Chronic pain after vaginal and cesarean delivery: a reality questioning our daily practice of obstetric anesthesia

The prevalence of chronic pain in our society reaches 35%, higher in women than men (40% vs. 31%).1 Looking at risk factors associated with chronic pelvic pain in the female population, a history of gynecological surgery and more particularly previous cesarean delivery is frequently highlighted.2, 3 Indeed, 20% of the patients seen in pain clinics report that a surgical procedure caused their pain. Thanks to several publications over the last decade, chronic pain is now recognized as an important outcome of surgery and a prevalent healthcare problem.4, 5 However, it is of interest that the first paper on persistent pain after the most common operation worldwide, i.e. cesarean delivery, was published as recently as 2004.6

Childbirth has always been considered as a natural process and associated long-term consequences have received little interest. Moreover, a majority of women are reluctant to discuss postnatal health problems and do not consult healthcare professionals even if their problems persist.7 In this issue of the International Journal of Obstetric Anesthesia, Kainu and colleagues from Finland present another retrospective study on this topic.8 They compare the incidence of persistent pain after cesarean and vaginal delivery, a pertinent question given the increasing cesarean rate in developed countries.

Several problems arise with the assessment of chronic post-surgical pain (CPSP). The working definition implies a duration of pain of at least two, if not three, months after the procedure. Furthermore, the evaluation of pain, by definition a personal experience, varies widely, a fortiori when it relies on patients’ recall as in retrospective studies. Consequently, it is important to evaluate not only the incidence but also the intensity of the pain and its impact on quality of life. Perhaps unsurprisingly, Kainu et al.8 found that 18% of women reported pain one year after caesarean delivery and 10% after vaginal birth, with 4% and 1% respectively suffering daily pain. Similar findings have been previously reported, clearly showing that for some, postpartum pain may persist for longer than a year.6, 9, 10, 11

These findings could be seen as encouraging because it would appear that CPSP is much less common after delivery than after thoracic surgery or amputation, which may affect over 50% of patients.4, 5 The problem, however, is not so simple. First, as cesarean and vaginal deliveries are the most common procedures worldwide, the small percentages reported represent an impressive number of women. Second, when considering the individual and social impact of this complication, it is recognized that a higher percentage of women report that persistent pain, even if not severe, has a negative effect on daily quality of life. Whatever the mode of delivery, persistent pain at two months has a negative impact on daily activities in 20-25%,10, 11 and pain still disturbs daily life of 14-15% at one year and even longer after childbirth.8, 9 Pain may therefore affect the lives of many young active women caring for small children.

The first role of the Finish paper must be to raise awareness amongst healthcare providers to an actual clinical problem. More importantly, such studies aim to identify risk factors for chronic pain in order to target vulnerable patients and improve peri-operative management. For instance, most retrospective studies have highlighted that women with persistent pain at six months had a higher recall of pain during the first days after delivery.6, 8 This was demonstrated in the prospective study by Eisenach and colleagues in which the severity of acute pain after childbirth, but not the type of delivery, predicted persistent pain.11 The study revealed a prevalence of severe pain of 17% at 24 hours after cesarean delivery (defined as a pain score of higher than 6 out of 10) compared to 8% after vaginal birth. Furthermore, women experiencing severe acute pain after childbirth had a 2.5-fold increased risk of persistent pain and a 3.0-fold risk of postpartum depression, compared to those women with only mild pain after delivery.11

Severe poorly managed postoperative pain is well recognized as a significant risk factor for developing persistent pain after surgery. They share many risk factors,4, 5 such as a pre-operative history of chronic pain, specifically back pain, and a regular use of analgesics, which may also presage post partum pain.6, 8, 9 Different types of chronic pain frequently co-occur and a history of chronic pain elsewhere in the body appears to predict the development of further chronic pain.

Among intra-operative factors, the depth of anesthesia might influence pain after cesarean delivery. Neuraxial blocks, specifically spinal anesthesia, are more effective in preventing nociceptive input from reaching the central nervous system, thereby preventing central sensitization, one of the mechanisms underlying development of persistent pain after tissue trauma.12 This is supported by evidence that the risk of CPSP after both cesarean delivery and hysterectomy is lower after spinal than general anesthesia.3, 6 Moreover, intrathecal anesthesia for elective cesarean delivery is followed by less pain during the first 24 hours than is epidural anesthesia.13

The role of epidural or CSE analgesia during labor in preventing the development of persistent pain after vaginal delivery remains unclear and the number of women included in the Finish study was too small to show any significant correlation. It is also noteworthy that trial of vaginal birth does not seem to increase the risk for CPSP and, conversely, elective cesarean delivery does not decrease the risk for persistent pain.6, 10 Although an association between perineal trauma and early postpartum pain has been demonstrated,14 very few data are currently available concerning its involvement in severe chronic postpartum pain. The topic certainly deserves further large prospective studies.

Surgical factors such as operative technique of cesarean delivery have been investigated. Although the type of incision does not seem to affect persistent pain,6, 8 most operations are performed via a Pfannenstiel incision. The procedure carries a risk for the entrapment of lower abdominal wall nerves and is associated with the development of chronic pain mainly of neuropathic origin.15 Uterine exteriorization increases visceral pain during the first 24 hours after surgery compared to in situ repair.16 Closure of the parietal peritoneum also increases early postoperative pain and the persistence of pain and discomfort eight months after cesarean delivery.17

Finally, severe acute pain is a striking risk factor for persistent pain after tissue trauma, therefore effective postoperative pain management is vital. The management of postoperative pain is currently far from optimal,18 and even more problematic after childbirth.9, 14 Intake of analgesics postpartum is often inadequate, as mothers wish to avoid medication during breastfeeding. In addition mothers may not receive adequate education regarding pain relief or there may be insufficient resources devoted to maternal care.

Overall the Finish study highlights the reality of persistent pain after delivery, which may seriously interfere with daily life for a significant number of women. Although the problem has received little interest until now, it represents a unique and exciting opportunity for anesthesiologists involved in obstetrics to expand their horizons,19 to question and examine prospectively the impact of the peri-operative management and care we provide routinely to our patients.