CHAPTER 45 DIAGNOSTIC PERITONEAL LAVAGE AND LAPAROSCOPY IN EVALUATION OF ABDOMINAL TRAUMA

Before 1965, lavage of the peritoneal cavity had a recognized role for the diagnosis and treatment of acute peritonitis, treatment of chronic renal failure, and treatment of drug overdosage. In 1965, Root published a landmark article describing the use of peritoneal lavage to diagnose occult intra-abdominal hemorrhage in 28 patients. Lavage of the abdominal cavity with 1 liter of an isotonic solution dramatically improved the sensitivity for detecting intra-abdominal hemorrhage compared with four quadrant paracentesis, which carried false negative rates of 17%–36%. In the period before 1965, blunt abdominal trauma mortality was over 45%, with two-thirds of deaths attributed to undiagnosed intra-abdominal hemorrhage or visceral injury. Root established the basic principles pertaining to diagnostic peritoneal lavage (DPL) that would be followed for over 20 years. These include controlling skin bleeding before catheter insertion to reduce contamination of the fluid, attempting aspiration of free blood before infusing fluid, mild rocking of the patient to improve the chance of a mixed sample, retrieving a large proportion of the infusate, and examining the lavage fluid for hemoglobin concentration, amylase, and bacteria. Root did not specify criteria for hemoglobin concentration or cell counts, but noted the subjective criterion of “more than a faint salmon pink tinge of blood in the retrieved perfusate is an indication of intra-peritoneal hemorrhage requiring laparotomy….” He noted the excellent sensitivity and found no false positives, but one case was reported as a possible complication because an isolated bowel perforation was encountered.

From 1966 to September 2005, there were 2445 Medline-indexed articles, which referred to “peritoneal lavage” as a medical subject heading (MESH) or in the title or abstract. Of these, 931 articles also map to the MESH term “wounds and injuries,” or mention “trauma” in the title or abstract. After eliminating review articles and those that do not pertain to humans, 791 remained that relate to diagnostic peritoneal lavage in the context of trauma. There are no randomized prospective clinical trials comparing DPL to other diagnostic maneuvers. However, there are nine randomized clinical trials comparing at least two distinct DPL techniques. While the transitions are indistinct, some generalizations can be made about observable patterns in the literature. Publications in the first decade following Root’s article consisted mainly of case reports and case series showing the adoption of DPL as a diagnostic maneuver for blunt abdominal trauma. The second decade (1976–1985) brought larger case series, describing variations in technique, defined specific criteria for a positive lavage, and compared DPL to computed tomography (CT) and ultrasound (US) for diagnosing abdominal injury. During this period, DPL was regarded as the gold standard to which developing technologies were compared. Comparisons were not randomized, but based on selection by hemodynamic stability. Many studies used a cross-over design, where patients underwent two studies and the results were compared. By the third decade (1986–1995), CT scanning emerged as the preferred modality for diagnosing traumatic abdominal injuries. US was being evaluated as a viable and less invasive substitute for DPL, and DPL was mentioned passively, predominantly as one of several modalities by which abdominal injuries were being diagnosed in larger retrospective series. Of the 205 articles mentioning DPL since 1996, only 42 were coded as having a focus on the subject. Seven of these pertain to an article and six comments entitled “Diagnostic Peritoneal Lavage—An Obituary.” Despite the implications of the article, there remains support for a limited role for DPL in trauma.

