Obstetric Fistula

Fig. 15.1

Early vesicovaginal fistula with sloughing tissue draining out through the vagina (Reproduced with permission of Dr. Andrew Browning)

Vesicovaginal fistulae are the most common type of fistulae. The site of vesicovaginal fistula varies depending on the level of impaction of labour; if the mechanical conflict is at the level of the pelvic inlet, usually the fistula develops intra- or juxtacervical (Fig. 15.2). If the impaction occurs lower in the pelvis, usually the urethra is involved (Fig. 15.3), with severe compromise of the continence mechanisms in the long term [9]. Urethral involvement is usually a predictor for poor prognosis regarding the continence outcome [10]. It can occur in up to one third of obstetric fistula patients and about 5 % of the cases can present total urethral loss [8]. Ureteral lesions can lead to genito-urinary fistula as well; in a small number of cases, involvement of the distal ureter is followed by uretero-vaginal fistula, with continuous free drainage of urine into the vagina [11]. The fistulous tract can involve the uterus as well, though more rare and usually due to operative injury after caesarean section [12]. Usually, they manifest as vaginal urinary leakage or sometimes as cyclical haematuria.

Fig. 15.2

Large vesicovaginal fistula at the level of midvagina, juxtacervical (Reproduced with permission of Dr. Andrew Browning)

Fig. 15.3

Small circumferential urethrovaginal fistula (Reproduced with permission of Dr. Andrew Browning)

Obstetric trauma can involve the digestive tract as well. Most commonly, rectovaginal fistulae are the consequence of fetal impaction against the rectum, followed by ischaemic necrosis of the rectovaginal septum. A study revealed a prevalence of rectovaginal fistula of 1–8 % of obstetric fistula and 1–23 % for combined vesico-vaginal and recto-vaginal fistula; vesico-vaginal fistula accounted for the vast majority of obstetric fistula (over 80 %) [13]. The level of the fistula is important because involvement of anal sphincter can compromise the fecal or flatal continence mechanism.

In developing countries, genitourinary fistulae can be associated with upper renal tract damage, from mild hydronephrosis to non-functioning kidney requiring nephrectomy [11, 14]. The upper urinary tract damage is usually secondary to obstructive uropathy caused by the scarred ureter. Bladder stones form due to recurrent infections, reduced water intake followed by concentrated urine, insertion of foreign bodies in the vagina that act as promoters for calculogenesis [7]. The continuous leakage of urine irritates the perineal skin, causing dermatitis, excoriations, superficial infections or hyperkeratosis.

Regarding the extent of the changes of the reproductive tract, these vary from minimal or mild changes in anatomy (though this is usually the case with surgical fistula) to extensive damage, with vaginal injuries up to necrosis of the whole vagina, torn cervix and involvement of the uterus. Vaginoplasty is required in about one third of the cases [8].

The reproductive outcome is frequently severely affected. Amenorrhoea occurs in half of the patients with obstetric fistula [8]. The aetiology has been debated; amenorrhoea is probably due to the stress of delivery and presence of fistula leading to social isolation, low BMI, pituitary failure after obstetric haemorrhage or shock in long labour, Asherman’s syndrome or obstructed outflow and subsequent haematometra [7]. The pregnancy rate in a patient previously treated for fistula is as low as 19 % [15]; small series of pregnant patients delivering post fistula repair showed high recurrence rates of fistulae after vaginal delivery (27 %) and good outcomes with no recurrence after caesarean delivery [16, 17].

Apart from the local anatomical changes related to the pathophysiology of the disease, there are also associated conditions that manifest commonly in patients with obstetric fistula. Obstetric fistula is usually associated with social consequences and an important impact on mental health due to its circumstances of occurrence: young women from low resource country that laboured for days and usually lost the baby, divorced and living in isolation because of the debilitating condition [5, 18]. The vast majority of fistula patients present with mental health problems; one study revealed 97 % of the patients with obstetric fistulae screened positive for mental disorders [19]. Other associated conditions cited in the literature are malnutrition or limb contractures [7].

Assessment

History and clinical examination are the first tools for the assessment of a patient with suspected obstetric fistula. Continuous incontinence that started soon after a long labour, ending usually with stillbirth, in a low resource area is characteristic for obstetric fistula. The clinical examination will enable the diagnosis of a large fistula, its location and the extent of scarring. If the size of the fistula is small and it cannot be identified during naked eye examination, a dye test can be undertaken. Swabs are placed in the vagina, the bladder is catheterized and methylene blue is retrograde injected in the bladder. After a few minutes, the swabs are checked for leakage. After identifying and localizing the genitourinary fistula, the posterior vaginal wall is carefully checked for rectovaginal fistula. The integrity of anal sphincter should be ascertained as well. When a rectovaginal fistula is identified close to the external anal sphincter, reconstruction of the sphincter might be required. Sometimes, when the patient is symptomatic (flatus or stool incontinence) and there is no obvious fistula on examination, a small fistula can be diagnosed using instillation of dye per rectum with the aid of a Foley catheter.

