the running suture technique may be used. Four quadrant sutures are placed at the 3-, 6-, 9-, and 12-0'clock positions about the wound. If the needle is left on the polypropylene for each quadrant stitch, the fascia can be sutured to the
> ((. \
~\\\, /
L
,
~
\/'-
/~
Figure 1. Placement and suturing of polypropylene mesh into the fascial defect on the abdominal wall.
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Figure 2. Placement of the flank counterincision prior to undermining the bipedicled flap to be transferred over the midline soft-tissue defect.
mesh by passing the needle down through fascia with a I-cm purchase from the fascial edge. A I-cm bite of the mesh is secured parallel to, and 1 em from, the edge of the mesh, and the needle is then passed back up through the fascia. The running suture is continued until one reaches the "free arm" of the adjacent quadrant stitch, where it is tied with multiple knots to prevent slippage. In both the interrupted and the running suture techniques, an attempt is made to suture the plane of the mesh parallel to the plane of the posterior fascia. This should avoid downward buckling of the mesh, which could be the source of intestinal erosion and fistula formation. When mesh is used as a temporary substitute for the difficult abdominal wall closure because of edematous and distended intestine but without fascial loss per se, the mesh can be removed 2 or 3 days later after edema and distention have subsided. The sutures simply are cut, and the mesh is removed. Primary fascial closure is completed. Delayed primary closure is necessary for the skin and subcutaneous tissues because of the inevitable contamination during the temporary mesh presence. When fascial losses secondary to infection, necrosis, or trauma preclude primary closure, the polypropylene mesh can be employed for reconstruction. The mesh is left in situ, and granulation tissue is permitted to proliferate between the interstices of the polypropylene. A confluent bed of red granulation tissue will then develop over the entire mesh. It is tempting to consider the placement of split-thickness skin grafts over the granulated mesh. However, the continued contraction of the wound and granulation tissue after skin grafting will result in buckling of the mesh with erosion of mesh material through the neoepithelial cover.!" Fullthickness flaps of skin and subcutaneous tissue are preferable. The flaps can be mobilized on one or both sides of the abdominal wall, depending
ABDOMINAL WALL CONSIDERATIONS AND COMPLICATIONS
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A
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S.L.
Figure 3. Unilateral bipedicled flap for closure of the midline defect. A, Undermining the flap. B, Medial displacement of the flap. The residual lateral skin defect on the abdominal wall is covered with a meshed split-thickness skin graft. The closed suction catheters have been placed in the potential dead space between the flap and the granulation tissue to avoid seroma or abscess formation.
on the magnitude of the defect. Bilateral mobilization alone may be sufficient to allow midline closure over the granulation tissue. In closures particularly difficult because of the size of the defect, counterincisions on the flanks will create bipedicled flaps, which can be created on one or both sides of the abdomen (Fig. 2). The bipedicled flaps are easily mobilized from the area of the counterincision to the edge of the granulating midline wound (Fig. 3A). The bipedicled flap is then displaced to the midline for closure, with split-thickness skin grafts being used to cover the skin defect
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on the flank (Fig. 3B). Closed suction drains are important to prevent seroma accumulation and potential abscess formation in the space between the granulation tissue and the overlying subcutaneous fat. Premature removal of the suction catheters is a temptation when the volume of drainage has declined to less than 30 to 50 ml per day, but the authors have seen delayed seroma accumulation and abscess formation when the catheters have been removed prior to resumption of full ambulatory activity by the patient. Accordingly, it is recommended that catheters not be removed until full ambulation is resumed and drainage stabilizes at less than 30 to 50 ml per day. A technique similar to that described above also can be employed in the repair of large ventral hernias or when fascial defects may be created by large resections of the abdominal wall in cancer operations. Such fascial defects may have the polypropylene placed and have immediate .fullthickness coverage by the same techniques employed for the delayed reconstruction that is illustrated and described above.
SUMMARY The abdominal wall is the source of significant problems for patients undergoing multiple abdominal operations. The orientation of sequential incisions must be carefully considered to avoid compromise of the abdominal wall blood supply, which may result in either acute (dehiscence) or delayed (ventral hernia) complications. Infections are the most serious problems of the multiply operated on abdominal wall. These complications may range from simple wound infection to necrotizing fasciitis. Management may require only simple drainage of the infection or may entail extensive debridement for the necrotizing processes. Regardless of the cause, the multiply operated on abdominal wall may require reconstruction because of lost fascia. Polypropylene mesh can be employed safely and effectively for this purpose.
