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

Metastatic choriocarcinoma with hemorrhagic complications and spontaneous ovarian hyperstimulation syndrome: A case report

Gestational choriocarcinoma is a malignant trophoblastic tumor arising from any gestational event, even with a long latency period, generally in the reproductive female. It is associated with a high level of beta-human chorionic gonadotropin. Its primary site is usually the uterus but not all patients have a detectable lesion in this site. Regression of the primary tumor after it has metastasized is not uncommon, and one-third of cases manifest as complications of metastatic disease. In this report we present an uncommon case of gestational choriocarcinoma with lung, liver and jejunal metastases at the time of diagnosis without evidence of pelvic disease, in 34-year-old woman. The main points of interest of our case were the development of the ovarian hyperstimulation syndrome with massive multicystic ovarian enlargement induced by high level of beta-human chorionic gonadotropin and the bleeding of jejunal and liver metastases, due to the high vascularity of the tumor tissue, a condition known as "Choriocarcinoma Syndrome". We will focus on the radiological findings of metastases, bleeding complications and ovarian hyperstimulation syndrome.

RXH-Reactive 18F-Vinyl Sulfones as Versatile Agents for PET Probe Construction

Efficient radiolabeling reactions are important chemical tools in biomedical research especially in probe construction. Herein, three ¹⁸F-labeled vinyl sulfones were prepared. In particular, ¹⁸F-PEG1-VS (((2-(2-(fluoro-¹⁸F)ethoxy)ethyl)sulfonyl)ethane) could not only allow chemoselective labeling of bioactive molecules containing -XH (X = S, NH) groups, but also react with red blood cells both in vitro and in living mice for potential cell tracking applications. In addition, these hydrophilic agents were found to cross the blood brain barrier (BBB) efficiently and localize at the cerebellum region. In summary, ¹⁸F-labeled vinyl sulfones provide a versatile platform for PET probe construction.

Role of imaging in diagnosis and management of left ventricular assist device complications

Heart failure is a clinical condition that is associated with significant morbidity and mortality. With the advent of left ventricular assist device (LVAD), an increasing number of patients have received an artificial heart both as a bridge-to-therapy and as a destination therapy. Clinical trials have shown clear survival benefits of LVAD implantation. However, the increased survival benefits and improved quality of life come at the expense of an increased complication rate. Common complications include perioperative bleeding, infection, device thrombosis, gastrointestinal bleeding, right heart failure, and aortic hemodynamic changes. The LVAD-associated complications have unique pathophysiology. Multiple imaging modalities can be employed to investigate the complications, including computed tomography (CT), positron emission tomography-computed tomography (PET-CT), catheter angiography and echocardiography. Imaging studies not only help ascertain diagnosis and evaluate the severity of disease, but also help direct relevant clinical management and predict prognosis. In this article, we aim to review the common LVAD complications, present the associated imaging features and discuss the role of imaging in their management.

Imaging Workup of Acute and Occult Lower Gastrointestinal Bleeding

Lower gastrointestinal bleeding is defined as occurring distal to the ligament of Treitz and presents as hematochezia, melena, or with anemia and positive fecal occult blood test. Imaging plays a pivotal role in the localization and treatment of lower gastrointestinal bleeds. Imaging tests in the workup of acute lower gastrointestinal bleeding include computed tomography (CT) angiography, nuclear medicine scintigraphy, and conventional catheter angiography. Catheter angiography can also be used to deliver treatment. Imaging tests in the workup of occult lower gastrointestinal bleeding include CT enterography and nuclear medicine Meckel scan.

Therapeutic management options for patients with obscure gastrointestinal bleeding

Obscure gastrointestinal bleeding (OGIB) is one of the most challenging disorders faced by gastroenterologists because of its evasive nature and difficulty in identifying the exact source of bleeding. Recent technological advances such as video capsule endoscopy and small bowel deep enteroscopy have revolutionized the diagnosis and management of patients with OGIB. In this paper, we review the various diagnostic and therapeutic options available for the management of patients with OGIB.

