Prospective Evaluation of a Single Incision Sling for Stress Urinary Incontinence

Results 

Baseline characteristics are shown in table 1. Of the 188 patients implanted 157 (83.5%) were evaluated at 12 months (fig. 1). Attrition was the result of loss to followup (7), withdrawal of consent (8) or missed visit (16). Of the 8 patients who withdrew consent in 4 this was due to sling failure.

Table 1. Baseline study population characteristics

			Median (range)
	Mean parity (SD)	2.0 (1.0)	2.0(0.0–8.0)
	Mean kg/m2 body mass index (SD)	27.9 (5.0)	27.5(17.9–40.1)
	No. menopausal (%)	97 (51.6)
	No. ethnicity (%):
	White	157 (83.5)
	Black	7 (3.7)
	Hispanic/Latina	24 (12.8)
	Mean UDI-6 score (SD)	49.8 (19.1)	44.4(0.0–100.0)
	Mean IIQ-7 score (SD)	43.8 (25.2)	40.5(4.8–100.0)
	Mean 1-hr pad wt (SD)	26.2 (38.2)	11.9(0.0–246.2)

Procedural data are shown in table 2. There were 3 reported intraoperative complications of vaginal wall perforation, conversion of monitored anesthesia care to general anesthesia secondary to airway difficulty and bronchospasm due to general anesthesia. The vaginal wall perforation was due to poor exposure of the sling placement site that was related to the choice of implant location (office). The perforation was managed by removing the initial tape and successfully placing a new sling during a different session at the hospital.

Table 2. Procedural anesthesia data

		Office	Hospital	Ambulatory Surgery Center	Totals
	No. procedures	38	127	23	188
	% General	0.0	44.1	5.3	49.5
	% Intravenous	5.3	19.7	6.9	31.9
	% Local	14.9	2.7	0.0	17.6
	% Epidural	0.0	1.1	0.0	1.1
	Totals (%)	20.2	67.6	12.2	100.0

The CST and PWT efficacy rates at 12 months were 90.6% and 84.5%, respectively. The details of the LFCF analyses can be found in table 3. Median pad weight decreased from 11.9 gm (IQR 3.6, 30.0) at baseline to 0.0 (IQR 0.0, 0.5) at 12 months (p <0.001). Four patients underwent a second sling procedure within the first year of followup, with 1 receiving a retropubic sling and 3 receiving transobturator slings. Table 4 presents post hoc efficacy analysis by procedure location.

Table 3. LFCF efficacy analysis

		CST	PWT
	Subjects with 12-mo visit	157	157
	Unable to complete or refused test at 12 mos	−2	−4
	Completed 12-mo tests	155	153
	Failures:
	Revision surgery for SUI	+4	+4
	Failures carried forward from 6-mo visit	+1	+4
	Pos test at 12 mos	+10	+17
	Total failures	15	25
	Successes:
	Neg test at 12 mos	145	136
	Efficacy rate at 12 mos	145/(145 + 15) = 90.6%	136/(136 + 25) = 84.5%

Table 4. Results by procedure location

		% Neg CST LFCF (No./total No.)	% PWT 1 gm or Less LFCF (No./total No.)
	Office	91.2 (31/34)	97.1 (33/34)
	Ambulatory surgery center	100 (18/18)	88.9 (16/18)
	Hospital	88.9 (96/108)	79.8 (87/109)

As shown in table 5 significant improvements occurred from baseline to 12 months in UDI-6 (p <0.001) and IIQ-7 (p <0.001) scores. The proportion of patients with improvement in the UDI-6 and IIQ-7 scores was 94.3% and 96.8%, respectively. Of those patients with bothersome urge urinary incontinence symptoms at baseline on UDI-6 question 2, 87.3% reported symptoms resolved at 12 months. De novo urge incontinence was reported in 7.7% of patients at 12 months based on UDI-6 question 2 as a change of a score at baseline of 0 or 1 to a score of 2 or more at 12 months. Based on the UDI-6 question 3, 89.9% of patients reported resolution of SUI symptoms at 12 months. Table 6 presents postoperative complications. Of the 6 patients with temporary urinary retention who required postoperative Foley catheterization 5 were under general anesthesia and underwent concomitant surgery. At the 7-day evaluation 96.8% of patients (181 of 187) reported normal voiding, 76.5% (143 of 187) considered themselves able to return to normal activities and median pain level was 0.0 (range 0.0 to 8.0).

Table 5. Changes from baseline in UDI-6 and IIQ-7 scores

		Baseline	12 Mos
	UDI-6:
	Median (IQR)	44.4(33.3,61.1)	11.1 (0.0,22.2)
	Median change (IQR)		−33.3 (−50.0,−22.2)
	IIQ-7:
	Median (IQR)	40.5(23.8,61.9)	0.0 (0.0,4.8)
	Median change (IQR)		−33.3 (−52.4,−19.1)

All values p <0.001.

Table 6. Postoperative complications

		No. (%)
	Urinary tract infection	8(4.3)
	Constipation	7(3.7)
	Pain/discomfort-other	6(3.2)
	Temporary urinary retention⁎	6(3.2)
	Urinary incontinence-de novo urge	5(2.7)
	Infection-vaginal	4(2.1)
	Dyspareunia	4(2.1)
	Urinary urgency	4(2.1)

⁎ Of the 6 patients 5 had general anesthesia and concomitant surgical repair.

