Assessment of chronic abdominal pain

Overview 
Theory 
Emergencies 
Diagnosis 
Resources 

Assessment includes four major components:[26][27]

History
Physical examination
Psychosocial assessment
Investigations.

The sensitivity of history and physical examination are low. Pain at right subcostal, epigastric, right or left flank, and mid-lower sites may be useful for identifying the organs involved.[28] The physical examination should be integrated with findings from the history and other collateral information to focus the diagnostic work-up on possible diagnoses.

Pain may arise from any system, including the genitourinary, gastrointestinal (GI), and gynaecological tracts. The aetiology of chronic abdominal pain is so wide that only the more common causes can be covered here.

Symptoms assessment

The localisation of pain from abdominal viscera, especially the small bowel, is imprecise. Most of the digestive tract is perceived in the midline due to its symmetrical innervation. Exceptions include pathologies of the ascending/descending colon and gallbladder, which may present with one-sided pain due to unilateral innervation.

The location of pain and the patient's perception of the anatomical distribution can sometimes help to narrow the differential diagnosis and guide diagnostic evaluation:

Epigastric and upper abdominal pain can indicate oesophageal (e.g., gastro-oesophageal reflux), stomach (e.g., gastritis, gastroparesis), duodenal (e.g., ulcer), gallbladder (e.g., cholecystitis), or pancreatic (e.g., pancreatitis) origin.
Lower abdominal pain can indicate large bowel involvement, and lateralisation may help to distinguish between descending/sigmoid colon (e.g., left-sided diverticulitis) and ascending/caecum (e.g., Crohn's ileocolitis), or appendix (e.g., appendicitis).
Pelvic pain can suggest gynaecological origin (e.g., ovarian cysts, pelvic inflammatory disease [PID]) or chronic pelvic pain syndrome (e.g., interstitial cystitis, endometriosis, urethral syndrome, or changes and dysfunction of the pelvic muscles).
Localised point of maximal pain in the anterior abdomen can indicate chronic abdominal wall pain or abdominal cutaneous nerve entrapment syndrome.[21][29][30]

Localised pain can also arise at specific sites such as the kidneys, ureters, and ovaries, or from a source of focal peritoneal irritation.

Information about exacerbating and relieving factors may provide further clues:

Pain made worse by eating (postprandial pain) may indicate gastric ulcer, chronic pancreatitis, gallstones, abdominal ischaemia (also called abdominal angina), or functional disorders such as irritable bowel syndrome, gastroparesis, functional dyspepsia, or postprandial distress syndrome (postprandial fullness).
Pain relieved by eating suggests duodenal peptic ulcer disease.
Pain relieved by defecation may indicate irritable bowel syndrome.[31]
Pain associated with menstrual cycle suggests gynaecological origin. Additional symptoms of dyspareunia, dysmenorrhoea, pain with defecation, and infertility suggest endometriosis.[32]
Pain associated with urinary urgency and frequent urination suggests interstitial cystitis.[33]
Pain in the anterior abdomen that is accentuated by physical activity can indicate chronic abdominal wall pain or abdominal cutaneous nerve entrapment syndrome.[29][34]

Clinicians should screen for associated symptoms of pain, including:

Fever
Chills
Night sweats
Nausea and vomiting
Diarrhoea
Constipation
Bloody stools[35]
Anaemia[35]
Change in appetite or bowel habit
Weight loss/gain.

Duration and frequency of symptoms forms part of the diagnostic criteria for most functional GI disorders. Diagnostic criteria for irritable bowel syndrome and functional dyspepsia include symptom onset at least 6 months before diagnosis and symptom presence over the preceding 3 months.[31][36]

Physical examination

The physical examination should first focus on the vital signs. Fever, tachycardia, tachypnoea, and hypotension suggest an acute illness requiring urgent evaluation.

A head and neck examination is useful for non-specific signs of intra-abdominal pathology, including:

Temporal muscle wasting, sunken eyes, and prominent clavicles, suggesting significant weight loss
Dry mucosal membranes, indicating volume depletion
Icteric sclera, indicating hepatobiliary disease
Pale conjunctiva, suggesting anaemia.

Peripheral vascular disease is suggested by diminished pulses and may coexist with intestinal angina or mesenteric ischaemia. Pain on deep inspiration suggests referred pain from the lungs, left upper quadrant (LUQ), or right upper quadrant (RUQ).

