Maternal Pelvic Floor Trauma

 
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Maternal pelvic floor trauma is when there is damage to the muscles, nerves, or other tissues of the pelvic floor which affects their functioning and leads to weakness of the pelvic floor. Forms of trauma can be divided into:

  • Mechanical injury. Injury resulting from the head of the fetus compressing, tearing or forcibly moving the muscle/connective tissues of the pelvic floor. Such injuries may also be caused by the forceps when used to perform an operative vaginal delivery.

  • Nerve injury. The pudendal nerve is the main nerve that supplies the pelvic floor. It can be compressed and damaged by the fetal head, a big baby, prolonged second stage of labor, and/or instrumental (particularly forceps) delivery.

  • Indirect injury. During pregnancy there are numerous hormonal and physiological changes that take place. These changes include the pelvic floor relaxing at the same time as the load put on the woman’s body increases due to the weight of the baby, the water around the baby, etc. These changes will occur regardless of the final outcome of pregnancy and cannot be avoided

Vaginal delivery (spontaneous or assisted) is the single risk factor most likely to cause maternal pelvic floor trauma. The first delivery tends to be associated with the greatest amount of damage. However, some women can identify the specific pregnancy or delivery that seemed to have the greatest adverse impact on their pelvic floor function.

Common risk factors for maternal pelvic floor damage include:

  • Vaginal birth (especially the first vaginal birth)

  • Pregnancy

  • Advanced maternal age

  • Assisted delivery with forceps

  • Raised Body Mass Index (BMI)

  • Big baby

  • Prolonged second stage of labor (i.e. when actively pushing)

  • Deep and extensive vaginal wall/perineal/sphincter tears

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