Somatic pain refers to pain originating from an injury to the skin or the musculoskeletal system (muscles, fascia, joints, bones, ligaments, tendons, etc.) Somatic pain is a subset of nociceptive pain; a normal response to a noxious injury to these tissues.1
Injuries to the musculoskeletal system of the abdomen and pelvis may include abdominal or pelvic muscle strains or sprains, pelvic fractures, pubic symphysis dysfunction and diastasis pubic symphysis. Referred pain to the abdomen and pelvis may occur from failed back surgery from T9-L1 or rarely from muscles attaching to this region like latissimus dorsi2,3. Chronic post-surgical pain may commonly result following gastrointestinal surgery, hysterectomy, or hernia repair.4
Epidemiology including risk factors and primary prevention
Somatic abdominal and pelvic pain covers a wide variety of individual diagnoses, each with its own prevalence, risk factors and prevention. Diagnoses may include nerve injury, muscle strain/sprain, childbirth trauma, fractures, ligamentous injury, post-surgical pain and/or complications as well as rheumatologic disease. In some cases of chronic pelvic pain, the definitive diagnosis remains uncertain.
- Risk for chronic post-surgical pain is 20-32%; epidural anesthesia as opposed to general anesthesia may reduce this risk4
- Abdominal oblique muscle strains constitute about 5% of all baseball injuries, with a re-injury rate around 12%, complete treatment with physical therapy and sufficient core muscle strengthening may reduce re-injury5
- Athletic pubalgia, “sports hernia” (disruption of the rectus abdominus muscle from the pubic tubercle) may occur in recreational, high school, college, or professional athletes6
- Chronic pelvic pain is present in 5-43% of women, with musculoskeletal disorders present in 75-85% of these women7
Nerves of the Anterolateral Abdominal Wall (may be susceptible to injury or irritation with abdominal surgery)
- Thoracoabdominal (T7-T11) – muscles of anterolateral abdominal wall and overlaying skin
- 7th-9th lateral cutaneous branches of the 7th- 9th intercostal nerves – skin of right and left hypochondriac regions
- Subcostal (T12) – muscles of anterolateral abdominal wall and overlaying skin
- Iliohypogastric (L1) – internal oblique, transversus abdominis, skin over the iliac crest, upper inguinal and hypogastric regions
- Ilioinguinal (L1) – inferiormost internal oblique, transversus abdominis, skin over lower inguinal region, mons pubis, anterior scrotum and labia majora
Pelvic Nerves (susceptible to injury during childbirth or surgery)
- Sacral plexus may be compressed by fetal head
- Obturator nerve vulnerable during lymph node retrieval in lateral pelvic wall
Muscles of anterolateral abdominal wall (susceptible to strain/sprain, as a group called oblique muscle strain or side strain). Side strains are common in sports where trunk rotation generates power for the upper extremities like baseball, tennis, golf, cricket, and Olympic throwing events.5
- Rectus Abdominis
- Transverse abdominal
- Internal Oblique
- External Oblique
- Pyrimidalis (absent in 20% people)
- Walls and Floor of the pelvic cavity (susceptible to childbirth trauma)
- Obturator internus – lateral wall
- Piriformis – posterolateral wall
- Coccygeus (isciococcygeus)
- Levator ani
- Pubococcygeus (most commonly torn during childbirth trauma)
Bones (and associated ligaments)
Pelvic Girdle (susceptible to fracture from high force injuries and childbirth trauma, ligamentous injuries as well as rheumatologic problems, such as ankylosing spondylitis)
- Pubic Symphysis
- Sacroiliac Joints
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time):
Disease progression in abdominal and pelvic somatic pain will vary widely depending on specific diagnosis. Correct early diagnosis and treatment can abate progression to the chronic pain state.
