Introduction

Chronic postsurgical pain (CPSP), or pain that persists after surgery, is an underrecognized cause of chronic pain and disability. CPSP has been defined as pain of at least 3 months duration with a significant negative effect on the quality of life, that developed or increased in intensity after a surgical procedure, for which other causes of pain such as infection have been excluded, which may be either a continuation of acute postoperative pain or develop after an asymptomatic period, that is localized to the surgical field or a referred area, and that does not appear to be attributable to a preexisting pain condition [1, 2]. Risk factors for CPSP include high preoperative pain levels, younger age, genetic predisposition, and psychological traits of catastrophizing and high anxiety or fear related to surgery [3].

It has been proposed that the majority of CPSP is neuropathic, due to damage to major nerves within the surgical field; genetic predisposition and mechanisms of chronic inflammation and central sensitization may also contribute to the etiology of CPSP [4]. Pain following gynecological surgery may also relate to muscle spasm, presence of intraperitoneal adhesions, incisional hernia, or scar endometrioma. Within gynecology, there are additionally several recognized iatrogenic postsurgical pain syndromes with unique mechanisms for generating chronic pain [5]. This chapter will review the phenomena of CPSP, its incidence following common gynecological procedures, and strategies for its prevention and management.

Causes of Pain Following Gynecological Surgery

Musculoskeletal pain is a common cause of CPSP. Myofascial pain syndrome, or pain originating from trigger points in skeletal muscle, is a poorly recognized and undertreated cause of acute and chronic pain [6], and may be a source of postoperative pain among gynecological patients, even following nonabdominal surgery [7]. Examination of the patient’s abdomen in the office, using one finger to palpate muscles, and assessing for an increase in pain with increased muscular tension induced through patient effort (a positive Carnett’s sign), can help to isolate musculoskeletal causes of abdominal pain. Surgery may also irritate and result in hypertonus of skeletal muscles of the pelvic floor, resulting in chronic pain and voiding dysfunction; this is especially a risk of gynecological surgeries that involve fixation of these muscles, such as sacrospinous vaginal vault suspension or mesh kits that employ muscular anchor sites [8]. Screening for symptoms of pelvic floor tension myalgia and performing an examination of pelvic floor muscle activity will confirm this etiology for postsurgical pelvic pain [9].

Incisional hernia should be considered for pain localized to an incision site, especially if a fascial defect or bulge is palpable at that site. CT imaging may be helpful in confirming suspected hernia, especially if the physical exam is equivocal [7]. Incarceration of omentum at a hernia site may cause severe pain without causing bowel obstruction [10].

Cyclical incisional pain and presence of a palpable mass that increases in size at the time of menstruation may be suggestive of scar endometrioma. Abdominal wall scars are the most common site of extrapelvic endometriosis, with only a minority of patients (approx. 14%) having associated pelvic endometriosis [11]. Accurate diagnosis of this condition can be challenging, requiring a high level of suspicion; for this reason the condition is not diagnosed until an average of 3.6–4.2 years following surgery [11, 12]. Imaging, such as MRI, may be helpful in diagnosis and perioperative planning; if possible, surgery should be scheduled to coincide with the time of menses, when the mass is at its largest.

Intraabdominal adhesions are considered a common cause of abdominopelvic pain, with 47% of adhesions shown to be a source of pain at the time of conscious laparoscopy [13]. Adhesions are thought to form in more than 70% of patients following abdominal or pelvic surgery, regardless of open or minimally invasive surgical approach [14]. Pain from adhesions is visceral in nature but may be referred to muscles and nerves of the abdominal wall, pelvis, or lower back through mechanisms of viscerosomatic convergence.

Nerve injury from stretching, ischemic compression, transection, blunt trauma, fibrosis with entrapment, or suture ligation may be a cause of postoperative pain. Nerve pain often has a burning quality, is aggravated by physical activity, and may arise anywhere from immediately postsurgery to several years after the surgery [15]. Familiarity with pelvic and abdominal wall neuroanatomy may help prevent nerve injury at the time of surgery and can assist in the accurate diagnose of nerve injury as a cause of postoperative pain.

