Identification of the site of severe colon bleeding by technetium-labeled red-cell scan

The Accuracy of Computed Tomography Angiography Compared With Technetium-99m Labelled Red Blood Cell Scintigraphy for the Diagnosis and Localization of Acute Gastrointestinal Bleeding: A Systematic Review and Meta-Analysis

Imaging tests are commonly used as an initial or early investigation for patients presenting with suspected acute gastrointestinal bleeding (AGIB). However, controversy remains regarding which of two frequently used modalities, computed tomography angiography (CTA) or technetium-99m labelled red blood cell scintigraphy (RBCS), is most accurate. This systematic review and meta-analysis was performed to compare the accuracy of CTA and RBCS for the detection and localization of AGIB. Five electronic databases were searched with additional manual searching of reference lists of relevant publications identified during the search. Two reviewers independently performed screening, data extraction and methodological assessments. Where appropriate, the bivariate model was used for meta-analysis of sensitivities and specificities for the detection of bleeding and Freeman-Tukey double-arcsine transformation used for meta-analysis of proportions of correctly localized bleeding sites. Forty-four unique primary studies were included: twenty-two investigating CTA, seventeen investigating RBCS and five investigating both modalities. Meta-analysis produced similar pooled sensitivities; 0.83 (95% CI 0.74-0.90) and 0.84 (0.68-0.92) for CTA and RBCS respectively. Pooled specificity for CTA was higher than RBCS; 0.90 (0.72-0.97) and 0.84 (0.71-0.91) respectively. However, differences were not statistically significant. CTA was superior to RBCS in correctly localizing bleeding; pooled proportions of 1.00 (0.98-1.00) and 0.90 (0.83-0.96) respectively (statistically significant difference, P < 0.001). There is no evidence that CTA and RBCS have different diagnostic performance with respect to the detection of AGIB. However, CTA is superior to RBCS in terms of correctly localising the bleeding site, supporting usage of CTA over RBCS as the first line imaging investigation.

Technetium-labeled erythrocyte scintigraphy in acute gastrointestinal bleeding

PURPOSE

Optimal management of acute gastrointestinal (GI) bleeding requires accurate localization of the bleeding source. The role of technetium-labeled erythrocyte scintigraphy (tagged red blood cell (TRBC) scan) in evaluating acute GI bleeding has been controversial, though recent literature suggests that it is a reliable tool and may be used as a first-line diagnostic test. We evaluated our recent experience with and the clinical outcomes of the TRBC scan in patients presenting with acute GI bleeding.

METHODS

A retrospective study of 100 consecutive TRBC scans performed between April 2006 and January 2009 was conducted. Medical records of each corresponding patient were queried for pertinent data. Twenty TRBC scans performed for occult GI bleeding or >48 h after hospital admission were excluded.

RESULTS

Of the 80 TRBC scans, 29 (36%) were positive and 51 (64%) were negative for bleeding. Eight (10%) were incorrect positive (leading to five incorrect operations), 12 (15%) true positive, 9 (11%) unconfirmed positive, 17 (21%) false negative, and 34 (43%) unconfirmed negative. The cause of bleeding was confirmed in 31 cases, of which the scan result was incorrect positive in 2 (7%), true positive in 12 (39%), and false negative in 17 (55%).

CONCLUSIONS

TRBC scans have low positive yield as well as high incorrect positive and high false negative rates in patients with acute GI bleeding. Further research is needed to improve scan technique, refine patient selection, and determine in what setting TRBC scanning may be more clinically useful.

Radionuclide small intestine imaging

The aim of this overview article is to present the current possibilities of radionuclide scintigraphic small intestine imaging. Nuclear medicine has a few methods-scintigraphy with red blood cells labelled by means of (99m)Tc for detection of the source of bleeding in the small intestine, Meckel's diverticulum scintigraphy for detection of the ectopic gastric mucosa, radionuclide somatostatin receptor imaging for carcinoid, and radionuclide inflammation imaging. Video capsule or deep enteroscopy is the method of choice for detection of most lesions in the small intestine. Small intestine scintigraphies are only a complementary imaging method and can be successful, for example, for the detection of the bleeding site in the small intestine, ectopic gastric mucosa, carcinoid and its metastasis, or inflammation. Radionuclide scintigraphic small intestine imaging is an effective imaging modality in the localisation of small intestine lesions for patients in whom other diagnostic tests have failed to locate any lesions or are not available.