Video capsule endoscopy in life-threatening GI hemorrhage after negative primary endoscopy (with video)

BACKGROUND

Video capsule endoscopy (VCE) continues to evolve as a key diagnostic tool. Traditionally VCE has been used to detect occult and obscure GI bleeding in adult patients. VCE has not been documented or accepted as an early diagnostic tool for acute life-threatening GI hemorrhage.

OBJECTIVE

Our purpose was to demonstrate the use of VCE as an early diagnostic tool in acute life-threatening GI hemorrhage.

DESIGN

Case series.

PATIENTS

Patients with life-threatening GI hemorrhage.

INTERVENTIONS

VCE after negative primary endoscopy.

RESULTS

VCE allowed rapid diagnosis and reliable data before surgical intervention. Although proving to be a beneficial diagnostic tool for acute GI hemorrhage, VCE was not associated with increased morbidity or mortality rates.

LIMITATIONS

This report only focuses on cases where VCE successfully led to a diagnosis. There is no prospective control group to which these patients can be compared. There were no other attempted acute VCE studies in patients with life-threatening bleeding during the time period of these case reports.

CONCLUSIONS

The use of VCE is a simple and relatively safe diagnostic tool in the evaluation of continuing GI hemorrhaging in endoscopy-negative patients. The use of VCE can be considered as a another useful tool in the armamentarium of the endoscopist in the evaluation of GI bleeding. Prospective studies should be undertaken to determine the appropriate timing and clinical use in this group of patients.

Significance of scintigraphy for the localization of obscure gastrointestinal bleedings

AIM: To determine the role of scintigraphy in patients with gastrointestinal (GI) bleeding of unknown localization.

METHODS: We performed retrospective analyses on 92 patients receiving scintigraphies from 1993 to 2000 in the University of Regensburg hospital, which were done for localization of GI bleeding as a diagnostic step after an unsuccessful endoscopy. In addition to the scintigraphies, further diagnostic steps such as endoscopy, angiography or operations were performed. In some of the scintigraphies with negative results, a provocation test for bleeding with heparinisation was carried out.

RESULTS: 73% of all scintigraphies showed a positive result. In 4.5% of the positive results, the source was located in the stomach, in 37% the source was the small bowel, in 25% the source was the right colon, in 4.5% the source was the left colon, and in 20% no clear localization was possible. Only 4% of all scintigraphies were false positive. A reliable positive scintigraphy was independent of the age of the examined patient. A provocation test for bleeding with heparin resulted in an additional 46% of positive scintigraphies with a reliable localization in primary negative scintigraphies.

CONCLUSION: Our results show that scintigraphy and scintigraphy with heparin provocation tests are reliable procedures. They enable a reliable localization in about half of the obscure GI-bleeding cases. Scintigraphy is superior to angiography in locating a bleeding. It is shown that even in the age of video capsule endoscopy and double-balloon enteroscopy, scintigraphy provides a reliable and directed localization of GI bleeding and offers carefully targeted guidance for other procedures.

Red blood cell scintigraphy in children with acute massive gastrointestinal bleeding

BACKGROUND

The main topic of the current review is the usefulness of technetium-99m-labeled red blood cell scintigraphy ((99m)Tc RBC scan) in children with acute massive gastrointestinal (GI) bleeding.

METHODS

The medical records of pediatric patients who experienced massive GI bleeding and who underwent (99m)Tc RBC scanning between November 1991 and December 2004 were reviewed and analyzed retrospectively.

RESULTS

The study included 22 patients who underwent 23 (99m)Tc RBC scans. The scans were usually performed after other diagnostic tests failed to locate the bleeding. The diagnostic sensitivity of the scans was nine out of 23 (39.1%). The test demonstrated a positive scan within the first 2 h in six patients, and three patients had positive results at 24 h. The locations of the lesions identified on scanning and surgical investigation were highly correlated in patients with a positive scan within 2 h.

