Pubic bone injuries in primiparous women: magnetic resonance imaging in detection and differential diagnosis of structural injury

Ultrasound Obstet Gynecol. 2012 Apr;39(4):444-51. doi: 10.1002/uog.9082.

Abstract

Objective: To evaluate the utility of magnetic resonance imaging (MRI) in diagnosing structural injury in primiparous women at risk for pelvic floor injury.

Methods: This was an observational study of 77 women who underwent 3T MRI after delivery. Women were operationally defined as high risk (n = 45) for levator ani muscle tears (risk factors: second-stage labor > 150 min or < 30 min, anal sphincter tear, forceps, maternal age > 35 years and birth weight > 4000 g) or low risk (n = 32): vaginally delivered without these risk factors (n = 12); delivered by Cesarean section after second-stage labor > 150 min (n = 14) or delivered by Cesarean section without labor (n = 6). All women were imaged using fluid-sensitive MRI sequences. Two musculoskeletal radiologists reviewed images for bone marrow edema, fracture, pubic symphysis measurements and levator ani tear.

Results: MRI showed pubic bone fractures in 38% of women at high risk for pelvic floor injury and in 13% of women at low risk for pelvic floor injury (χ(2) (3) = 9.27, P = 0.03). Levator ani muscle tears were present in 44% of the high-risk women and in 9% of the low-risk women (χ(2) (3) = 11.57, P = 0.010). Bone marrow edema in the pubic bones was present in 61% of women studied across delivery categories. Complex patterns of injury included combinations of bone marrow edema, fractures, levator ani tears and pubic symphysis injuries. No MRI-documented injuries were present in 18% of women at high risk and 44% at low risk for pelvic floor injury (χ(2) (1) = 6.2, P = 0.013).

Conclusions: Criteria identifying primiparous women at risk for pelvic floor injury can predict increased risk of bone and soft tissue changes at the pubic symphysis. Fluid-sensitive MRI has utility for differential diagnosis of structural injury in postpartum women.

Publication types

  • Evaluation Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Bone Marrow Diseases / diagnosis*
  • Bone Marrow Diseases / pathology
  • Cesarean Section
  • Delivery, Obstetric / adverse effects*
  • Diagnosis, Differential
  • Edema / diagnosis*
  • Edema / pathology
  • Female
  • Humans
  • Infant, Newborn
  • Magnetic Resonance Imaging*
  • Parity
  • Pelvic Floor / injuries*
  • Pelvic Floor / pathology
  • Pregnancy
  • Pubic Bone / injuries*
  • Pubic Bone / pathology
  • Retrospective Studies
  • Risk Assessment
  • Risk Factors