In many cases examination is unremarkable, but rebound tenderness, guarding, or tenderness on palpation require urgent consideration. Precise localisation of the pain in the anterior abdomen with positive Carnett's sign (i.e., increase of pain/tenderness on re-palpation during contraction of abdominal muscles, suggesting abdominal wall origin) can help to differentiate between abdominal wall pain and intra-abdominal pathology.[21][29][30]

Careful rectal examination and pelvic examination are part of a thorough evaluation. Bleeding, diarrhoea, discharge/mucus, tenderness, rectal masses, or obstruction can provide important additional clues for underlying disease processes. In women with pelvic/lower abdominal pain, gynaecological examination should be considered.

Physical examination should include skin and mouth for non-specific findings such as ulcers, vesicles, angiomata, bleeding or bruising, or specific lesions (e.g., erythema nodosum).

The pelvic girdle, lower back, and thorax (ribs and spine) should be examined, because this may yield clues about symptoms wrongly attributed to abdominal organs.

Psychosocial assessment

The association between chronic abdominal pain and a history of PTSD, abuse, somatisation, anxiety, and depression is well recognised.[37][38] In addition, family relationship and functioning may be important factors in the evaluation of pain-related disability, particularly in children and adolescents.[39] Evaluation of psychosocial factors can help to minimise unnecessary investigations, determine an appropriate management plan, and influence treatment outcome.

Affective disturbance can both result from and contribute to the experience of chronic pain. Clinical presentation, symptom severity, and response to treatment can all vary according to mental state abnormalities.[40]

Symptom fluctuations and mental state should be monitored closely.

Investigations

Specific algorithms for the diagnostic work-up of chronic abdominal pain do not exist. Appropriate investigations should be tailored to history and examination findings and be made on a case-by-case basis. In the absence of alarm features, laboratory and imaging tests should be ordered in a conservative and cost-effective manner.

Laboratory investigations

The patient should be asked about previous investigations as, owing to the chronicity of their symptoms, many patients will already have been investigated and existing information may be available for review.

Standard laboratory tests include:

FBC with differential, to screen for infection or anaemia.[35] The platelet count and erythrocyte sedimentation rate may signify an inflammatory process.
Serum electrolytes, glucose, creatinine, and urea for metabolic causes.
Liver function tests, lipase, and amylase, particularly in patients with upper abdominal pain.
Urine analysis and urine culture to help exclude urinary tract infection and interstitial cystitis.[33]

Additional laboratory tests based on the individual case include:

Stool tests for culture, ova and parasites, and Giardia antigen should be done if bacterial, parasitic, or protozoal cause of abdominal pain is suspected.
Faecal calprotectin testing is a validated, non-invasive biomarker that can be helpful in discriminating inflammatory bowel disease (IBD) from non-IBD conditions (including irritable bowel syndrome) in adults and children. It enables evaluation of the severity and course of gut inflammation.[41][42]
Urine or serum pregnancy test: this should also be done prior to radiographic or endoscopic investigations.
Serology testing for Helicobacter pylori in patients with upper gastrointestinal symptoms, including early satiety and epigastric discomfort (i.e., dyspeptic symptoms).
Serology testing including immunoglobulin A tissue transglutaminase (IgA-tTG), immunoglobulin G tissue transglutaminase (IgG-tTG), IgG-deamidated gliadin peptides (DGPs), and endomysial antibody (EMA) for patients with suspected coeliac disease.[43]
Vaginal swabs, prostate-specific antigen, and urine cytology can be helpful in certain cases with pelvic and lower abdominal pain.
Assessment for colorectal cancer: US and UK guidelines report risk thresholds for testing symptomatic patients.[44][45][46] US guidelines recommend adults aged <50 years with colorectal bleeding symptoms undergo colonoscopy or evaluation sufficient to determine a bleeding cause.[44] UK guidelines recommend certain quantitative faecal immunochemical tests (FITs) to guide referral for suspected colorectal cancer in adults:[45][46]
- aged 40 years and over with unexplained weight loss and abdominal pain
- aged under 50 years with rectal bleeding and unexplained abdominal pain
- aged 50 years and over with unexplained abdominal pain.

Refer to guidelines for an exhaustive list of signs and/or symptoms that may prompt assessment for colorectal cancer.[44][45][46]

Endoscopy

Considered for any patient aged >50 years old with chronic abdominal pain and is indicated in some individuals who have specified concurrent symptoms.