CONCLUSIONS

The (99m)Tc RBC scan is a sensitive, albeit non-specific, method for detecting GI bleeding. The location of a lesion as indicated by a positive scan within 2 h is helpful for guiding surgical intervention and angiography, although a definitive diagnosis should be made with other methods, particularly laparotomy.

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.

Does hemodynamic instability predict positive technetium-labeled red blood cell scintigraphy in patients with acute lower gastrointestinal bleeding? A review of 50 patients

PURPOSE

Technetium-99m-labeled red blood cell scintigraphy, commonly used in the evaluation of acute lower gastrointestinal hemorrhage, often fails to demonstrate a source of bleeding. It would be helpful to characterize a subset of patients more likely to have a positive scan. This study was undertaken to determine whether hemodynamic instability can predict tagged red blood cell scan positivity.

METHODS

The records of 50 consecutive patients who underwent tagged red blood cell scanning for the evaluation of acute lower gastrointestinal bleeding were reviewed retrospectively.

RESULTS

Patients presenting with a heart rate >100 beats per minute or a systolic blood pressure <100 mmHg up to 24 hours before undergoing tagged red blood cell scanning were considered hemodynamically unstable. Thirteen of 21 unstable patients (62 percent) had positive scans, whereas only 6 of 29 stable patients (21 percent) had positive scintigraphy (odds ratio, 6; 95 percent confidence interval, 1.79-22.1).

CONCLUSIONS

Hemodynamic instability in the setting of acute lower gastrointestinal bleeding may be a predictor of positive tagged red blood cell scanning. Incorporating this into the diagnostic algorithm used to evaluate patients with acute lower gastrointestinal bleeding may allow physicians to reserve red blood cell scintigraphy for patients who have demonstrated transient hemodynamic compromise.

Diagnostic yield and therapeutic implications of capsule endoscopy in obscure gastrointestinal bleeding

AIM

The main aim of this study was to evaluate efficacy and therapeutic impact of capsule endoscopy (CE) in obscure gastrointestinal bleeding (OGIB). In addition, we evaluated the software of automatic detection of red zones (SBI, Given Imaging).

PATIENTS AND METHODS

From June 2002 to June 2003, thirty-five patients with OGIB underwent capsule endoscopy after negative upper and lower digestive endoscopy. Capsule endoscopy was performed following a 12-hour fasting period and some received 2 L of PEG the night before for bowel preparation.

RESULTS

CE was performed for occult (N=18) or overt (N=17) OGIB. Potentially bleeding lesions were found in 16/35 patients (45.7%). Lesions were angiodysplasias (N=8), ulcerations (N=4), tumors (N=2) and active bleeding without visible lesion (N=2). Lesions were located in gastric antrum (N=1), duodenum (N=2) and jejuno-ileum (N=13). Endoscopic (N=10), surgical (N=2) or medical (N=1) treatments were performed in 13/35 (37%). SBI was retrospectively evaluated in 24 patients with sensitivity, specificity, positive and negative predictive value of respectively 45%, 73%, 50% and 69%. CE retention during 10 days occurred in a patient with a small bowel NSAID-induced stricture.

CONCLUSION

CE is a safe and effective procedure in the management of OGIB and had a therapeutic impact in more than one third of patients.

Management of massive lower gastrointestinal bleeding: should there be surgical intervention without initial endoscopy and radiological evidence of the source of bleeding?

We report two case histories of patients with massive rectal blood loss. Endoscopic and radiological investigations could not identify the source of bleeding at admission. Initially, both patients recovered without surgical intervention, receiving a large number of blood transfusions only. Extensive subsequent radiological analysis showed that the bleeding was due to a pathological part of the proximal jejunum in one case and of the colon transversum in the other. Although immediate surgical intervention was not needed at presentation, both patients underwent resection of a part of the bowel some time thereafter. Surgery was performed after hemodynamic stabilization in the first case. However, in the second case, emergency surgical intervention was needed due to persistent bleeding 4 days after admission. Both patients are still doing well half a year after this massive gastrointestinal (GI) hemorrhage. Aside from a small area of chronic inflammation and fibrosis of the jejunum in one patient, histopathological evaluation of the surgical resection specimens revealed no specific cause for these massive gastrointestinal bleedings. We discuss the general approach of gastrointestinal hemorrhage and the several (dis)advantages of the various imaging techniques and the order in which they should be used.