DPL can be performed by either an “open” or “closed” technique. It can also be considered in the context of three distinct portions of the examination: initial aspiration, visual examination of the lavage fluid, and microscopic examination of lavage fluid. In addition, consideration has been given to the potential role of (1) delayed DPL, when an extended time interval has passed since the occurrence of injury; and (2) repeat DPL for clarification of initially ambiguous findings. Unfortunately, these additional roles are not well defined and are unlikely to be studied in the future. The technique of DPL is the only aspect compared in a randomized clinical trial (RCT) model. Of the nine RCTs performed between 1980 and 1991, two compared catheter types or the position for access. The remaining seven compared open and closed techniques. One article provides evidence for a lower complication rate with the open technique. Six articles indicate an equal or lower complication rate with the percutaneous or closed technique. General conditions for keeping the closed technique safe include decompression of the stomach and bladder, exclusion of patients with major pelvic fracture or pregnancy, absence of prior abdominal surgery, and experience of the surgeon. The closed technique is recognized to be faster. It is performed by sterile preparation, infiltration of local anesthetic, creation of a small skin incision, and the insertion of a multiholed catheter over a trocar or the use of a Seldinger needle–guide-wire technique. Initial aspiration of 10 cc–20 cc of gross blood is considered an indication of intra-abdominal injury. If aspiration is negative, 1 liter of saline or lactated Ringers is infused and recovered by the siphon effect. It is expected that 60%–90% of the instilled volume must be recovered to provide a reliable sample, although some claim that recovery of 200 ml is adequate. The open technique is preferred in cases in which gastric and bladder decompression is not practical, the patient is pregnant, or a pelvic fracture is present. Similar preliminary preparations are made; however, the open procedure is facilitated by two operators or an assistant. Performing a 2-cm incision in the supraumbilical position avoids potential injury to the gravid uterus or decompression of a suprapubic hematoma. The fascia is sharply incised under direct visualization, and the peritoneum is drawn upward and incised between clamps. A catheter can then be directly inserted into the peritoneal cavity and directed toward the pelvis. Aspiration and lavage are then performed as in the closed technique. Technical complications are reported to occur in less than 1%–5%, with the most common occurrence being failure to recover the desired volume of fluid. Iatrogenic perforation of the bladder, stomach, small bowel, or colon occurs rarely. Traditionally, such perforations, indicated by retrieval of luminal contents rather than blood, were considered an indication for abdominal exploration. It is recognized that these needle and catheter size injuries can be selectively managed nonoperatively in the stable patient.

Options for diagnostic evaluation of the ambiguous abdomen include serial clinical exam, DPL, US, and CT. Clinical exam is notoriously unreliable, particularly when confounded by distracting injuries and altered sensorium resulting from intoxication, head injury, or both. Serial exam and repeat hemoglobin measurement continues to be a viable approach for stable, alert patients, with a low suspicion for abdominal injury. Some advocate a more definitive objective evaluation for the sake of shortening hospital stay and reducing resource utilization. DPL emerged as the standard for resolving the ambiguous abdominal exam. Its primary advantages and disadvantages are noted in Table 1. When considered as a diagnostic tool for hemoperitoneum, DPL is highly sensitive, specific, and accurate. However, according to current concepts in the management of abdominal trauma, hemoperitoneum alone does not constitute an indication for operative exploration. Thus, DPL is too sensitive and leads to a high incidence of nontherapeutic laparotomy. When used to indicate the need for laparotomy, the specificity is low and accuracy is limited. Given that low-grade splenic and hepatic injuries are the most common cause of hemoperitoneum after blunt trauma, and that most of these can be successfully managed nonoperatively, DPL has been largely replaced by focused assessment with sonography for trauma (FAST) and CT as the preferred diagnostic modalities by which therapeutic decisions are made.

Table 1 Primary Advantages and Disadvantages of DPL

In an effort to refine the diagnostic value of DPL, attention was directed toward microscopic examination of lavage fluid. Rather than merely characterizing the color of the fluid as “salmon pink,” the inability to “read newsprint” through the fluid was used as a predictive criteria. This evolved into the use of automated cell counts with varying thresholds. Greater than 100,000 red blood cells per cubic millimeter of lavage fluid or greater than 500 white blood cells per cubic millimeter became commonly accepted as an indication for abdominal exploration following blunt injury. By these criteria, Nagy achieved a sensitivity of 100% and specificity of 96% for 2500 patients. However, like much of the literature pertaining to DPL, the incidence of nontherapeutic laparotomy is not reported. Although the criteria are variable, nontherapeutic laparotomy rates associated with DPL are reported as high as 36%. In cases of penetrating trauma, a lower red cell count, 10,000/mm³–50,000/mm³, are used as criteria to establish penetration of the abdominal wall. A similar dilemma exists regarding the incidence of nontherapeutic laparotomy, because penetration is not always accompanied by visceral perforation. For both blunt and penetrating trauma, if one accepts that the amount of blood in the peritoneal cavity is proportional to the severity of the injury, then an inverse relationship can be predicted between the quantified cell counts and the likelihood of nontherapeutic laparotomy. If one lowers the threshold to designate DPL as positive, then the sensitivity for hemoperitoneum will be high, but the incidence of nontherapeutic operations will rise.

