Diagnostic peritoneal lavage: is an isolated WBC count greater than or equal to 500/mm3 predictive of intra-abdominal injury requiring celiotomy in blunt trauma patients?

A 5-year retrospective review of 3,503 diagnostic peritoneal lavage (DPL) patients was conducted, identifying 48 (13%) blunt trauma patients who had a DPL WBC count greater than or equal to 500/mm3. The mean DPL WBC count was 1,646 +/- 2,275. Twenty (42%) of these patients were observed and discharged without subsequent operation or morbidity. Laparotomy was performed on 28 (58%) patients; 17 (61%) had a negative lap, 11 (39%) had intra-abdominal injuries requiring surgical repair or drainage (54% solid organ, 27% hollow viscus, 18% diaphragmatic). There were no significant differences between the three subgroups with regards to age, injury severity, time interval between injury and DPL, or mean DPL WBC count (p greater than 0.05). The negative-lap and no-lap groups had a significantly larger number of females; one presented with PID. The positive predictive value (PPV) of an isolated lavage WBC count of greater than or equal to 500/mm3 for intra-abdominal injury was 23% (11/48). The PPVs for DPLs performed less than and greater than or equal to 3 hours or those recalculated using WBC values higher than 500/mm3 were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peritoneal lavage white count: a reassessment

Of 29 blunt trauma victims with a diagnostic peritoneal lavage white blood cell count (DPL:WBC) greater than or equal to 500/mm3 as the sole positive lavage criterion, only four underwent laparotomy at admission, and only one of these had sustained intestinal perforation. Two of the remaining 25 succumbed to extra-abdominal injuries within 24 hours, leaving 23 patients, who were followed clinically for an average of 34.7 days. None was ever discovered to have sustained intestinal perforation. Throughout the study period, 27 patients were seen who had sustained intestinal perforation from blunt abdominal trauma. Nine were explored based upon an initial physical examination suggestive of peritonitis. The remaining 18 underwent DPL: 17 demonstrated gross blood, and only one patient was diagnosed solely by an elevated DPL:WBC. We conclude that DPL:WBC is a nonspecific indicator of intestinal perforation from blunt abdominal trauma, and prospective studies are needed to properly define its role. Sequential determinations of DPL:WBC may be useful in the diagnosis of intestinal perforation.     

Detection of intra-abdominal injury using diagnostic peritoneal lavage after shotgun wound to the abdomen

BACKGROUND: The utility of diagnostic peritoneal lavage (DPL) as a diagnostic tool specifically for shotgun wound to the abdomen (SGWA) is unknown. This prospective study was undertaken to determine the sensitivity, specificity, and accuracy of DPL for the detection of intra-abdominal injuries following SGWA. METHODS: DPL was performed on all patients sustaining SGWA who lacked a clear indication for laparotomy. Patients exceeding 10,000 red blood cells (RBC)/mm were taken for exploratory laparotomy. A prospective database was kept with information on wound location, DPL result, findings upon laparotomy and outcome. RESULTS: Thirty-two DPLs were performed at our urban Level I trauma center for SGWA. Of these, 8 patients had a positive DPL. Upon laparotomy, 7 patients were found to have intra-abdominal injuries, 6 of which required surgical intervention. One patient had no peritoneal penetration or intra-abdominal injury. Of the 24 patients that had a negative DPL, 1 subsequently developed indications for laparotomy and was found to have operative injuries. For predicting intra-abdominal injuries DPL has a sensitivity, specificity and accuracy of 87.5%, 95.8% and 93.8%, respectively. CONCLUSION: For patients presenting with SGWA who do not present with indications for immediate laparotomy, DPL is a reliable indicator of intra-abdominal injury and need for operative intervention.     

Is diagnostic peritoneal lavage for blunt trauma obsolete?