REFERENCES 1. Arnaud JP, Eloy R, Adloff M, et al.: Critical evaluation of prosthetic materials in repair of abdominal hernias. Am J Surg 133:338, 1977 2. Bernard HR" Cole WR: Wound infections following potentially contaminated operations: Effect of delayed primary closure of the skin and subcutaneous tissue. JAMA 184:290, 1963 3. Clarke JS, Condon RE, Bartlett JC, et al: Preoperative oral antibiotics reduce septic complications of colon operations: Results of prospective, randomized, double-blind clinical study. Ann Surg 186:251, 1977 4. Fry DE: The surgical incision in reoperation of the abdomen. In Fry DE (ed): Reoperative Surgery of the Abdomen. New York, Marcel Dekker, 1986, pp 1-12 5. Fry DE, Osler T, Clevenger F, et al: The use of polypropylene mesh in abdominal wall reconstruction. Perspect Cen Surg 1:93, 1990 6. Hunt TK: Wound healing. In: Hunt TK, Dunphy JE (eds): Fundamentals of Wound Management. New York, Appleton-Century-Crofts, 1979, pp 1-10
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7. Meleney FL: Bacterial synergism in disease processes with a confirmation of the synergistic etiology of a certain type of progressive gangrene of the abdominal wall. Ann Surg 94:961, 1931 8. Polk HC Jr, Lopez-Mayor JF: Postoperative wound infection: A prospective study of determinant factors and prevention. Surgery 66:97, 1969 9. Polk HC Jr, Trachtenberg L, Finn MP: Antibiotic activity in surgical incisions: The basis for prophylaxis in selected operations. JAMA 244:1353, 1980 10. Rouse TM, Malongoni MA, Schulte WJ: Necrotizing fasciitis: A preventable disaster. Surgery 92:765, 1970 11. Rubio PA: New technique for repairing large ventral incisional hernias with Marlex mesh. Surg Gynecol Obstet 162:275, 1986 12. Stone HH, Martin JD Jr: Synergistic necrotizing cellulitis. Ann Surg 175:702, 1973 13. Stone HH, Fabian TC, Turkleson ML, et al: Management of acute full-thickness losses of the abdominal wall. Ann Surg 193:612, 1981 14. Voyles CR, Richardson JD, Bland KI, et al: Emergency abdominal wall reconstruction with polypropylene mesh. Ann Surg 194:219, 1981 15. Wouters DB, Krom RAF, Slooff MJH, et al: The use of Marlex mesh in patients with generalized peritonitis and multiple organ system failure. Surg Gynecol Obstet 156:609, 1983
Address reprint requests to Donald E. Fry, MD Department of Surgery The University of New Mexico School of Medicine Albuquerque, New Mexico 87131
0039-6109/91 $0.00
+ .20
Abdominal Wall Considerations and
Complications in Reoperative Surgery Donald E. Fry, MD, * and Turner Osler, MDt
The abdominal wall represents the gateway for all operative procedures within the coelomic cavity and for most procedures within the abdominal retroperitoneal areas. When a patient is having an elective procedure within the abdomen, any number of incisions may be selected; and personal preference or optimization of exposure for a given location within the abdominal cavity usually governs the selection of a midline, transverse, or paramedian incision. However, when a patient has had a prior procedure within the abdomen, caution must be exercised when making the incision for a second intervention. Because the prior incision may have dense adherence of intestinal loops from the previous procedure, a separate incision may be desirable to reduce the risk of enterotomy and the tedious dissection of bowel from the site of entry into the abdomen. The second incision site must be selected with a full understanding of abdominal wall blood supply, because a poorly placed reoperative site may cause serious morbidity.
