Definition and Prevalence

The American College of Obstetricians and Gynecologists defines chronic pelvic pain (CPP) as “pain symptoms perceived to originate from pelvic organs and structures typically lasting more than 6 months. It is often associated with negative cognitive behavioral, sexual, and emotional consequences as well as with symptoms suggestive of lower urinary tract, sexual, bowel, pelvic floor, myofascial, or gynecologic dysfunction.” ^, The prevalence of CPP in heterosexual women is estimated to be 5.7% to 26.6% as demonstrated by a 2014 systematic review of 7 CPP studies. More recently, a 2022 study further characterized the prevalence of CPP in 6,150 US women of different sexual orientations and found an increased prevalence of lifetime CPP among women who identified as mostly heterosexual and lesbian when compared to completely heterosexual women. In addition, CPP was found to be more common in women who reported to have both men and women as past sexual partners compared to women who reported only past male sexual partners. Risk factors associated with CPP include psychological morbidity, history of sexual abuse, substance use disorders, low physical activity, and body mass index. ^,

CPP has a significant impact on quality of life and disability. CPP is associated with significant morbidity and contributes to long-term medical therapies. In a 1996 study, it was estimated that about $2.8 billion is spent annually on the management of CPP (about $5.5 billion in 2024). Women with CPP account for 40% of laparoscopies and 12% of the hysterectomies in the United States, yet the origin of CPP is found to be not gynecologic in 80% of patients. ^,

Etiology of Chronic Pelvic Pain

CPP is multifactorial in nature and can be associated with visceral, neuropathic, musculoskeletal, and psychological symptoms. Additionally, there is significant overlap of these systems, making it difficult to target one system as the primary pain generator. For example, the visceral and somatic structures including the skin, muscles, and bones share neurologic pathways in the brain and spinal cord. The sharing of these pathways can lead to viscerosomatic convergence or viscero-viscero cross sensitization in which painful stimuli from one organ can result in painful stimulation in another organ or tissue. Similarly, painful stimuli from muscle or tissue can lead to noxious stimuli in organs. Due to the repeated stimulation into the central nervous system, responsiveness of the brain and spinal cord becomes enhanced leading to decreased pain inhibition. This can result in the phenomenon called central sensitization involving widespread hypersensitivity to pain in addition to associated sleep disturbances and poor mood and coping mechanisms. ^, There are several conditions which, when present with CPP, are strongly suggestive of central sensitization. These conditions include chronic low back pain, fibromyalgia, irritable bowel syndrome, temporomandibular joint disorder, endometriosis, interstitial cystitis, and chronic fatigue. Organ-specific treatment is often insufficient to treat CPP in the setting of sensitization and myofascial dysfunction. ^, In fact, 50% to 90% of women who have a musculoskeletal examination of the pelvic floor, back, and hips have pain originating from these structures. If the musculoskeletal examination is dismissed, patients may experience a delay in treatment, unnecessary surgical procedures, and prolonged pain. ^,

Overlapping Pain Diagnoses

Common comorbid contributors to pelvic pain include irritable bowel syndrome (IBS), interstitial cystitis or painful bladder syndrome, pelvic floor muscle myofascial pain, endometriosis, and depression. Prevalence of these conditions in women with CPP ranges from about 20% to 60%. There are also several conditions in which the prevalence of CPP is higher including generalized hypermobility spectrum disorders such as Ehlers-Danlos in addition to common chronic overlapping pain syndrome conditions including fibromyalgia, temporomandibular disorder, urologic syndrome, vulvodynia, chronic low back pain, chronic tension type headache, migraines, and chronic fatigue syndrome. Additionally, patients with CPP have been found to often have comorbid endometriosis, vulvodynia, IBS, interstitial cystitis, hip or lumbar pain ( Table 1 ).

Mechanisms that may be involved in these overlapping disorders may include neurotransmitter or neuroendocrine dysfunction in the central nervous system, adverse childhood events, and psychological distress or psychiatric disorders. ^{, ,} Given the many overlapping conditions of numerous organ systems in addition to coordinating treatment for comorbid conditions, such as depression and anxiety, interdisciplinary care is critical for the treatment of CPP. ^,

The Bony Pelvis

The posterior pelvic ring is made up of the 2 sacroiliac joints (SIJ) and the anterior and posterior sacroiliac ligaments. The anterior sacroiliac ligaments include the anterior longitudinal ligament, the anterior sacroiliac ligament, and the sacrospinous ligament. Their primary function is to resist upward movement of the sacrum and lateral movement of the ilium. The posterior sacroiliac ligaments include the supraspinous ligament, iliolumbar ligament, sacrotuberous ligament, and the short and long dorsal sacroiliac ligaments. They function to resist downward and upward movement of the sacrum and medial motion of the ilium. Importantly, the long dorsal sacroiliac ligament is thought to be a source of posterior pelvic pain as forces are transmitted from the SIJ and hip to the nociceptors in the ligament. The anterior pelvic ring includes the pubic symphysis which is a cartilaginous joint between the 2 pubic bones. The 4 pubic ligaments, anterior, posterior, inferior, and superior pubic ligaments, help stabilize the pubic symphysis against tension or compression stresses.