Other more complex diagnostic tests (intravenous urography etc) may be required to establish a diagnosis of fistula. The fistula location and its relationship with the ureteral orifices and urethra are very important to plan management. Large fistulae may allow the identification and catheterization of ureteral orifices vaginally through the fistula tract. Cystoscopy is helpful for small fistulae or for fistulae located high, and are difficult to be accessed vaginally.

Classification of Fistulae

To date, there is no consensus regarding the classification of obstetric fistulae. A valid classification should follow criteria according to the impact on treatment outcome; there are no prospective studies to evaluate the prognosis of different categories of fistulae. Accordingly, all the present classifications of obstetric fistulae are of limited clinical use concerning the impact on treatment outcome [20].

The World Health Organization (WHO) proposed a classification of obstetric fistulae. This classification takes into account the difficulty of the surgical repair. Depending on the complexity, there are two types of fistulae [21]:

Simple fistulae, with good prognosis, that can be repaired by surgeons trained to treat uncomplicated fistula; they are usually single vesico-vaginal fistulae, under 4 cm diameter, without urethral or ureteral involvement, minimal vaginal scarring and tissue loss, no previous fistula surgery (Fig. 15.4).

Fig. 15.4

Medium vesicovaginal fistula at the level of midvagina. No urethral involvement is seen (Reproduced with permission of Dr. Andrew Browning)
Complicated fistula, requiring usually referral to be repaired only by specialist fistulae surgeons; they are multiple, recto-vaginal or combined vesico- and recto-vaginal, involvement of cervix, urethra, ureters draining into the vagina, vaginal tissue scarring, circumferential loss, recurrent fistulae after failed repairs (Fig. 15.5).

Fig. 15.5

Complicated fistula: double urethrovaginal and vesicovaginal, circumferential, with almost complete urethral loss (Reproduced with permission of Dr. Andrew Browning)

Other classification systems have also been proposed (Table 15.1).

Table 15.1

Classification systems of vesicovaginal fistulae of obstetric origin

Author (year)	Criteria considered	Classification/type
Waaldijk (1995) [22]	Urethral closing mechanism involvement	I. Urethral closing mechanism intact IIAa. Urethal closing mechanism affected, without (sub)total urethral involvement or circumferential defect IIAb. Without (sub)total urethral closing mechanism involvement, with circumferential defect IIBa. (Sub)total urethral involvement, without circumferential defect IIBb. (Sub)total urethral involvement and circumferential defect III. Ureteric involvement; other rare fistulae.
Browning (2004) [9]	Vaginal scarring Bladder volume	1. Simple – reduced vaginal scarring and normal bladder volume 2. Complex – severe vaginal scarring and/or reduced bladder volume; needs vaginoplasty or reconstruction
Goh (2004) [23]	Distance to urethral meatus Size of fistula Vaginal fibrosis/length/capacity	1. distal edge > 3.5 cm from external urethral meatus (EUM) 2. distal edge at 2.5–3.5 cm from EUM 3. distal edge 1.5–2.5 cm from EUM 4. distal edge <1.5 cm from EUM (a) size < 1.5 cm in maximal diameter (b) size 1.5–3 cm in maximal diameter (c) size > 3 cm in maximal diameter (i) minimal or absent vaginal/perifistular fibrosis, vaginal length > 6 cm, normal vaginal capacity (ii) moderate to severe fibrosis and/or reduced vaginal length and/or capacity (iii) special considerations (ureteric involvement, previous repair, circumferential fistula)

The prognostic factors associated with the outcome of the repair of obstetric fistula are the size of the fistula, concurrent lesions (rectovaginal fistula), degree of scarring around the fistula and involvement of the continence mechanism, including urethral damage [10, 24]. Apart from the factors already mentioned, the vaginal route of repair instead of abdominal route and duration of catheterization more than 14 days have been associated with increased risk of failure of the repair [25].

Management

When the management of obstetric fistula is considered, general aspects should be discussed (Table 15.2).

Table 15.2

General considerations in obstetric fistula management

Aspects of management of obstetric fistula
Timing of surgery
Abdominal/vaginal approach
Excision/conservation of fistulous tract
Tissue interposition:
Omental flap
Labial fat pad (Martius graft)
Peritoneal flap
Muscle flap
Concomitant procedures: stress urinary incontinence treatment, cystoplasty, vaginoplasty
Adjuvant treatment: postoperative drainage, anticholinergic therapy, antibiotics, HRT

The timing of repair is very important especially for obstetric fistula where the main aetiologic factor is extensive ischaemic necrosis; the time of surgical intervention should be carefully selected, due to the need for good quality tissue for the fistula to heal properly and to avoid recurrences. Usually, it is recommended to wait for at least 3–6 months from the causative injury. The waiting time should allow the necrotic tissue to separate from the normal one that will be used in the repair. Some authors advocate for immediate repair to avoid issues related to potential social rejection experienced by the patient. They claim, there is no significant difference between early repair and the classic repair performed after a few months. The cited study consisted of more than 1700 cases operated by an experienced fistula surgeon with roughly 95 % success rate for first attempt repair; however, the results might not be reproducible in other services with less experience in fistula treatment [26].