Imaging of gastrointestinal bleeding

Radiological techniques are important in evaluating patients with gastrointestinal bleeding. Scintigraphic, computed tomographic angiographic, and enterographic techniques are sensitive tools in identifying the source of bleeding and may be useful in identifying patients likely to have a benign course and in selecting patients for therapeutic intervention. Angiography plays a key role in bleeding localization, and modern embolization techniques make this a viable therapeutic option. With the refining developments in body imaging and related reconstructive techniques, it is likely that radiological interventions will play an expanding and critical role in evaluating patients with gastrointestinal hemorrhage in the future.

A Role for Subtraction Scintigraphy in the Evaluation of Lower Gastrointestinal Bleeding in the Athlete

While lower gastrointestinal haemorrhage (LGIH) in the athlete tends to be self-limiting in the majority of athletes, recurrent symptoms occur in some athletes. It is important to identify the smaller percentage of athletes in whom risks and recurrence are greater because both their general health and athletic performance might benefit from more rigorous clinical evaluation. Technetium-99m red blood cell ((99m)Tc RBC) scintigraphy is a technique for detection and localisation of LGIH and offers a number of significant advantages over other imaging modalities in the evaluation of LGIH. Nonetheless, there are a number of limitations recognised in (99m)Tc RBC scintigraphic evaluation of LGIH. Subtraction scintigraphy in (99m)Tc RBC evaluation of gastrointestinal haemorrhage may offer a tool to overcome limitations of conventional scintigraphy. In essence, subtracting a nominal 'mask' or reference image from all subsequent images provides a mechanism to view only the information contributed by accumulated bleeding, removing potential sources of both false-positive and false-negative findings. While the limitations of procedures available for the evaluation of LGIH are generally prohibitive of effective application in the obscure bleeding associated with athletic performance, adopting subtraction methods in conjunction with conventional (99m)Tc RBC scintigraphy may offer a valuable tool in identification and localisation of bleeding sites. The general health and athletic performance may be enhanced in some athletes when the underlying cause of bleeding can be more appropriately managed.

The management of lower gastrointestinal hemorrhage

PURPOSE

Gastrointestinal hemorrhage is a common clinical problem, which accounts for approximately 1 to 2 percent of acute hospital admissions. The colon is responsible for approximately 87 to 95 percent of all cases of lower gastrointestinal bleeding, with the remaining cases arising in the small bowel. The etiology, diagnostic evaluation, management, and treatment options available for lower gastrointestinal hemorrhage were reviewed.

METHODS

A review of lower gastrointestinal bleeding was performed, which discussed the most common etiologies with a few rare and unusual causes. The current literature about different diagnostic techniques, management problems, and therapeutic options was reviewed. Current management strategies and treatment options for the many causes of lower gastrointestinal bleeding will be reviewed.

RESULTS

A review of the different causes of lower gastrointestinal hemorrhage and available diagnostic studies was performed. Management strategies based on the etiology of the bleeding and results of the diagnostic studies were discussed. An algorithm was provided to develop a diagnostic and therapeutic treatment strategy for lower gastrointestinal hemorrhage.

CONCLUSIONS

Lower gastrointestinal hemorrhage can be a difficult and frustrating problem to both the clinician and the patient. Knowledge of the available diagnostic tests to help identify the source of bleeding is essential to the practicing clinician. Once the source is identified, management strategies and available treatment options need to be specific for each individual case. This review will aid the practicing physician in developing an algorithm for lower gastrointestinal hemorrhage.

