During pregnancy the soft tissue of the birth canal undergoes considerable changes under the impact of hormonal transformation so they can withstand considerable pressure and distension during childbirth. Sometimes bruises and cracks arise in external genitals, perineum, vagina and cervix. These superficial lesions are asymptomatic and heal spontaneously over the first days after childbirth. When labor gets complicated, there can be lacerations of external genitals, perineum, vagina and cervix, edema can develop. On the whole, trauma is noted in every fifth parturient woman. Sometimes there are life threatening lesions that can end in the parturient woman's death or long-term incapacitation or disability (rupture of uterus, bladder and rectum, inversion of uterus, genitourinary and intestinogenital fistulas, lesions of pubic symphyses, injury of pubic bones). In about 20% of puerperas the trauma of soft tissues in the birth canal is accompanied by infection.
Epidemiology. Tears of soft tissues in the birth canal often occur in primiparous women, and uterine rupture - in multiparous women mostly. There are no accurate data on vulvar lesions. Cervical tears occur in 6-15% of childbirths, third and fourth degree perineal tears occur at a rate of 3:10,000, uterine rupture - at a rate of 1:10,000.
Causes of obstetric trauma:
• mechanical (excessive distension of tissue);
• structural (histopathological alterations in tissue);
• mixed (mechanical and histopathological).
Obstetric trauma can be spontaneous or forced, brought about by obstetric intervention.
Etiology. Causes of obstetric trauma of soft tissues in the birth canal, cervix and body of uterus are similar; they are as follows: