Chapter 158

Chronic Pelvic Pain

Patricia Polgar-Bailey

Definition and Epidemiology

Chronic pelvic pain (CPP) is a continuous or episodic, nonmenstrual pain of at least 6 months’ duration, which may be sudden or gradual in onset, occurs at or below the umbilicus, and is severe enough to interrupt normal activities of daily life.¹ CPP may involve gastroenterologic, urologic, gynecologic, oncologic, musculoskeletal, and psychosocial systems, and its cause is often multifactorial, making it challenging for patients and providers.² Ideally, the cause of CPP is elucidated; however, in up to 50% to 60% of patients no clear cause is established and the absence of pathology often exacerbates the challenge of CPP.²^,³ CPP affects both men and women. Chronic prostatitis/chronic pelvic pain (CP/CPP) is a well-established cause of pelvic pain in men²; however, this chapter refers to the assessment and management of CPP in women. Chronic cyclic pelvic pain (CCPP) is a subset of CPP and is generally used to describe a CPP syndrome that occurs in relation to the menstrual cycle.¹ However, CCPP may also be used to describe pelvic pain that occurs in a cyclic pattern that is unrelated to the menstrual cycle.⁴

CPP is one of the most common medical problems affecting women today. In the United States CPP is estimated to affect approximately 15% of the female population aged 18 to 50.² In other parts of the world the prevalence of CPP is estimated to be higher. Recent studies demonstrated prevalence rates of approximately 25% in the United Kingdom and New Zealand.² Data indicate that the prevalence of CPP (38 per 1000) is similar to that of migraine, back pain, and asthma.⁵ CPP is considered the principal indication for 40% of gynecologic laparoscopies and 12 of all hysterectomies performed for benign disease annually in the United States.⁶ Epidemiologic studies have found that women with CPP are more likely to have a history of spontaneous abortion, nongynecologic surgery, and nonpelvic complaints than women without CPP.² In addition, a positive correlation has been demonstrated between CPP and a history of multiple sexual partners and psychosocial trauma and abuse. Women with CPP are four times more likely to have a history of pelvic inflammatory disease (PID), as well as higher incidences of constipation, irritable bowel syndrome (IBS), depression, and anxiety than those not affected by CPP.

Potential visceral sources of CPP include the reproductive, genitourinary, and gastrointestinal tracts; potential somatic sources include the pelvic bones, ligaments, muscles, and fascia. CPP may result from psychological disorders or neurologic diseases, both central and peripheral.⁷ It may be caused by one disorder, or it can be the end result of several diagnoses, with each contributing to the generation of pain and requiring management. Women with diagnoses that involve more than one organ system have greater pain than do women with only one system involved.⁸ The distinction between acute and chronic pain is significant. In acute pain, the pain is often a symptom of underlying tissue damage, such as anal fissure, and the diagnosis can be precise, but with CPP, the pain itself becomes the disease; CPP is itself the diagnosis.²^,⁹

Populations at Increased Risk of Chronic Pelvic Pain

Physical and Sexual Abuse.

A significant association exists between physical and sexual abuse and CPP. If a history of abuse is obtained, it is important to ensure that the woman is not currently being abused or in danger.

Pelvic Inflammatory Disease.

Approximately 18% to 35% of all women with acute PID develop CPP.¹⁰ The mechanisms by which CPP results from PID are not known, but the extent of adhesive disease, tubal damage, and pelvic tenderness present 30 days after treatment correlates with the likelihood of development of CPP. Whether acute PID is treated with inpatient or outpatient regimens does not appear to alter the odds for development of subsequent CPP (34% with outpatient therapy versus 30% with inpatient therapy).¹⁰

Endometriosis.

Endometriosis is the one of the leading causes of CPP in women and the most common diagnosis made at the time of gynecologic laparoscopy for the evaluation of CPP. Most often, women diagnosed with CPP in the setting of endometriosis are nulliparous, in their 20s to 30s, with symptoms associated with their menstrual cycle, including dysmenorrhea or pain.² Although endometriosis is diagnosed laparoscopically in approximately 33% of women with CPP, up to 40% of women with endometriosis and CPP will have no findings on laparoscopy.² There is often no correlation between severity of pain and pathologic findings.²

Interstitial Cystitis.

