Urethral Bulking Agent Injections


Urethral bulking agent injections are done to treat stress urinary incontinence (SUI), a condition characterized by the involuntary loss of urine. SUI may occur during or after physical exertion, sneezing, coughing, laughing, lifting, sexual activity, or other activities that increase intra-abdominal pressure.

Risk Factors for SUI

The risk of developing SUI is higher for individuals who are older, Caucasian, smokers, obese, and diagnosed with lung disease. Other risk factors include being female, pregnancy, childbirth, chronic coughing, nerve injuries to the lower back, and pelvic or prostate surgery.

In women, SUI is associated with urethral hypermobility and intrinsic sphincter deficiency (ISD). Urethral hypermobility is when the urethra has lost its anatomic support.


Diagnosing SUI

To determine whether a patient is suffering from stress urinary incontinence, the physician will evaluate the triggers of incontinence, subjective distress, frequency of incontinence, leakage quantity, and treatment goals and expectations.

As part of the physical examination, the physician will evaluate the patient for pelvic organ prolapse, urethral hypermobility, and vaginal atrophy. A standing stress test will also be done to assess leakage. A urinalysis can help screen for urinary tract infection and hematuria, and a post void residual may be done to rule out urinary retention.

Men experiencing symptoms of SUI will have their abdomen, prostate, rectum, and genitalia evaluated. Patients may be asked to squeeze their pelvic muscles and sphincter muscles during a Kegel test. The physician may also ask the patient to perform certain actions, such as straining down, stepping, and coughing to see if these actions cause the patient to leak urine.

Patients may also need to keep a voiding diary, and undergo pad testing, urodynamics, and cystoscopy. A voiding diary will be used to track daily symptoms, fluid intake, and urination frequency. The patient will also need to write down how often they have leaks and what they were doing when the leak occurred.

A pad test can be done for one hour or 24 hours. The test is done to learn about leakage with exercise or movement. The pad will be weighed after the test is complete to evaluate the amount of urine leaked.

Treating SUI with Urethral Bulking Agent Injections

Urethral injections are done to “bulk up” the urethral sphincter muscle that keeps the urethra closed. “Bulking agents” are injected into the urethra to help the sphincter effectively close the bladder.

The four FDA-approved agents in use today include: silicon microparticles (Macroplastique®), pyrolytic carbon-coated zirconium oxide bead (Durasphere™). calcium hydroxyapatite (Coaptite®), and polyacrylamide hydrogel (Bulkamid®).

Injections are typically done under local anesthesia in a physician’s office. The injections may be repeated if necessary. Though injections are not as effective as other surgeries, the recovery time is short. Bulking agents are a temporary treatment for SUI. For every ten women treated with urethral bulking agent injections, between one in three are cured of incontinence for up to one year.

Risks of Urethral Bulking Agent Injections

The risks of treatment include transient hematuria, temporary urinary retention, temporary irritative voiding symptoms, transient difficulty voiding, urinary tract infection, and elevated post void residual urine. Rare adverse effects include material erosion.

Patients should speak to their physician to find out if they could benefit from urethral bulking agent injections.