Pain is characterized by a sudden, sharp onset of pain with localized tenderness
Recovery stage: in routine healing, the patient’s somatic pain will continue to improve, with decreased use of analgesics and improving function
Untreated or insufficiently treated, pain may progress to the chronic pain state
Chronic pelvic pain may be a result of viscero-visceral, viscero-somatic or somato-visceral convergence6 convergence7 whereby pathology in one viscera or myotome may create pathology in another organ or muscle group which share the same innervation levels in the central nervous system
Metastases to pelvic girdle or abdominal wall may be the pain generating source, or may lead to pathologic fractures or tissue injuries
2. ESSENTIALS OF ASSESSMENT
Identify location, onset, palliative and provocative factors. Assess quality, radiation of pain, severity and timing. Past surgical history including remote and recent surgeries, as well as pregnancies and delivery history may provide trauma clues in both abdominal and pelvic pain. Visceral source for the pain must be ruled out, including red flags for malignancy or infection. Psychosocial aspects include depression, disability and history of rape or abuse.
- General assessment of appearance and degree of discomfort, surgical scars
- Vital signs to help to rule out systemic or visceral pathologies
- Abdominal examination including palpation, percussion and auscultation to evaluate both superficial musculature as well as to rule out visceral pathologies including masses, hernias, ascites, hepatomegaly or splenomegaly
- Pelvic examination including bimanual examination for cervical, adnexal and uterine tenderness as well as pelvic floor muscle tenderness
- Rectal examination including prostate examination
- Special Tests: Flank percussion for renal pathology, rebound, guarding, Murphy’s sign for gall bladder pathology, Rovsing’s sign for appendicitis
- Evaluation for provocative maneuvers for myofascial pain
- Hip examination including ROM, muscle testing and FABERE/FADIR tests
Functional assessment: mobility, self care, cognition/behavior/affective state
Severe abdominal and/or pelvic somatic pain, such as that caused by pelvic fractures, or post-operative pain, may limit a patient’s independence with mobility and/or self-care. Both inpatient and outpatient evaluations of patients with severe pain should address this possibility.
Chronic abdominal and/or pelvic pain has a strong association with psychological comorbidities, including anxiety, depression and disability.
Laboratory studies are used to rule out visceral causes of abdominal and pelvic pain (including but not limited to urinalysis, complete metabolic panel, amylase, lipase, stool occult blood, PAP smear), as well as systemic diseases (CRP, ESR, CK, CBC). If visceral source for pain is suspected, referral to an internist, gastroenterologist or gynecologist is appropriate.
Imaging may be ordered to rule out visceral pathology or for definitive diagnosis of musculoskeletal pathology. Musculoskeletal ultrasound is gaining increased utilization for abdominal wall sprains, strains and nerve injuries.2,5 Plain films will show most fractures as well as pubic symphysis diastases, though MRI or CT scans may be required in some if strong clinical suspicion persists despite negative X-rays.
Supplemental assessment tools
- Pelvic EMG to evaluate for pelvic floor dysfunction
- Pudendal nerve conduction study
- Perineometry(instrumental measurement of pelvic muscle tone and/or strength)
- Diagnostic nerve blocks
- Behavioral and psychological screening
- Pain Catastrophizing Scale9
- Musculoskeletal ultrasound
Early prediction of outcomes
Patients with prior psychiatric diagnoses, prior history of drug and/or alcohol abuse, unemployed status, higher pain catastrophizing scores, higher emotional distress, less family/social support and poor motivation may be more likely to progress to chronic pain state 9,10
For athletes with injuries inhibiting return to play, it is important to ensure the athletic directors, managers, patient and physicians are on the same page to allow proper healing and decrease the risk for re-injury.
For patients with chronic pain, a social worker or case manager may be utilized to assist with home assessments and to evaluate for safety in cases where physical or sexual abuse is apparent or suspected.
Social role and social support system
Support groups or counseling may be available for patients with chronic pain or cancer pain, as well as patients with a history of physical abuse or rape. For patients for whom their pain inhibits or interferes with sexual activity, specialized support is needed and may be crucial.
Ethical and legal considerations
Patients with a history of polysubstance abuse may face physician bias when presenting with pain. Use of opiates in patients with a history of substance abuse is controversial and often under-prescribed for patients with real pain and this past medical history
Unnecessary progression to opiate use may contribute to a patient’s progression to the chronic pain state, upsetting the balance between maleficence and beneficence
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
The hallmark of treatment for somatic abdominal and pelvic pain relies on proper diagnosis of the underlying pathology, Postoperative pain and fractures may require more aggressive acute pain treatment to prevent progression to the chronic pain state. Pain from metastases to the pelvic girdle or abdominal wall may also require high amounts of pain medications and more aggressive treatments.
