Dynamic helical CT, colonoscopy, and angiography are essential for the diagnosis and treatment of colonic diverticular bleeding [1–12]. However, precise localization and definite hemostasis are often difficult because diverticula are usually numerous and bleeding is intermittent [2, 5]. Blind segmental resection in the cases of undiagnosed bleeding site is responsible for a high re-bleeding rate of 42% and mortality of 57% [13]. Therefore, precise localization is essential for treatment in patients with a life-threatening diverticular bleeding. We herein describe a patient with relapsing severe colonic diverticular bleeding, who was finally managed by superselective arterial embolization immediately after the accurate diagnosis of bleeding site on CT angiography.

Case report

A 50-year-old Japanese man was admitted to our hospital on ambulance, presenting hemorrhagic shock by severe hematochezia. Dynamic enhanced helical CT revealed high-density fluid in the sigmoid colon and rectum. The patient was resuscitated, and the bleeding decreased over a day. On the third hospital day, we attempted a colonoscopy equipped with a translucent cap after colonic purge of 1 L polyethylene glycol. While there were many diverticula from the ascending colon to the sigmoid colon, a diverticulum with fresh coagula was identified in the distal descending colon. We therefore regarded it as a bleeding spot, which was closed with hemoclips after sucked into the cap. However, massive re-bleeding occurred on the fourth hospital day, requiring 6 units of blood transfusion. The patient underwent emergent CT and angiography of superior and inferior mesenteric artery, but extravasation was not evident. Despite the continuing bowel rest without oral ingestion, the patient re-bled on the seventh and the tenth hospital days, requiring 2 and 6 units of blood transfusion, respectively. Since repeated CT and angiography on the tenth hospital day could not specify any source of re-bleeding (Figs. 1A and 2A), we conducted abdominal CT combined with angiography. Consequently, a re-bleeding spot could be clearly identified in the ascending colon (Fig. 1B), where we could selectively advance micro-catheter into the vasa recta (Fig. 2B) and successfully embolize the ruptured vessel with microcoils. Since then, the patient never bled and discharged uneventfully.

Fig. 1
figure 1

Abdominal CT pre (A) and post (B) superior mesenteric angiography on the tenth hospital day. Bleeding site (arrow) could be firstly identified immediately after angiography.

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Fig. 2
figure 2

Repeated angiography on the tenth hospital day failed to show a bleeding diverticulum (A). Superselective angiography guided by CT angiography clearly indicates the bleeding site (arrow, B). The lower collection (*) is contrast material within the ascending colon, visualized even on subtraction images due to the patient’s movement.

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Discussion

Vas rectum is displaced over diverticular formation and occasionally rupture on its antimesenteric side, where it penetrates to the submucosa by injurious factors [1]. Colonic diverticular bleeding is one of the most frequent causes of hematochezia. Although bleeding will occur in 15% of patients with diverticulosis, it usually stops spontaneously [5]. Massive hemorrhage requiring blood transfusion more than 4 units/day occurs in only 1% in episodes [7]. Although a life-threatening hemorrhage is a rare event in colonic diverticulosis, accurate diagnosis of the bleeding site is necessary for successful treatment.

Enhanced helical CT is the initial examination of choice for screening the site and the severity of colonic bleeding [10, 14]. Subsequently, colonoscopy is considered useful for precise diagnosis and treatment [8–12]. In order to obtain clear visualization, we usually plan it after rapid preparation with polyethylene glycol on the day when bleeding improves by bowel rest. In addition, we equip the colonoscope with a translucent cap, into which a bleeding spot is easily sucked and certainly grasped with hemoclips. Although we treated the patient by the procedure, he re-bled thereafter.

Interventional radiology (IVR) is an alternative strategy before surgery in the cases of unstable and untreatable bleeding by colonoscopy [3, 6]. Angiography may also fail to reveal precise localization even when a life-threatening hemorrhage occurs as our experience. A trial infusion of vasopressin into the indicated artery may be effective for such an undiagnosed occasion [2]. Singer [15] reported a case of arterio-venous malformation diagnosed as ileal hemorrhage on preoperative CT following negative angiograpy. In the present case, CT in combination with angiography could clearly demonstrate the bleeding site, which was successfully embolized on subsequent superselective angiography.

To date, an IVR-CT system, newly developed equipment enabling CT and angiography simultaneously, has been applied in various radiological interventions. This report is the first description concerning precise localization and successful management of colonic diverticular bleeding by the combination of CT angiography and IVR. We believe that IVR-CT system is a useful method for obscure and untreatable colonic diverticular bleeding.