ABDOMINAL WALL ANATOMY The components of the abdominal wall are well known to general surgeons but are sometimes not seriously considered in terms of their clinical relevance. A generic enumeration of the abdominal wall anatomy in an anterior-to-posterior orientation would include the skin, subcutaneous fat of highly variable thickness, an anterior and posterior fascial envelope with one or more layers of muscle in between, preperitoneal fat, and finally the glistening mesenchymal layer of the peritoneal lining. The arterial blood supply is quantitatively different in the component parts of the abdominal wall. The skin and subcutaneous fat receive their *Professor and Chairman, Department of Surgery, University of New Mexico School of Medicine, Albuquerque, New Mexico tAssistant Professor, Department of Surgery, University of New Mexico School of Medicine, Albuquerque, New Mexico
Surgical Clinics of North America-Vol. 71, No.1, February 1991
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arterial supply from perforating vessels through the fascia from deeper sources. These various perforating sources form a random arcade of vascular intercommunications that make it difficult to cause ischemic necrosis by combinations of interdigitating incisions. The blood supply of the subcutaneous fat is the least among the abdominal wall components. Accordingly, bacterial contamination of the subcutaneous fat represents the anatomic focus for the development of most wound infections. The fascial blood supply arises from vascular branches via the rich arterial supply of the underlying or overlying muscle. This is best illustrated by the continued viability of the anterior fascia when full-thickness abdominal wall skin-subcutaneous flaps are developed for certain wound closures. However, dissection of the fascia from the underlying muscle results in fascial necrosis. Thus, incisions and combinations of incisions that compromise muscle blood supply will also reduce arterial perfusion of the associated fascia. The arterial blood supply of muscle usually parallels the course of the muscle fibers." The blood supply of the rectus muscle comes from the superior and inferior epigastric arteries, which form a rich anastomotic arcade across this muscle. The lateral abdominal muscles have a dermatomal blood supply, which comes from a lateral to a medial direction. There are anastomotic networks between each dermatomal artery so that muscle ischemia or necrosis requires division of numerous branches feeding a given area. The linea alba represents the midline fusion of the fascia from the anterior and posterior sheaths of the rectus muscle. It is a clearly developed structure in the upper midline but is much more poorly defined in the suprapubic area. The relatively avascular and midline location of the linea alba makes it popular for the fascial access site into the abdomen.
STRATEGY FOR PLACEMENT OF THE REOPERATIVE INCISION The selection of an incision for reoperation within the abdomen is of considerable significance if one is to avoid serious morbidity during the patient's subsequent convalescence. For purposes of this discussion, reoperations will be subdivided into those that are acute and those that are remote from the previous procedure. Acute reoperations are those in which the original procedure has not resulted in a mature and fully healed primary operative site. Evidence of inflammation in the healing wound is still present. Reoperation for postoperative bleeding, intra-abdominal sepsis complicating a previous procedure, and reoperations for acute postoperative obstruction or anastomotic failure are acute reoperations. Remote reoperations are those procedures where the prior incision or incisions are fully mature. Commonly, the procedure in the remote reoperation group has an anatomic location and indications that are totally separate from the earlier procedure. Nevertheless, the site and configuration of the prior wound assume significance. In acute reoperations, the surgeon usually will operate through the previous incision. Because acute reoperations usually involve the anatomic
ABDOMINAL WALL CONSIDERATIONS AND COMPLICATIONS
3
structures and sites that were the focus of the original procedure, the exposure afforded by the original incision usually will prove adequate. Depending on the interval between the reoperation and the original procedure, the adhesive attachment of omentum and intestine usually will not be extensive nor difficult to disrupt when approached through the original incision. Finally, acute reoperation through the original incision will take advantage of the healing process that has already transpired." A 7-day-old surgical wound that is reopened and then reclosed remains a 7day wound at the time of reclosure. It does not revert to being a fresh wound. Because acute reoperation is commonly indicated because of intraabdominal infection or may be attended by significant contamination as suture lines are reconstructed or the intestinal tract is opened for any number of reasons, closure of the abdominal wound completely may not be desirable. Although definitive data are not currently available, it is felt that wounds reopened even for noninfectious indications are at increased risk for infection, dehiscence, evisceration, and perhaps even necrotizing fasciitis. Thus, delayed primary closure or even secondary closure may prove desirable for many acute reoperative wounds." Obviously, the advantages from prior days of the healing process that one may gain by using the same incisions are lost if the subcutaneous fat and skin are left open for delayed closure. Clinical judgment is important in weighing the merits of primary wound closure at the acute reoperation against the potential risks of contamination incurred at the reintervention. When remote reoperation is undertaken, opening the abdominal cavity through the previous incision commonly is less desirable. Old scar is less vascularized and is at least theoretically at greater risk for infection. Adhesions of omentum and intestine may make the old wound a difficult means for entrance into the abdominal cavity. Certainly, inadvertent enterotomy has been experienced