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Arteriovenous malformations (AVMs) are abnormal shunts between arteries and veins without a capillary bed and account for only 3% of lower GI bleeding.
Polypoid AVMs are subepithelial hypervascular lesions that are challenging to resect endoscopically. Endoscopic full-thickness resection (EFTR) is a technique that allows for the removal of deeper or fibrotic lesions not suitable for conventional methods such as endoscopic mucosal resection or endoscopic submucosal dissection.
A dedicated full-thickness resection device (FTRD; Ovesco Endoscopy USA, Inc, Cary, NC, USA) is approved by the U.S. Food and Drug Administration for full-thickness and diagnostic tissue acquisition through resection of suitable lesions in the colon and rectum. The device, conceptually based on an over-the-scope clip, is endoscopically analogous to surgical wedge resection and allows for a nonexposed EFTR approach, which avoids free perforation (Video 1, available online at www.giejournal.org).
A 46-year-old healthy woman presented with hematochezia and was found, during a colonoscopy, to have a 15-mm vascular subepithelial lesion at the hepatic flexure with stigmata of recent hemorrhage. The mucosal biopsies were nondiagnostic and resulted in significant bleeding that was controlled with hemostatic clips. A tattoo was placed, and she was referred for further evaluation. After discussion of risks, benefits, and alternatives, she elected to proceed with endoscopic resection for excisional biopsy and possible definitive management.
The patient was placed under general anesthesia for stability purposes, and a colonoscope (CF-HQ190L; Olympus America, Center Valley, Pa, USA) was advanced to the hepatic flexure, revealing a 15-mm subepithelial lesion that was vascular in appearance (Fig. 1). A previously placed hemostatic clip was removed using rat-toothed forceps.
Figure 1A 15-mm subepithelial vascular lesion at the hepatic flexure.
Given the risks of incomplete resection and anticipated significant bleeding with standard endoscopic resection techniques, preparations were made for an EFTR approach. The lesion was marked using a marking probe (Fig. 2). An adult colonoscope mounted with the FTRD was advanced to the hepatic flexure where the marking dots were visualized. Given the uncertain etiology, endoscopic ultrasound using a 20-MHz miniprobe (Olympus America) was attempted for further assessment; however, visualization was inadequate and we therefore proceeded with EFTR. The lesion could not be initially grasped with standard grasping forceps, and was ultimately grasped using a tri-pronged anchor (OTSC Anchor; Ovesco Endoscopy USA, Inc). The lesion was then carefully and fully retracted into the FTRD cap (Fig. 3). The FTRD clip was deployed, and a nonexposed EFTR was successfully performed with snare resection above the clip.
Figure 2Thermal markings were placed at the borders of the lesion.
The resection defect was carefully examined and the FTRD clip was stable without evidence of perforation or bleeding (Fig. 4). Visible vessels within the resection defect were treated using hemostatic forceps (Coagrasper; Olympus America). The final specimen measured 20 × 20 mm, and histopathology demonstrated discrete clusters of dilated, tortuous, thin-walled submucosal veins and venules, consistent with an AVM (Fig. 5). At the patient’s 6-month follow-up, the scar was well-healed with no evidence of recurrent or residual lesion (Fig. 6). The patient did not experience further episodes of hematochezia.
Figure 4Nonexposed endoscopic full-thickness resection defect without evidence of perforation or bleeding.
Colonic AVMs are thought to result from intermittent, low-grade obstruction of submucosal veins leading to hypoxia, which stimulates neovascular growth factors and new abnormal vessel formation.
Polypoid AVMs are extremely rare and can be difficult to adequately diagnose on endoscopic examination or superficial biopsy.
Because of the subepithelial nature of the lesion, hypervascular characteristics, and sessile morphology, conventional endoscopic resection methods pose a high risk of incomplete resection and major bleeding. Nonexposed colorectal EFTR provides a useful organ-sparing minimally invasive option in situations where superficial techniques including EMR and endoscopic mucosal dissection are unfavorable. Adequate retraction of the lesion into the full-thickness resection device cap is vital for successful and safe full-thickness resection. Because of the fibrotic or subepithelial nature of many lesions intended for full-thickness resection, the grasping forceps may not always provide adequate retraction, and alternative tools such as the tri-pronged anchor could be beneficial as in this case. This case demonstrates that the dedicated FTRD can be successfully and safely applied to resect polypoid AVMs, and may expand the endoscopic approach to these challenging lesions.
Disclosure
Dr Ge is a consultant for Alira Health, Boston Scientific, and Ovesco Endoscopy USA. All other authors disclosed no financial relationships.
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