Obstetric Fistula: A Preventable Tragedy

Suellen Miller, CNM, PhD; Felicia Lester, MPH, MS; Monique Webster, MPH; Beth Cowan, MD

Disclosures

J Midwifery Womens Health. 2005;50(4):286-294. 

In This Article

Etiologies of Vesicovaginal and Rectovaginal Fistulas

In the United States and the United Kingdom, 70% of fistulas are a result of pelvic surgery.[11] Other nonobstetric etiologies of fistula include malignancies, radiation therapy, infection, and trauma. Based on a review by Cron,[5] data from the United States and the United Kingdom indicate that fistula is rare in developed countries and almost never results from obstructed or prolonged labor. A study from UCLA cited by Cron found only 43 cases of fistula over 20 years, with only 2 cases due to obstetric causes; the other cases were due to surgical complications and radiation treatment.[5] Also cited in Cron, a UK study found 166 cases over 18 years, with only 21 of these due to obstetric causes.[5] By contrast, 1 region in Nigeria reported 377 cases over 16 years, with 369 of these due to obstructed labor.[5]

In developing countries, 90% of fistulas are caused by obstructed labor.[12] One study at the Addis Ababa fistula hospital in Ethiopia noted an average labor duration of 3.9 days in patients who subsequently presented with a fistula.[13] During prolonged/obstructed labor, the soft tissue of the vagina is trapped between the fetal head and the bony pelvis. If the compression is not relieved, the tissue will become necrotic. Usually between 3 and 10 days postpartum, this necrotic tissue sloughs off and a fistula develops between the bladder and the vagina (vesicovaginal) or the rectum and the vagina (rectovaginal).[9] Rectovaginal fistulas occur far less frequently, comprising 10% of fistulas.[10] Lack of skilled attendance at birth, lack of emergency obstetric care, and lack of transportation to maternity facilities contribute to the high rates of prolonged and obstructed labor and resultant fistula in developing countries.

Direct and indirect factors predisposing to prolonged and obstructed labor include malpresentation and cephalopelvic disproportion. Malpresentation can occur in any woman, but it is more frequent in grand multiparas with lax uterine muscles.

Young girls and women (aged 10 to 19) suffer disproportionately from fistula. Although more women aged 20 to 45 give birth than women in the age group 10 to 19, close to 50% of all fistula cases occur in women aged 10 to 19. In Jos, Nigeria, 45.8% of the fistula cases occurred in primiparous women.[14] In studies from Nigeria and Ethiopia, adolescents constitute a disproportionate number of fistula cases.[13,15,16,17,18] In Ethiopia, it is estimated that 3 in 1000 parturients develop fistula, the majority of whom are under 20.[13,19] A Nigerian case-control study of 241 cases of fistula and 148 controls found that 27% occurred in women 15 years old or younger, and 59% occurred in women 18 years old or younger. Earlier age at marriage was also significantly associated with risk of fistula (P < .01).[15]

The association between young age and fistula is most likely secondary to the increased incidence of cephalopelvic disproportion in younger women. Neither young age itself, early marriage, nor low parity alone are likely independent risk factors for cephalopelvic disproportion and subsequent obstructed labor and fistula, but they serve as proxies for pelvic immaturity. Pelvic bone maturity is a combination of the size and diameter of the pelvic bones as well as the diameter of the pelvic opening. Moerman,[20] in a radiologic study of 90 early and middle adolescent girls in the United States, found that the actual size of the birth canal was smaller the first 3 years after menarche than at age 18, and that the dimensions of the inlet, midplane, and outlet of the birth canal of these young adolescent girls were contracted. According to Treffers,[21] the pelvic bones of adolescents less than16 years of age may be immature, particularly in the very poorest developing countries, where onset of puberty is late. This delay in pelvic maturity may correlate with the noted relationship between younger age and more frequent incidence of obstructed labor.

Zlatnik and Burmeister[22] first defined gynecologic age as the difference between chronologic age minus age at menarche; Scholl et al.[23] defined "low" gynecologic age as less than 2 years between chronologic age and menarche. Miller and Lester[24] posited that low gynecologic age might contribute to obstructed labor resulting in fistula. Although decreasing in developing countries, the age at menarche remains higher than seen in developed countries.[25,26,27] Higher age at menarche, together with younger age at marriage, means that young, first-time mothers in developing countries are likely to have a lower gynecologic age than adolescent mothers in developed countries, even at the same chronologic age. Countries where the mean age at marriage is age 15 or below, such as Nigeria, Ethiopia, and Bangladesh, also exhibit high rates of fistula.[10,24]

Other factors contributing to cephalopelvic disproportion and therefore, prolonged/obstructed labor among girls in developing countries, is chronic undernutrition and malnutrition, contributing to their being less likely to have reached adult size by menarche.[24] In a study of fistula patients in Ethiopia, short height (less than 150 cm) imparted a relative risk of fistula of 1.83.[15] Early malnutrition with resultant underdeveloped bone structure may have serious implications for women whose first pregnancy occurs soon after menarche.[28] The frequency of underdeveloped pelvis and short height secondary to malnutrition further contributes to the high rates of obstructed and prolonged labor in some developing countries.[29]

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