by all surgeons reoperating through a remote incision. As noted previously, unlike the situation in acute reoperation, remote reoperations commonly are for indications different from those of the original procedure and may have distinct features thatnecessitate a separate incision for exposure. When patients have one or more previous mature incision sites on the abdominal wall, the following recommendations by the authors are thought to be justified. First, the surgeon should avoid the creation of a new incision that intercepts a prior incision at an acute angle. Rather, one should attempt to interdigitate new incision lines at right angles to old ones. The classic example where an angle less than 90 degrees is commonly created is the subcostal incision for cholecystectomy when the patient has had a prior midline incision. The 45-degree angle creates an ischemic area that may form the basis for a wound separation or infection or the delayed development of a ventral hernia. When a right subcostal incision is desirable, a less acute angle can be created by making the incision more transverse and less oblique. In selected cases, it may not be necessary to intercept the two incisions at all. Second, one should avoid parallel vertical incisions. Indeed, a corollary might well be to avoid vertical incisions altogether except for midline
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incisions. Parallel vertical incisions create a relative area of ischemia at the centralmost portion of their parallel extent. A midline and a paramedian incision create a high-risk area of acute (dehiscence) or delayed (ventral hernia) separation. Because the crossover of fascial and muscle blood supply across the linea alba is minimal, a paramedian incision, even without a prior midline incision, creates a relatively ischemic edge to the medial aspect of the wound. In the authors' opinion, a paramedian incision is generally to be avoided in all abdominal operations.
PREVENTION OF ABDOMINAL WALL COMPLICATIONS Whether for acute or remote reoperations, the abdominal wall subjected to reoperation is thought to be at increased risk for infection, dehiscence, or ventral herniation. Wound ischemia, tension, postoperative infection, and technical failures of wound closure become interrelated variables that are commonly impossible to separate when one attempts to analyze a bad outcome in a given patient. Wound ischemia begets infections, which commonly are identified as dissolution of the fascia and an apparent pullthrough of suture material. Tension creates ischemia, and certainly, infection of tissues can create ischemia as well. Wound edge ischemia from strangulating fascial sutures may result in fascial necrosis, infection, or both. In general, preventive systemic antibiotics would appear to be a prudent choice whether for acute or remote reoperations. The antibiotic should be administered preoperatively, should have activity against the likely contaminants identified, and should have a pharmacokinetic profile that will ensure its presence in the tissues throughout the procedure. 8, 9 In the acute reoperation, the choice of drug should be tempered by the patient's history before the reoperative event. If a patient has already had a course of antibiotic therapy during the postoperative period of the initial procedure, then conventional antimicrobial prophylaxis with commonly used antibiotics may not prove adequate. For example, if a patient has already had a 7-day course of broad-spectrum antibiotics for peritonitis, it is unlikely that a first-generation cephalosporin will be of great utility as a preventive antibiotic. On the other hand, in the absence of prior antibiotic administration, an early-generation cephalosporin may be useful for prophylaxis. Because no data are really available to guide antibiotic selection for infection prevention in the acute reoperative patient, the decision is an empiric one that is predicated on which drugs have previously been used and what culture data are available to identify current colonization of the patient. In remote reoperations, use of the oral antibiotic bowel preparation in conjunction with mechanical colon preparation may offer some advantages. 3 Reoperation into the upper abdomen is associated with the risks of inadvertent enterotomy into the transverse colon. The preoperative mechanical preparation of the colon and use of neomycin-erythromycin will allow a safe primary closure for these colonic enterotomies. Although it has not been proved to be beneficial, the simultaneous use of systemic antibiotics
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5
together with the oral intestinal antibiotic preparation probably will provide additional protection against infectious morbidity in these complex cases. At the time of reoperation, the edges of the incision may be suboptimal for wound closure. In acute reoperation, particularly in infected or trauma patients, the subcutaneous fat and fascial edges of the wound commonly will require debridement before reapproximation. Tenuously viable wound margins, particularly when increased intra-abdominal pressure is present from distended and edematous intestine, certainly will set the stage for dehiscence or subsequent ventral herniation. In some cases, intestinal decompression with a long intestinal tube may prove desirable in reducing intra-abdominal pressure and abdominal wall tension for primary closure. In some complex cases, the use of synthetic polypropylene mesh will obviate attempted closure of the fascia under conditions of increased abdominal wall tension. The wound edges are simply allowed to retract to a resting position, and the mesh is sewn in place. Commonly, the resolution of gastrointestinal ileus and bowel wall edema will allow primary fascial closure later. If not, a more complicated reconstruction may be necessary. In remote reoperation, broad splayed or attenuated segments of the prior surgical wound may be undesirable for wound closure. Primary closure of scar may increase infection rates by virtue of its avascular nature and may also be undesirable from a cosmetic perspective. Thus, excision of the prior wound scar may be useful.
