Research by Wong and colleagues published by the American College of Obstetricians and Gynecologists reported on the incidence of postpartum lumbosacral and lower extremity injuries. Of 6048 women who were interviewed, 56 had a new injury, confirmed by physiatrist evaluation. The researchers noted that "Women with nerve injury spend more time pushing in the semi-Fowler-lithotomy position than women without injury." The researchers also noted that women who were nulliparous (had not given birth previously who had an assisted (forceps or vacuum) birth, or who experienced a prolonged second stage of labor, were at increased risk of nerve injury.
The most common nerves involved included the lateral femoral cutaneous nerve, followed by the femoral nerve. Radiculopathies occurred at the L4, L5, and S1 levels. The authors make the following recommendations: changing positions frequently during the pushing phase, avoiding prolonged thigh flexion, avoiding extreme thigh abduction and external rotation. Other labor-related perineal nerve injuries have been documented by Sahai-Srivastava et al. to occur due to prolonged squatting or to prolonged pressure from birth attendants at the knees.
The research by Wong and colleagues highlights the important of interviewing patients about past and current symptoms, birth histories including length of time spent pushing and in what positions a woman was pushing. Teaching a woman and her birth assistants about providing support to the birthing woman's body can be very helpful; a birthing woman may welcome support of a limb, yet avoiding over-compression or sustained positions without intermittent breaks may reduce risk of nerve injury. Because the authors also noted a correlation between nerve injuries and maternal pushing at higher fetal stations (the fetus had not descended as far into the birth canal they recommend attempting to shorten active pushing time by allowing the fetus to descend further prior to pushing. (This concept in itself is a very interesting topic to be followed-up on in another post!)
To discuss issues of postpartum evaluation and nerve dysfunction, you can sign up for the Care of the Postpartum Patientor our Postpartum Special Topicsin which we dedicate an entire lab to this topic.