Arteriocolonic fistula of inferior mesenteric artery aneurysm: A case with lower gastrointestinal and intra-abdominal hemorrhage

Abstract

Introduction

Arteriocolonic fistula of Inferior Mesenteric Artery Aneurysm (IMAA) refers to a spontaneous formation of pathological communication between the artery and the adjacent gastrointestinal tract. It is a rare, life-threatening condition primarily manifesting as abdominal pain, gastrointestinal bleeding, abdominal pulsating masses. However, its clinical manifestations are usually atypical with a difficult diagnosis and treatment.

Case presentation

We report a rare case of a 50-year-old male with a hemorrhagic shock due to primary arteriocolonic fistula of IMAA. Instead of sigmoidectomy, super selective transcatheter arterial embolization (TAE) was performed after diagnostic angiography. Postoperatively, dynamic contrast-enhanced abdominal computed tomography (CT) demonstrated no recanalization of the aneurysm, absence of abnormal collateral vessels, no active hemorrhage. The patient was discharged uneventfully after 2 weeks without abdominal pain or tension.

Discussion

Colorectal tumor rupture is a major cause of lower gastrointestinal bleeding (LGIB), with IMAA being an uncommon etiology. Because of the high mortality of explorative laparotomy with an unclear bleeding site, diagnostic angiography and therapeutic TAE are viable options for diagnosing hemodynamic instability.

Conclusion

Arteriocolonic fistulas commonly occur secondary to a pseudoaneurysm formed at the anastomosis of the transplanted blood vessel after an artery surgery, which ruptures and penetrates into the intestine. We reported a unique case of primary arteriocolonic fistula of IMAA: aneurysm rupture and bleeding from the abdomen into the hematochezia. After multidisciplinary consultations, our patient obtained the best outcome using the most minimally invasive surgical methods. With an abdominal artery aneurysm presenting with colorectal hemorrhage, arteriocolonic fistula of IMAA should be suspected.

1. Introduction

Visceral artery aneurysms are fairly rare with cited incidence varies from 0.01% to 0.2% [1]. Inferior mesenteric artery (IMA) aneurysms, accounting for approximately 1% of visceral artery aneurysms, are the rarest of all visceral artery aneurysms, with most resulting from atherosclerotic disease [2]. We reported a unique case of arteriocolonic fistula: aneurysm rupture and bleeding from the abdomen into the hematochezia. Instead of sigmoidectomy, super selective transcatheter arterial embolization (TAE) was performed after diagnostic angiography. Our patient obtained the best outcome using the most minimally invasive surgical methods. With an abdominal artery aneurysm presenting with colorectal hemorrhage, arteriocolonic fistula of IMAA should be suspected.

2. Case presentation

A 50-year-old male was admitted to the emergency department with a complaint of paroxysmal abdominal pain for 4 days. The pain increased in intensity 7 h after admission in the left lower abdomen. He had no history of fever, weight loss, pancreatitis, surgery, hematochezia, vascular diseases, or did not undergo angiography. Physical examination revealed the following: tenderness in the left lower quadrant of the abdomen; blood pressure (BP), 145/91 mmHg; heart rate, 93 beats/min; and respiratory rate, 20 breaths/min. His hemoglobin concentration was low (8.2 g/dl; normal range, 13.0–17.5 g/dl), the serum amylase level was normal. He was hemodynamically stabilized without administering intravenous fluids. Abdominal ultrasonography revealed a massive fluid collection in the abdomen. A dynamic contrast-enhanced abdominal computed tomography (CT) showed nodular contrast medium staining, extravasation in the left middle abdomen and intra-abdominal hemorrhage. The arterial blood supply came from the branches of the inferior mesenteric artery. The CT demonstrated a pseudoaneurysm formation in the left branch of the inferior mesenteric artery (Fig. 1a, b) and multiple hematoceles in the abdomen and pelvis (Fig. 1b, c). The patient lost consciousness, and his blood pressure could not be measured due to a sudden increase in the amount of fresh hematochezia. Emergency digital subtraction angiography (DSA) was performed. A pseudoaneurysm formation, 4 mm in diameter, arising from the left branch of the inferior mesenteric artery (IMA) was confirmed using superselective transcatheter arterial embolization (TAE) (Fig. 2a). Hematochezia was caused due to the formation of an arteriocolonic fistula.

Fig. 1.

Preoperative and postoperative dynamic contrast-enhanced abdominal computer tomography examination. (a, b) Pseudoaneurysm formation of the left branch of the IMA (white arrow). (b, c) Massive hematocele in the abdomen and pelvis (black arrow). (c, d) No recanalization of the aneurysm, absence of anomalous collateral vessels and no active hemorrhage after TAE (white arrow).

Fig. 2.

IMA digital subtraction angiography and Embolization of IMAA involving the sigmoid colon. (a) Catheter angiography of the IMA (white arrow) before embolization. (b) Superselective intubation of the microcatheter to the proximal end of aneurysm for angiography (white arrow). (c) Superselective intubation of the microcatheter to the distal vessel for embolization (white arrow). (d) The angiography after embolization revealed that there was a blood vessel supplying the aneurysm at the distal end (black arrow). (e) IMA after embolization of the proximal and distal vessels (white arrow).

After performing a diagnostic angiography, superselective TAE was performed. Using spring coils and gelatin sponge, via the IMA, the pseudoaneurysm was embolized distal and near (Fig. 2b–d) the origin of the aneurysm. Subsequent angiography confirmed the successful occlusion of the aneurysm (Fig. 2e). After the procedure, the patient recovered uneventfully without rebleeding.

