Teaching Case

A patient on oral anticoagulant therapy after an episode of thrombosis of the portal vein, superior mesenteric vein and splenic vein, presented with acute lower gastrointestinal bleeding. The bleeding was localized with MSCT. The patient underwent laparotomy, which confirmed the diagnosis.

The patient, a 50 years old woman, underwent splenectomy because of idiopathic thrombocytopenic purpura and developed a massive thrombosis of the portal vein, the superior mesenteric vein and the splenic vein. Anticoagulation was performed. A month later she presented with acute lower gastrointestinal bleeding.
MSCT scanning (16-slice scanner) was carried out to localize the bleeding and possibly to depict the bleeding source and underlying pathology. No oral contrast was used. Non-contrast enhanced imaging was followed by post-contrast imaging in the arterial and portal-venous phases. An area of focal high attenuation on arterial and portal-venous phase MSCT images was seen in the lumen of the ileum, due to ongoing contrast extravasation at this site. High attenuation was not present in this location in the corresponding non-contrast images. The bleeding point was identified on MIP reformatted images and three-dimensional image reconstruction: an ileal branch of the superior mesenteric artery.

The small intestine is an uncommon site of hemorrhage, relatively inaccessible and not routinely considered. Lower gastrointestinal bleeding is less common than upper gastrointestinal bleeding and accounts for approximately 30% of all gastrointestinal bleeding sites. Common causes are: diverticular disease (20–55%), angiodysplasia (3–40%), neoplasms (8–26%), colitis (6–22%) and benign anorectal lesions (9–10%). Imaging techniques used to deal with lower gastrointestinal bleeding are: radionuclide imaging, angiography, endoscopy, CT-angiography [1]. The length of the small intestine, overlying loops, its free intraperitoneal location and strong contractility limit the diagnostic ability of barium studies, endoscopy, nuclear medicine scans and angiography.
There is no gold-standard regarding the diagnostic work-up and therapy of an acute lower gastrointestinal hemorrhage. Contrast-enhanced MSCT has established itself as a noninvasive, rapid and accurate diagnostic method in suspected acute gastrointestinal bleeding [2]. Angiographic-like images can be easily produced to plan and guide therapeutic procedures [2]. The non-invasive nature of the technique compared with conventional angiography, makes CT angiography the imaging modality of choice for these patients [2]. CT angiography, like conventional angiography, has to be performed when the patient is actively bleeding.
Active bleeding was depicted as an area of focal high attenuation within the bowel lumen on arterial and portal-venous phase MSCT images, with attenuation greater than and distinct from the normal mucosal enhancement or focal pooling of increased attenuation contrast material within a bowel segment on portal-venous images, which was not present at unenhanced MSCT scans performed immediately prior the MSCT angiography [4]. An unenhanced MSCT scan is obtained immediately prior to MSCT angiography to identify any preexisting hyperattenuating areas within the bowel lumen that could be confused with hemorrhage at MSCT angiography. The diagnosis of active gastrointestinal bleeding is made when hyperattenuating extravasated contrast material is seen within the bowel lumen. We then compare the unenhanced MSCT findings to confirm the diagnosis [5]. The extravasated contrast material may demonstrate linear, swirled, ellipsoid or pooled configurations or may fill the entire bowel lumen, resulting in a hyperattenuating loop [1]. It is important to distinguish intraluminal contrast material extravasation from mucosal enhancement, which can have a similar appearance, especially when the bowel loop is collapsed [1]. Coronal MIP reformatted images are useful for localizing the bleeding segment of bowel and are also used in conjunction with axial images to evaluate the proximal femoral vasculature when transcatheter intervention is anticipated. Sagittal MIP reformatted images are useful for evaluating the rectum as well as the aorta and the origins of the celiac artery, superior and inferior mesenteric artery [5].
New MSCT technologies also facilitate three-dimensional image reconstruction and higher temporal resolution is available [4]. This allows for the acquisition of arterial and portal-venous phase images of the whole abdomen, revealing potential bleeding sources and depicting morphological changes in the abdomen [4]. Compared to other diagnostic methods MSCT is widely available, fast and low-risk technique for the localization of active gastrointestinal hemorrhage [3].