Within the abdominal wall, the ilioinguinal, iliohypogastric, and genitofemoral nerves may be affected by transection, suture ligation, or fibrosis entrapment at the lateral margins of a low-transverse skin incision or lateral trocar sites [7], and have an overlapping sensory distribution in the vicinity of the groin and pubic symphysis. Cadaveric studies have demonstrated that the ilioinguinal nerve emerges from the transverse abdominal plane through the internal oblique muscle at an average of 2.5 cm, but up to 5.1 cm medial and at an average of 2.4 cm, but ranging from 0 to 5.3 cm inferior to the anterior superior iliac spine (ASIS); the iliohypogastric nerve similarly emerges at an average of 2.5 cm, but up to 4.6 cm and at an average of 2.0 cm, but ranging from 0 to 4.6 cm inferior to the ASIS [16]. The genital branch of the genitofemoral nerve passes through the inguinal canal and supplies the skin of the mons pubis and labium majus; the femoral branch passes lateral to the external iliac artery, behind the inguinal ligament, and throughout the fascia lata into the femoral sheath, where it supplies the skin of the femoral triangle; injury may occur from postappendectomy fibrosis overlying the psoas muscle, or from hernia repair [15]. The lateral femoral cutaneous nerve similarly passes under the inguinal ligament to supply the skin of the lateral upper thigh, and is susceptible to compression injury that can occur from a variety of causes, including surgery; this neuropathic syndrome is termed meralgia paresthetica [15].

The pudendal nerve enters the pelvis through the lesser sciatic foramen and wraps superior to the ischial spine, passing through Alcock’s canal; in this area, it may undergo constriction between the sacrotuberous and sacrospinous ligaments that results in chronic pelvic pain [17]. Pudendal nerve injury may be caused by surgery, such as sacrospinous vaginal vault suspension or mesh kit placement, or following vaginal delivery [15]. Pudendal neuralgia should be suspected in patients with burning pain of the vulva, vagina, clitoris, perineum, or rectum, who report pain with sitting that is relieved with standing; onset of symptoms may be immediate following vaginal surgery [18]. Table 17.1 summarizes chronic pain after surgery by etiology.

When postoperative nerve injury is suspected, nerve blocks may be both diagnostic and therapeutic, and should be performed several times prior to proceeding with surgical management such as nerve transection or neuroma resection [15]. Abdominal wall nerve blocks can be performed under ultrasound guidance; pudendal nerve block can be performed transvaginally or via a transgluteal route under CT guidance [19]. Relief of pain with local anesthetic injection implicates the nerve as a cause of pain; lasting benefit may derive from steroid injection in the vicinity of the nerve.

Incidence of Chronic Postsurgical Pain Within Gynecology

There are limited studies assessing the incidence of persistent postoperative pain following laparoscopy for gynecological surgery, with a significant confounding factor being that laparoscopy is often performed to assess and treat causes of chronic pelvic pain, so that presence of pain at several months postsurgery may be due to persistence or recurrence of the preoperative pain etiology. One study compared 61 women undergoing laparoscopy for evaluation of nonacute pelvic pain to 16 women undergoing laparoscopy for tubal ligation, and found that women undergoing laparoscopy for tubal ligation had low preoperative pain scores (average 0.5) as well as no pain at 6 months postsurgery (average 0.0); this was in contrast to patients undergoing laparoscopy for evaluation of chronic pain, who exhibited an average decrease in pain from 5 to 3 (mean −1.8, p < 0.001), with 10 of 61 women (16%) reporting increased pain at 6 months postsurgery [20]; presence of pain at 6 months postsurgery was predicted by preoperative factors of pain levels, catastrophizing, and presence of cutaneous allodynia. Small sample sizes from this study impair conclusions about frequency of CPSP following laparoscopy for tubal ligation or assessment of chronic pain. A study comparing outcomes among women undergoing hysteroscopic sterilization versus laparoscopic tubal ligation reported an incidence of chronic pelvic pain of 26.8% at 24 months among the tubal ligation group; propensity score matching to control patient variables between the two groups had led to a study population with a baseline pelvic pain rate of 18.9%, although the initial patient population reported baseline chronic pelvic pain among 25.7% of women [21]; the presence of baseline pain was highly predictive of CPSP (odds ratio [OR] 2.59, p < 0.001). A retrospective study of 8,051 women undergoing laparoscopic sterilization reported a diagnosis of chronic pelvic pain within 2 years post procedure among 11.4% of women who did not have a preexisting pain condition, compared to 23.8% of women who did have a preexisting pain condition (OR 2.3, p < 0.001) [22]. Overall, these studies suggest a new diagnosis of chronic pelvic pain among 7.9%–11.4% of women following laparoscopic tubal ligation.

Hysteroscopic sterilization with the Essure® device has been reported to result in cases of postprocedure chronic pain, often due to complicated placement such as device malposition or corneal perforation; a retrospective study of 458 patients showed persistent pain at more than 3 months post procedure in 4.2% of patients, with a previous chronic pain diagnosis such as chronic pelvic pain, fibromyalgia, chronic low back pain, or headaches significantly increasing one’s risk for chronic postprocedure pain (OR 6.15, 95% confidence interval [CI] 2.09–18.05) [23]. A case series study of 4,274 patients undergoing Essure® microinsert placement reported chronic pain among 7 women (0.16%)[24]. Overall, these studies suggest an incidence of chronic pelvic pain of 0.16%–4.2% following hysteroscopic tubal occlusion with Essure®.