CT-Angiography for the Detection of a Lower Gastrointestinal Bleeding Source

The evaluation of lower gastrointestinal bleeding (LGIB) often involves the collaborative efforts of the gastroenterologist, radiologist, and surgeon. Efforts to localize the acute LGIB have traditionally involved colonoscopy, technetium-labeled red blood cell (RBC) scintigraphy, angiography, or a combination of these modalities. The sensitivity of each method of diagnosis is limited, with the most common cause of a negative study the spontaneous cessation of hemorrhage. Other technical factors include vasospasm, lack of adequate contrast volume or exposure time, a venous bleeding source, and a large surface bleeding area. We report the use of multidetector computed tomography (MDCT), or CT-angiography (CT-A), in the initial evaluation of LGIB, and speculate on the incorporation of this technique into a diagnostic algorithm to treat LGIB. MDCT may offer a very sensitive means to evaluate the source of acute LGIB, while avoiding some of the morbidity and intense resource use of contrast angiography, and may provide unique morphologic information regarding the type of pathology. Screening with the more rapid and available MDCT, followed by either directed therapeutic angiography or surgical management, may represent a reasonable algorithm for the early evaluation and management of acute LGIB in which an active bleeding source is strongly suspected.

[Acute lower gastrointestinal hemorrhage. Diagnosis and management]

In most cases (80%), acute lower gastrointestinal bleeding stops spontaneously, but rebleeding is frequent (25%). The intensity and quality of the bleeding--hematochezia, melena, or occult bleeding--determines the diagnostic and therapeutic strategy (endoscopic evaluation of the upper and lower gastrointestinal tract, mesenteric angiography, scintigraphy, enteroscopy, capsule endoscopy) and its urgency. Acute lower gastrointestinal bleeding can mostly be treated conservatively or by endoscopic interventions (injection therapy, clip application, coagulation and ligation methods). Severe hemorrhage can render colonoscopy and the identification of the bleeding source technically difficult. Emergency operations are only indicated when patients with severe hemorrhage cannot be stabilized by interventional endoscopy or angiography with selective embolization.

Retrospective study of the utility of nuclear scintigraphic-labelled red cell scanning for lower gastrointestinal bleeding

BACKGROUND

The aim of the present study was to evaluate the utility of nuclear scintigraphic-labelled red cell scanning in the management of bleeding in patients with acute lower gastrointestinal haemorrhage (GIH) who require surgery.

METHODS

A prospective database was used to source data on all patients with lower GIH who underwent technetium-99m (99mTc)-labelled red cell scanning over a 10-year period. A subgroup was identified from cross-reference with the medical records identifying only those patients who continued to bleed and subsequently required laparotomy for further detailed retrospective study. One key question was asked: did the labelled red cell scan influence the type of operation performed by the operating surgeon?

RESULTS

The study identified 249 patients who underwent 287 labelled red cell scans for GIH. Forty patients (16%) underwent laparotomy for ongoing bleeding; 28/40 (70%) of the red cell scans were positive for bleeding. Six patients (15%) died postoperatively, none because of continued bleeding. The 99mTc-labelled red cell scan was deemed to have been unhelpful in 22 (55%) cases. Twelve of the 22 scans were negative and 10 of the 22 scans were positive but were ignored by the surgeon. The 99mTc-labelled red cell scan influenced the choice of operation in 18 out of 40 patients (45% of the operated group but only 7.2% of the total scanned group). Of these, 15 patients underwent colonic resection and three patients underwent small bowel resection.

CONCLUSION

The present study demonstrates that labelled red cell scanning has only a small role to play in managing lower GIH. The 99mTc-labelled red cell scanning should be used much more selectively. Its use should be limited to patients who continue to bleed after conservative management; it may allow these patients to be effectively treated by segmental bowel resection. Its most critical role, however, is probably to prevent suspected small bowel bleeding from being missed at operation.

