General Laparotomy

Chapter 6 General Laparotomy




INTRODUCTION


Conviction that one should undertake only an invasive procedure whose complications one can manage is a fast-fading tenet as increasing numbers of nonsurgical specialists attempt invasive procedures. The granting of privileges in abdominal surgery, however, still assumes that the individual so honored will be able to plan an approach, accommodate to the sequelae of previous abdominal surgery, enter the abdomen, accomplish the intended task, repair or otherwise manage injuries created while doing so, deal with the sequelae of inflammation, treat infection, and deliver postoperative care with minimal assistance.


No amount of technical expertise trumps careful preoperative planning. Strategies to avoid traumatic entry into the peritoneal cavity, preoperative determination of the need for mechanical and antibiotic bowel preparation, choice of incision, and planning optimal exposure are as important as intra-operative technical judgment and facility with the instruments. In some cases, the surgeon may have weeks to contemplate these issues, whereas in more urgent situations, such as frank peritonitis, ruptured viscus, leaking aneurysm, or trauma, the planning stage is significantly truncated. Patients who have had prior abdominal surgery or exposure to radiation, in particular, require extensive contingency planning by the operating surgeon. Previously radiated patients may be particularly unforgiving of operative misadventure because radiation may impede repair mechanisms and both the cellular and the vascular phases of wound healing.1


Unlike laparoscopic surgery, in which incision choice is often dictated by optical considerations, instrument trajectory, and vantage point, the surgeon performing open surgery can select from several standard incisions. However, not all incisions adapt well to unexpected operative findings. Traditionally, operations in which the exact source or extent of acute intraabdominal pathology is not known are approached through an abdominal midline incision, which can be readily extended in either direction, as dictated by operative findings. In the case of patients with a previous midline incision, the incision at reoperation is often begun well above or below the previous laparotomy scar to permit atraumatic entry into the peritoneum. Pragmatically, the midline incision is also useful for operations on large abdominal tumors or spleens, which, because of their size, may not be able to be delivered through a transverse incision. Caudad extension of a midline incision allows improved exposure of pelvic tumors, whereas cephalad extension facilitates release of the colonic flexures.


Detailed knowledge of embryology and anatomy begets well-vascularized incisions and tension-free, well-perfused anastomoses. For example, a surgeon familiar with the trajectory of counterclockwise midgut rotation about the superior mesenteric vessels during the second trimester of gestation2 can draw on the knowledge to reverse the process at operation to facilitate tension-free low pelvic anastomosis of the colon (Fig. 6-1) or to expose the lateral retroperitoneum in the avascular planes described by Cattell, Braasch, and Maddox and associates (Figs. 6-2 and 6-3).3,4





Some have advocated avoidance of midline incisions because of controversial concerns related to structural weakness and attenuated blood supply. Evidence supporting these misgivings is not convincing in studies in animals or humans, but transverse incisions may have other advantages. Sometimes, selecting a low transverse incision over a midline incision extending more cephalad will favorably affect pulmonary toilet and maintain functional reserve capacity without compromising intraabdominal exposure. The right lower quadrant (RLQ) transverse incision, for example, both allows for optimal operative exposure and facilitates pulmonary toilet in resection of cecal cancers. In the upper abdomen, transverse incisions can facilitate open packing or repetitive entry, as when multiple sequential laparotomies are required for the débridement of pancreatic necrosis. A once-common belief that muscle-dividing transverse incisions or muscle-reflecting paramedian incisions convey additional strength solely because of their multiple separately closed fascial layers or superior blood supply is also unsupported by experimental or clinical evidence. Indeed, a contradicting body of evidence supports the superiority of mass closure over layered closure even in areas off the midline, where multiple fascial layers exist (Fig. 6-4).5



In circumstances in which the pathology is confidently delineated by a preoperative history, physical examination, and/or preoperative imaging studies, it may be preferable to use one of a number of anatomically defined “specialty” incisions. Examples are the right subcostal (Kocher) incision for open cholecystectomy and duodenal exploration, the muscle-splitting RLQ incision for appendectomy, and the Pfannenstiel incision for nonmalignant gynecologic pathology.





