A 28-year-old woman, gravida 1 para 1, is seen in the clinic a week after spontaneous vaginal delivery. The delivery was performed under epidural analgesia and complicated by a prolonged second stage of labor. Since delivery, the patient has had frequent episodes of fecal incontinence, as well as mild perineal pain that is relieved by ibuprofen and opioid analgesics. She reports no other medical conditions, and her pregnancy was otherwise uncomplicated. On examination, a healing perineal laceration shows no signs of infection. Digital anorectal examination reveals decreased anal sphincter tone and loss of the anal wink reflex. Bilateral lower extremity reflexes are 2+ with normal tone. Which of the following is the most likely cause of this patient's fecal incontinence?

Question

A 28-year-old woman, gravida 1 para 1, is seen in the clinic a week after spontaneous vaginal delivery.  The delivery was performed under epidural analgesia and complicated by a prolonged second stage of labor.  Since delivery, the patient has had frequent episodes of fecal incontinence, as well as mild perineal pain that is relieved by ibuprofen and opioid analgesics.  She reports no other medical conditions, and her pregnancy was otherwise uncomplicated.  On examination, a healing perineal laceration shows no signs of infection.  Digital anorectal examination reveals decreased anal sphincter tone and loss of the anal wink reflex.  Bilateral lower extremity reflexes are 2+ with normal tone.  Which of the following is the most likely cause of this patient's fecal incontinence?

Quizplus · Accepted Answer

11ec160b_35ac_0551_9249_d17eb4e4e20b_MD0001_00 This postpartum patient has fecal incontinence consistent with pudendal nerve injury, which compromises motor and sensory innervation to the perineal region. The pudendal nerve originates from the ventral rami of S2-S4 and passes between the piriformis and coccygeus muscles as it exits the pelvis through the greater sciatic foramen. It then reenters the pelvis near the ischial spine through the lesser sciatic foramen before dividing into its terminal branches. Sensory branches innervate the external genitalia and skin around the anus and perineum. Motor branches innervate the pelvic floor muscles and external urethral and anal sphincters. The pudendal nerve is vulnerable to stretch injury because of its curved course around the ischial spine. Labor and delivery (particularly active pushing during a prolonged second stage of labor) place excess tension on the pudendal nerve, increasing the likelihood of injury. Injury may result in denervation and weakness of the voluntary perineal musculature, including the external anal sphincter, which can present as new-onset fecal incontinence and decreased anal sphincter tone on digital anorectal examination. Because perianal skin sensation is compromised, patients also have loss of the anal wink reflex. (Choice A) Cauda equina syndrome results from the compression of spinal nerve roots below the level of the conus medullaris. Patients present with severe unilateral or bilateral radicular pain, saddle anesthesia, and lower extremity weakness and hyporeflexia. Bowel and bladder incontinence are typically late manifestations. (Choice B) Lumbosacral plexopathy can occur due to direct compression of the lumbosacral trunk during fetal descent. Patients typically have transient footdrop and numbness of the lateral leg and dorsal foot. (Choice C) An adverse effect of opioids is constipation, not fecal incontinence, due to decreased intestinal motility from the activation of gastrointestinal mu-opioid receptors. Opioids do not affect anal sphincter tone or the anal wink reflex. (Choice E) Epidural hematoma is a rare complication of epidural analgesia that usually presents within hours to days, not weeks. Patients typically have sudden-onset back pain or radicular pain with progression to complete or partial paralysis of the lower extremities. Educational objective: Pudendal nerve injury can occur due to excessive stress on the pelvic floor during labor and delivery (eg, prolonged second stage). Nerve injury leads to denervation and weakness of the perineal musculature (eg, external anal sphincter), which can present as new-onset fecal incontinence. __________ References: Electrophysiological basis of fecal incontinence and its implications for treatment. (http://www.ncbi.nlm.nih.gov/pubmed/29159162)

A 28-Year-Old Woman, Gravida 1 Para 1, Is Seen in the Clinic