The clinical utility of nuclear medicine imaging for the detection of occult gastrointestinal haemorrhage

Acute gastrointestinal bleeding is often intermittent and the bleeding source may be difficult to locate, resulting in delay of potentially life-saving treatment. The aim of this study was to determine the clinical utility of 99mTc labelled red blood cell imaging and [99mTc]pertechnetate (Meckel's scan) imaging in a series of 137 patients admitted over a 5 year period to hospital for management of acute gastrointestinal bleeding. Of the 137 patients, 70 had positive 99mTc red blood cell studies. Eleven of 24 patients who had imaging performed beyond 3 h had positive scans that would otherwise have been missed. Only 47 patients had a definite final diagnosis at the time of hospital discharge, of which six were negative on 99mTc red blood cell imaging. The correct site of bleeding was localized in seven of 21 patients with foregut bleeding, and 15 of 20 patients with colonic bleeding. Endoscopy yielded a diagnosis in 13 of the 47 patients (28%). Eleven patients had Meckel's scans but all were negative. Angiography was diagnostic in one of 17 patients studied. 99mTc red blood cell imaging is a useful test in the management of acute gastrointestinal bleeding. Imaging beyond 3 h may further improve the bleeding detection rate. This test, however, may be an unreliable means of localization of bleeding, particularly in the foregut.

The importance of delayed images in gastrointestinal bleeding scintigraphy

Although radionuclide methods for the detection of gastrointestinal (GI) bleeding have been available for more than 20 years, the value of delayed images in GI bleeding scintigraphy is still regarded controversially. The aim of this study was to determine the value of delayed images in a group of patients with predominantly low-grade intermittent bleeding. Eighty-nine consecutive GI bleeding scintigraphies of 75 patients were analysed retrospectively. All patients were referred to our department after other diagnostic methods had failed to identify the localization of GI bleeding. After the dynamic study, delayed images were acquired for up to 24 h until a bleeding site was identified. Data on the clinical outcome were available in all but five patients. No patient with a negative scan died from GI bleeding. A positive result was found in 41 patients (55%). The scans of 11 of these 41 patients (27%) became positive during dynamic imaging. Four required immediate surgery and, in another patient, surgery was not performed because of diffuse bleeding of the entire GI tract. One patient died without surgical intervention. Thirty-three scans of 30 of these 41 patients (73%) were positive on delayed imaging only, leading to surgery in 12 individuals. Our findings demonstrate the importance of delayed images in GI bleeding scintigraphy. Many of our patients who required surgery had scans that did not become positive for several hours.

Investigative modalities for massive lower gastrointestinal bleeding

The objective of this study was to evaluate the efficacy of various diagnostic modalities in the assessment of patients with massive lower gastrointestinal bleeding. The charts of all patients admitted to a McGill University affiliated teaching hospital with the diagnosis of lower gastrointestinal bleeding over a 25-year period were reviewed. There were 136 patients who underwent 202 admissions. The information documented included demographics on age, gender, co-morbid disease, prescribed medications, requirements for blood transfusions, orthostatic change in blood pressure, acute drop in hematocrit (to <30%), and exclusion of upper gastrointestinal bleeding. Among the 202 admitted patients there were 116 men and 86 women), with an average age of 70 years (range 16-95 years). At least one significant medical disease was found in 93% of these patients; and 20% were on aspirin and 5% on anticoagulants at the time of diagnosis. Rigid or flexible sigmoidoscopy was performed in 68 and 18 patients, respectively, with a definitive diagnosis made in 2.9% and 11.0%, respectively. Colonoscopy was performed in 152 cases, 20 of which were incomplete; a specific diagnosis was made for 59 admissions (45%). A red blood cell or colloid scan was performed on 53 patients, with extravasation noted in 13 (24.5%); a localized site of bleeding was identified in 9 cases (17%). Angiography was performed on 31 patients with bleeding sites localized in 6 (19%). Barium enemas were completed in 85 of 92 patients, and the presumptive cause of bleeding was identified in 72% of those with a complete examination. The most common causes identified were diverticulosis in 52 patients and angiodysplasia in 14. The cause of bleeding was not detected in 48 (35%). Bleeding stopped in most patients spontaneously, with only 7 requiring operation. The average number of units transfused was 3 (range 0-26). Scintigraphy and angiography were less efficacious than colonoscopy for localizing the site and etiology of the bleeding. Despite the combination of investigative modalities, a definitive diagnosis was not made in 35% of the admitted patients. The need for operative intervention in our study was lower than in most previous reports.