Diagnostic peritoneal lavage was 97 percent accurate, with a 2 percent false positive rate and a 1 percent false negative rate in this series of 414 patients. The ease, safety, and accuracy of diagnostic peritoneal lavage justify its continued use in evaluating these patients. Recent studies show computerized tomography (CT) can be highly accurate in detecting intra-abdominal injuries after blunt trauma. We reviewed our experience with diagnostic peritoneal lavage (DPL) to evaluate whether the accuracy, safety, speed, and cost justified its continued use. Four hundred fifteen DPLs were performed on 414 patients from February 1, 1983, through December 31, 1987. All DPLs were done by the open technique. The lavage was considered grossly positive if 10 cc gross blood were aspirated. If there were greater than 100,000 red blood cells (RBC)/mm3, greater than 500 white blood cells (WBC)/mm3, elevated amylase or bilirubin, or bacteria or vegetable fibers the lavage was microscopically positive. There were no cases with elevated bilirubin, amylase, or presence of bacteria. All four cases with "rare vegetable fibers" were false positive. Six DPLs were for penetrating trauma to the lower chest or back. There were 291 negative lavages, including five false negatives (1%), and 124 positive DPLs, including seven false positives (2%), resulting in a crude accuracy of 97 percent. Three of the five false negative lavages had a ruptured diaphragm as the only intra-abdominal injury. There was one minor complication. DPL was usually performed in the trauma resuscitation room during the secondary survey. At our institution, the total fees for DPL are +185 less than the fees for CT. DPL is accurate, rapid, safe, and avoids the disruption of patient care that results in the radiology suite. DPL remains our procedure of choice for evaluating blunt abdominal trauma in the adult.     

Analysis of peritoneal lavage parameters in blunt abdominal trauma

Peritoneal lavage is the most valuable diagnostic modality presently available for the evaluation of patients with blunt abdominal trauma. A retrospective review of 523 patients who underwent open peritoneal lavage for blunt abdominal trauma over a 3 1/2-year period revealed serious intra-abdominal pathology in 83% of patients undergoing laparotomy with RBC lavage counts in the range of 20,000 to 100,000 cells/mm3, a level considered by many authors to be negative or indeterminate. Two patients with isolated small bowel perforations had an elevated amylase level as the only measured abnormality. The data indicate that the standard guidelines for RBC positivity (positive count greater than 100,000 cells/mm3 and indeterminate count 50,000 to 100,000 cells/mm3) result in missed intraperitoneal injuries in a large percentage of patients and therefore require reevaluation. Lavage amylase determinations, previously stated to be costly and of insignificant yield, should be performed on patients whose lavage would otherwise be considered negative by RBC and WBC counts.     

Pelvic fracture hemorrhage. Priorities in management

Hemorrhage remains the leading cause of mortality in patients with severe pelvic fractures. To evaluate diagnostic and treatment priorities for this problem, we retrospectively reviewed 245 consecutive patients admitted to our institution with pelvic fractures. Supraumbilical diagnostic peritoneal lavage (DPL) was grossly positive in 27 patients, and eight (30%) of these had life-threatening intra-abdominal hemorrhage identified at laparotomy. No patient with a positive DPL by count alone had life-threatening intra-abdominal hemorrhage. Pelvic fracture stabilization with early external pelvic fixation was associated with less requirement for blood transfusion (10 +/- 1 U) than with the pneumatic antishock garment (17 +/- 3 U). Nine patients with pelvic arterial injuries underwent angiographic embolization, and eight patients died (89%). We conclude that pelvic angiography should be performed before laparotomy in hemodynamically unstable patients with pelvic fracture, unless the DPL is grossly positive.     

Unreliability of standard quantitative criteria in diagnostic peritoneal lavage performed for suspected penetrating abdominal stab wounds

Thirty-five patients with abdominal stab wounds in whom clinical examination was equivocal on 2 separate occasions underwent diagnostic peritoneal lavage (DPL) prior to laparotomy. The red and white blood cell counts (cells/mm3) of the lavage effluent were compared with the operative findings. There were 26 positive and 9 unnecessary laparotomies, the latter consisting of 4 negative and 5 non-therapeutic operations. Use of the standard quantitative criteria for red cells in DPL failed to identify significant injury in eight patients (31%), while the standard white cell count missed six injuries (23%). Their combined use resulted in three missed injuries (12%). Two false-positive results occurred using the red cell count alone and four using the white cell count alone, producing a combined false-positive result in four patients (11%). Reducing the cell threshold level to exclude missed injuries would increase dramatically the rate of unnecessary laparotomies. Although the standard quantitative criteria for DPL are superior to clinical assessment in patients with equivocal findings, their use in penetrating trauma does not achieve the same diagnostic accuracy as in blunt abdominal trauma.     