Interstitial cystitis is a chronic inflammatory condition of the bladder. It is clinically characterized by bladder pain, urinary frequency or urgency, or nocturia in the absence of evidence of another disease that could cause the symptoms.² Pain is often present in the suprapubic area but may also occur in the lower back or buttock. As many as 50% of women complain of dyspareunia; fibromyalgia, vulvodynia, anxiety, and depression are often associated complaints.²

Irritable Bowel Syndrome.

Approximately one third of women with CPP have IBS,⁸ and an estimated 65% to 70% of person with IBS have CPP.² IBS is a functional gastrointestinal disorder characterized by intermittent or chronic abdominal pain that is associated with bowel symptoms such as bloating, urgency, diarrhea, and constipation. IBS is associated with certain gynecologic problems, such as endometriosis, dyspareunia, and dysmenorrhea.¹¹ Women with both CPP and IBS are more likely to have screening and diagnostic procedures done and are less likely to have improvement after laparoscopy compared with women with only CPP.¹¹

Musculoskeletal Disorders.

Faulty posture may contribute to weak and deconditioned muscles, which allow imbalances in the pelvis with formation of trigger points and hypertonicity and, as a result, pelvic pain. Other musculoskeletal disorders, such as trigger points, lumbar vertebral disorders, pelvic floor myalgia, and fibromyalgia, may cause or contribute to pelvic pain.

Postsurgical Pain.

Chronic pain has been reported after several types of surgical procedures, including after cholecystectomy and groin hernia repair in less than 30% of patients and after cesarean section in 6% of patients. A study also found a 48.4% incidence of CPP in patients up to 5.6 years after surgery for pelvic fracture.¹²

Pathophysiology

The pathogenesis of CPP remains poorly understood, and diagnostic studies, such as laparoscopy, reveal no obvious cause of the pain in up to 35% of cases.² In a U.S. population study, 61% of women with CPP did not have a clear cause of their pain.⁵ Thus, chronic pain is thought to be a dynamic interaction of the combined influences of the mind and nervous system on the body. In addition to the organ system where the pain originated, other organ systems become involved and emotional changes occur with the long-term tension of CPP. For example, pain can cause muscle tension, which can in turn cause changes in the muscles of the pelvis, adjacent urinary tract (bladder, urethra), bowel, connective tissue, and even skin of the area. These secondary changes often become more significant than the original cause of the pain and also may overshadow the original disease process, making it more difficult to diagnose.

There are different theories about the development of chronic pain. According to an older theory of pain, called the cartesian theory, neurons carry pain signals from the damaged areas through the spinal cord directly to the cortex of the brain, where the pain is perceived. This theory is now thought to be an oversimplification of the development of chronic pain.

A newer theory, the gate control theory, posits that pain signals arise from the injured or adversely affected tissues and travel through specialized nerve cells to the spinal cord, where they can be intensified, reduced, and even blocked before they are transmitted to the brain. The spinal cord acts as a functional “gate” with respect to the pain signals. This gate is influenced by local factors such as nerve inputs in the spinal cord and by descending signals from higher brain centers. Thus, internal influences, other than the pain itself, and external environmental factors affect the nature of the pain’s impulse transmission. If the gates are damaged by chronic pain, they may remain open even after the tissue damage has resolved or been controlled. In other words, the pain remains despite the fact that the original cause of the pain has been treated; this type of pain is referred to as neuropathic pain, a key factor in CPP.⁹

Clinical Presentation

The evaluation of CPP can require many office visits and become a highly frustrating experience for both patient and provider. A complete and thorough history and physical examination are crucial in developing a rational approach to women with CPP. It is important that the patient understand early on that visits are not only for evaluation and treatment but also for the formation of a continued therapeutic relationship between patient and provider.

The history should include a description of the nature, intensity, distribution, radiation, location, and daily pattern of the pain, as well as the relationship of the pain to each organ system. Associated events, including complaints of fever, sweats, fatigue, anorexia, nausea, vomiting, and constipation, should be elicited. The relationship of the pain to posture, meals, bowel movements, voiding, menstruation, intercourse, and medications as well as any factors that aggravate or alleviate the pain should be determined. Past surgeries, pelvic infections, and a history of infertility are important diagnostic clues to the origin of the pain.

It is helpful to obtain an understanding from the woman of the past and present status of her pain, the chronology, and how it developed. It can be helpful to have the woman complete a detailed pain questionnaire before her first visit. Box 158-1 includes some questions that should be included on a CPP questionnaire.

Box 158-1

Chronic Pelvic Pain Questionnaire (Sample Questions)