Technetium-labelled red blood cell scintigraphy: is it useful in acute lower gastrointestinal bleeding?

Radionuclide scintigraphy is commonly utilized as a screening examination before performing more invasive procedures in the work-up of patients with lower gastrointestinal (GI) bleeding. We reviewed our institutional experience with technetium-labelled red blood cell scintigraphy (TRCS) in detecting and localising acute lower GI bleeding. The study group included 72 patients who had 80 red cells scans over a five year period. Thirty-eight scans were positive (47.5%), and 42 were negative (52.5%). Sites of lower GI bleeding were confirmed by endoscopy, arteriography, surgery and/or pathology in 22 of the 38 positive scans. There were four false-negative scans (9.5%). The overall sensitivity and specificity of TRCS in detecting lower GI bleeding was 84.6% (22/26) and 70.4% (38/54), respectively. The accuracy of localization of bleeding sites in the patients with confirmed positive scans was 72.7% (16/22). Thirty mesenteric arteriograms were performed on patients in this series. Eleven arteriograms were performed after negative TRCS; one was positive. Technetium-labelled red blood cell scintigraphy appears to be a useful screening examination for patients with lower GI bleeding who are hemodynamically stable. This may avoid the potential morbidity of arteriography in patients who are not actively bleeding.

Obscure digestive bleeding

Obscure digestive bleeding is defined as recurrent bleeding for which no definite source has been identified by routine endoscopic or barium studies. Mucosal vascular abnormality or 'angioectasia' is the most common course of obscure bleeding, especially in elderly patients. Small bowel tumours are more frequent in patients younger than 50 years. However, missed or underestimated upper and lower gastrointestinal lesions at the initial endoscopic investigation may be the source of a so-called obscure intestinal bleeding. The various radiological procedures, including enteroclysis, visceral angiography and CT scan as well as radioisotope bleeding scans have limitations in the case of obscure gastrointestinal bleeding. Recent developments in magnetic resonance imaging are promising. The different methods of enteroscopy have a similar diagnostic yield, reaching approximately 40-65%. Endoscopic cauterization of small bowel angioectasias seems to be efficacious but randomized trials are needed. Efficacy of hormonal therapy is very controversial. The extent of diagnostic and therapeutic strategies must be based on a number of factors including the patient's parameters, bleeding characteristics and also the result of previous work-up.

Surgical management of gastrointestinal bleeding

Severe gastrointestinal bleeding has historically been a clinical problem primarily under the purview of the general surgeon. Diagnostic advances made as the result of newer technologies, such as fiberoptic and video endoscopy, selective visceral arteriography, and nuclear scintigraphy, have permitted more accurate and targeted operations. More importantly, they have led to safe, effective nonoperative therapeutic interventions that have obviated the need for surgery in many patients. Today, most gastrointestinal bleeding episodes are initially managed by endoscopic or angiographic control measures. Such interventions are often definitive in obtaining hemostasis. Even temporary cessation or attenuation of massive bleeding in an unstable patient permits a safer, more controlled operative procedure by allowing an adequate period of preoperative resuscitation. Despite the less frequent need for surgical intervention, traditional operative approaches, such as suture ligation, lesion or organ excision, vagotomy, portasystemic anastomosis, and devascularization procedures, continue to be life-saving in many instances. The proliferation of laparoscopic surgery has fostered the application of minimally invasive techniques to highly selected patients with gastrointestinal bleeding. Intraoperative endoscopy has greatly facilitated the accuracy of laparoscopic surgery by endoscopic localization of bleeding lesions requiring excision. It is anticipated that the evolving technologies pertinent to the diagnosis and management of gastrointestinal bleeding will continue to promote collaboration and cooperation between gastroenterologists, radiologists, and surgeons.

Mesenteric angiography for lower gastrointestinal hemorrhage: are there predictors for a positive study?