The Pelvic Floor

The muscles of the pelvic floor function to maintain continence and allow micturition and defecation and assist in vaginal childbirth. When the muscles of the pelvic floor contract, they act to close the urethra, anal sphincters, and vagina, helping maintain continence. When the muscles relax, they aid in micturition and defecation. The muscles that make up the pelvic floor are organized into 3 categories: the superficial perineal layer, the deep urogenital diaphragm layer, and the pelvic diaphragm. In the superficial perineal layer are the bulbospongiosus, ischiocavernosus, and the superficial and deep transverse perineal muscles. The deep pelvic floor muscles include coccygeus and levator ani which is made up by the puborectalis, pubococcygeus, and iliococcygeus muscles ( Fig. 1 ). The pelvic diaphragm is composed of levator ani, coccygeus, and the endopelvic fascia. The deep external rotators of the hip—piriformis and obturator internus muscles, while not directly a part of the pelvic floor, make up the lateral walls of the pelvis and can often contribute to pelvic pain. A key structure in the pelvic floor is the perineal body, also called the central perineal tendon. The perineal body is the attachment for many pelvic muscles and sphincters and is located between the vagina and the anus. Of note, rupture of this entity, which can occur in childbirth, can lead to pelvic organ prolapse.

Pelvic floor musculature.

( From Braddom’s Physical Medicine and Rehabilitation, 774-788 . Sixth edition. Copyright @ Elsevier, 2021. The muscles of the (A) superficial pelvic floor and (B) deep pelvic floor. Illustration by Elijah Leonard. Redrawn from Prather H, Dugan S, Fitzgerald C, Hunt D: Review of anatomy, evaluation, and treatment of musculoskeletal pelvic floor pain in women, PMR 2009;1:346–358.)

Innervation of the Pelvic Floor

Innervation of the pelvic structures is through somatic, visceral, and central pathways ( Table 2 ). The sacral plexus is responsible for the majority of innervation of the pelvic floor. The iliohypogastric, ilioinguinal, and genitofemoral nerves (L1 to L3 nerve roots) innervate the skin of the lower trunk, perineum, and proximal thigh. The lateral femoral cutaneous nerve innervates the lateral thigh and the obturator nerve innervates the skin of the medial thigh along with the adductor muscles in the medial thigh. The pudendal nerve originates from the ventral branches of S2 to S4 of the sacral plexus. The pudendal nerve takes a tortuous route in the pelvis, passing between the piriformis and coccygeal muscles, through the greater sciatic foramen, over the spine of ischium, and then reentering the pelvis through the lesser sciatic foramen. The pudendal nerve borders the lateral wall of the ischiorectal fossa where it is held in the sheath from the obturator fascia called Alock’s canal. ^,

The pudendal nerve and its 3 branches, the inferior rectal/hemorrhoidal nerve, the perineal nerve, and the dorsal nerve of the clitoris, mainly innervate the superficial and anterior muscles in the pelvic floor. Namely, the pudendal nerve innervates the bulbospongiosus, ischiocavernosus, and anterior portions of levator ani muscles, the perineum, anus, external anal and urethral sphincters, and clitoris ( Fig. 2 ). The pudendal nerve, therefore, is responsible for external genital sensation, continence, and orgasm. Of note, although the anterior portion of levator ani is innervated by the pudendal nerve, most of the levator ani is innervated directly from sacral nerves S3 to S5. ^, This innervation pattern is important when considering symptomatology for pudendal neuralgia which will be discussion in subsequent articles.

Pelvic floor muscle innervation and nerve routes.

( From Braddom’s Physical Medicine and Rehabilitation , 774-788. Sixth edition. Copyright @ Elsevier, 2021. Redrawn from Prather H, Dugan S, Fitzgerald C, Hunt D: Review of anatomy, evaluation, and treatment of musculoskeletal pelvic floor pain in women. PMR 2009;1:346–358.)