MSK- MRI detects lingering bone and levator ani injuries from vaginal childbirth delivery
Natural childbirth can cause pelvic injuries that typically resolve. But up to 15% of women sustain pelvic injuries that do not heal, according to a study published in the American Journal of Obstetrics and Gynecology. Researchers from the University of Michigan in Ann Arbor are using musculoskeletal magnetic resonance imaging (MSK-MRI) fluid sensitive sequences to identify pelvic injuries and to follow a patient’s recovery.
Over the past ten years, special sequences in MSK-MRI have been shown to offer advantages over other types of imaging techniques for the study of deep bony and soft-tissue changes. Because fluid-sensitive sequences have the best combined specificity and sensitivity for revealing areas of injury and edema, they are the recommended diagnostic imaging procedure for stress injuries, such as those sustained from sports-related activities.
The University of Michigan added MSK-MRI fluid-sensitive sequences to its protocol of anatomical MRI sequences to better characterize the full scope of possible injuries and pattern of recover after researchers started conducting a study of levator ani (LA) muscle injury following vaginal birth. The additional MRI sequences show increased signal indicating edema in bone,
matched linear signal changes in bone that indicate a fracture, and/ Increased signal that indicates edema in muscle. It is also easier to identify detection of tears and their magnitude with the use of fluid sensitive sequences.
Because MSK-MRI fluid sensitive sequences are not commonly used for childbirth related injuries, lead author Janis Miller, Ph.D., an associate professor at the University of Michigan School of Nursing, and colleagues conducted a retrospective study to describe the occurrence, recovery, and consequences of musculoskeletal (MSK) injuries in women at risk for childbirth-related pelvic floor injury at first vaginal birth. They wanted to identify and report on the occurrence and severity of bony and levator ani (LA) injuries observed in high risk patients, and how the magnitude of tissue trauma relates to clinical consequences in the first eight months postpartum.
Their research was a subset of the Evaluating Maternal Recovery from Labor and Delivery (EMRLD) study, a longitudinal cohort study following up primiparous women with a recent history of childhood. Data was collected from participants approximately seven weeks after a first vaginal birth and eight months later. The analysis of this study was based on a cohort of 68 high risk women who had MRI scans at these follow-up times. However, nine of the women did not have fluid-sensitive sequences during their eight month scan, leaving a total of 59 women who had complete scans each time.
The MRIs were reviewed by two board-certified fellowship-trained MSK radiologists who were blinded to details of an individual woman’s birth data and risk category. Standard MSK-MRI radiology grading categories were used to evaluate edema and fractures in bone and muscle injuries. Bone marrow edema, pubic bone fractures in the cortical or trabecular bone, LA edema, and LA discontinuity of muscle observed as loss if visible muscle (indicating muscle tear) were evaluated.
The findings showed that seven weeks’ postpartum, 90% of the 59 women had LA muscle edema, 66% had pubic bone marrow edema, 41% had low-grade or greater LA tear, and 29% had subcortical fracture. The researchers reported that the magnitude of LA muscle tear did not substantially change by eight months postpartum, with 89% having the same magnitude of levator injury. However, LA muscle edema and bone injuries showed total or near total resolution.
“We cannot rely on clinical examination to intuit the full spectrum of MSK issues associated with higher-risk birth. In select women, MSK-MRI may be warranted clinically, since MSK-MRI can provide the full spectrum of MSK injuries….The role of MSK-MRI in evaluation of postpartum women could be expanded into situations of unexplained or prolonged pain after delivery, nonrecoverable ability to contract the LA, or non-resolving postpartum pelvic organ descent,” the authors wrote.
While MSK-MRI scans are usually used for sports medicine, they make sense to use with patients who have high-risk factors of muscle tear. Childbirth is as traumatic as many endurance sports. “If an athlete sustained a similar injury in the field, she’d be in an MRI machine in an instant,” commented Miller in a press release about the study published December 1st. “We’re not saying that every woman who gives burth needs an MRI nor that women should not do Kegel exercises. A key point is that if a woman is sensing that she has delayed recovery or unusual symptoms….she should see a specialist.”
REFERENCE
- Miller, JM, Low LK, Zielinsk R, et al. Evaluating maternal recovery from labor and delivery: bone and levator ani injuries. 2015 Am J Obstet Gynecol. 213;2:188.e1-188.e11.