Pelvic Pain

This chapter presents the most common causes of chronic pelvic pain (CPP). CPP is a prevalent and challenging disorder to manage. CPP is a noncyclic pain of 6 or more months’ duration that localizes to the anatomic pelvic, anterior abdominal wall at or below the umbilicus, the lumbosacral back, or the buttocks and is of sufficient severity to cause functional disability or lead to care. Roughly 38 of 1,000 visits in the primary care setting among women aged 15 to 73 is for CPP, comparable to the incidence of asthma visits.¹ CPP is the most common reason for referral to gynecology clinics, accounting for 20% of all appointments.² In one-third to one-half of these cases, the pathology cannot be identified.³ To make treatment even more challenging, CPP may occur in 50% of patients with a history of physical or sexual abuse.⁴

This chapter covers diagnosis and treatment modalities for the most common causes of CPP. Treatment for known diagnoses is explored first. These common causes of CPP, for which the diagnosis is known, are described in Table 5-1. It is important to remember that patients with CPP may have more than one disease that may lead to pain.

In fact, endometriosis and interstitial cystitis (IC) are commonly referred as the evil twins. Cancer as a cause of pelvic pain is covered in Chapter 3, Cancer Pain. Some of the most challenging CPP cases are those for which the diagnosis cannot be determined.

How to determine the cause of CPP when the diagnosis is not readily known is beyond the scope of this book. Although we cannot currently make the diagnosis, we understand the painful symptoms and what treatment modalities work well for those symptoms. In these cases, the therapeutic plan will be treating the symptoms. Treating pelvic pain of unknown etiology can be frustrating to both the patient and the physician.

Common Causes of Chronic Pelvic Pain

Common Known Diagnosis of Chronic Pelvic Pain

If the diagnosis is known, you have the pain generator. Table 5-1 lists the most common, high-yield causes of CPP, and how they present.

If the diagnosis is unknown, it is important to determine whether the pain is visceral, somatic, neuropathic, or a combination.

Visceral Pelvic Pain

Visceral pain is pain that comes from an organ, such as the bladder or rectum, or in females the uterus, ovaries, and fallopian tubes. Pain is elicited with distension, compression, or torsion of an organ. Visceral pain is not well localized and often described as dull and achy. This is because there are a small number of visceral afferent nerves covering a large area (e.g., the bladder), thus many fewer nerves to help pinpoint the exact pain location.

Somatic Pelvic Pain

Somatic structures are the support structure of the pelvic cavity, which include fascia, muscles, and the pelvic floor. Somatic pain is often well localized and typically described as sharp and focal.

Neuropathic Pelvic Pain

Nerves send sensory impulses to the brain for interpretation. These impulses travel along a nerve axon in a regular pattern when the nervous system is working correctly. When a nerve is injured, this regular controlled transmission of impulses fails and the nerve
fires aberrantly. Injured nerves develop pathologic activity, manifesting as abnormal excitability. They have an elevated sensitivity to normal chemical, thermal, and mechanical stimuli that would not typically trigger a nerve to fire. This aberrant nerve firing is interpreted by the brain as neuropathic pain. Nerves can be damaged in a number of ways: Mechanically, via infection, from metabolic conditions, toxins, radiation, and idiopathically. In neuropathic pain, the patient usually reports an electric, shooting, burning pain rather than an achy, dull pain.

Table 5-1 Most Common High-yield Causes of CPP and their Pathology and Presentation

Diagnosis	Pathology and Presentation
Postoperative pelvic adhesions	Abnormal bands of scar tissue. Typically, adhesions show no symptoms. Adhesions may cause visceral pain by impairing organ mobility. Of open gynecologic procedures, ovarian surgery carries the highest risk of readmissions directly related to adhesions (7.5/100).⁵ When symptomatic they can present as deep, dull, achy pain. Adhesions involving the vagina or uterus may cause pain during intercourse.
Endometriosis	Collection of endometrial cells that develop remote from the uterus. During hormonal stimulation, the endometrial tissue triggers an inflammatory response. This is a surgical diagnosis confirmed by pathology. The degree of visible endometriosis has no correlation with the degree of pain, because location is more predictive than total volume. Increased pain usually occurs a few days before menses and begins to resolve 1–2 d into the menses. Pain during or after sex is common with endometriosis and usually predictive of deep rectovaginal endometriosis. Sonographic findings may include cysts in the ovaries, referred to as endometriomas. Patients may present with problems becoming pregnant.
Pelvic congestion syndrome (pelvic varices)	Overfilling of the pelvic venous system. This can be a result of pregnancy or of unknown origin. This pain is not related to the menstrual cycle. Pain is constant and worse with standing; patients may get some relief when they lie down. Pain is worse as the day goes on. Patients often complain of postcoital ache and may have heavy vaginal discharge.
Leiomyoma (fibroid)	A commonly benign tumor that occurs within the uterus. The pathogenesis of pain associated with these lesions is unclear. They are more common in African-Americans than Whites. Increased menstrual bleeding, known as menorrhagia occurs. Pain can be spontaneous or induced by tactile pressure. Symptoms often become worse during pregnancy.
Interstitial cystitis (IC)	Inflammation of the bladder wall. The cause is unknown. It is more common in women than men. There are no radiographic, laboratory, or serologic findings; and no biopsy patterns that are pathognomonic for interstitial cystitis. Daytime and nighttime urinary frequency, urgency, and pelvic pain for at least 6 wks are characteristic. The cystitis may be worse around the menstrual cycle. There is an absence of proven urinary infection. There are intermittent periods of exacerbations and remissions. Approximately 90% of cases are female.
Chronic prostatitis	Found in males, this term is a misnomer as there is no evidence, it is associated with infection. Nonetheless it is usually treated with oral antibiotics. This condition involves intermittent dysuria and pelvic pain or discomfort, for more than 3 of the previous 6 mos without documented urinary tract infections. Patients may have ejaculatory pain and erectile dysfunction.
Irritable bowel syndrome	Irritable bowel syndrome (IBS) is a functional GI disorder characterized by abdominal pain and altered bowel habits in the absence of specific and unique organic pathology. Spasmodic pelvic and abdominal cramping that varies in location. Often associated with pain relief with defecation. May be associated with constipation, diarrhea, or mixed picture. Symptoms may increase with menses.
Extra-pelvic referred pain	E.g., thoracic–lumbar spine pathology. Symptoms vary.