PURPOSE

Selective mesenteric angiography is an expensive, invasive, diagnostic, and therapeutic tool for lower gastrointestinal hemorrhage. Some institutions have required a positive nuclear medicine bleeding scan before angiography. We have attempted to determine if this is a valid screening test for mesenteric angiography. Are there any other factors to predict which patients are actively bleeding and who will benefit from angiography?

METHODS

All cases of mesenteric angiography for hemorrhage performed during a 12-year period were reviewed.

RESULTS

A total of 131 angiograms were performed during a 12-year period with 45 patients demonstrating active bleeding; 54 patients had a bleeding scan before angiography. A positive bleeding scan did not increase the percentage of positive angiograms. A history of prior gastrointestinal bleeding, transfusions, orthostatic hypotension, or tachycardia were not predictors for a positive angiogram.

DISCUSSION

This study could not identify any single useful predictor that will increase the likelihood of obtaining a positive angiogram. Nuclear medicine scans should not be used routinely as a screening test for angiography.

Predictive value of technetium Tc 99m-labeled red blood cell scintigraphy for positive angiogram in massive lower gastrointestinal hemorrhage

PURPOSE

This study was performed to evaluate whether the time interval from injection of technetium Tc 99m (99mTc)-labeled red blood cells to the time of a radionuclide "blush" (positive scan) can be used to improve the efficacy in predicting a positive angiogram.

METHOD

A retrospective review revealed 160 patients who received 99mTc-labeled red blood cell scintigraphy for evaluation of massive lower gastrointestinal hemorrhage between 1989 and 1994. Patients were included who demonstrated signs of shock on admission, had an initial decrease in hematocrit of > or = 6 percent, or required a minimum transfusion of two units of packed red blood cells. Scanning duration was 90 minutes, with imaging every 2 minutes. Time interval from injection to a positive scan was analyzed to determine predictability of a positive angiography.

RESULTS

Of 160 patients, 86 demonstrated positive scans, of whom 47 underwent angiography. These 47 patients were divided into two groups according to scan results. Group 1 (n = 33) had immediate appearance of blush; Group 2 (n = 14) had blush after two minutes. In Group 1, 20 of 33 patients had a positive angiogram, yielding a positive predictive value of 60 percent (P = 0.033). Of the 14 patients with negative angiograms (13 from Group 1, and 1 with a negative scan), 6 had radiographic occlusion of the inferior mesenteric artery and 1 had spasm of the right colic artery, with scans that blushed in the respective distributions. Excluding these seven patients yielded a positive predictive value of 75 percent (P = 0.0072) for angiography. In patients with a delayed blush (Group 2), 13 of 14 had negative angiograms, yielding a negative predictive value of 93 percent (92 percent excluding those with nonvisualization of the inferior mesenteric artery). Twenty of 21 (95 percent) positive angiograms occurred in Group 1 patients. Of the 27 patients with negative angiograms, 13 were Group 2 patients.

CONCLUSION

Patients with immediate blush on 99mTc-labeled red blood cell scintigraphy required urgent angiography. Patients with delayed blush have low angiographic yields. These data suggest that patients with delayed blush or negative scans may be observed and evaluated with colonoscopy.

The conundrum of lower gastrointestinal bleeding

Acute massive hematochezia provides one of the greatest diagnostic and therapeutic challenges to the physician. Although most patients stop bleeding spontaneously and further evaluation can be carried on with less urgency, 10% to 15% require urgent diagnostic and therapeutic procedures. Clearly, the least invasive effective solution to the bleeding problem is generally the best, although in some cases, emergency undirected surgery may be necessary. Subtotal colectomy can be done with acceptable morbidity and mortality in this situation, provided that the surgeon is confident of a colonic source of the bleeding. An understanding of the strategies outlined above encourages the management of such patients with an eye to maximizing therapeutic benefit while minimizing morbidity.

Technetium-99m-labeled red blood cell scans in the investigation of gastrointestinal bleeding

PURPOSE

Technetium-99m-labeled red blood cell scans (Tc99m RBC scan) are recommended to confirm gastrointestinal (GI) bleeding. It is controversial whether these scans are sufficient to localize the site of bleeding. This study evaluated the efficacy of RBC scans in confirming and localizing GI bleeding. Our hypothesis was that these scans were effective in localizing GI bleeding if positive within the continuous phase of imaging.