After 9 days, dynamic contrast-enhanced abdominal CT demonstrated no recanalization of the aneurysm, absence of anomalous collateral vessels, no active hemorrhage (Fig. 1c, d). After a normal dietary intake, the patient was discharged uneventfully without abdominal pain or tension.

Colonoscopy revealed inflammation of sigmoid colon (Fig. 3a and b), 25 cm away from the anus, which was suspected to be the perforation of sigmoid colon postoperative. The healing scar was seen on colonoscopy 15 months later (Fig. 3c). The patient has been well for 22 months without recurrence of the sigmoid. The patient provided informed consent, and the study design was approved by the appropriate ethics review board.

Fig. 3.

Postoperative colonoscopy. (a) Colonoscopy revealed inflammation (white arrow) of the sigmoid colon, 25 cm away from the anus. (b) Colonic inflammation improved during the endoscopic mucosal resection of multiple colonic polyps 10 days later (white arrow). (c) The healing scar (white arrow) as observed using colonoscopy after 15 months.

3. Discussion and conclusion

Acute gastrointestinal (GI) bleeding is generally a difficult and urgent clinical emergency. Acute massive lower gastrointestinal bleeding (LGIB) can lead to hemodynamic instability, which can cause hemorrhagic shock and even death in a few patients [4]. Its etiology is complex, and the diversity of blood supply origins and bleeding characteristics has led to differences in the imaging, diagnosis, treatments and outcomes [4].

In addition to the colorectal tumor rupture, cavernous haemangioma [5] and aneurysms [6] maybe the unknown etiologies of hemorrhagic shock. Colorectal cancer cause weight loss, hematochezia, and changes in the defecation habits. Aneurysms of the visceral arteries are uncommon. Aneurysms of the IMA and/or the superior mesenteric artery (SMA) [6], associated with aneurysmal rupture and presenting with massive gastrointestinal or peritoneal bleeding are extremely rare.

The patient had no history of vascular diseases or did not undergo angiography. He demonstrated an aneurysm rupture and bleeding from the abdomen into the hematochezia, referred to as an arteriocolonic fistula, which includes the spontaneous formation of a pathological communication between the artery vascular system and the adjacent gastrointestinal tract [3]. Arteriocolonic fistula of Inferior Mesenteric Artery Aneurysm (IMAA) involving the sigmoid colon is uncommon. The fistula is most likely the result of a spontaneous erosion of the artery aneurysm causing chronic inflammation, enabling aorto-enteric fixation [7].

Multidisciplinary management involving a radiologist, gastroenterologist, endoscopist, surgeons was performed. Colonoscopy is the first-line diagnostic tool when bleeding from the colorectal region is suspected. Hemodynamics immediately become unstable with the discharge of massive bloody stools, leading to hemorrhagic shock, which was a contraindication for colonoscopy in our patient [8]. An explorative laparotomy would have been justified in this emergency condition; however, the surgical mortality rates are as high as 15–30% [9]. Specifically, patients experiencing a failure of conservative treatment or unknown etiology required emergency surgery [5]. In this patient, without knowing the exact bleeding site, the anastomotic leakage or colostomy became life-threatening, and a secondary operation after HartMann surgery was required. Even if the intestine was ischemic, necrosed, and perforated, a first-stage operation can be performed based on bowel preparation without colostomy using TAE.

Furthermore, the bowel wall thickening near the aneurysm and extravasation of the contrast media from the distal branches were not observed [10]. In recent years, TAE has been used for the diagnosis and treatment of LGIB. The development of microcatheters with a small caliber and various embolic materials has enabled the use of superselective TAE [3,9]. However, colonic ischemic [11], necrosis, or perforation are the complications of secondary exploratory surgery in addition to rebleeding.

Ischemic colitis is a complication following the repair of an abdominal artery aneurysm [[10], [11], [12]]. Hemodynamic instability, emergencies, congenitally inadequate mesenteric collaterals may be the factors associated with the development of ischemic colitis [11,12]. After detecting ischemic colitis and the conservative treatments failed, the resection of the ischemic colon segment was required as an emergency, increasing the length of hospitalization and cost for the patient; however, no performing colostomy reduces medical care and improves the quality of life. In addition, the probability of colon ischemia can be evaluated by preoperative recognition of high-risk patients and careful imaging study of the vascular system [11].

Fortunately, our patients achieved optimal results using the most minimally invasive approach. However, due to poor compliance, besides colonoscopy, the patient did not come to the hospital for further examination to diagnose the etiology, one of which may be abdominal arteritis. Regarding the follow-up progress of this case, attention is still required regarding the occurrence of aortoenteric fistula, which is the primary concern in the follow-up.

In patients with an abdominal artery aneurysm presenting with gastrointestinal hemorrhage without a remarkable history and endoscopy, arteriointestinal fistula should be suspected. In such conditions, performing of a DSA is essential for obtaining an accurate diagnosis of the presence of an aortoenteric fistula and minimally invasive treatment using superselective TAE. Despite the high success rate when attempting TAE, the difficulty in reaching the target location maybe one of the limitations. Although the mortality rate is high, emergency laparotomy has to be performed when the embolization fails.

Ethics approval and consent to participate

No ethical clearance required as it only involves a case report.

Author contribution statement

All authors listed have significantly contributed to the investigation, development and writing of this article.

Funding statement

Zengxin Lu was supported by Zhejiang Province Public Welfare Technology Application Research Project [LGF19H220002].

Data availability statement

Data included in article/supp. material/referenced in article.

Declaration of interest's statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.