0022-5347 /88/1391-0727$02.00/0 Vol. 139, April Printed in U.S.A. THE JOURNAL OF UROLOGY Copyright © 1988 by The Williams & Wilkins Co. STRESS INCONTINENCE: CLASSIFICATION AND SURGICAL APPROACH JERRY G. BLAIVAS AND CARL A. OLSSON From the Department of Urology, Columbia University and J. Bentley Squire Urologic Clinic, and The Presbyterian Hospital in the City of New York, New York, New York ABSTRACT We present a modified classification for stress urinary incontinence based on the nature of vesical neck descent and the integrity of the intrinsic sphinteric mechanism. Surgical treatment was undertaken in 72 patients with this classification. With a minimum followup of 18 months there was a 94 per cent cure rate with respect to stress incontinence. However, in 14 patients significant frequency and urgency developed, which persisted for at least 6 months postoperatively. Of these patients 13 had undergone a pubovaginal sling procedure, 3 of whom had refractory symptoms, including urge incontinence, which resulted in augmentation cystoplasty in 2 and supravesical urinary diversion in 1. (J. Ural., 139: 727-731, 1988) The precise anatomical and physiological mechanisms involved in the maintenance of urinary continence are poorly understood. Nevertheless, certain basic observations have withstood the test of time and the pursuits of many investigators. Since the classical work of Enhorning1 and Hodgkinson,2· 3 it has been well documented that urinary continence is achieved because maximum urethral pressure remains greater than intravesical pressure during bladder filling and that increases in intra-abdominal pressure are transmitted approximately equally to the bladder and proximal urethra. 4 - 7 It has been further suggested that, to a large extent, the vesical neck and proximal urethra are normally "intra-abdominal" structures, that is they lie above a well supported pelvic diaphragm and they are positioned in such a way to promote the equal distribution of forces to the bladder and urethra during increases in intra-abdominal pressure. It follows then that stress incontinence may occur by 2 mechanisms. In the first and by far the most common condition the vesical neck and proximal urethra retain their basic sphincteric function. Resting urethral pressure is much greater than intravesical pressure but during sudden increases in intraabdominal pressure transmission becomes unequal, intravesical pressure exceeds urethral pressure and leakage occurs. This unequal transmission of pressure occurs because there is a loss of support to the vesical neck such that during stress it descends to a position that is "outside" of the abdominal cavity. In practical terms this condition may be thought of as a "hernia" of the vesical neck and operations that are designed to "repair the hernia" generally are successful, with reported cure rates in excess of 90 per cent.8 - 17 In the second condition the urethra no longer functions as a sphincter. Urethral pressure often is low and urinary leakage occurs with the slightest provocation. In other instances the urethra has become fibrotic, rigid and deformed, usually from multiple prior operations. In either case since the incontinence is not owing to abnormalities of descent, there is no "hernia" to repair and the usual urethropexy operations have a failure rate of at least 15 to 20 per cent. 17- 19 On the other hand, surgical repair with a pubovaginal sling has been effective in 95 to 98 per cent of these patients. 20 • 21 This type of incontinence is almost always owing to multiple failed operations for stress incontinence, myelodysplasia or other neurological lesions involving sympathetic outflow. 20 - 23 From these observations it is obvious that a clear understanding of the underlying pathophysiology is of the utmost imporAccepted for publication July 17, 1987. 727 tance for the proper selection of the most appropriate surgical repair. We present our experience with a modified classification system and the results of surgical treatment based on that system. MATERIALS AND METHODS We analyzed retrospectively 181 consecutive women with a clinical and urodynamic diagnosis of stress urinary incontinence seen between January 1983 and July 1985. Each patient had been referred by a urologist or gynecologist for videourodynamic studies. A detailed history was obtained from each patient and each was examined in the dorsal lithotomy position with a full bladder. If incontinence was not demonstrated with cough or Valsalva's maneuver, the patient was re-examined in the sitting or standing position. Videourodynamic studies were performed as described previously. 24 Stress incontinence was defined as the involuntary loss of urine per urethram that occurred when, in the absence of a detrusor contraction, intravesical pressure exceeded urethral pressure. 25 Detrusor instability was defined as a sudden, involuntary increase in detrusor pressure of any magnitude that occurred during bladder filling at a rate consistent with medium fill cystometry. During cystometry the patient was instructed not to void or try to suppress micturition but, rather, to report the sensations to the examiner. It should be noted that this definition of instability differs from that recommended by the International Continence Society. 26 The patients were classified further according to a scheme that was modified from Green, 26 McGuire and associates, 11 and Blaivas. 