Colonoscopy (and/or FIT) is indicated for a patient with suspected colorectal cancer. Refer to guidelines for an exhaustive list of signs and/or symptoms suggestive of colorectal cancer.[44][45][46]
Upper GI endoscopy is indicated if the pain is localised in the upper abdomen, particularly if other upper GI symptoms (early satiety, nausea, vomiting) are present or if coeliac disease is highly suspected.[43]
The UK National Institute for Health and Care Excellence (NICE) recommends that patients aged 55 years and over with upper abdominal pain and weight loss should have urgent upper endoscopy (within 2 weeks).[45] Those aged 55 years and over with upper abdominal pain with a raised platelet count or low haemoglobin levels or nausea and vomiting should have non-urgent upper endoscopy.[45]

Imaging

Further investigations depend on the clinical findings.

Upper abdominal ultrasound and/or abdominal CT may be indicated to evaluate RUQ or epigastric pain, particularly if elevated liver or pancreatic enzymes are found.[47][48]
Pelvic abdominal ultrasound and transvaginal and/or transrectal ultrasound is indicated for evaluating lower abdominal pain.[49] UK guidelines recommend that women who have a serum Ca125 measurement of ≥35 IU/mL have an ultrasound scan of the abdomen and pelvis.[45]
CT scanning and/or MRI can help evaluate dilated intestinal loops; exclude partial intestinal obstruction; detect abnormalities in other abdominal organs (e.g., pancreas, liver, kidneys); identify inflammatory processes (e.g., inflammatory bowel disease, diverticulitis, abscesses); investigate retroperitoneal or pelvic masses; and identify congenital anatomical abnormalities (e.g., duodenal duplication cyst).[50][51] An urgent CT scan (within 2 weeks) should be considered for patients aged 60 and over with abdominal pain and weight loss, to evaluate for pancreatic cancer. If urgent CT is unavailable, an urgent ultrasound scan should be performed.[45]
Abdominal ultrasound can be used to determine the presence of post-surgical adhesions between bowel and the abdominal wall.[52] MRI can be used to visualise adhesions between viscera; however, there is a tendency to over diagnose adhesions.[52] There is insufficient evidence to support the use of CT as a diagnostic modality for adhesions.[52] Gastric emptying study should be considered in patients with symptoms suggesting gastroparesis.[53]

Surgery

Abdominal laparoscopy may be considered in appropriate patients with chronic abdominal pain, in whom organic aetiology is suspected. Diagnostic laparoscopy may be used to identify organic causes such as intestinal adhesions, internal hernias, enlarged mesenteric lymph nodes, endometriosis, and chronic appendicitis.[54]

Functional GI disorders

If all investigations are negative, the likely diagnosis is a functional GI disorder (FGID), currently also referred to as disorders of gut-brain interaction (DGBI).[55] The diagnosis of specific functional disorders depends on the presence and characteristics of abdominal pain and additional associated symptoms. Irritable bowel syndrome and functional dyspepsia are common causes of chronic abdominal pain in adults.[12]

If abdominal pain is present, independent of other intestinal symptoms or intestinal sensory-motor disturbances, a centrally mediated abdominal pain syndrome (CAPS) is a possible diagnosis.[25] The diagnosis is clinical and characterised by a strong central component of pain that is not explained by any other structural or functional GI disorder, or other medical conditions.[25] CAPS (formerly called functional abdominal pain syndrome) is believed to result from central sensitisation, with disinhibition of pain signals, rather than increased afferent excitability.[25]

Pain due to CAPS is often located in the abdomen rather than the pelvic region and is not related to food intake or defecation. The abdominal pain is recurrent, continuous, or near-continuous, associated with a loss of daily activities, and must be present for at least 6 months before diagnosis.[25]

Narcotic bowel syndrome, another entity of centrally mediated disorders of GI pain, refers to opioid-induced GI hyperalgesia. It is characterised by a paradoxical increase in abdominal pain with continued or escalating doses of narcotics.[25][56]

Like other functional GI disorders, CAPS and narcotic bowel syndrome cannot be explained by structural or metabolic disorders, and it is thought that they may be caused by altered pain perception and pain modulation circuits.[25][57]

It is important to recognise that FGID/DGBI or CAPS may be present and coexist in patients with known organic GI diseases, such as quiescent IBD or celiac disease. Identifying and managing functional GI symptoms in these conditions may be helpful in directing appropriate treatment and avoiding unnecessary diagnostic tests and treatments.[58]

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