Other maneuvers used to improve the accuracy of DPL include the measurement of amylase and bilirubin and microscopic examination for particulate matter. These maneuvers are aimed at adding sensitivity for hollow viscus injury, which may occur in the presence or absence of significant hemoperitoneum. In addition, the use of the “cell count ratio,” defined as the ratio between white blood cell count and red blood cell count in the lavage fluid divided by the ratio of the same parameters in the peripheral blood, was reported to yield a sensitivity of 100% and specificity of 97% for hollow viscus perforation when the cell count ratio was greater than 1. A special consideration arises when DPL is employed in the presence of diaphragmatic rupture or intraperitoneal bladder rupture. Failure to recover the lavage fluid may indicate that the fluid has found another route to egress the abdomen. A sudden increase in clear or bloody drainage through a chest tube or urinary catheter is practically diagnostic of injury to those structures.

The general acceptance of CT and FAST exams as the mainstay for abdominal evaluation in preference to DPL has led to the perhaps premature publication of its obituary. Despite the advantage of providing sufficient anatomic detail to grade the severity of liver and spleen injuries, and the ability to evaluate retroperitoneal structures, early implementation of the CT scan required an extended visit to the radiology suite and was practical only for stable patients. In addition, early generation scanners provided limited anatomic detail. Improvements in resuscitation techniques and advancing technology have dramatically increased the applicability of CT scans to the multiply injured patient. Fast, high-resolution scanners, strategically located in proximity to the resuscitation bay, have made it practical to evaluate the abdomen in conjunction with the head, neck, chest, and pelvis, with virtually no exclusions.

Because the CT is relatively expensive and carries the disadvantage of radiation exposure, an alternative method for screening the abdomen is desirable. FAST by surgeons and emergency physicians has flourished in common practice as a means to detect intraabdominal free fluid, which is presumed to be blood until proven otherwise. Despite its popularity, there are few instances where the FAST exam leads directly to the decision to operate without obtaining an additional study. A recent systematic review of randomized prospective studies by the Cochrane Collaboration was unable to establish a clear advantage for US-based evaluation algorithms to affect the frequency of CT scans, DPL, or mortality. Yet, the FAST exam has been reported to carry a lower rate of nontherapeutic laparotomy (13%) than DPL (36%); however, statistical significance was not reached in this sample. The question remains whether there is a residual role for DPL in contemporary trauma care. Given the propensity for injuries to occur across a broad spectrum of combinations, severity, and demographic and geographic circumstances, and given the complex nature of resuscitation and treatment decisions applicable to trauma, it is unlikely that a single diagnostic maneuver will address all situations. The acceptability of nonoperative management in the face of mechanisms and patterns of injury that previously called for compulsory surgical exploration has placed a burden of diagnostic accuracy on trauma surgeons that DPL will never again satisfy. However, not all cases hinge on the decision of whether to operate on the hemodynamically stable patient. When an unstable patient presents with more than one potential source of hypotension, a negative DPL may sway the decision to explore the abdomen first, and thus preserve a transient opportunity for timely angiography, thoracotomy, decompressive craniotomy, or pelvic fixation. A case can be made for the application of the FAST exam under those circumstances. However, the FAST exam requires availability of the technology and an operator with experience and skill. It can also be confounded easily by body habitus, bowel gas, nonhemorrhagic abdominal fluid, and other factors. Less dramatic circumstances where DPL may still have a role include the early identification of hollow viscus injury resulting from either blunt or penetrating trauma. Both US and CT are notoriously weak in identifying small bowel and colon injuries, although it remains a difficult decision to consider when a DPL might be appropriate in favor of serial examination and specialized radiographic techniques, such as triple-contrast CT scan.

Ultrasound-guided paracentesis is a technique which combines principles of DPL and FAST. In performing US examinations for the diagnosis of intra-abdominal, intra-thoracic, or cardiac injury, it is assumed that the hypoechoic areas seen on the video screen represent blood. In most instances, this assumption is correct. Trauma victims, to some degree, reflect the population as a whole with respect to underlying disease processes. Thus, incidental nonhemoglobin-containing fluid collections will be identified. Fluid collections from infection, chronic organ dysfunction (such as cirrhosis), end-stage renal disease, cardiomyopathy, and malignancy will be encountered.