REOPERATION FOR ABDOMINAL WALL COMPLICATIONS Unfortunately, the abdominal wall incision and its associated complications may itself be the focus of the reoperation. The continuum of postoperative abdominal wall complications may range from simple wound infection to necrotizing fasciitis. Simple wound infections commonly are managed by removing the skin sutures and separating the subcutaneous fat. The adjuvant effects of dermal sutures are thus eliminated. Pus is evacuated, and the fibrinous debris can be removed mechanically. With local care, these wound infections will heal uneventfully by secondary intention. Antibiotics are rarely indicated and should be employed only when either cellulitis or tissue necrosis is present. Thus, routine cultures for every wound infection hardly seem justified, and culture should be reserved for the more complex complications. Fascial separations may occur with or without infection and with or without evisceration. One or two broken sutures may create a small area of dehiscence secondary to purely technical error. TJnraveled knots or "scored" monofilament sutures that subsequently break are common causes for these complications. In complex cases, the small area of dehiscence without evisceration can be handled without reoperation. However, in general, localized fascial separations are certain to result in ventral hernia and are best managed by a return to the operating room and appropriate repair. With the increased popularity of running fascial repairs, the localized fascial dehiscence means that total wound separation and evisceration are eminent, and repair should be undertaken immediately.
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When repairing dehiscence or evisceration, the surgeon must take into consideration those variables that were responsible for the complication. If a purely technical error was indeed the cause of the fascial separation, then suture repair alone will be sufficient. If fascial infection and necrosis were responsible, then appropriate debridement of the fascial layer back to viable, bleeding tissue is essential. Debridement should not be abbreviated in the interest of trying to bring the fascia back together for closure. Such short cuts invariably lead to reseparation of the fascia and further reoperations. Intestinal intubation may reduce the intra-abdominal pressure in selected cases and allow primary closure after dehiscence. In general, the use of retention sutures, with or without all the different bridge devices that are employed, may prevent evisceration of the abdominal contents, but they do not prevent dehiscence events. Necrotizing fasciitis of the abdominal wound is a complication that must be promptly appreciated and managed. 10, 12 These infections usually are polymicrobial and can have a fulminant course." In many patients, dehiscence is the event that leads to the diagnosis, although fever, leukocytosis, and other evidence of clinical infection usually are present. Wide and appropriate debridement requires removal of considerable fascia and muscle to eradicate the infection. The overlying subcutaneous tissue may remain viable and should be preserved in the interest of subsequent reconstruction.
