Definition

Chronic pelvic pain (CPP), a common condition among women, affects up to one in four women of reproductive age at some point in their lifetime [1,2]. It can be an elusive disorder to diagnose and to treat, challenging even the most experienced clinicians. Despite variable opinions as to what constitutes this disorder, a widely accepted definition of CPP is noncyclic pain localized primarily in the anatomic pelvis, the anterior abdominal wall at or below the umbilicus, the lumbosacral spine, or the buttocks [3]. Traditionally, CPP must be of 6 months’ duration and severe enough to cause functional disability or to require treatment. It can be of gynecologic, urologic, gastrointestinal, musculoskeletal, or neurologic etiology. The pain that arises from CPP can be categorized into somatic, visceral, neuropathic, or referred pain.

The prevalence of CPP is estimated to be 3.8% in women aged 15 to 73 years, similar to that of asthma, back pain, and migraine headaches. In primary care practices, it is estimated that 39% of women have complained of pelvic pain [1,2,4]. There are no known demographic factors—age, race, ethnicity, education, or socioeconomic status—that put women at risk for development of CPP, although women with CPP tend to be of reproductive age.

Discovering the etiology of CPP (and therefore appropriate treatment) can be difficult because of the broad differential diagnoses and their many overlapping symptoms (see Table 106.1 for a complete list by organ system). In addition, these diagnoses are not mutually exclusive but in many cases may coexist. For example, endometriosis and myofascial pain are often known to overlap. Because of the diagnostic complexity of CPP, an accurate diagnostic approach cannot always be assumed. This is especially true if medical or surgical therapies for discrete diagnoses have failed to provide relief.

The initial diagnostic approach should begin with a thorough history to narrow the differential diagnosis. The pain history should include pain characteristics such as first occurrence, location, duration, temporal pattern, precipitating and alleviating factors, relationship to urination and defecation, patterns of radiation, intensity, and effect of pain on life activities (such as activities of daily living, sleep, work, sexual intercourse, and social or recreational activities). A monthly pain calendar, which records episodes, location, severity, and associated factors, is useful to obtain accurate and detailed information. The history should also include prior treatments; history of substance abuse; history of sexual, physical, and psychological abuse; and thorough review of systems. A pain map of the body is a useful tool to help the physician and patient specify pain patterns. The usual components of a patient history, such as medical problems, previous surgeries, and reproductive history, should be included as well. To streamline the process of obtaining a history for patients with CPP, the International Pelvic Pain Society has created the Pelvic Pain Assessment Form, which is an excellent and freely reproducible tool that can be found on its website [5].

The most common causes of CPP are of gynecologic, gastrointestinal, urologic, and musculoskeletal origin and include specific diagnoses, such as endometriosis, chronic pelvic inflammatory disease (PID), irritable bowel syndrome, bladder pain syndrome, and myofascial pelvic pain [6].

Endometriosis is a common gynecologic condition affecting women of reproductive age. It is characterized by the presence of endometrial tissue (the inner layer of the uterus) outside of the uterus. The extrauterine endometrial implants respond to the hormonal stimuli in the same way as intrauterine endometrium does, causing cyclic bleeding in the sensitive tissues of the peritoneum, ovaries, fallopian tubes, and elsewhere. This process can lead to formation of pelvic adhesions, scar tissue, and endometriomas.

This disorder is found in 10% to 15% of women of reproductive age, in 25% to 40% of women undergoing treatment for infertility, and in 33% of women who have laparoscopy for CPP. Risk factors include early menarche, short menstrual cycles (less than 27 days), and müllerian anomalies that involve vaginal or uterine obstruction of blood flow. Symptoms include long-standing cyclic pelvic pain, dysmenorrhea, menorrhagia, and deep dyspareunia. Severity of symptoms does not necessarily correlate with visual disease burden at time of surgery.