27 Type O (fig. 1). There is a typical history of stress incontinence but no urinary leakage is demonstrated during the clinical and urodynamic investigation. At videourodynamic study the vesical neck and proximal urethra are closed at rest and situated at or above the superior margin of the symphysis pubis. During stress the vesical neck and proximal urethra descend and open, assuming an anatomical configuration similar to that seen in types I and II to be described. Failure to demonstrate incontinence probably is owing to momentary voluntary contraction of the external urethral sphincter during the examination. Type I (fig. 2). The vesical neck is closed at rest and situated at or above the inferior margin of the symphysis. During stress the vesical neck and proximal urethra open and descend less than 2 cm., and urinary incontinence is apparent during periods of increased intra-abdominal pressure. There is little or no cystocele. 728 BLAIVAS AND OLSSON A B FJG. 1. Type O stress incontinence. A, at rest base of bladder is flat and situated above superior margin of symphysis pubis (solid line). B, during cough there is rotational descent of urethra and bladder base. Vesical neck opens but urinary leakage is not visualized. A B FIG. 2. Type I stress incontinence. A, at rest base of bladder is flat and situated at superior margin of symphysis pubis (solid line). B, during Valsalva's maneuver bladder base descends approximately 1 cm., vesical neck and urethra open, and leakage occurs. A B FIG. 3. Type IIA stress incontinence. A, during bladder filling base of bladder is flat and situated at level of superior margin of symphysis pubis. B, during cough there are marked descent and rotation of bladder and urethra well below inferior margin of pubis. Urethra opens widely and leakage occurs. Type IIA (fig. 3). The vesical neck is closed at rest and situated above the inferior margin of the symphysis pubis. During stress the vesical neck and proximal urethra open and descend more than 2 cm., and there is an obvious cystourethrocele. Urinary incontinence is apparent during periods of increased intra-abdominal pressure. Type JIB (fig. 4). The vesical neck is closed at rest and situated below the inferior margin of the symphysis pubis. During stress there may or may not be further descent but the proximal urethra opens and incontinence ensues. Type III (fig. 5). The hallmark of type III stress urinary incontinence is that the vesical neck and proximal urethra are open at rest in the absence of a detrusor contraction. The proximal urethra no longer functions as a sphincter. In most instances there is obvious urinary leakage that may be gravitational in nature or associated with minimal increases in intravesical pressure. However, if the urethra is fibrotic and narrowed, incontinence may only be demonstrated with large increases in intra-abdominal pressure. The type of anti-incontinence surgery performed was determined according to the following rationale. Initially in this series either a Marshall-Marchetti-Krantz or Burch procedure was recommended for patients with types Oto HA incontinence. However, in the subsequent 2 years a modified Pereyra operation, as described by Raz, 14 was the procedure of choice. The modified Pereyra operation also was chosen for patients with type IIB incontinence but in these patients it was considered particularly important to ensure adequate mobilization of the vesical neck and proximal urethra, freeing these structures from their vaginal attachments. Creation of a pubovaginal sling was the treatment of choice for patients with type III incontinence unless they had not undergone previous anti-incontinence procedures, in which case an inflatable sphincter prosthesis was recommended. RESULTS The 181 female patients were from 12 to 86 years old, with a mean age of 55 years. Of the women 58 had undergone a total 729 STRESS INCONTINENCE: CLASSIFICATION AND SURGICAL APPROACH A FIG. 4. Type IIB stress incontinence. A, during filling base of bladder is flat but it is situated below level of inferior margin of pubis. B, during cough there are further descent and opening of urethra with visible leakage. Type of incontinence compared to symptoms (urinary frequency, urgency and/or urge incontinence) and prior surgery TABLE 1. Symptoms Reproduced Total No. by Operations/No. Incontinence Detrusor Previous Pts. Who Had Type No. Pts. (%) Instability/ Hysterectomy Undergone Prior Total No. Anti-Incontinence Pts. With Operations Symptoms 0 I II III Totals 21 30 92 38 181 (11) (17) (51) (21) (100) TABLE FIG. 5. Type III stress incontinence. During bladder filling base of bladder is just below superior margin of symphysis pubis. Indentation on either side of vesical neck is from 2 prior Marshall-MarchettiKrantz operations. Proximal urethra and vesical neck are open despite intravesical pressure of only 6 cm. water. of 117 previous anti-incontinence operations and 41 hysterectomies. In 31 patients hysterectomy was performed at the same time as an anti-incontinence operation and in 11 it was an isolated procedure. Over-all, type O incontinence was found in 21 patients (11 per cent), type I in 30 (17 per cent), type II in 92 (51 per cent) and type III in 38 (21 per cent). Of the patients 96 complained of urinary frequency, urgency and urge incontinence, 35 of whom had detrusor instability. Two patients had concomitant vesicovaginal fistulas and 3 had urethral diverticula. A further breakdown of these data is presented in table 1. Urodynamic data are presented in table 2. Over-all, detrusor