This section describes safety outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
5.1 One case of intravascular injection of hydrogel spacer was reported on the US Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database. The clinician stated that this might have been caused by needle tip movement into a vein after aspiration and before hydrogel injection, allowing the hydrogel to enter the vessel. The patient remained asymptomatic and was prescribed a low-dose anticoagulant daily as prophylaxis against venous thrombosis. Radiation treatment was given as planned.
5.2 Inadvertent rectal wall injection (with hydrogel) resulting in focal rectal mucosal necrosis and bladder perforation was reported after the procedure in 1 patient in a case series of 52 patients. This resolved with no sequelae.
5.3 A rectal ulcer, 1 cm in diameter and causing frequent rectal bleeding, mucus discharge and bowel movements, was reported in a case report of 1 patient 2 months after hydrogel injection. This had resolved without further intervention by 3 months. Digital rectal examination at 6 months revealed a healed ulcer, with only a non-tender slit in the anterior rectal wall. At subsequent examinations over 3 years, there was no recurrence of bowel symptoms.
5.4 Haematoma developed behind the bladder in 1 patient with a moderate platelet count (within hours after injection) in a case series of 36 patients injected with a hyaluronic acid spacer. This was removed by laparotomy.
5.5 Infections (bacterial peritonitis in 2 patients and bacterial epididymitis in 1 patient) were reported in 3% (3/100) of patients injected with a hydrogel spacer in a retrospective comparative case series of 200 patients. The bacterial peritonitis occurred after prostate biopsies. All 3 infections resolved with antibiotic therapy. No infections were reported in the 100 patients treated with high-dose rate brachytherapy without hydrogel.
5.6 Penile bleeding was reported in 1 patient during balloon insertion in a case series of 27 patients. Further details were not reported.
5.7 Acute urinary retention (which needed catheterisation, and resolved within a few hours) was reported in 12% (3/26) of patients during balloon insertion and in 1 patient during radiotherapy in the case series of 27 patients.
5.8 Dysuria and nocturia (grade 1 to 2) was reported in 12% (3/26) of patients during balloon insertion and in 65% (15/23) of patients during radiotherapy in the case series of 27 patients. Further details were not reported. Other events reported during radiotherapy in the same study included diarrhoea in 17% (4/23) of patients, mild proctitis in 8% (2/23) of patients and, in 1 patient each, blood in the faeces, constipation, erectile dysfunction, itching, fatigue and decreased urine flow.
5.9 As well as safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed no anecdotal adverse events. They considered that the following were theoretical adverse events: damage to urethra, and prostate; allergy; and unknown long-term effects of the hydrogel spacer.
5.10 One commentary from a patient who had experience of this procedure was received, which was discussed by the committee.