Early treatment of fistula could be achieved using continuous bladder drainage as sole therapy, especially for a small fistula that can be closed conservatively thus avoiding surgery. The bladder in this circumstance should be kept on free drainage for 3–4 weeks depending on the fistula size and extension of necrosis. The reported cure rates vary between 7 and 15 % [26, 27]. The success rates depend on the degree of atrophy secondary to menopause, size of the fistula or scarring extent. If closure does not occur after 4 weeks of continuous drainage, surgical treatment is usually needed [28].

A fistula can be repaired vaginally or abdominally. The route of repair depends on the accessibility to the surgical site and experience and skills of the surgeon. The abdominal route is used for vault fistula, juxtacervical or vesicouterine location [7]; ureteral injury, need for augmentation cystoplasty or concomitant abdominal pathology mandate abdominal approach as well. The abdominal approach is associated with morbidity related to laparotomy and requires cystotomy to access fistula site. When the exposure of the superior vagina is difficult, relaxing perineal incisions can be used to facilitate accessibility via the vaginal route (Fig. 15.6) [29]. A study suggested though that for particular indications, the abdominal approach might have better success rate than the vaginal route. Factors like extensive scarring, ureteric, trigonal or supratrigonal involvement, vesicouterine or vesicocervical location were followed by better outcomes of the repair when approached transabdominally; the relative risk of failure for vaginal approach was 1.41 [30].

Fig. 15.6

Relaxing perineal incision for juxtacervical ureterovaginal fistula with narrowed introitus (Reproduced with permission of Dr. Andrew Browning)

Regarding the excision of fistula tract, the opinions are divided. Some authors suggest excising it to reduce the recurrence rate, while others advocate a surgical repair without excising the fistula tract which would increase the fistula size and might require electrocautery to control bleeding, thus creating more nonviable tissue. The fistula tissue provides good support for the first layer of sutures. It is important to dissect and mobilize the bladder wall in order to avoid any tension on the repair site with suturing. Care should be taken to avoid ureteral injuries, during surgical repair. The ureters should be catheterized for all fistulae involving the trigone or located supratrigonally [7]. Because of the big size of obstetric fistulae, ureteral catheterization can often be undertaken through the fistula tract.

A flap of tissue or graft is occasionally used to repair a fistula involving urethra or urethrovesical junction to limit the scarring and avoid recurrence. The options are labial or bulbospongiosus fat pad (Martius graft), omental flap, peritoneal flap, gluteal or gracilis flap [29]. The use of tissue interposition techniques optimized the success rate of the procedure in a couple of studies [31, 32]. However, the use of vascular tissue flaps is still controversial. Authors with vast experience in fistula surgery report similar success rates independent of the graft use [33].

Most commonly, the graft used is harvested from the labia majora (Martius graft); a longitudinal incision is made along the labia majora, exposing the underlying fat. The flap of fat is then developed, conserving the posterior vascular pedicle to ensure viability. The flap is then rotated medially, reaching the fistula site through a tunnel created in front of the pubic ramus and behind the bulbospongiosus muscle. The flap is anchored at the site of fistula to promote healing. Some surgeons drain the labial site to prevent hematoma formation.

Important principles that should be followed for the surgical treatment of fistula include mobilization of the fistulous tract enough to enable closure without tension, water-tight closure of the injury site and careful postoperative management, providing adequate bladder drainage to promote wound healing [34].

When approaching the fistula vaginally, the patient is placed in lithotomy position and the entire fistula tract is exposed. The vaginal opening of the fistula is incised circumferentially and the fistula mobilized so that the fistula margins can be brought together without tension to close the communication between urinary and genital tract. After mobilization of the fistulous tract and the surrounding tissue, the edges of the fistula are closed with absorbable material, either interrupted or continuous depending on the surgeon’s preference. The second layer of sutures in the bladder wall could be considered in the absence of extensive scarring. It is very important to ensure that the suture in the bladder wall is water-tight. Therefore, 100–250 ml of diluted methylene blue or indigo carmine dye are instilled in the bladder and the suture line is checked for leakage. If leakage occurs, revision of the suture line is considered until it is water-tight. The instilled fluid should not exceed 250 ml to avoid bladder over-distension and break-down of the fresh repair. The vaginal epithelium is closed with running absorbable sutures.

Urinary Incontinence After Repair

Persistent urine loss after fistula repair can have multiple causes. Recurrence of fistula should be excluded first: the patient should be examined to rule out a recurrence and if transurethral incontinence is diagnosed, other causes of incontinence should be considered. Frequently, urinary incontinence occurs after surgical treatment of fistula, either due to loss of the sphincteric mechanism of vesicourethral junction and urethral injury or reduced bladder capacity and urgency urinary incontinence. Browning assessed the risk of urinary incontinence after fistula closure on 318 patients and divided them into two groups: simple fistulae with minimal scarring and good bladder volume and complex fistulae with severe scarring and/or reduced bladder volume. The risk of incontinence after fistula repair was 50 % in the first group and 100 % in the complex fistulae group [9].

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