Incorrect Choice of the Muscle-Splitting Appendectomy Incision






Incorrect Choice of the Pfannenstiel Incision






Failure to Consider the Consequences of an Incision’s Innervation and Blood Supply






Failure to Anticipate Malignant or Nonmalignant Adhesions when Making the Abdominal Incision


An abdominal scar should alert the surgeon to the potential for intraabdominal adhesions caused iatrogenically or in response to the original pathology. The abdominal surgeon should be aware of any existing muscular defect in an area of intended incision as well as whether prosthetic mesh has been previously placed to repair a defect of the abdominal wall. Adhesion of the viscera to the abdominal wall in these circumstances, and in the case of tumors close to the anterior abdominal wall, should be presumed.





Prevention




Small incisions reduce, and may compromise, exposure. In the case of malignancy, a longer incision may preserve the opportunity for en-bloc resection. Incisional planning for removal of large tumors or the extirpation of pathologically enlarged organs can be facilitated by abdominal palpation after anesthetic agents have relaxed the abdominal wall, thereby avoiding incision directly into the tumor or its parietal peritoneal attachments. The surgeon should not forego this one last opportunity for the physical examination to inform incisional planning.



Failure to Identify the Peritoneal Cavity





Prevention





Independent of the choice or direction of incision, the anterior surface of the parietal peritoneum is often fused to the deepest layer of fascia. Thus, the safest entry into the peritoneal cavity is with a knife. The surgeon and first assistant should elevate the peritoneum with toothed forceps; peritoneal entry is made with the belly of a No. 10 blade. Although compelling reasons of hemostasis, economy of time, and surgeon experience might suggest division of the muscle layers with the electrocautery, with rare exception, the initial entry into the peritoneal cavity should be made with cold steel. Even the unfortunate surgeon who finds that an incision intended only for the peritoneum has also entered a loop of intestine will be gratified at the time of repair that she or he has cleanly incised, rather than burned or spread, her or his way into the intestine.


Once a small entry has been made into the peritoneal cavity, the operating surgeon should insert his or her finger and palpate the parietal peritoneum in the direction of intended incisional extension, in order to see whether the incision may be atraumatically developed in that direction. If free of adhesions, the incision can then be enlarged with the electrocautery, dividing all layers of the abdominal wall simultaneously rather than in sequence. In the case of previous laparotomy, hernia, inflamed abdominal viscera, enterocutaneous fistula, or adherent tumor, the laparotomy incision should be developed under direct vision and only as far as the first intraperitoneal adhesion. At this point, Kocher clamps should be placed to elevate the fascial edges of both sides of the incision so that loops of bowel adherent to it might be visualized. For initial dissection, after careful fascial division, an area is typically chosen in which the adhesions are translucent because a pocket of air or fluid has collected beneath them and their associated loops of intestine, signaling the absence of other viscera at risk beyond them. Translucent adhesions may be taken down sharply, and the free abdominal cavity may be thus visualized and entered (Fig. 6-9). For the same reason that spreading with the scissors is not desirable in entering the peritoneal cavity, minimal spreading is often best in the early development of the laparotomy. With traction provided by Kocher clamps in the vertical direction, the operating surgeon can often, with the aid of a Mikulicz pad held by the “clawed” nondominant hand, apply atraumatic tangential traction to the adhered loop of bowel, thereby permitting identification of interloop adhesions or adhesions of bowel to abdominal wall. The adhesions are maximally exposed and lengthened by this maneuver, and lysis can occur with sharp dissection as the fingers of the surgeon’s nondominant hand subsequently shift into the free space thus created (Fig. 6-10).




