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case_images: The hydrogel spacer is inserted transperineally between the anterior rectal wall and prostate fascia (a). Computed tomography image (b) of the abdomen shows a low-density area that extends from the prostate to the rectal wall (red arrow). Axial T2-weighted (c) and sagittal T2-weighted magnetic resonance imaging images of the abdomen show the hydrogel spacer in the area between the anterior rectal wall and prostate as well as within the rectal wall (white arrow). An image obtained during colonoscopy (d) shows an approximately 2 cm ulcer in the rectum with bleeding around the hydrogel spacer.
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case_images: He had been diagnosed with prostate cancer (stage 1) 1 month previously and had undergone gold marker injection and hydrogel spacer insertion 3 weeks previously to prepare for RT (Figure 1a). Computed tomography (CT) identified a low-density area that extended from the prostate to the rectal wall (Figure 1b). Axial T2-weighted (Figure 1c) and sagittal T2-weighted abdominal magnetic resonance imaging (MRI) revealed a hydrogel spacer between the anterior rectal wall and prostate. A colonoscopy revealed an approximately 2 cm ulcer in the rectum with bleeding around the hydrogel spacer (Figure 1d).
case_images: Clinical course of the rectal ulcer caused by hydrogel spacer insertion (a). Images obtained during colonoscopy 1 month after the diagnosis. The ulcer shows signs of improvement (b, c).
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case_images: Because symptoms of peritoneal irritation and evidence of perforation of the gastrointestinal wall were not observed, magnesium oxide and sodium carbazochrome sulfonate were administered orally and a low-residue diet was allowed (Figure 2a). The center of the ulcer contained a jelly-like substance similar to the hydrogel spacer (referred to as a jelly ulcer), and no signs of perforation were observed (Figure 2b,c).
case_images: Colonoscopy (a), computed tomography (b), and magnetic resonance imaging (c) images obtained 2 months after the diagnosis indicating complete healing of the rectal ulcer. Scarring of the ulcer is observed during colonoscopy performed 6 months after hydrogel spacer insertion (d).
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case_images: Two months after the diagnosis, the jelly ulcer was no longer visible and granulation formation was observed at the base of the ulcer during colonoscopy (Figure 3a). Complete healing of the rectal ulcer was confirmed by CT and MRI (Figure 3b,c). During a colonoscopy performed 6 months after hydrogel spacer insertion, scarring of the ulcer was observed (Figure 3d).