Acute gastrointestinal bleeding

Radionuclide bleeding scintigraphy remains a simple yet powerful method of localizing sites of gastrointestinal hemorrhage and is most commonly performed today using the red blood cell technique. Radionuclide techniques for detecting bleeding remain safe, sensitive, and noninvasive. Based on several simple concepts, including the use of cine-mode imaging over the abdomen, it is possible to achieve excellent accuracy in localizing the site of bleeding. Studies often contain additional ancillary information, which is helpful for diagnosis and patient treatment.

Review article: The advent of capsule endoscopy--a not-so-futuristic approach to obscure gastrointestinal bleeding

Capsule endoscopy is a new, wireless, endoscopic examination of the small intestine. To date, two small clinical trials have been reported utilizing capsule endoscopy in patients with obscure gastrointestinal bleeding, and have shown its superiority to push enteroscopy in diagnosing the cause of blood loss. No outcome studies have been reported. This paper proposes a change in practice guidelines for obscure bleeding. It is our opinion that, in the future, with the advent of wireless capsule endoscopy, the evaluation of patients with obscure gastrointestinal bleeding will be very different from the practice of medicine today. We believe that capsule endoscopy will become the first-line method for the evaluation of patients with obscure bleeding, once upper endoscopy and colonoscopy have been shown to be negative. In patients with active bleeding, capsule endoscopy will confirm the small bowel as the site of bleeding, providing a location, or, if the study is negative for the small intestine, may indicate that the bleeding is either colonic or gastric in origin. In a patient with active bleeding within the small intestine, the capsule will guide further evaluation and therapy. A patient with a small bowel tumour detected by capsule endoscopy will proceed directly to laparoscopic surgery. If the site of bleeding is identified in the proximal small bowel and there is no mass, push enteroscopy will be used to re-identify the site and cauterize it. A distal small bowel site will require surgical intervention, coupled with intra-operative enteroscopy. Should the patient be too sick to undergo surgery, medical therapy utilizing hormonal agents will be considered. A colonic site will be evaluated by colonoscopy. In patients with a more occult or intermittent type of bleeding and in those whose upper endoscopies and colonoscopies are negative, capsule endoscopy will be used similarly to identify a bleeding lesion and thereby direct subsequent testing or treatment.

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.

Colonoscopic management of lower gastrointestinal hemorrhage

Lower gastrointestinal bleeding is a common reason for hospitalization, especially among the elderly. Unlike that of upper gastrointestinal bleeding, the diagnostic and therapeutic approach to individuals with lower gastrointestinal bleeding is not well standardized. Recent reports indicate that early colonoscopy may be the best strategy to improve outcomes and reduce costs. However, good prospective, controlled data on the role of colonoscopy in the management of lower gastrointestinal bleeding are still required. Colonoscopy can establish a definite or probable diagnosis in greater than 80% of individuals with lower gastrointestinal bleeding. Based on the best available evidence, it appears that clinical and colonoscopic data may be combined in an effort to predict outcome and suggest optimal length of stay. It also appears that therapeutic colonoscopy can arrest or prevent bleeding in certain high-risk patients, offering the opportunity to change the natural history of the bleed.

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.