At different disease stages:
- Activity modification
- Tylenol, NSAIDs first line
- Opiates may be indicated for severe pain, post-operative pain, fractures
- Muscle relaxants may be considered
- Gradual increase in activity
- Core or pelvic floor muscle strengthening
- Physical therapy
- Includes all of the above
- Botulinum toxin type A for abdominal or pelvic wall muscle spasms7
- Interventional procedures including neural blockades
pre-terminal or end of life care
- Cancer related abdominal wall pain may require opiates or interventional procedures including nerve blocks. Palliative radiation may be considered with bony metastases.
Spectrum of treatment approaches
Treatment availability may vary greatly depending on regional resources. Physical therapists trained in pelvic floor rehab are often sparse, as may be physiatrists with knowledge in this area. Accordingly, these patients may be cared for by gynecologists and internists. It is important to advocate for the patient to utilize all resources available.
Patient & family education
Both the patient and family members should be kept informed of diagnosis and disease progression, treatment options and potential complications of treating or not treating the disease process, as well as reasonable goals and expectations throughout the different stages of treatment and recovery.
Translation into Practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
Treatment of somatic abdominal and pelvic pain requires adequate diagnosis of the underlying cause. The WHO analgesic ladder can be used as a guide for medication management.
4. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
There is a sparseness of high evidence based literature pertaining to somatic abdominal and pelvic pain, with much of the evidence coming from case studies. 7 Diagnosis in abdominal and pelvic somatic pain remains challenging, with much variability between physicians.
5. CUTTING EDGE CONCEPTS AND PRACTICE
Neural blockade of the thoracolumbar nerves supplying the anterior abdominal wall through transversus abdominis plane (TAP) provides sensory blockade of the T9-L1 dermatomes. This procedure is typically used for acute pain management following abdominal surgery. However case reports exist using this procedure for chronic pain syndromes.2 Following initial ultrasound guided TAP block, a pulse generator or infusion pump may be placed for long term pain relief.9
- Ganong, William R. Review of Medical Physiology. New York: McGraw-Hill Medical, 2005. Print
- Asensio-Samper JM, De Andrés-Ibáñez J, Fabregat Cid G, Villanueva Pérez V, Alarcón L. Ultrasound-guided transversus abdominis plane block for spinal infusion and neurostimulation implantation in two patients with chronic pain. Pain Pract. 2010 Mar-Apr;10(2):158-62.
- Sandford PR, Barry DT. Acute somatic pain can refer to sites of chronic abdominal pain. Arch Phys Med Rehabil. 1988 Jul;69(7):532-3.
- Bouman EA et al. Reduced incidence of chronic postsurgical pain after epidural analgesia for abdominal surgery. Pain Pract. 2014 Feb;14(2): E76-84.
- Conte SA, Thompson MM, Marks MA, Dines JS. Abdominal muscle strains in professional baseball: 1991-2010. Am J Sports Med. 2012 Mar;40(3):650-6.
- Ahumada LA, Ashruf S, Espinosa-de-los-Monteros A, Long JN, de la Torre JI, Garth WP, Vasconez LO. “Athletic pubalgia: definition and surgical treatment”. Ann Plast Surg. 2005;55 (4): 393–6.
- Bhide AA, Puccini F, Khullar V, Elneil S, Digesu GA. Botulinum neurotoxin type A injection of the pelvic floor muscle in pain due to spasticity: a review of the current literature. Int Urogynecol J. 2013 Sep;24(9):1429-34.
- Moore, Keith L. and Arthur F. Daley. Clinically Oriented Anatomy, Fifth Edition. Maryland: Lippincott Williams & Wilkins, 2006. Print.
- The Pain Catastrophizing Scale: Development and validation. Sullivan ML, Bishop SR, Pivik J. Psychological Assessment. Dec 1995; 7(4): 524-532.
- Guirguis MN, Abd-Elsayed AA, Girgis G, Soliman LM. Ultrasound-guided transversus abdominis plane catheter for chronic abdominal pain. Pain Pract. 2013 Mar;13(3):235-8.
Stephanie E. Rand, MD
Nothing to Disclose