Presented by: Jennifer Hah, MD, MS
Instructor, Division of Pain Medicine
Department of Anesthesiology, Perioperative and Pain Medicine
Stanford University Medical Center
February 20, 2014
Because the pelvis is such a large and complex area, pelvic pain can be diffuse and difficult to isolate. It can remain localized at its source, or it can interact with the other organs crowded within the lower abdomen, including the bladder, colon, and reproductive organs.
Pain is caused when visceral nerves in the pelvis, which are usually silent, are activated. Visceral pain is usually poorly localized and often described as a vague discomfort. These nerves can interact with somatic nerves and the sympathetic and parasympathetic nervous system.
Sympathetic system activation can result in sweating and increased blood pressure, while parasympathetic system activation can lead to decreased blood pressure and heart rate.
In some cases, either the sympathetic or parasympathetic system can remain activated and perpetuate the pain. The nerves communicate and interact so closely, a process called viscerosomatic convergence, that it can sometimes make it difficult for patients and physicians to pinpoint the origin of the problem.
“In cases of pelvic pain, there are so many organs, muscles, ligaments, and nerves in such a small area that it that can require the expertise of a number of specialties, such as gynecology, urology, gastroenterology, neurology, and colorectal surgery,” said Jennifer Hah, MD, an instructor in the Department of Anesthesiology, Perioperative and Pain Medicine, at a presentation sponsored by Stanford Hospital Health Library.
One of the bony components of the pelvis susceptible to pain is the coccyx, the structure at the bottom of the vertebral column. Also known as the tailbone, it is composed of four bony segments held in place by numerous ligaments, and serves as the attachment for the levator ani muscles, which stabilize the pelvic floor.
One source of chronic pain emanating from this area can be a Tarlov cyst, a fluid-filled sac that contains nerve root fibers usually in the sacral region. These meningeal cysts may cause sharp, burning pain in the hip and down the back of the thigh. The pain related to these cysts can be treated non-surgically through procedures such as caudal epidural steroid injections, sacral selective nerve root blocks, or ganglion impar blocks performed by pain medicine specialists
“The muscles of the pelvic region form a big bowl that literally holds the organs in place,” Dr. Hah said. “There are a lot of structures in this tiny area that we have to assess to determine where the pain starts. They all work in conjunction.”
For example, the muscle that creates a “sling” around the rectum, the puborectalis, can respond inappropriately during defecation by remaining contracted, causing constipation and pain. Treatment may require blockade of the pudendal nerves.
Another muscle that can cause chronic pain is the piriformis, located near the top of the hip joint. When the piriformis muscle compresses the sciatic nerve, it can cause shooting pain down the leg. Treatment can involve ultrasound-guided injections of the muscle to relieve tension on the sciatic nerve.
In certain cases, treatment may involve strategies to block the painful sensations by targeting a plexus containing visceral nerves, sympathetic fibers, and parasympathetic fibers. One option is a superior hypogastric plexus block, used to target pain emanating from organs including the uterus, cervix, prostate, rectum, or bladder. Pain related to conditions such as endometriosis, pelvic malignancies, or post-herpetic neuralgia involving the sacral region can be treated with a superior hypogastric plexus block. A ganglion impar block can be used to reduce symptoms in the perineum, rectum, or genitalia, or coccydynia (tailbone).
Dr. Hah also mentioned some of the numerous peripheral nerves that can cause chronic pelvic pain, including the iliohypogastric nerve and the ilioinguinal nerve, which can be irritated by surgical retraction, or entrapped by scars after surgery. Pain related to these nerves is often perceived in the groin region. These nerves are often blocked together under direct ultrasound guidance, she said. Another common treatment for pain related to any peripheral nerve is pulsed radiofrequency. Similarly, the pudendal nerve, which provides the main skin sensory of the pelvic floor, can be damaged by many causes including prolonged labor, straddle injuries, or constipation.
Diagnosing the cause of pelvic pain requires a careful history and a thorough exam. “We need to consider all factors, even things that may have happened 10 years ago,” said Dr. Hah.
Diagnosis and Assessment
It’s estimated that 16 to 25 percent of adult women have pelvic pain, said Dr. Hah, and as much as one-third are affected by endometriosis, an often painful disorder caused when the endometrial tissue that normally lines the inside of the uterus starts to grow outside its boundaries. Endometriosis, which occurs several years after the onset of menstruation, causes high levels of pain and can affect fertility. The condition is usually treated with oral contraceptives or other hormonal agents, or surgery.
Pain related to endometriosis can be managed through multidisciplinary care involving physical therapy, , pain psychology modalities, medication, and injections, such as a superior hypogastric plexus block.
Pelvic congestion syndrome often causes deep pain during and after intercourse, with increased pain during prolonged standing, lifting, or walking. This condition can be treated hormonally, with physical therapy, or through surgical intervention.
When no identifiable cause can be determined, chronic pain in the external vaginal area is called vulvodynia. It can involve chronic and severe vulvar pain, itching, stinging, or burning. This condition can be treated in a number of ways, ranging from estrogen creams, lidocaine gel, and Botox, to biofeedback and counseling, to surgery, she said.
Interstitial cystitis, or bladder pain syndrome, is a chronic condition that encompasses pain, pressure, or discomfort associated with urinary urgency, frequency, and painful urination. For these patients, experts in pain management work closely with colleagues in urology and gynecology to develop the optimal multidisciplinary treatment strategies.
These approaches focus on dietary modifications, pelvic floor physical therapy, and psychosocial support, Dr. Hah said, and may involve tactics like keeping a food diary, voiding by the clock, and, as well as medication management.
“In time there will be more options and more effective therapies based on phenotype, so that we can target treatment based on how each patient will respond,” she said.
About the Speaker
Jennifer Hah, MD, MS, is an instructor in the Department of Anesthesiology, Perioperative and Pain Medicine. She is board certified in pain medicine and in anesthesiology by the American Board of Anesthesiology. Dr. Hah received her MD at Northeast Ohio Medical University and her MS in epidemiology at Stanford. She did her residency and internship in anesthesiology at the Cleveland Clinic Foundation in Ohio and at Stanford, where she completed her fellowship in pain medicine.
For More Information:
Stanford Pain Management Center
Stanford Department of Anesthesiology
Women’s Health @ Stanford