Assessment of chronic pain following hysterectomy has been thoroughly studied, with a range of frequencies reported from 10% to 50%, with severe pain reported by 1%–7% of women, and pain that has a significant effect on daily activities reported among 17%–18% of women [25]. Among women with CPSP following hysterectomy, 17%–52% describe symptoms suggestive of neuropathic pain. Incidence of CPSP after hysterectomy varies by surgical approach, with incidence after open abdominal hysterectomy of 25%–26%, compared to 12%–18% after vaginal hysterectomy, and 20%–31% after laparoscopic hysterectomy [26]. As with gynecological laparoscopy, a confounding factor for CPSP is the present of preoperative pelvic pain, which is a common cause for hysterectomy; one reason for decreased incidence of CPSP following vaginal hysterectomy compared to abdominal or laparoscopic approaches may be that patients selected to undergo vaginal hysterectomy are less likely to have preexisting pelvic pain conditions that would benefit from abdominal/intraperitoneal assessment.

Assessment of chronic pain following cesarean section has also been studied through a variety of clinical trials. A meta-analysis of chronic postsurgical pain following cesarean section included 38 trials; CPSP at 3–6 months ranged from 0% to 56%, with most studies reporting 26% or less, CPSP at 6–12 months ranged from 4% to 19%, and CPSP at 12+ months ranged from 2% to 35% [26]. One of the studies included in the meta-analysis was a retrospective survey of 220 patients at an average of 10.8 months following cesarean section; they showed chronic intermittent pain in 12.3% of patients, with 5.9% having daily or almost daily pain symptoms; patients with chronic postsurgical pain were more likely to have undergone general anesthesia and not spinal anesthesia, and were more likely to recall severe acute postoperative pain [27]. A prospective study too recent to be included within the meta-analysis followed 527 women undergoing cesarean section, and showed CPSP rates of 18.3%, 11.3%, and 6.8% at 3, 6, and 12 months, respectively; risk factors for CPSP included intensity of pain with movement in the immediate postoperative period, preoperative depression, and longer surgical time [28].

Chronic pain following global endometrial ablation most likely relates to persistent or recurrent endometrium in the uterine cornua that leads to hematometra. This condition is thought to be more prevalent in women who have also undergone tubal ligation, due to obstruction of retrograde menstruation, and has led to the identification of a “postablation tubal sterilization syndrome”; however, painful hematometra may occur following endometrial ablation in the absence of tubal ligation [5]. A retrospective cohort study of 270 women undergoing endometrial ablation showed new or worsening postprocedure pain in 23%, with history of tubal sterilization doubling one’s risk for postprocedure pain (OR 2.06, 95% CI 1.14–3.70); a history of preprocedure dysmenorrhea was also a risk factor for pain after ablation (OR 1.74, 95% CI 1.06–2.87) [29]. Similar results were seen in a retrospective cohort study of 437 women following endometrial ablation, in which 20.8% of women reported postprocedure chronic pain, with history of dysmenorrhea (OR 1.73) and prior tubal ligation (OR 1.68) both associated with increased risk for pain; age less than 40 years (OR 1.90) and smoking status (OR 2.31) were additional risk factors for CPSP [30]. Hysterectomy is considered curative for pain of this etiology, but does not appear to be pursued by most affected patients; a retrospective study of 553 women undergoing endometrial ablation demonstrated similar rates of subsequent hysterectomy between women with prior tubal sterilization and those without (16.5% vs. 11.3%, χ² = 2.95, p = 0.09) [31].

History of synthetic vaginal mesh placement in pelvic reconstructive surgery for pelvic organ prolapse and/or stress urinary incontinence is addressed in Chapter 18 in this book but is worth mentioning here as a syndrome of iatrogenic chronic postsurgical pelvic pain. Pain may relate to mesh contraction as well as mesh erosion and may include musculoskeletal as well as neuropathic pain symptoms. Table 17.2 summarizes the incidence of chronic postoperative pain by surgery.

Table 17.2 Incidence of chronic postoperative pain by surgery

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Related

Related posts:

1. Chapter 2 – Neurobiological Basis of Pelvic Pain
2. Chapter 10 – Pelvic Pain Arising from Pelvic Congestion Syndrome
3. Chapter 11 – Irritable Bowel Syndrome
4. Chapter 16 – Other Peripheral Pelvic Neuralgias

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