Diagnostic peritoneal lavage. Limited indications due to evolving concepts in trauma care

This study was undertaken to determine the appropriateness of celiotomy in 100 consecutive patients who underwent celiotomy solely because of positive diagnostic peritoneal lavage (DPL) following blunt (B) or stab (S) abdominal trauma. A total of 32 (32%) patients had positive DPL by laboratory criteria: blunt trauma: greater than 100K RBC/mm3, greater than 500 WBC/mm3; stab trauma: greater than 50K RBC/mm3, greater than 250 WBC/mm3. DPL in 68 patients was positive by gross inspection; 18 of these 68 patients' DPL laboratory results returned after surgery and did not satisfy the laboratory definition of positive DPL. In all 61 per cent underwent therapeutic celiotomy (TC) and 39 per cent underwent nontherapeutic celiotomy (NTC). Grade I and II spleen and/or liver injuries led to 79 per cent of NTCs. Positive DPL, determined by gross inspection or by laboratory testing, has a very poor accuracy rate when evaluated in light of evolving beliefs that promote nonoperative therapy for grade I and II liver and spleen injuries. When positive DPL is the sole indication for celiotomy in patients with blunt or stab abdominal trauma, an unacceptably large number of NTCs will be performed. DPL should have a limited role in the evaluation of patients with abdominal trauma.     

Management of patients with indeterminate diagnostic peritoneal lavage results following blunt trauma.

The management of blunt trauma victims with indeterminate diagnostic peritoneal lavage (DPL) findings remains controversial. We reviewed 1,196 patients undergoing DPL to identify patients with indeterminate DPL (red cell counts of 20,000 to 99,999 rbc/mm3). Only 4% (48%) had indeterminate DPL results. Repeat DPL (R-DPL) was performed in 31 patients. Six repeat DPLs produced positive results (greater than 100,000 rbc/mm3), 15 produced indeterminate results, and 10 produced negative results (less than 20,000 rbc/mm3). A review of the nine laparotomies performed in this group revealed only two operations that were therapeutic. Twelve patients had abdominal CT scans following indeterminate DPL. Six patients had negative CT scans and were successfully managed without operation. The findings were positive on six other CT scans. Four patients with positive CT scans, including two splenic injuries, one liver injury, and one renal laceration, were managed successfully without surgery. The remaining two patients with positive CT scans underwent laparotomy. The first had a renovascular injury diagnosed from the CT scan after negative findings on repeat DPL. The second had a minor splenic injury diagnosed from the CT scan. A subsequent repeat DPL produced a positive result prompting a nontherapeutic operation. Eleven patients were observed without repeat DPL or CT scanning. Of these, four eventually underwent laparotomy on the basis of clinical suspicion alone. Only one of these patients required therapeutic intervention at the time of laparotomy. Intra-abdominal injury was common in patients with indeterminate DPL results, however, only four (8%) of the patients required a therapeutic operation. Both negative repeat DPL results or negative findings on CT scans predicted successful nonoperative management.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical uses of diagnostic peritoneal lavage in stab wounds of the anterior abdomen: a prospective study.

OBJECTIVE: To evaluate patients with stab wounds of the anterior abdomen with diagnostic peritoneal lavage (DPL), by using initial aspiration of gross blood from the lavage catheter of more than 10 ml or red blood cell (RBC) count in the lavage fluid of more than 10,000/mm3 as criteria for exploratory laparotomy. DESIGN: Prospective study. SETTING: University hospital, Thailand. PATIENTS: 40 patients who had stab wounds of the anterior abdomen penetrating through the peritoneum but had no obvious indications for immediate exploratory laparotomy. INTERVENTIONS: Diagnostic peritoneal lavage (DPL), exploratory laparotomy. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of positive DPL as an indication for exploratory laparotomy. RESULTS: In 27 patients (68%) the DPL was positive and in 13 (33%) it was negative. In 18 patients (67%) the initial aspiration of gross blood was more than 10 ml and in 9 (33%) the RBC count in lavage fluid was more than 10,000/mm3. These 27 patients had exploratory laparotomies, 2 of which were negative. All 13 patients who had negative DPL were observed and discharged home uneventfully. The sensitivity of DPL for positive laparotomy was 100%, the specificity was 87%, the PPV was 93%, the NPV was 100% and the accuracy was 95%. When operative findings of bleeding from the stab wound into the peritoneal cavity were considered as a "negative" laparotomy (n = 7) the sensitivity, the specificity, the PPV, the NPV and the accuracy became 100%, 59%, 67%, 100%, and 78%, respectively. CONCLUSION: The use of DPL in patients with stab wounds of the anterior abdomen, using initial aspiration of gross blood from the lavage catheter of more than 10 ml or RBC count in the lavage fluid of more than 10,000/mm3 as positive criteria for exploratory laparotomy, is safe and practical.     