instability was seen in 50 women (28 per cent) but in 11 of them it was asymptomatic. There was no correlation between the type of incontinence and the presence of instability. Moreover, only 36 per cent of the patients who complained of urinary frequency, urgency or urge incontinence had demonstrable detrusor instability. A total of 152 women (84 per cent) were able to void with a voluntary detrusor contraction during the videourodynamic evaluation. Corrective surgery was performed in 72 patients (table 3). With a minimum followup of 18 months (range 18 months to 4 years), stress incontinence was cured in 68 patients (94 per cent). Three patients were asymptomatic for 1 to 2 months after undergoing a modified Pereyra operation for type IIA stress incontinence but, subsequently, stress incontinence recurred (type III in 2 patients and type IIA in 1). In 1 patient type II stress incontinence recurred 6 months after a Burch colposuspension. Of the 4 surgical failures 3 subsequently 2/11 7/14 19/55 7/16 35/96 3 0 6 3/3 36/26 78/29 117 /58 22 11 42 2. Urodynamic data No. Pts. Who Voided With Voluntary Incontinence Cystometric Maximum Detrusor Detrusor Detrusor Type (No. Capacity Pressure During Instability Contractions Voiding (mean) pts.) (mean) During Videourodynamic Study 0 (21) I (30) II (92) II (38) 100-600 150-750 100-800 75-750 (365) (410) (400) (350) 7 9 23 11 21 26 75 30 21-90 15-66 12-90 6-39 (37) (25) (30) (24) underwent a pubovaginal sling procedure and all are now completely continent with a minimum followup of 6 months. However, the second operations are not included in the data from this study because of the short followup. In 14 patients clinically significant frequency, urgency and urge incontinence developed, which persisted for more than 6 months postoperatively. Of these patients 13 had detrusor instability and only 5 of them had had this condition preoperatively. Thus, there was no correlation between the presence of preoperative detrusor instability and postoperative symptoms. Of the 8 patients in whom detrusor instability developed postoperatively 7 had undergone a pubovaginal sling procedure for type III stress incontinence and 1 had undergone a MarshallMarchetti-Krantz operation for type IIA. All of these patients had objective videourodynamic documentation of urethral obstruction at the site of surgical repair. Three patients, all of whom had undergone a pubovaginal sling procedure, failed all attempts at conservative treatment of instability (manifest as urge incontinence) and 2 underwent augmentation cystoplasty. These latter 2 patients are completely continent, although they require intermittent self-catheterization. The third patient elected supravesical urinary diversion. The other 11 patients in this group are no longer incontinent but they void on the average of every 2 hours during the day. None of these patients desires further treatment. 730 BLAIVAS AND OLSSON TABLE Incontinence Type 0 I II III Totals 3. Surgical treatment MarshallMarchettiKrantz or Burch Total No. Pts. Modified Pereyra 12 13 27 20 7 7 13 13 72 27 22 4 5 Anteroposterior Repair Pubovaginal Sling Sphincter Prosthesis 1 I 1 1 19 1 21 I * Repair of urethral diverticulum. t Repair of vesicovaginal fistula. A woman with type II stress incontinence and asymptomatic detrusor instability preoperatively suffered frequency, urgency and urge incontinence postoperatively, although detrusor instability was not demonstrated. Repeat urinalysis and culture were normal, cystourethroscopy was unremarkable and videourodynamic studies revealed unobstructed micturition. DISCUSSION The original impetus for classifying stress urinary incontinence was provided by the observations of Jeffcoate and Roberts, 28 and Hodgkinson 2 that the anatomical relationship between the urethra and bladder base was important for the maintenance of continence. Subsequently, Green described 2 distinct types of stress incontinence: type I was characterized by loss of the posterior urethrovesical angle and in type II, not only was this angle lost, but there was posterior, inferior and rotational descent of the the bladder base and urethra. 26 The anatomy of type II corresponded to that of a cystourethrocele. The importance of this classification was obvious; patients with type I anatomy had an initial cure rate of 90 per cent after simple vaginal operations (anterior colporrhaphy), whereas the cure rate in type II was only 50 per cent. 26 • 29- 31 Furthermore, when a retropubic suspension operation (Marshall-MarchettiKrantz) was performed for type II anatomy the cure rate was in excess of 90 per cent. Subsequent reports have documented the efficacy of retropubic suspensions.B-17 McGuire and associates modified Green's original classification to include type III stress incontinence, which was characterized by a proximal urethra that no longer functioned as a sphincter. 11 •12 Urethral pressure was decreased markedly and the vesical neck was open at rest. Although the posterior urethrovesical angle and the urethral inclination were not assessed, from a clinical standpoint types I and II of McGuire and associates were identical to those of Green. In their series the surgical approach was dictated by the type of incontinence. All 69 patients with type I underwent anterior colporrhaphy. The over-all cure rate was 86 per cent. Of those 176 patients with type II incontinence an anterior urethropexy (MarshallMarchetti-Krantz or Burch) was curative in 172 (98 per cent). Of the 102 patients with type III 98 were continent after creation of a pubovaginal sling (98 per cent). Stamey recommended a much simpler approach. 