Uterine Leiomyomas

Leiomyomas (uterine fibroids, myomas) are benign smooth muscle tumors of the uterus and the most common neoplasm in women of reproductive age, with the highest prevalence in the fifth decade of life. The lifetime incidence of leiomyoma is 50% and up to 60% in women of African descent. Fibroids are thought to grow from estrogen stimulation. The most common symptoms are pressure from an enlarging pelvic mass, pain and dysmenorrhea, and abnormal uterine bleeding. The severity of symptoms is related to the size, number, and location of the tumors, although many women with fibroids are asymptomatic. In general, fibroids shrink after menopause. A myoma that grows rapidly after menopause is concerning for leiomyosarcoma, which occurs in 0.5% of fibroids.

Adenomyosis

Similar to endometriosis, adenomyosis is the presence of ectopic endometrial tissue in the myometrium (muscle layer) of the uterus. Adenomyosis develops from aberrant glands of the basalis layer of the endometrium and causes pain, dysmenorrhea, and menorrhagia. Some women experience intense pelvic cramping and pressure that radiates to the lower back, groin, rectum, and anterior thighs. Symptomatic adenomyosis usually is manifested in women aged 35 to 50 years, although adenomyosis can be found in asymptomatic women. The incidence of this disorder is unknown. As the ectopic endometrial tissue proliferates, the uterus takes on an enlarged, globular shape, which can sometimes be appreciated on examination.

Adhesive Disease

The correlation between abdominal adhesions and CPP is poorly understood, and studies of these are limited. It is thought that certain types of adhesions, particularly densely vascular adhesions to the bowel and peritoneum, cause CPP. Diagnosis can be made only at the time of laparoscopy as there are no examination findings, laboratory tests, or imaging studies that are reliably useful. Risk factors include a history of prior pelvic surgery, PID, endometriosis, inflammatory bowel disease, radiation therapy, and peritoneal dialysis.

Pelvic Congestion Syndrome

Pelvic congestion syndrome is a condition of vascular engorgement of the ovarian veins or internal iliac veins that leads to pelvic pain. Characteristic findings of gross dilation, incompetence, and reflux of the ovarian veins are seen on venography, sometimes forming parovarian pelvic varicosities. Dysfunction in the one-way valves of the ovarian veins is postulated as the underlying etiology. There is limited understanding of the prevalence of this condition as there are no definitive diagnostic criteria. As with most causes of pelvic pain, anatomic anomalies are not necessarily indicative of the presence or severity of pain. Pelvic congestion syndrome has been described only in premenopausal women. Typically, pain is worse after prolonged standing and improves in the morning after rest. Associated symptoms include marked ovarian tenderness, shifting location of pain, and deep dyspareunia or postcoital pain.

Chronic Pelvic Inflammatory Disease

PID starts as an acute condition and can become a chronic condition causing CPP. The transition from acute PID to chronic PID is incompletely understood and occurs in about 18% to 35% of women with acute PID. Women at risk for development of chronic PID include those who are not initially treated for the acute phase or are treated incompletely. In addition, the development of more severe adhesions or tubal damage and persistent pelvic tenderness 30 days after diagnosis and treatment increase the likelihood for development of CPP. Whether a woman is treated with an inpatient or outpatient regimen for acute PID does not have any bearing on the risk for later development of chronic PID or CPP [7]. Most PID is caused by Chlamydia trachomatis and Neisseria gonorrhoeae. Other implicated pathogens are Gardnerella vaginalis, Haemophilus influenzae, enteric gram-negative rods, and Streptococcus agalactiae. Diagnostic criteria and treatment of acute PID are published and maintained by the Centers for Disease Control and Prevention [8].

Gastrointestinal

Irritable bowel syndrome is a common functional bowel disorder of uncertain etiology characterized by a chronic, relapsing pattern of abdominopelvic pain and altered bowel habits in the absence of an organic cause. Although not all patients with this disorder seek treatment, the estimated prevalence is 10% to 15% in North America. The abdominal and pelvic pain is usually crampy in nature and varies in location, often exacerbated by emotional stress and eating habits and relieved by defecation. Patients also often complain of nongastrointestinal symptoms, such as altered sexual function, dysmenorrhea, urinary frequency, or dyspareunia.