POLYPROPYLENE RECONSTRUCTION OF THE ABDOMINAL WALL Synthetic material has become somewhat popular as a replacement for lost fascia. 1, 5, 11, 13-15 The availability of these synthetic meshes has allowed the surgeon to debride the abdominal wall with necrotizing infection fully without worry about closure of the wound at the time of the procedure. In selected difficult trauma cases, when shock, extensive resuscitation, and edema of the intestinal contents make closure of the abdominal fascia difficult, a temporary mesh interposition can permit immediate closure. As noted above, when the distended and edematous state of the intestine has resolved, primary closure of the fascia can be achieved. Polypropylene mesh has been extensively used for fascial replacement. The polypropylene itself is relatively inert and does not appear to foster infection with the same degree of efficiency as is seen with braided materials. The coarse weave of the mesh allows effective drainage between the interstices and permits drainage to the exterior. The relatively inert character of polypropylene combined with the coarse weave has allowed this synthetic material to be used as a fascial substitute even when infection has been active within the abdomen or in the abdominal wall. As in other clinical circumstances, the mesh will become infected itself if necrotic elements of fascia and soft tissue are sewn into the mesh or if the mesh is covered prematurely with grafts or flaps when large concentrations of bacteria have colonized the mesh surface. The technique for mesh placement is relatively simple." After complete
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wound debridement, the fascial edges are allowed to retract to a resting position. A large sheet of polypropylene mesh is contoured to fill the defect. The mesh is then cut so that a l-cm excess is present all around the wound for suturing. When contouring the mesh, it is always best to err in favor of cutting the sheet too large rather than too small. The redundency can be corrected by the placement of sutures as the mesh is sewn in place. The contoured piece of mesh is then placed in the wound and sutured to the fascia with 0 polypropylene suture. The mesh edge is placed beneath the native fascia and peritoneum. Horizontal mattress suturing is then used to sew the mesh to the posterior surface of the fascia and peritoneum. The stitch is passed anterior to posterior through both the anterior and the posterior fascial layers, then passed down through the mesh and back up through the mesh with a l-cm gap between the entering and exiting sites on the mesh. Thus, the polypropylene suture will have a l-cm bite on the mesh that is 1 em from the edge. Sutures are placed in an interrupted fashion, 1 em apart, about the perimeter of the inlaid mesh (Fig. 1). It generally is desirable to employ interrupted sutures when mesh is used for infection or necrotizing fasciitis, because persistent local infection or necrosis may result in the failure of several sutures. If a running technique is employed, a failed suture that pulls through subsequently necrotic fascia may result in separation of the entire segment. In elective repair of large ventral hernia defects or in the placement of mesh in uninfected but difficult-to-close abdominal walls, the running suture technique may be used. Four quadrant sutures are placed at the 3-, 6-, 9-, and 12-0'clock positions about the wound. If the needle is left on the polypropylene for each quadrant stitch, the fascia can be sutured to the
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,
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Figure 1. Placement and suturing of polypropylene mesh into the fascial defect on the abdominal wall.
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Figure 2. Placement of the flank counterincision prior to undermining the bipedicled flap to be transferred over the midline soft-tissue defect.
mesh by passing the needle down through fascia with a I-cm purchase from the fascial edge. A I-cm bite of the mesh is secured parallel to, and 1 em from, the edge of the mesh, and the needle is then passed back up through the fascia. The running suture is continued until one reaches the "free arm" of the adjacent quadrant stitch, where it is tied with multiple knots to prevent slippage. In both the interrupted and the running suture techniques, an attempt is made to suture the plane of the mesh parallel to the plane of the posterior fascia. This should avoid downward buckling of the mesh, which could be the source of intestinal erosion and fistula formation. When mesh is used as a temporary substitute for the difficult abdominal wall closure because of edematous and distended intestine but without fascial loss per se, the mesh can be removed 2 or 3 days later after edema and distention have subsided. The sutures simply are cut, and the mesh is removed. Primary fascial closure is completed. Delayed primary closure is necessary for the skin and subcutaneous tissues because of the inevitable contamination during the temporary mesh presence. When fascial losses secondary to infection, necrosis, or trauma preclude primary closure, the polypropylene mesh can be employed for reconstruction. The mesh is left in situ, and granulation tissue is permitted to proliferate between the interstices of the polypropylene. A confluent bed of red granulation tissue will then develop over the entire mesh. It is tempting to consider the placement of split-thickness skin grafts over the granulated mesh. However, the continued contraction of the wound and granulation tissue after skin grafting will result in buckling of the mesh with erosion of mesh material through the neoepithelial cover.!" Fullthickness flaps of skin and subcutaneous tissue are preferable. The flaps can be mobilized on one or both sides of the abdominal wall, depending
ABDOMINAL WALL CONSIDERATIONS AND COMPLICATIONS
9
A
8
S.L.
Figure 3. Unilateral bipedicled flap for closure of the midline defect. A, Undermining the flap. B, Medial displacement of the flap. The residual lateral skin defect on the abdominal wall is covered with a meshed split-thickness skin graft. The closed suction catheters have been placed in the potential dead space between the flap and the granulation tissue to avoid seroma or abscess formation.
