Lower Urinary Tract Fistulas
Zhou Jianhong
HISTORIC PERSPECTIVES
The earliest evidence of a vesicovaginal fistula was reported by
Derry (1935)in the mummified remains of Queen Henhenit，one of the of
King Mentuhotep II of Egypt （11th Dynasty，circa 2050 b.c）. In his
dissection of the mummy at the Cairo School of Medicine in 1923，Derry
noted a large vesicovaginal fistula in the presence of a severely contracted
pelvis；he concluded that the presence of a severely contracted obstructed
labor.
Zacharin (1988) states that de Mercado first used the term fistula
instead of the usual term rupture.
The discovery of antibiotics and the development of general and
regional anesthesia contributed significantly to the surgical treatment of
vesicovaginal fistulas in the twentieth century.
EPIDEMIOLOGY AND ETIOLOGY
Wounded tissue undergoes four phases of healing：coagulation,
inflammation, fibroplasia, and remodeling. Between the first and third
weeks, healing is most vulnerable to hypoxia, ischemia, malnutrition,
radiation, and chemotherapy, so this is the time when most fistulas
present.
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Obstetric Fistulas
The vast majority of vesicovaginal fistulas that occur in developing
countries are caused by obstetric trauma. Of 377 cases reported by
Lawson (1989) from Ibadan, Nigeria, 369(97.9%) were obstetric and 343
were a consequence of obstructed labor.
Obstructed labor remains the most important cause of vesicovaginal
fistulas in developing countries. Absent or untrained birth attendants,
reduced pelvic dimensions (caused by early childbearing, chronic disease,
malnutrition, and rickets), uncorrected inefficient uterine action,
malpresentations, hydrocephalus, and introital stenosis secondary to tribal
circumcision all contribute to obstructed labor. Prolonged impaction of
the presenting fetal part against a distended edmatous bladder eventually
leads to pressure necrosis and fistula formation. Fistulas may be caused
by trauma from forceps, instruments used to dismember and deliver
stillborn infants, and surgical abortion.
Vesicovaginal fistulas can follow cesarean delivery of peripatum
hysterectomy (particularly in the presence of distorted anatomy, e.g,
massive fibroids), hemorrhage, and surgical inexperience.
Gynecologic Fistulas
In developed countries, abdominal surgery, particularly total
abdominal hysterectomy, is the major cause of genitourinary fistulas.
Fistulas related to surgery performed by obstetrician-gynecologists
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account for approximately 80% of all urogenital fistulas. The remaining
20% is divided among urologists and colorectal, vascular, and general
surgeons.
Predisposing risk factors for vesicovaginal fistula include a history
of pelvic irradiation, cesarean section, endometriosis, previous pelvic
surgery or pelvic inflammatory disease, diabetes mellitus, concurrent
infection, vasculopathy, and tobacco use. The risk of ureteral injury was
greater with laparoscopic procedures than with open procedures.
PRESENTATION AND INVESTIGATION
Patients with genitourinary fistulas present in many ways. Gross
hematuria or abnormal intraperitoneal fluid accumulation (urinoma)
noted during or after surgery should raise suspicion of an unrecognized
urinary tract injury and dictates immediate investigation. Post-surgical
fistulas usually present 7 to 21 days after surgery. Most patients have
urinary incontinence or persistent vaginal discharge. Other signs and
symptoms include unexplained fever; hematuria; recurrent cystitis or
pyelonephritis; vaginal, suprapubic, of flank pain; and abnormal urinary
stream.
The initial evaluation of all patients with symptoms of genitourinary
fistulas starts with a complete physical examination. A thorough
speculum examination of the vagina may reveal the source of fluid, which
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can then be collected; measurement of its urea concentration may identify
it as urine. Urine should be examined microscopically and cultured, and
appropriate treatment should be instituted for infection. Urethrovaginal
fistulas are usually easily diagnosed on physical examination. Further
office evaluation, cystourethroscopy, and intravenous urogram permit the
physician to localize the fistula, determine adequacy of renal function,
and exclude or identify other types of urinary tract injury.
Office testing is often able to distinguish between fistulas involving
the bladder or ureters. Instillation of methylene blue or sterile milk into
the bladder stains vaginal swabs or tampons in the presence of a
vesicovaginal swabs or tampons in the presence of a vesicovaginal fistula.
Unstained, but wet, swabs may indicate a ureterovaginal fistula.
Intravenous indigo carmine can be given and the tampon observed for
blue staining. Use of intravenous methylene blue must be chosen with
caution because of the risk of methemoglobinemia, a rare but serious
complication.
Radiologic imaging is recommended in most cases and usually
includes intravenous urography or cystoscopic retrograde urography.
Renal ultrasound may miss up to 20% of ureteral injuries. A Tratner
catheter may be useful in cases of suspected urethrovaginal fistula.
Cystourethroscopy is indicated in most cases. The size, site, and
number of fistulas and condition of local tissues are carefully noted. Key
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observations include the fistula’s proximity to the bladder neck, urethral
sphincter, and ureteral orifices as well as the presence of tissue edema,
slough, infection, induration, scarring, and fixity to bone.
CONSERVATIVE MANAGEMENT
Various conservative or minimally invasive therapies are available
for vesicovaginal and ureterovaginal fistulas. However, the true viability
and success of these treatment modalities remain to be determined.
Various conservative or minimally invasive therapies are available for
vesicovaginal and ureterovaginal fistulas.
Previously, it bas been
empirically stated that fistulas diagnosed within 7 days of occurrence,
that are less than 1 cm in diameter and unrelated to malignancy or
radiation, may spontaneously resolve with up to 4 weeks of continuous
drainage in anywhere from 12% to 80% of cases.
Once the diagnosis of a ureterovaginal fistula is confirmed,
recommended initial management is ureteral stenting (de Baere et al,
1995; Selzman et al., 1995). Stenting is more successful when performed
sooner rather than later.
If a stent is placed successfully, it should be left in for 6 to 8 weeks.
If the fistula has not healed at 6 weeks, a repeat examination may be
performed at 8 weeks, with preparation to proceed with preparation to
proceed with surgical repair, if the fistula has still not healed.
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TIMING OF SURGICAL REPAIR
Ideally, early repair of vesicovaginal fistulas requires diagnosis of
the fistula within 72 hours of the injury. During this period, the tissues are
often supple and normal in appearance and can be dissected and closed
without tension. Early repair can be performed either transvaginally or
transabdominally. Fistulas identified, at this time, are complicated by
infection and induration, making closure difficult. Once these changes
have occurred, a 3-to 6-month waiting period bas been recommended,
allowing for maturity of the fistula. During this waiting period, vaginal
examination should be performed every 3 to 4 weeks to monitor the
inflammation and infection.
PRESURGICAL MANAGEMENT
Once the decision has been made to proceed with surgical
correction of the fistula, patients waiting surgical repair need considerable
psychological support. Leakage from small fistulas may be controlled by
frequent voiding and the use of tampons, perineal pads, or
silica-impregnated incontinence pants. A vaginal diaphragm with a
watertight attachment to a urinary catheter can collect urine from larger
fistulas in a leg bag. Perineal care is important and makes the patient
more comfortable and tolerant of delayed closure. Before surgical repair,
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vaginal or oral estrogen should be given to women who are surgically or
naturally postmenopausal to improve urogenital tissue integrity. In
malnourished patients a high-protein diet, Vitamin, and trace elements
supplements, and correction of anemia are essential before surgical repair,
Surgery should not be performed during menstruation because of the
increased tissue vascularity at that time.
SURGICAL REPAIR
Vaginal Repair of Vesicovaginal Fistula
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