Abdominal Pain



Abdominal Pain


Joshua Lee, MD

Jon Zhou, MD



FAST FACTS



  • Most patients with chronic abdominal pain have functional GI disorders such as functional dyspepsia or irritable bowel syndrome.


  • Chronic abdominal pain syndromes can be subdivided into 2 categories: intra-abdominal and abdominal wall origin.


  • Chronic abdominal pain may coexist with other medical and psychological syndromes such as obesity, depression, and anxiety.


  • Abdominal pain is the second most common recurrent pain condition in children after headaches.




MECHANISMS AND PAIN PATHWAYS

Anatomical abdominal pain pathways are complex owing to the presence of and possible coexistence of different types of nociceptive pain: visceral, somatic, and referred pain.

Somatic pain is defined as “pain arising from tissues such as the skin, muscle, joint capsules, and bone.” Stimuli from somatic pain are primarily mediated by the C and A-delta afferent fibers, which also innervate the mesentery. Direct damage to the gastrointestinal tissue, such as ischemia, triggers firing of C and A-delta afferents that are present within the serosal layer of the gastrointestinal (GI) tract.

Visceral pain is defined as “pain arising from visceral organs.” Visceral pain can often be diffuse, vague, and difficult to localize in some cases. Abdominal pain is mediated by the dual supply of visceral sensory information received by the splanchnic nerves and somatic information from cerebrospinal innervations. The splanchnic pathway innervates the visceral organs, where pain signals are transmitted by free afferent nerve endings through the spinal cord to the thalamus via the paleospinal and archispinal thalamic tracts. These afferent receptors are primarily located within
the mucosal epithelium of the gastrointestinal tract and are mechanosensitive, receiving information from physical alterations in the tissue due to stretch and spasms2 (Figure 18-1). Caustic agents and extreme changes in intraluminal pH can also cause firing of these visceral afferents (Table 18-1).


CLINICAL PRESENTATIONS OF ABDOMINAL PAIN

According to the CDC report, acute abdominal pain was the most common presenting complaint to emergency departments in the United States between 1998 and 2008.3 Although less common in the office-based setting, abdominal pain remains a common reason for primary care visits.4 Appropriate triaging and timely referrals by the primary physician could be potentially life-saving, especially in a practice far removed from a major facility with the capacity to intervene on major vascular emergencies.

In the primary care setting, the presentation of acute abdominal pain is most likely to be acutely atraumatic in nature (Figure 18-2).

The first immediate step in evaluating acute abdominal pain in an office-based practice should be a focused and general assessment of the patient’s appearance and vital signs, with an emphasis on any objective evidence of possible hemodynamic instability. The goal of this very first step is to determine whether emergent interventions and resuscitative measures are required before transport to the higher level-of-care and to reduce overall morbidity and mortality.






FIGURE 18-1 Neural pathways carrying pain information from visceral organs. ©2019 Lippincott Professional Development®.


APPROACH TO CHRONIC ABDOMINAL PAIN DISORDERS

Chronic abdominal pain syndromes can be subdivided into two categories: intra-abdominal and abdominal wall origin. Evaluation of chronic abdominal pain can be complex given the myriad of possible causes, some possibly overlapping in presentation. It is also important to keep in mind that pain syndromes, regardless of their etiologies, often coexist with other medical and psychological syndromes such as obesity, depression, and anxiety.








































































Malabsorptive Conditions


Inflammatory Bowel Disease


Postsurgery


Crohn disease



Gastrectomy


Ulcerative colitis


Intestinal disease


Other microscopic colitis



Sprue


Pancreatic insufficiency



Collagenous colitis


Mast cell disease


Dietary Factors


Psychiatric Conditions


Lactose intolerance


Panic disorder


Caffiene


Depression


Alcohol


Somatization disorders


Fat-containing, gas-producing foods



Cruciferous vegetables



Infections


Miscellaneous Conditions


Bacteria


Endometriosis



Campylobacter, Salmonella, Yersinia


Endocrine tumors



Cacinoid



Zollinger-Ellison syndrome


Parasites



Giardia lamblia



VIPoma



HIV disease










TABLE 18-1 General Characteristics of Pain due to Visceral Pathology















1. Is poorly localized with referral to somatic structures


2. Produces nonspecific regional or whole-body motor responses


3. Produces strong autonomic responses


4. Leads to sensitization of somatic tissues


5. Produces strong affective responses


Reprinted with permission from Sikandar S, Dickenson AH. Visceral pain: the ins and outs, the ups and downs. Curr Opin Support Palliat Care. 2012;6(1):17-26.


Careful attention to reported or presenting signs and symptoms during a thorough history-taking should be of utmost importance, as physical findings may not be reproducible. Additionally, clues within the patient’s presenting complaints may lead an astute clinician to a diagnosis without ordering otherwise unnecessary or costly radiologic imaging and laboratory tests.

The initial assessment of any abdominal pain during history-taking should the 6 following features:



  • 1. Onset: Rapid, sudden, slow onset.


