MONTEREY, CALIF. – Chronic pain after cesarean delivery is uncommon and generally mild, new data show. Additionally, women undergoing repeat cesarean do not have worse pain than their counterparts undergoing primary cesarean.
These were among the key findings of a pair of prospective longitudinal studies that investigators reported at the annual meeting of the Society for Obstetric Anesthesia and Perinatology.
The studies took place among healthy women from Brazil and the United States who were having scheduled elective cesarean deliveries with no prior labor, using standardized spinal anesthesia, surgical techniques, and multimodal postoperative analgesia.
Prevalence and description of chronic pain
In the first study, investigators led by Dr. Clemens M. Ortner of the department of anesthesiology and pain medicine at the University of Washington Medical Center in Seattle, followed 360 women from São Paulo, Brazil.
They used two tools recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT), which is endorsed by the Food and Drug Administration: the Brief Pain Inventory (BPI), which captures the effect of pain on physical functioning, and the Short-Form McGill Pain Questionnaire 2 (SF-MPQ-2), which evaluates the nature of pain using 22 descriptors that are grouped into four overarching types of pain.
The women were a mean 31 years. For the large majority (70%), the cesarean was their first. Mean surgical time was 40 minutes.
Results with the BPI showed that 3% of women had pain at 6 months, Dr. Ortner reported. However, in the majority of cases, the pain was rated as mild.
Data from the SF-MPQ-2 suggested that the pain was most often of the neuropathic type and seldom of the continuous, intermittent, or affective types.
The leading descriptor the women selected for the pain, cited by 38% of those affected, was numbness. "Some would actually even argue [that numbness] does not qualify as a pain symptom," commented Dr. Ortner. Descriptors such as throbbing, tender, cramping, stabbing, and piercing were rarely used.
"This is the first prospective longitudinal study to characterize chronic pain after cesarean delivery using the SF-MPQ-2, and to our knowledge, is actually the first study that uses the SF-MPQ-2 that tries to characterize chronic postoperative pain," Dr. Ortner noted.
"Our incidence of chronic pain was very low at 6 months: It was 3%. However, this population was a very healthy population that had no other risk factors, like prior sensitization or other chronic pain syndromes," he cautioned.
"We can take this information from our study as a control for future analysis where we can use the SF-MPQ-2 to investigate chronic pain in high-risk populations undergoing cesarean delivery," he added.
Dr. Kenneth E. Nelson, session moderator and an obstetrical anesthesiologist at Wake Forest Baptist Medical Center in Winston Salem, N.C., wondered if the pain descriptors of the SF-MPQ-2 had the same meaning in the Brazilian context. "Some of those words are pretty esoteric. How culturally sensitive are they? Do you see a difference in different cultures using those words to describe pain, and is that potentially an issue with comparing one of these studies to another?" he asked.
"It is true that the SF-MPQ-2 was validated in an English-speaking population. However, these descriptors have been retrieved from a very, very large population of patients, how they describe their pain," Dr. Ortner replied. Additionally, the questionnaire underwent a rigorous validation process, whereby it was translated for a Portuguese-speaking population and then translated back to English. "However, of course, cultural differences can have an impact on these results, yes."
Pain with primary vs. repeat cesarean
In the second study – the only prospective evaluation of pain among healthy women after primary vs. repeat cesareans – a team led by Dr. Ruth Landau studied 451 women from São Paulo, Brazil, and Seattle.
Subsequent cesarean deliveries are noteworthy among surgical procedures in that surgeons typically go through the same scar again, a process that some speculate may contribute to greater pain, she noted.
"The hypothesis is that central sensitization as can be elicited by scar hyperalgesia after a previous cesarean section could result in increased pain if the surgery is repeated," she explained. "And the clinical implications for that would be that analgesic regimens may need to be adapted in women undergoing a repeat cesarean delivery, and that we should tailor our postoperative analgesia based on whether it’s a primary or repeat cesarean section."
Overall, 67% of the women studied were undergoing a primary cesarean delivery, whereas 33% were undergoing a repeat cesarean delivery. They had a mean age of about 30 years.