Discussion 

The MiniArc sling was first introduced internationally in August 2007. The device was designed to simplify previous midurethral techniques, minimize complication rates related to needle passage and, most importantly, improve outcomes including QOL. Our prospective multicenter study demonstrated that the MiniArc procedure is quick and carries minimal patient morbidity without the significant blind passage of needles. Although not a comparative trial, MiniArc appears to have similar procedural data to the Monarc™ transobturator sling. In a prospective Monarc sling trial Moore et al reported a 13-minute procedure time, average estimated blood loss of 35 ml, a mean time to void without a catheter of 13 hours and 11% of patients needing a Foley catheter postoperatively.11

The patient tolerability of the MiniArc procedure in our study was highlighted by the short facility stay, minimal postoperative discomfort and quick return to normal activities. As a testament to the minimal invasiveness of the procedure and patient acceptability, our study demonstrated that MiniArc may be safely and effectively performed in an office setting (20% of the study population), often with the patient under only local anesthesia.

Several complications have been documented from the blind passage of needles in the retropubic space (major vascular, bowel, and bladder injuries) and obturator regions (groin/leg neuropathy, thigh abscess).12, 13 Although less invasive than retropubic slings, transobturator slings are not without risk. The development of clinically significant groin pain/leg neuropathy following inside-out transobturator slings was 24.4% initially and 3.7% in the long term.14 The mesh is thought to undergo various form changes of ingrowth and fibrosis causing contracture and shrinkage of the material that may contribute to the leg neuropathy. No trauma to the urethra, bladder, bowel or blood vessels occurred during this study and no patients experienced a thigh abscess or leg neuropathy. By avoiding the transobturator space and the medial groin muscles MiniArc minimizes these complications as demonstrated by the current study. Although our study resulted in no bladder perforations, cystoscopy was only performed in 55.3% of cases. Surgeons may consider cystoscopy when first learning this technique or when the dissection is not straightforward.

There is a paucity of published data available and certainly to our knowledge no published comparative trials of the MiniArc. Our study success rates are consistent with what has been reported to date in other 12-month MiniArc and traditional transobturator sling series. In a retrospective MiniArc trial Moore et al reported an overall 12-month cure rate of 91.4% determined by physician and patient assessment in 58 of 61 patients.15 UDI-6 total scores decreased from an average of 41.8 ± 24.9 preoperatively to 11.2 ± 13.8 postoperatively (p <0.001). In a prospective multicenter trial on TOT DeRidder et al reported an 87.6% negative CST and a 1-hour pad weight decrease from 65.8 gm preoperatively to 9.5 gm 2 years postoperatively.16 Improvements in global UDI-6 and IIQ-7 QOL scores were also statistically significant (p <0.001). In a multicenter, randomized trial comparing retropubic TVT with TOT Barber et al reported similar negative CST results at 1 year (90% TOT and 91% TVT).17

Recent published data on the MiniArc by Gauruder-Burmester and Popken18 and Debodinance and Delporte19 have shown lower efficacy rates of 77.8% at 12 months and 75.7% at 2 months, respectively, as opposed to our 90.6% CST and 84.5% PWT success at 1 year. The factors that may have impacted lower efficacy rates in the articles by Gauruder-Burmester and Popken18 and Debodinance and Delporte19 may be due to patient selection (eg enrolling patients with failed prior sling procedures, low urethral pressure or intrinsic sphincter deficiency and mixed urinary incontinence). The patient population in our MiniArc prospective study was fairly homogeneous in that those with a prior failed synthetic sling were excluded from study, all had urethral hypermobility and only 5.9% (11 of 188) had mixed incontinence.

MiniArc effectiveness may be attributed in part to the design of the self-fixating tip and needle introducer. The small tissue tunnel delivery of the sling allows minimal tissue disruption with immediate and excellent tip fixation into the obturator muscles, minimizing early sling slippage and failure. Bench testing indicates that the average pull-out force to remove the MiniArc from the obturator muscle is 5.5 lbs of force (4 times the normal pelvic floor pressures of 1.3 lbs).3, 20

However, our study has several limitations. It was not randomized for comparison to another conventional treatment for SUI to apply a more rigorous assessment. In addition, concomitant procedures were allowed in the study as per surgeon discretion. As a result the additional repairs may have impacted the effectiveness by perhaps altering urethral mobility and increasing the number of adverse events. Lastly there was no standardized tensioning technique for the MiniArc sling. Intraoperative cough testing to enhance continence efficacy was not uniformly used for tensioning because this hypothesis is controversial and not all investigators were familiar with this practice.21, 22, 23, 24 In our series less than half of patients underwent the procedure under general anesthesia. The intraoperative cough test was performed in 12.8% of cases. Although the study was not designed for this comparison, post hoc analysis did not demonstrate any efficacy differences between cases with general vs local anesthesia, or with or without intraoperative CST.

The study also has several strengths. It is a large, international, multicenter, prospective study design using up-to-date validated outcome measures. The use of subjective and objective outcome measures complies with National Institutes of Health recommendations for outcomes of urinary incontinence trials.25 In addition, the study is designed for followup of an international patient population representative of the condition of female SUI.

Conclusions 

Based on objective and subjective measures this 12-month prospective study demonstrates effective and safe treatment for SUI in women. The data showed excellent patient tolerability with minimal pain, early return to normal activity, low morbidity and a procedure profile that may allow for in-office placement. This multicenter prospective study shows encouraging results for the MiniArc sling as a first line treatment for female patients with SUI. Additional followup along with appropriately powered randomized comparative sling trials is warranted.