A 22-year-old woman, gravida 1 para 1, is evaluated in the postpartum unit for lower abdominal pressure and pain. The patient underwent an induction of labor at 41 weeks gestation due to oligohydramnios. She received epidural anesthesia and had a forceps-assisted vaginal delivery due to prolonged second stage of labor. A second-degree perineal laceration was repaired after delivery, and she had a postpartum hemorrhage that resolved with uterotonic medications. The patient is now 6 hours postpartum; she has been unable to void since delivery and has persistent urine dribbling while lying in bed. Temperature is 37.2 C (99 F), blood pressure is 100/60 mm Hg, and pulse is 92/min. BMI is 33 kg/m². Physical examination reveals a firm uterine fundus and diffuse lower abdominal tenderness to palpation. The perineal repair is intact and there is moderate lochia. Deep tendon reflexes are normal. Which of the following is the most likely cause of this patient's urinary symptoms?

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Explanation: 11ec25c8_da8d_de06_bc81_296c6a00ccf6_MD0003_00 This patient has acute postpartum urinary retention, defined as an inability to void ≥6 hours after vaginal delivery or ≥6 hours after urinary catheter removal following cesarean delivery. Patients with acute urinary retention can develop a concomitant overflow incontinence, resulting in clinical features such as urinary dribbling and lower abdominal pressure from an overdistended bladder. Postpartum urinary retention often occurs due to the following: Perineal trauma from a prolonged second stage of labor and/or perineal laceration that results in a pudendal nerve injury. Damage to the pudendal nerve can result in a decreased voiding sensation, thereby promoting urinary retention, and cause external urethral sphincter dysfunction. Reduced sensory and motor sacral spinal cord impulses from regional neuraxial anesthesia (eg, epidural anesthesia), which can suppress the micturition reflex and decrease detrusor tone, resulting in bladder atony. Other risk factors include primiparity and operative (forceps-assisted) vaginal delivery. Management is with intermittent urethral catheterization and reassurance as retention is typically self-limited and resolves in <1 week. (Choice B) In contrast to this patient, those with detrusor overactivity have urinary urgency followed by immediate loss of urine (urge incontinence) due to bladder spasms. (Choice C) Hypovolemia from postpartum hemorrhage may result in acute kidney injury due to acute tubular necrosis or renal ischemia. Patients typically have decreased urine production rather than urinary retention. (Choice D) Urethral injury may result from pelvic floor surgery or perineal laceration repair from a foreign body (eg, mesh, suture). Patients can have urinary retention and dribbling; however, they typically have urinary frequency, dysuria, and a slow or interrupted stream from the foreign body. (Choice E) Vaginal atrophy can develop postpartum and present with urinary symptoms (eg, urethral discomfort, stress urinary incontinence). However, vaginal atrophy is unlikely immediately postpartum (due to high estrogen levels during pregnancy) and typically occurs in women with prolonged low estrogen levels from lactational amenorrhea. (Choice F) Vesicovaginal fistula may occur secondary to obstetric complications (eg, prolonged labor, operative vaginal delivery) and cause persistent urinary dribbling; however, it often takes days to develop and there is typically no associated bladder distention as urine continuously drains through the fistula. Vesicovaginal fistula Educational objective: Acute postpartum urinary retention causes an inability to void as well as overflow incontinence due to pudendal nerve injury and bladder atony. Risk factors include prolonged labor, perineal trauma, and regional neuraxial anesthesia. References: Risk factors and management of persistent postpartum urinary retention. (http://www.ncbi.nlm.nih.gov/pubmed/30142472) Acceptable postvoid residual urine volume after vaginal delivery and its association with various obstetric parameters. (http://www.ncbi.nlm.nih.gov/pubmed/30158981) Delivery-related risk factors for covert postpartum urinary retention after vaginal delivery. (http://www.ncbi.nlm.nih.gov/pubmed/26224379)

A 22-Year-Old Woman, Gravida 1 Para 1, Is Evaluated in the Postpartum