Lysis of adhesions is a shared and dynamic responsibility between the operating surgeon (often positioned on the patient’s right and lysing adhesions to the left of midline) and the first assistant (often positioned on the patient’s left and lysing adhesions to the right of midline). Assuming right-handed dominance and these positions at the operating table, the operating surgeon is best positioned to lyse adhesions in the epigastric midline and the first assistant is optimally positioned to lyse adhesions in the pelvis. For this reason, in pelvic operations, the surgeon stands on the patient’s left side. Although it is tempting to identify and “chase” interloop adhesions deep into the peritoneal cavity, a focused determination and a synergistic cooperative strategy should be formulated between first assistant and operating surgeon to first identify and free the entire underside of the parietal peritoneum and to develop the entire length of the contemplated abdominal wall incision before deeper intraabdominal pathology is addressed.



Injury to the Intestine




Repair




Partial-thickness injuries usually need not be repaired. However, in the presence of severe adhesive disease, prior radiation, hematoma, or other comorbidity compromising repair, the relative paucity of a normal blood supply may cause a partial-thickness injury to evolve to a full-thickness injury in the postoperative period.


When a loop of bowel is injured, it is tempting to react immediately by attempting to place sutures or Babcock or Allis clamps to stem the flow of enteric contents. However, even atraumatic clamping of a partially defined enterotomy often helps very little and sometimes induces further trauma. Rather than close the enterotomy in an adhered loop of bowel in situ, the loop should be freed from adjacent structures, mobilized for complete inspection, and assessed for its salvage potential. Mobilization may demonstrate significant bowel injury or devascularization. A temporizing “damage control” approach, with temporary suture or stapling of the bowel, or division of the bowel with subsequent reassessment, may well be appropriate, but only after mobilization. To commit to definitive repair, resection, and/or anastomosis at the time of injury, before mobilization, or before the goals of the operation have been achieved has the potential to waste time; the initial closure may be inadequate or multiple injuries in the same short segment of bowel may be identified and need to be handled by incorporation of several injuries into a single resection.


Full-thickness small bowel injuries are handled differently than full-thickness large bowel injuries. In general, independent of whether the bowel has had mechanical or antibiotic preparation, most small bowel injuries may be handled with simple repair or resection and repair with anastomosis; uncomplicated full-thickness large bowel injuries in unprepared intestine should, generally, be handled with simple repair if they are solitary and if minimal fecal contamination has occurred. When possible, intestinal injuries should be closed transversely to minimize the likelihood that the repair would “hourglass” or narrow the caliber of the involved viscus. The Heineke-Mikulicz pyloroplasty6 gives good evidence that even when a rent is absolutely and deliberately longitudinal, most enterotomies can be closed transversely.


If resection is required for extensive large bowel injury in circumstances in which there has been no bowel preparation, consideration should be given to exteriorizing the ends of the bowel, with reanastomosis at a subsequent surgery. Primary closure of a large bowel injury becomes more and more indefensible when the patient is ill; the operation is extensive; the injuries are unexpected, multiple, or substantial; or compromise of a prosthetic device by failed closure is possible. Permanent prosthetic devices such as nonabsorbable mesh should generally not be electively placed in the setting of enteric injury.


Whereas patient, unhurried dissection along the antimesenteric surface of the small intestine is often successful in freeing even the densest of adhesions, in some circumstances, it becomes abundantly clear that a loop of small intestine diving into the pelvis will not be able to be freed under direct visualization. In operations for intestinal obstruction, this situation is heralded by a dilated loop diving into the pelvis adjacent to an unobstructed loop coming out of the pelvis. When this circumstance exists, and when injury to such bowel in freeing it is judged to be inevitable, the appropriate goal is to expeditiously resect as short a segment of intestine as is possible, while preserving and minimizing injury to the structures to which the involved loop is adhered. To commit to the tedious freeing of such a loop in the hope of salvaging it is a fool’s errand; it often proves to not be possible, and the futile attempt wastes a significant amount of operating time. When small bowel resection is judged to be inevitable in adhesive disease, the afflicted loop should be delivered into the upper abdomen by the least traumatic means possible, and an assessment should then be made as to whether repair or resection with anastomosis is most appropriate. When the afflicted loop is attached to tumor and en-bloc resection is contemplated, the loop adherent to the tumor is isolated and left in situ for future mobilization with the specimen, and fecal continuity is restored by anastomosis of the two functioning ends of the bowel thus freed from the tumor.