Use of peritoneal lavage to evaluate abdominal penetration

A retrospective study was undertaken to evaluate peritoneal lavage in detecting abdominal penetration. Two hundred thirty-five patients with thoracoabdominal, flank, or tangential abdominal gunshot wounds were lavaged. Of these patients, 44 (18.7%) had positive lavages, defined as red blood cell counts greater than 10,000 cells/mm3, white blood cell counts greater than 500 cells/mm3, or the presence of bile, feces, or vegetable matter. There were 13.6% false positives and 1.0% false negatives, with an overall accuracy of 96.6%. The results were unaffected by mechanism or site of injury. If the criteria were changed to include red blood cell counts greater than 100,000 cells/mm3, there would have been no false positives, but an unacceptably high 11.1% false negative rate. Therefore we conclude that peritoneal lavage can be a reliable indicator of abdominal penetration provided sufficiently sensitive criteria are used. These criteria should include red blood cell counts greater than 10,000 cells/mm3 instead of 100,000 cells/mm3.     

Diagnostic Peritoneal Lavage for Diagnosing Blunt Hollow Visceral Injury: The Accuracy of Two Different Criteria and Their Combination

Purpose To test the usefulness of diagnostic peritoneal lavage (DPL) for identifying blunt hollow visceral injury with two different sets of criteria or a combination of the two. Methods Fifty victims with physical examinations and/or computed tomography findings equivocal for blunt hollow visceral injury underwent DPL. Whether or not to perform surgery was determined based on Otomo's DPL criteria [lavage white blood cell counts (L-WBC) over lavage red blood cell counts (L-RBC) divided by 150 (L-WBC ≥ L-RBC/150) in the presence of hemoperitoneum, or L-WBC over 500/mm³ (L-WBC ≥ 500) in the absence of hemoperitoneum]. The cell count ratio, a comparison of L-WBC, L-RBC, peripheral WBC (P-WBC), and peripheral RBC (P-RBC) [(L-WBC/L-RBC)/(P-WBC/P-RBC) ≥ 1] were all calculated retrospectively. Results There were one and two false-positive cases based on Otomo's criteria and the cell count ratio, respectively, with corresponding accuracies of 97.8% and 95.7%, respectively. There were no false-positive or -negative cases according to the combined use of Otomo's criteria and cell count ratio, yielding an accuracy of 100%. Conclusion Although each criterion alone is very accurate in predicting the presence of blunt hollow visceral injury, the combined use of the two would further improve the accuracy of the diagnosis and thereby reduce the number of unnecessary celiotomies.     

Complementary roles of diagnostic peritoneal lavage and computed tomography in the evaluation of blunt abdominal trauma.

OBJECTIVE: To assess in randomized prospective format sensitivity, laparotomy rate, and cost-effectiveness of using diagnostic peritoneal lavage (DPL) in a complementary role with computed tomography (CT) in the evaluation of blunt abdominal trauma. METHODS: Blunt trauma patients greater than 18 years of age were eligible for entry in the study. The study period was from February 1999 to July 2000 at an urban Level I trauma center. All patients were hemodynamically stable upon study entry and had abdominal tenderness with Glasgow Coma Scale (GCS) scores > 13 or GCS < 14. Patients were randomized to a DPL arm (DPL-CT) versus a CT arm. If randomized to the CT arm, patients underwent abdominal/pelvis CT. If CT was positive for solid organ injury, patients were observed. If free fluid was identified on CT without solid organ injury, patients were explored. If randomized to DPL-CT, patients underwent closed infraumbilical DPL, except pelvic fractures that were done with the open supraumbilical technique. If the DPL result was > 20,000 RBCs/mm3, patients underwent abdominal/pelvis CT. If the CT following DPL was consistent with solid organ injury, patients were observed. If the CT following DPL identified free fluid without solid organ injury and DPL was > 100,000 RBCs/mm3, patients were explored. RESULTS: Two hundred fifty-two patients were entered; 127 patients were randomized to DPL-CT and 125 to CT. Of the 125 patients randomized to CT, 102 (82%) CT scans were negative, 19 (15%) were positive for solid organ injury, and 3 (2%) had free fluid. Three (2%) of the initial negative CT scan patients underwent delayed laparotomy for missed injuries. Of the 127 patients randomized to DPL-CT, 26 (20%) required CT scan, of which 13 (10%) were positive for solid organ injury and 13 (10%) for free fluid. Positive DPL results that were indications for CT ranged from 21,000 to 1 million RBCs/mm3. Eight of the 13 DPL-CT patients with free fluid on CT had DPL results less than 100,000 RBCs/mm3 and did not require laparotomy. There were no known missed injuries in the DPL-CT arm. Seven (6%) laparotomies were performed in the DPL-CT arm and 10 (8%) in the CT arm. The average cost to the patient for abdominal evaluation in the CT arm was 1611 dollars and 650 dollars in the DPL-CT arm. CONCLUSION: Screening DPL with complementary CT has a low nontherapeutic laparotomy rate and is a sensitive and cost-effective method for the evaluation of blunt abdominal trauma.     