17 He suggested that "surgically curable urinary incontinence in females should be defined literally as the visual demonstration of a simultaneous loss of urine with the rise and fall of abdominal pressure during coughing. Without this demonstration, no patient should be operated upon for stress urinary incontinence." He further classified the incontinence according to severity. Grade I was leakage only with severe stress, such as coughing or laughing, grade 2 was leakage with· walking, running and so forth, and grade 3 was total urinary incontinence. Using these criteria he reported a 91 per cent success rate in 203 patients treated by endoscopic suspension of the vesical neck. 17 Of the patients 188 had undergone previous anti-incontinence surgery and 41 had total incontinence. The cure rate in this latter group was 78 per cent. We have modified the most recent classification to include types 0, IIA and IIB. In type O the patient complains of stress incontinence but it is not objectively demonstrated. Nevertheless, the anatomical substrate for stress incontinence is seen at fluoroscopy when during stress the vesical neck opens and descends. According to Stamey's thesis, these patients would not be candidates for surgical repair. All 12 patients in our series with type O stress incontinence were cured by surgery (retropubic suspension in 4, modified Pererya procedure in 7 and anterior repair in 1). Type IIA corresponds to Green's type 2. Type IIB is characterized by a vesical neck and proximal urethra that are fixed at or below the level of the inferior border of the symphysis pubis. In our series there were 27 patients who underwent surgical treatment for types IIA and IIB incontinence and all but 1 were cured of the stress incontinence. In the patients with type IIB incontinence care was taken to free the proximal urethra and vesical neck completely from the vaginal wall so that they could be suspended without tension. The preoperative recognition of type III stress incontinence is of the utmost importance because, in our opinion, the usual urethropexy operations have an unacceptably high failure rate. The treatment of choice is a pubovaginal sling except for those few patients who have not had prior surgery. In these latter cases a sphincter prosthesis theoretically is ideal. Unfortunately, there are only a few published series to support these contentions. However, some observations have been confirmed. Type III stress incontinence is seen in approximately 75 per cent of the patients who have failed 2 or more urethropexy operations. 20• 23 In several series the failure rate for those conditions most likely to represent type III stress incontinence (grade 3 according to Stamey's classification) ranged from 15 to 22 per cent. 17' 19 In our previous series20 and that of McGuire and associates 11 the surgical cure rate of type III stress incontinence treated by a pubovaginal sling was greater than 90 per cent. Moreover, none of our patients has had recurrent stress incontinence. Rather, 3 patients had refractory urge incontinence that was cured by augmentation cystoplasty in 2. Four other patients had persistent problems with urinary frequency, all of whom had bladder outlet obstruction at the level of the sling. Thus, it appears that the major disadvantage of the pubovaginal sling is the propensity to cause urethral obstruction. Although the sphincter prosthesis theoretically is ideal for the treatment of type III stress incontinence, in practice the complication rate after multiple previous operations precludes this modality of treatment for most patients. In the series of Light and Scott 39 women with 2.2 prior incontinence operations underwent implantation of a sphincter prosthesis. 32 In 4 patients (10 per cent) the prosthesis was removed because of infection or erosion and 14 (36 per cent) required 21 additional operations because of surgical complications. Despite these multiple operations and revisions, the final failure rate was still 15 per cent with a followup of 3 to 78 months (mean 38 months). Of further interest is the fact that in none of the reported series was preoperative detrusor instability a significant risk factor mitigating against successful surgery, provided that stress incontinence was demonstrated objectively. Our data are STRESS INCONTINENCE: CLASSIFICATION AND SURGICAL APPROACH in complete accord with these findings. In conclusion, we believe that an accurate assessment of the underlying pathophysiology is essential for successful treatment of stress urinary incontinence and that the presence of detrusor instability and/ or urinary frequency and urgency does not preclude a successful outcome. REFERENCES 1. Enhorning, G.: Simultaneous recording of intravesical and intraurethral pressure. A study on urethral closure in normal and stress incontinent women. Acta Chir. Scand., suppl. 276, p. 1, 1961. 2. Hodgkinson, C. P.: Relationships of the female urethra and bladder in urinary stress incontinence. Amer. J. Obst. Gynec., 65: 560, 1953. 3. Hodgkinson, G. P.: Direct urethrocystometry. Amer. J. Obst. Gynec., 79: 648, 1960. 4. Constantinou, C. and Govan, D. E.: Contribution and timing of transmitted and generated pressure components in the female urethra. In: Female Incontinence. Edited by N. R. 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