  • 2. Quality: Cramping, burning, sharpness, dullness, episodic.


  • 3. Intensity: The severity of the pain perceived by the patient.


  • 4. Evolution: Increasing, decreasing, or unchanged in intensity.


  • 5. Migration: Radiation of the pain from a primary site, to another.


  • 6. Localization: Involvement of the epigastrium, mid-abdominal, or lower abdominal areas.

Diagnostic modalities can be considered if the outcomes were to be affected, significantly altering your clinical decision-making (Figure 18-3).

Abdominal wall pain, being somatic in origin, is distinct from visceral pain syndromes also with different anatomical considerations. In distinguishing abdominal wall pain from intra-abdominal sources, the abdominal examination could assess for Carnett sign: unchanged or an increase in abdominal pain with the abdomen tensed (Table 18-2).






FIGURE 18-2 Common functional gastrointestinal disorders. * indicates conditions associated with pain. Reprinted from Bharucha AE, Chakraborty S, Sletten CD. Common functional gastroenterological disorders associated with abdominal pain. Mayo Clin Proc. 2016;91(8):1118-1132. Copyright © 2016 Elsevier. With permission.

Although opioids may be useful for acute intolerable pain including abdominal pain, it is often not the best first-line solution for chronic nonmalignant abdominal pain because of opioid-induced side effects including nausea/vomiting and constipation, which all may exacerbate the pain state. In patients with chronic abdominal pain, a multidisciplinary approach that includes cognitive behavioral therapy would be most ideal. Unless a recent intra-abdominal surgical history is present in the review of systems or history, surgical interventions are less likely to be of benefit as the first initial step. In these patients, diagnostic laparoscopies for chronic abdominal pain of unknown etiology have only been shown to result in symptomatic improvement in 50% of patients.5 In this subset of patients, symptoms may be due to postsurgical development of adhesions, cholecystitis, internal hernias, or a defect in the mesentery. Although uncommon, abdominal wall abscess formation should also be considered in the differential diagnosis.

In female patients with recent pelvic or abdominal wall surgeries, most commonly low-transverse cesarean sections, presenting with chronic abdominal wall pain of unclear etiology can be challenging. After ruling out postsurgical and incision pain, one consideration can include the diagnosis of abdominal wall endometriosis with implantation of lesions within the wall, diagnosable using ultrasound. If patient habitus prevents appropriate visualization of suspected lesions, abdominal magnetic resonance imaging can be considered.

Surgical excision of such isolated lesions has been reported to be successful, without very low recurrence rates.6






FIGURE 18-3 Approach to possible cyclic vomiting syndrome. Copyright © 2017 Rome Foundation, Inc. All Rights Reserved.








TABLE 18-2 Etiology of Abdominal Wall Pain

































































ETIOLOGY


COMMENTS


DIAGNOSIS


Hernia


Protuberance in abdominal wall that usually decreases in size when patient is supine


Abdominal CT scanning, abdominal ultrasonography, herniography


Rectus nerve entrapment


Occurs along lateral edge of rectus sheath; worsening of pain with tensing of muscles


Injection of local anesthetic


Thoracic lateral cutaneous nerve entrapment


Occurs spontaneously, after surgery or during pregnancy


History and physical examination


Ilioinguinal and iliohypogastric nerve entrapment


Lower abdominal pain that occurs after inguinal hernia repair


History and physical examination


Endometriosis


Cyclic abdominal pain


Laparoscopy


Diabetic radiculopathy


Acute, severe truncal pain involving T6-T12 nerve roots


Paraspinal EMG


Abdominal wall tear


Occurs mainly in athletes


History and physical examination


Abdominal wall hematoma


Complication of abdominal laparoscopic procedures


Abdominal CT scanning, abdominal ultrasonography


Spontaneous rectus sheath hematoma


Presents as tender, usually unilateral mass that does not extend beyond midline


Abdominal CT scanning, abdominal ultrasonography


Desmoid tumor


Dysplastic tumor of connective tissue; occurs in young patients (women more often than men)


Surgical excision


Herpes zoster


Pain and hyperesthesia followed by vesicles along a dermatome


History and physical examination


Spinal nerve irritation


Caused by disorders of thoracic spine


CT scanning or MRI studies of thoracic spine


Slipping rib syndrome


Sharp, stabbing pain in upper abdomen caused by luxation of 8th to 10th ribs


Hooking maneuver to pull lower ribs anteriorly, which reproduces the pain and sometimes a click


Idiopathic


Myofascial pain


History and physical examination


Reprinted with permission from The Abdominal Wall: An Overlooked Source of Pain, August 1, 2001, Vol 64, No 3, American Family Physician. Copyright © 2001 American Academy of Family Physicians, All Rights Reserved.


CT, computed tomography; EMG, electromyography; MRI, magnetic resonance imaging.

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Mar 10, 2020 | Posted by in PAIN MEDICINE | Comments Off on Abdominal Pain

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