Diagnostic peritoneal lavage in the management of blunt abdominal trauma: a reassessment

In order to reassess the value of diagnostic peritoneal lavage (DPL) in patients with blunt abdominal trauma, we conducted a prospective study over a 15-month period involving 138 patients. There were 29 (28.3%) patients with positive DPL and 103 (71.7%) with negative DPL in this series. Of the 29 patients with positive DPL, 28 (96.5%) were found to have significant intra-abdominal injuries; 27 by exploratory laparotomy and in one case at autopsy. One patient with a grossly positive DPL had a negative exploratory laparotomy (3.4% false positive rate). All 109 patients with negative DPL were admitted. In only one case a significant intra-abdominal injury was demonstrated (0.9% false negative rate). The overall mortality in this series was 11.6% and there were no complications related to the DPL. Our results suggest that DPL is indeed an accurate indicator of significant intra-abdominal injuries in patients with blunt abdominal trauma.     

Analytical diagnostic peritoneal lavage in the diagnosis of intra-abdominal injury

Diagnostic peritoneal lavage (DPL) was modified to detect dynamic changes occurring in lavage fluid in dogs following liver, spleen, or intestinal injury. In 33 animals lavage fluid was serially sampled over 75 minutes and analyzed for RBC and other variables. The spun sediment was Gram stained. In control groups, either saline or autologous blood was instilled into the peritoneal cavity at a known rate. In these experiments, the composition of lavage fluid did not significantly change over time. Blood infused at a constant rate into the abdominal cavity produced corresponding, continuing increases in the RBC count. In experimental groups, the liver, spleen, or intestine were injured before lavage. Only initial RBC counts greater than 1 million/mm3 or rising RBC counts in serial lavage samples were associated with life-threatening hemorrhage. Gram stains of samples were positive for bacteria in 43% of fasted dogs and in 80% of fed dogs with intestinal perforation.     

Open versus closed diagnostic peritoneal lavage in the evaluation of abdominal trauma

Two hundred forty-two patients underwent diagnostic peritoneal lavage (DPL) over a 12-month period. One hundred sixteen patients (48%) were randomized to an open lavage technique and 126 (52%) to a percutaneous (closed) guide wire procedure. The closed procedure required an average of 16 minutes to complete with one operator, whereas the open method required two operators and an average time of 26 minutes (p less than 0.001). Technical complications occurred in 31 patients undergoing closed lavage (25%) and 4 patients undergoing open lavage (3%) (p less than 0.01). Fifty-eight percent of the closed lavage complications were related to fluid return and 42% to guide wire placement. All the open lavage complications were caused by inadequate fluid return. These data do not support the initial use of percutaneous lavage. The open technique is favored and certainly used when the closed method fails or when direct visualization of the peritoneal cavity is indicated. Physicians involved in the management of abdominal trauma must be familiar with both methods of DPL.     

Local wound exploration remains a valuable triage tool for the evaluation of anterior abdominal stab wounds

Background

Recent guidelines do not support local wound exploration (LWE) or diagnostic peritoneal lavage (DPL) in the evaluation of patients with anterior abdominal stab wounds (AASWs), favoring computed tomography scanning or serial examinations. In patients without immediate indications for laparotomy, we hypothesized that LWE/DPL would identify patients requiring surgery while limiting unnecessary hospital admissions.