METHOD

Tc99m RBC scans were performed on a total of 80 patients over a four-year period to localize GI bleeding (59 male, 21 female; age range 6-88 (mean, 48) years). Films of 75 of the 80 patients were reread by a nuclear medicine physician who was blinded to the original reading and identity and history of the patient. Results of scans were compared with confirmatory studies.

RESULTS

A total of 21 patients had positive scans (28 percent). Of these, the site of bleeding in 16 of 21 patients (76 percent) was confirmed by angiography (4/16), endoscopy (10/16), surgery (10/16), or a combination of these. In 14 of the 16 confirmed studies (88 percent), RBC scan correctly localized site of bleeding by our rigid definition. In six patients (4 not confirmed, 2 erroneously localized), scans were positive only at greater than 15 hours. Ten of the 14 correctly localized studies and none of the incorrectly localized studies were positive in the continuous phase of imaging.

CONCLUSION

Tc99m RBC scan is effective in localizing GI bleeding when positive within the continuous phase of imaging. In this population supplemental angiography or endoscopy for the purpose of localization would seem unnecessary.

Accurate localization and surgical management of active lower gastrointestinal hemorrhage with technetium-labeled erythrocyte scintigraphy

OBJECTIVE

There is disagreement over the reliability of technetium Tc 99m (99mTc)-labeled erythrocyte scintigraphy in the localization of active lower gastrointestinal hemorrhage. A previous study at The New York Hospital-Cornell Medical Center that showed a superior sensitivity for localization of scintigraphy versus angiography in surgical patients led the authors to emphasize scintigraphy as the diagnostic test of first choice in the clinical diagnostic algorithm. The authors hypothesized that tagged erythrocyte scintigraphy can be used accurately as the primary diagnostic modality in localizing acute bleeding and guiding surgical intervention.

METHODS

The authors conducted a 5-year, retrospective analysis of 224 inpatients who underwent scintigraphic imaging for diagnosis and localization of active lower gastrointestinal bleeding. Using scintigraphy as the primary diagnostic test, with colonoscopy, upper endoscopy, and angiography as adjunctive studies, 99mTc-labeled erythrocyte scans were performed at the clinician's discretion and were reviewed again for study purposes by two nuclear radiologists who were blinded to clinical outcome. Adjunctive diagnostic tests also were ordered for clinical indications.

RESULTS

Using delayed periodic scintigraphic imaging, results of 115 scans (51.3%) demonstrated bleeding, with 96 scans (42.9%) localizing to a specific anatomic site. Patients with positive scans were five times more likely to require surgery (p < 0.005) than patients with negative scans, and surgical patients were twice as likely to localize by scintigraphy (p < 0.0001). Fifty patients (22.3%) required surgical intervention to control hemorrhage and had a bleeding site confirmed by both clinical and pathologic examinations. Forty-eight of those patients (96%) had a bleeding site determined preoperatively. For 37 patients with bleeding sites localized preoperatively by scintigraphy, 36 (97.3%) had correct localization based on surgical pathology. Only one patient required a subtotal colectomy solely because of nonlocalized bleeding. No patient bled postoperatively, and there was no mortality in either operated or nonoperated patients. The mean volume of transfused erythrocytes was similar in both scan-localized and nonlocalized surgical patients.

CONCLUSION

When performed correctly and interpreted conservatively, scintigraphy is a useful and safe means of guiding segmental resection, and should be the primary tool used in the diagnosis of patients with active lower gastrointestinal bleeding.

Use of a water enema to facilitate localization of gastrointestinal hemorrhage during Tc-99m labeled RBC scintigraphy

The authors report the use of a tap water enema to displace, and thereby localize, a site of colonic bleeding that had remained fixed in the left lower quadrant of the abdomen and could not be accurately localized. In similar cases, this maneuver may help to localize colonic bleeds in a timely fashion, avoiding protracted imaging and obviating the need for additional diagnostic testing.