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

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.

Stress incontinence and cystoceles

We studied prospectively 62 women with cystoceles by video-urodynamics before and after operative repair. Of 29 women with grades 1 and 2 cystoceles 8 had residual urine, 14 had urge incontinence and 24 had symptoms of stress urinary incontinence. Of these women 23 had urodynamic evidence of stress incontinence, as did 3 of 5 without stress incontinence symptoms. Of 33 women with large cystoceles 22 had symptoms of stress urinary incontinence but 10 more had urodynamic evidence of stress urinary incontinence. Of these 33 women 18 had significant residual urine and 24 had urge incontinence. Operative repair resolved stress incontinence in 51 of 54 women, urge incontinence in 33 of 38 and residual urine in 24 of 26. Cystoceles recurred in 3 patients, and enteroceles developed in 3 and recurred in 2. These findings indicate that cystoceles may cause voiding dysfunction and lack of symptoms of stress incontinence is unreliable in patients with cystoceles. In addition, cystoceles are associated with other symptoms, most of which actually resolve after operative repair.