Methods

Patients sustaining penetrating trauma at our level I trauma center over a 3-year period were reviewed.

Results

During the study period, 139 patients with AASW followed our LWE/DPL algorithm. Fifty-six patients had LWE without fascial penetration: 46 were discharged immediately, 10 required admission. Fifty-eight patients had fascial penetration on LWE but negative DPL: 37 were observed for less than 24 hours, 19 were observed for more than 24 hours, and 2 patients developed peritonitis requiring exploration. Twenty-five patients had positive LWE/DPL: 13 had therapeutic laparotomy, 12 had nontherapeutic laparotomy.

Conclusions

Only 11% of patients with AASWs without overt indication for laparotomy require surgical care. LWE remains a valid method to exclude intra-abdominal injury and to eliminate hospitalization in more than one third of AASW patients.     

Percutaneous peritoneal lavage in blunt trauma patients: a safe and accurate diagnostic method

We reviewed the records of 395 patients seen from January 1983 through May 1988, who after sustaining blunt thoracoabdominal trauma had diagnostic peritoneal lavage (DPL) performed percutaneously by the Seldinger wire technique of Lazarus and Nelson. The test was considered grossly positive if 10 cc of blood were aspirated from the catheter immediately after its insertion into the peritoneal cavity. Microscopic criteria for positivity included more than 100,000 RBC or 500 WBC/cc of lavage return, elevated amylase or bilirubin, or the presence of vegetable fibers or bacteria. Seventy-two (18%) of the patients were true positives and 315 (80%) were true negatives. There were four false positives (1.3%) and one false negative (0.2%), giving the test a sensitivity of 99% and a specificity of 98%. Complications occurred in three patients, for a rate of 0.8%, and included catheter insertion into a large ovarian dermoid cyst, needle perforation of the ileum, and needle perforation of the sigmoid colon. This technique of DPL can consistently be performed much more rapidly than the open method. Therefore we conclude that percutaneous DPL is as accurate as, as safe as, and quicker than open DPL for determining intra-abdominal injury in blunt trauma patients.     

Value of quantitative cell count and amylase activity of peritoneal lavage fluid

From January 1974 through July 1979, 1,588 patients underwent diagnostic peritoneal lavage. The test had an accuracy of 98.6%, sensitivity of 94.3%, and specificity of 99.8%. It was true positive in 21.9%, false positive in 0.1%, false negative in 1.3%, and true negative in 76.6%. Fifty-nine patients from the true-positive group had grossly equivocal tests, but had positive lavage results based on quantitative cell count. Thus without cell count the test would have a sensitivity of 78.3%, accuracy of 94.8%, and specificity of 99.8. Eight patients had positive lavage based on WBC count but negative RBC count; all of these patients had bowel injuries. Measurement of lavage fluid amylase resulted in minimal or no improvement in the accuracy (0.06%), sensitivity (0.3%), or specificity (0.0%). Five of six patients with positive amylase levels but grossly negative tests had concomitant positive WBC count. The added cost of the amylase measurement is estimated to be $154,472. Peritoneal lavage has high accuracy, sensitivity, and specificity. Cell counts significantly improve sensitivity. Patients with a grossly equivocal test but with a positive cell count should undergo laparotomy. The lavage-fluid amylase measurement is costly and is of insignificantly yield.     

Diagnostic peritoneal lavage: volume of lavage effluent needed for accurate determination of a negative lavage

While the ability of diagnostic peritoneal lavage (DPL) to ‘rule out’ occult intra-abdominal injuries has been well established, the volume of lavage effluent necessary for accurate prediction of a negative lavage has not been determined. To address this, 60 injured adults with blunt (N = 45) or penetrating (N = 15) trauma undergoing DPL were evaluated prospectively through protocol. After infusion of 11 of Ringer's lactate solution, samples of lavage effluent were obtained at 100 cm³, 250 cm³, 500 cm³, and 759 cm³, and when no more effluent could be returned (final sample). DPL was considered negative if final sample RBC count was ≤ 100 000/mm³ for blunt injury and < 50 000/mm³ for penetrating injury. The conclusion is that at 100 cm³ of lavage effluent returned, negative results are highly predictive of a negative DPL (98 per cent), though 250 cm³ of lavage effluent is required to predict a negative DPL uniformly (100 per cent).