Ultrasound-guided paracentesis is within the ability of the trained surgeon. The procedure is already well within the skill set of those that perform US-guided biopsy or US-guided central line insertion. Like other US-guided needle placement procedures, the procedure is done in two parts. First, the fluid collection is identified and localized using routine scanning windows. Care should be taken to select a sonographic window and needle path that will cause the least amount of collateral damage to other structures such as bowel, solid organs, and intercostal vessels. Care should also be taken to select a pathway to minimize traversing the pleura, if not necessary, to decrease the chances of creating an iatrogenic pneumothorax. Once the sonographic window and needle pathway have been chosen, the area is prepped and draped in the standard fashion. Local anesthesia should be used to anesthetize the intended needle pathway. For US-guided diagnostic fluid sampling, we have found that prepping the US probe along with the use of sterile US gel is adequate aseptic technique and that a sterile probe cover is not necessary. The access window can be located where there is a clear access to the fluid without traversing solid or hollow viscera. Locating or creating dependent fluid collections can be accomplished by changing the patient’s position. This is accomplished by allowing the fluid to pool by placing the patient in a lateral decubitus or semi-Fowler position.

Many recently trained surgeons have little or no experience in performing DPL or in exercising the complex decision making that might lead to its appropriate application in special circumstances. For many, exposure to DPL is limited to animal or mannequin practice during the Advanced Trauma Life Support (ATLS) course. Fortunately, both the open and closed techniques are paralleled by the common practice of laparoscopic port placement. In addition, the burgeoning interest in virtual simulation technology has created an opportunity to demonstrate its potential usefulness to teach uncommon procedures through the development of a DPL training simulator. While advanced imaging techniques have been extremely beneficial for trauma care and are likely to dominate the diagnostic approach in the future, it would benefit surgical science to preserve and teach DPL techniques and strategies. Although the opportunity to use it may be rare, understanding its historical development and limitations parallels our understanding of the anatomic and pathologic implications of abdominal trauma. Even if the technique of DPL is considered to be retired, it should not be buried.

LAPAROSCOPY IN TRAUMA

Evaluation of the abdomen in potentially injured patients remains one of the greatest challenges faced by surgeons. None of the current diagnostic modalities available to the trauma surgeon are completely accurate. All of the available techniques, including DPL, sonography, CT, and laparoscopy, have advantages and disadvantages. At present, laparoscopy is not considered a frontline method for evaluation of the abdomen, but it is an important adjunct.

Laparoscopy has been used sporadically over the past four decades in the evaluation of patients at risk for abdominal injury. Utilization of laparoscopy in the trauma setting has increased dramatically over the past 15 years. This increase in utilization corresponds to the greater availability of high-quality laparoscopic equipment and the greater penetration of laparoscopy into general surgery training programs. At present, laparoscopy holds the greatest promise in evaluating a select group of patients with penetrating injury. A number of recent series have documented the utility of laparoscopy in the evaluation of the diaphragm in hemodynamically stable patients with a history of thoracoabdominal wounds. The use of laparoscopy in the blunt trauma setting is much less frequent and its indications remain controversial in this group of patients.

Sporadic reports of novel uses of laparoscopy, for example, laparoscopically guided blood salvage and laparoscopic decompression of abdominal compartment syndrome, have appeared more recently. In some centers, laparoscopy is used for the assessment of the hollow viscera in patients who are suspected of having a seat-belt injury that cannot be ruled out with other diagnostic modalities. Therapeutic laparoscopy for a select group of isolated patients, that is, those with small diaphragmatic lacerations, is used more frequently and may be applicable for a small subset of patients. In addition, some centers have reported repair of small enterotomies with laparoscopic techniques, if these injuries are isolated.

Sound surgical judgment must be used in choosing patients for laparoscopic evaluation after injury. Any injured patient with hemodynamic instability or obvious complex intra-abdominal injury, is not a candidate for laparoscopy, but instead requires immediate laparotomy. Several large series performed by experienced groups have demonstrated that only about 15% of patients with suspected intra-abdominal injury are reasonable candidates for adjunctive laparoscopic evaluation or treatment. For patients with gunshot wounds to the abdomen, laparoscopy has proved most useful for evaluation of the diaphragm in patients with thoracoabdominal wounds (Figure 1). In addition, laparoscopy has proven useful to determine if peritoneal penetration has occurred from tangential gunshot wounds or stab wounds.

Figure 1 Algorithm for management of a gunshot wound in a stable patient. (1) Laparoscopic repair may be performed for limited injuries, depending on the capabilities of the surgeon. (2) Posterior wounds may be more easily identified and repaired with a thoracoscopic approach. Identification of injuries of associated abdominal organs may necessitate laparotomy. (3) Gunshot wounds in this location have a greater than 90% probability of producing wounds that require definitive surgical repair.

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