on the magnitude of the defect. Bilateral mobilization alone may be sufficient to allow midline closure over the granulation tissue. In closures particularly difficult because of the size of the defect, counterincisions on the flanks will create bipedicled flaps, which can be created on one or both sides of the abdomen (Fig. 2). The bipedicled flaps are easily mobilized from the area of the counterincision to the edge of the granulating midline wound (Fig. 3A). The bipedicled flap is then displaced to the midline for closure, with split-thickness skin grafts being used to cover the skin defect
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on the flank (Fig. 3B). Closed suction drains are important to prevent seroma accumulation and potential abscess formation in the space between the granulation tissue and the overlying subcutaneous fat. Premature removal of the suction catheters is a temptation when the volume of drainage has declined to less than 30 to 50 ml per day, but the authors have seen delayed seroma accumulation and abscess formation when the catheters have been removed prior to resumption of full ambulatory activity by the patient. Accordingly, it is recommended that catheters not be removed until full ambulation is resumed and drainage stabilizes at less than 30 to 50 ml per day. A technique similar to that described above also can be employed in the repair of large ventral hernias or when fascial defects may be created by large resections of the abdominal wall in cancer operations. Such fascial defects may have the polypropylene placed and have immediate .fullthickness coverage by the same techniques employed for the delayed reconstruction that is illustrated and described above.
SUMMARY The abdominal wall is the source of significant problems for patients undergoing multiple abdominal operations. The orientation of sequential incisions must be carefully considered to avoid compromise of the abdominal wall blood supply, which may result in either acute (dehiscence) or delayed (ventral hernia) complications. Infections are the most serious problems of the multiply operated on abdominal wall. These complications may range from simple wound infection to necrotizing fasciitis. Management may require only simple drainage of the infection or may entail extensive debridement for the necrotizing processes. Regardless of the cause, the multiply operated on abdominal wall may require reconstruction because of lost fascia. Polypropylene mesh can be employed safely and effectively for this purpose.
REFERENCES 1. Arnaud JP, Eloy R, Adloff M, et al.: Critical evaluation of prosthetic materials in repair of abdominal hernias. Am J Surg 133:338, 1977 2. Bernard HR" Cole WR: Wound infections following potentially contaminated operations: Effect of delayed primary closure of the skin and subcutaneous tissue. JAMA 184:290, 1963 3. Clarke JS, Condon RE, Bartlett JC, et al: Preoperative oral antibiotics reduce septic complications of colon operations: Results of prospective, randomized, double-blind clinical study. Ann Surg 186:251, 1977 4. Fry DE: The surgical incision in reoperation of the abdomen. In Fry DE (ed): Reoperative Surgery of the Abdomen. New York, Marcel Dekker, 1986, pp 1-12 5. Fry DE, Osler T, Clevenger F, et al: The use of polypropylene mesh in abdominal wall reconstruction. Perspect Cen Surg 1:93, 1990 6. Hunt TK: Wound healing. In: Hunt TK, Dunphy JE (eds): Fundamentals of Wound Management. New York, Appleton-Century-Crofts, 1979, pp 1-10
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7. Meleney FL: Bacterial synergism in disease processes with a confirmation of the synergistic etiology of a certain type of progressive gangrene of the abdominal wall. Ann Surg 94:961, 1931 8. Polk HC Jr, Lopez-Mayor JF: Postoperative wound infection: A prospective study of determinant factors and prevention. Surgery 66:97, 1969 9. Polk HC Jr, Trachtenberg L, Finn MP: Antibiotic activity in surgical incisions: The basis for prophylaxis in selected operations. JAMA 244:1353, 1980 10. Rouse TM, Malongoni MA, Schulte WJ: Necrotizing fasciitis: A preventable disaster. Surgery 92:765, 1970 11. Rubio PA: New technique for repairing large ventral incisional hernias with Marlex mesh. Surg Gynecol Obstet 162:275, 1986 12. Stone HH, Martin JD Jr: Synergistic necrotizing cellulitis. Ann Surg 175:702, 1973 13. Stone HH, Fabian TC, Turkleson ML, et al: Management of acute full-thickness losses of the abdominal wall. Ann Surg 193:612, 1981 14. Voyles CR, Richardson JD, Bland KI, et al: Emergency abdominal wall reconstruction with polypropylene mesh. Ann Surg 194:219, 1981 15. Wouters DB, Krom RAF, Slooff MJH, et al: The use of Marlex mesh in patients with generalized peritonitis and multiple organ system failure. Surg Gynecol Obstet 156:609, 1983
Address reprint requests to Donald E. Fry, MD Department of Surgery The University of New Mexico School of Medicine Albuquerque, New Mexico 87131