Prevention





Adhesiolysis with the No. 10 blade should not be attempted by the novice surgeon because it requires a delicate touch and considerable experience with the texture and spectrum of abdominal adhesions. Frequent blade changes are necessary for effective use of the technique because it is the knife’s tip, rather than its belly, that incises the adhesion. The tip of the blade should be placed at the position of intended initiation of the adhesiolysis and rotated counterclockwise to form a large acute angle with the intended direction of incision. The knife should then be dragged to the right, maintaining this acute angle as the adhesion is lysed. The largest acute angle of blade with trajectory permitting the knife to be moved in the intended direction should be chosen and maintained as the blade is moved (Fig. 6-12). Smaller angles will increase the likelihood of bowel injury.



Lysis of adhesions is among the most sophisticated tasks performed by the abdominal surgeon, and no preconceived time should be allotted for its completion. Extensive adhesions demand extensive patience and meticulous dissection. When dense adhesions are anticipated, no competing commitments on the surgeon’s time should be made. When adhesions are encountered unexpectedly in the course of dissection, arrangements should be made for all competing commitments to be rescheduled to minimize the risk of bowel injury. The first assistant should provide the operating surgeon with as panoramic a view as the anatomic situation permits. Success is often less the result of heroic traction than of an assessment as to how the bowel can be manipulated to best display the desired incisional plane.



Visceral Injury during Exposure of a Ventral Hernia Defect





Prevention




The techniques for safe subsequent laparotomy, as described previously, may be adapted to permit definition and exposure of ventral hernias. An incision is begun at some distance from the palpable hernia sac in order to avoid entry into a peritoneal sac apposed to the skin. As the hernia occupies space in the subcutaneous tissue that is vacated after repair, incorporating an overlying ellipse of skin at the beginning of the operation serves three useful purposes. The maneuver minimizes the timeconsuming need for dissection of the sac from the overlying and often attenuated skin, which is often subsequently discarded. Improved visibility created by wider exposure enhances the surgeon’s ability to define the sac’s interface with the fascia and to avoid visceral injury. Finally, resection of redundant skin and subcutaneous tissue acknowledges the new geometry of the wound and the absence of a visceral bulge after fascial repair, thereby minimizing the magnitude of the skin flaps and making seroma formation less likely.


In either mobilizing a hernia sac or identifying the serosal surface of an externalized viscus during stomal reversal, blunt dissection is the surgeon’s friend. For ventral hernias, the sac is exposed after careful incision of the skin and subcutaneous tissue. The gloved hand invaginated into a Mikulicz pad strips the subcutaneous fat away from the sac to allow visualization of the sac’s origin at the disrupted fascia of the abdominal wall. Three approaches to safe repair are possible. For hernias in which incarceration is not suspected, some surgeons prefer to bluntly develop the plane between the abdominal wall’s musculature and the sac’s parietal peritoneum without ever entering the peritoneal cavity. They then close the muscular wall extraperitoneally. Other surgeons prefer to identify a point in the sac at which the viscera are not believed to be adherent to the peritoneum. They open the sac in that region, dissect the omentum or hollow viscus away from the parietal peritoneum, resect the sac, and then close the defect. A third option is to open the peritoneum only after circumferential identification of the sac’s interface with the fascial ring is complete (Fig. 6-13). In the latter two instances, safe entry into the peritoneal cavity is pursued with adhesiolysis as described previously for recurrent laparotomy.


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Jun 21, 2017 | Posted by in GENERAL SURGERY | Comments Off on General Laparotomy

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