Bulking Agents Injectable (so-called bulking) agents are less invasive than surgery, and although they are less likely than surgery to result in cure, they relieve symptoms in many women. In the United States, glutaraldehyde cross-linked bovine collagen (Contigen), carbon beads (Durasphere), cross-linked polydimethylsiloxane (Macroplastique), and calcium hydroxylapatite (Coaptite) are approved for use to treat stress urinary incontinence and can be injected either peri-or transurethrally. The newer agents were studied primarily by transurethral injection. Injecting a material around the periurethral tissues facilitates coaptation of the urethra under conditions of increased intra-abdominal pressure (111–116). In a 15-article review, the short-term cure or improvement rate was 75% (117). Contigen can be passed easily through small-bore needles under local anesthesia but requires preoperative skin testing to check for possible allergic reactions (3%). Durasphere is nonantigenic (thus no skin testing is required) and does not migrate. As compared with collagen, Durasphere appears to have similar reduction in leakage episodes and is more likely to require only a single injection (112). This bulking agent does require a larger-gauge needle for injection and is somewhat more difficult to inject than collagen. Macroplastique is approved for use in the United States. This material appears to offer better outcomes as defined by improvement and cure rates than Contigen at 12 months (113). A follow-up 24-month study revealed that 84% of patients maintained improvement from the 12-month assessment (114). A recent prospective randomized trial of Coaptite versus Contigen revealed similar improvement and safety profile at 12 months when compared Contigen. Coaptite required less material per injection (4 mL vs. 6.6 mL) and was more likely to require only a single injection (115). These techniques may require several injections to achieve continence, and the long-term success of these operations remains poorly studied.
Complications In choosing surgical management, surgeons must weigh the chance of cure against the chance of severe complications. In the aforementioned randomized trial comparing TVT and Burch, women undergoing TVT were more likely to experience a bladder perforation than those undergoing the Burch procedure (9% vs. 2%, respectively) but less likely to have a fever (1% vs. 5%) or prolonged catheterization more than 29 days (3% vs. 13%) (118). Less common complications require a large sample size to detect differences. Severe complications reported on the FDA manufacturer and user facility device experience (MAUDE) database include vascular injuries, bowel injuries, and patient deaths after retropubic midurethral slings and groin and leg pain, visceral injuries, and severe infections from transobturator approaches (119). Even though these serious life-threatening complications are rare, surgeons must be cognizant of the risks and use intraoperative safety measures to prevent their occurrence.
Actual complication rates are often difficult to discern because denominators often are not available. In a nationwide analysis of 367 complications associated with 1,455 TVT procedures performed in Finland, there was a 1.9% rate (95% CI, 1.2–2.7) of blood loss over 200 mL, a 1.9% rate (95% CI, 1.2–2.7) of retropubic hematoma, a 0.5% rate (95% CI, 0.2–1.0) of hematoma outside the retropubic area, a 0.1% rate (95% CI, 0.0–0.4) of injury to the epigastric vessel, a 0.1% rate (95% CI, 0.0–0.4) of injury to the obturator nerve, and a 3.8% rate (95% CI, 2.9–5.0) of bladder perforation (120).