The application of technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled white blood cells for the diagnosis of right dorsal ulcerative colitis in two horses

The application of 99mTc-HMPAO labeled white blood cells to support the diagnosis of right dorsal ulcerative colitis was studied in two horses with a history and clinical signs consistent with phenylbutazone toxicity. These images were compared to a reference horse unaffected by right dorsal ulcerative colitis. Blood was collected aseptically in heparinized syringes from the patients for in vitro white blood cell (WBC) radiolabeling. The buffy coat was separated out and radiolabeled with 99mTc-HMPAO. The radiolabeled blood was re-injected i.v. and four images of the right and left side of the patient's abdomen were acquired at 4 hours and 20 hours post-injection. Results of the nuclear study revealed no abnormal findings in the abdomen at the four-hour post-injection images in any horse. Images obtained 20 hours post-injection revealed a linear uptake of radiolabeled WBCs in the right cranioventral abdomen in the region of the right dorsal colon in both horses with right dorsal ulcerative colitis. The reference horse had no radiopharmaceutical uptake in this region. This nuclear imaging study was a rapid, non-invasive method to identify right dorsal colon inflammation. These findings not only supported the diagnosis of right dorsal ulcerative colitis, but also facilitated appropriate medical management of each horse.

Life-threatening hemorrhage of an unanticipated superficial circumflex iliac artery origin imaged with Tc-99m-labeled erythrocytes

The authors report, for the first time, the nuclear medicine diagnosis of extraperitoneal bleeding that originated from the superficial circumflex iliac artery and review the critical role of dynamic nuclear imaging techniques in the localization of sites of nonenteric hemorrhage. Dynamic imaging techniques using Tc-99m-labeled erythrocytes played a critical role in the localization of an extraperitoneal bleeding site near the entrance site of a Jackson-Pratt drain. Localization of the site remained undiagnosed before nuclear imaging despite two exploratory laparotomies and diagnostic angiography.

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.

Evaluation of the patient with gastrointestinal bleeding: an evidence based approach

Gastrointestinal bleeding is a common and potentially life-threatening problem. The incidence of upper gastrointestinal bleeding (UGIB) is 40 to 150 episodes per 100,000 population per year. Mortality in large series is 6% to 10% for UGIB and has remained unchanged over the past 30 to 60 years. The incidence of hospitalization for acute lower gastrointestinal bleeding is about 20 to 27 episodes per 100,000 population per year, with a 200-fold increase with advancing age from the third to ninth decades. The mortality rate is 4% to 10% or higher. The evaluation of overt or acute gastrointestinal bleeding in the ED is reviewed here from the perspective of evidence-based medicine.

BUN/creatinine ratios: aid to decision making about delayed imaging in Tc-99m red blood cell scans for gastrointestinal hemorrhage

In patients with gastrointestinal hemorrhage, delayed or late scans with Tc-99m labeled red blood cells are readily performed and have prognostic impact when early images are negative. Nevertheless, there have been no indicators for the likelihood of detecting bleeding on such images. In a review of all gastrointestinal bleeding scans over an 8-year period, 73 patients had delayed images (> 3 hours) following early negative exams. For these patients, determinations of serum blood urea nitrogen (BUN) and creatinine (Cr) were evaluated as the BUN/Cr ratio and were compared against delayed scan findings and confirmed diagnoses. Patients with significant renal failure were excluded from analysis. There were 34 late positive (46%) and 39 late negative (54%) studies. Mean BUN/Cr was 26.5 and 20.0 in patients with late positive and late negative scans, respectively (p < 0.05). Occurrence of late positive scans was 38% (19/50) for BUN/Cr < 25.0 vs. 65% (15/23) for BUN/Cr > 25.0 (p < 0.05). Patients with early negative images and a BUN/Cr ratio of 25 or greater have a greater likelihood of a positive delayed image. Late imaging should be encouraged in patients with elevated BUN/Cr and early negative scintigraphy.

Small intestinal bleeding

Bleeding from the small intestine may be difficult to diagnose, because of the organ's length and free intraperitoneal location. Although there is a variety of causes of intestinal bleeding, angiodysplasia is the most common. Several different tests can be used to identify the bleeding site preoperatively or intraoperatively, including enteroscopy.