Abdominal pain

The most frequent reasons for abdominal pain are gastroenteritis (13%), irritable bowel syndrome (8%), urinary tract problems (5%), inflammation of the stomach (5%) and constipation (5%). In about 30% of cases, the cause is not determined. About 10% of cases have a more serious cause including gallbladder (gallstones or biliary dyskinesia) or pancreas problems (4%), diverticulitis (3%), appendicitis (2%) and cancer (1%).[2] More common in those who are older, ischemic colitis,[4] mesenteric ischemia, and abdominal aortic aneurysms are other serious causes.[5]

Abdominal pain can be referred to as visceral pain or peritoneal pain. The contents of the abdomen can be divided into the foregut, midgut, and hindgut.[9] The foregut contains the pharynx, lower respiratory tract, portions of the esophagus, stomach, portions of the duodenum (proximal), liver, biliary tract (including the gallbladder and bile ducts), and the pancreas.[9] The midgut contains portions of the duodenum (distal), cecum, appendix, ascending colon, and first half of the transverse colon.[9] The hindgut contains the distal half of the transverse colon, descending colon, sigmoid colon, rectum, and superior anal canal.[9]

Each subsection of the gut has an associated visceral afferent nerve that transmits sensory information from the viscera to the spinal cord, traveling with the autonomic sympathetic nerves.[11] The visceral sensory information from the gut traveling to the spinal cord, termed the visceral afferent, is non-specific and overlaps with the somatic afferent nerves, which are very specific.[12] Therefore, visceral afferent information traveling to the spinal cord can present in the distribution of the somatic afferent nerve; this is why appendicitis initially presents with T10 periumbilical pain when it first begins and becomes T12 pain as the abdominal wall peritoneum (which is rich with somatic afferent nerves) is involved.[12]

A thorough patient history and physical examination is used to better understand the underlying cause of abdominal pain.

The process of gathering a history may include:[13]

• Identifying more information about the chief complaint by eliciting a history of present illness; i.e. a narrative of the current symptoms such as the onset, location, duration, character, aggravating or relieving factors, and temporal nature of the pain. Identifying other possible factors may aid in the diagnosis of the underlying cause of abdominal pain, such as recent travel, recent contact with other ill individuals, and for females, a thorough gynecologic history.
• Learning about the patient's past medical history, focusing on any prior issues or surgical procedures.
• Clarifying the patient's current medication regimen, including prescriptions, over-the-counter medications, and supplements.
• Confirming the patient's drug and food allergies.
• Discussing with the patient any family history of disease processes, focusing on conditions that might resemble the patient's current presentation.
• Discussing with the patient any health-related behaviors (e.g. tobacco use, alcohol consumption, drug use, and sexual activity) that might make certain diagnoses more likely.
• Reviewing the presence of non-abdominal symptoms (e.g., fever, chills, chest pain, shortness of breath, vaginal bleeding) that can further clarify the diagnostic picture.
• Using Carnett's sign to differentiate between visceral pain and pain originating in the muscles of the abdominal wall.[14]

After gathering a thorough history, one should perform a physical exam in order to identify important physical signs that might clarify the diagnosis, including a cardiovascular exam, lung exam, thorough abdominal exam, and for females, a genitourinary exam.[13]

Additional investigations that can aid diagnosis include:[15]

• Blood tests including complete blood count, basic metabolic panel, electrolytes, liver function tests, amylase, lipase, troponin I, and for females, a serum pregnancy test.
• Urinalysis
• Imaging including chest and abdominal X-rays
• Electrocardiogram

If diagnosis remains unclear after history, examination, and basic investigations as above, then more advanced investigations may reveal a diagnosis. Such tests include:[15]

• Computed tomography of the abdomen/pelvis
• Abdominal or pelvic ultrasound
• Endoscopy and/or colonoscopy

The management of abdominal pain depends on many factors, including the etiology of the pain. In the emergency department, a person presenting with abdominal pain may initially require IV fluids due to decreased intake secondary to abdominal pain and possible emesis or vomiting.[16] Treatment for abdominal pain includes analgesia, such as non-opioid (ketorolac) and opioid medications (morphine, fentanyl).[16] Choice of analgesia is dependent on the cause of the pain, as ketorolac can worsen some intra-abdominal processes.[16] Patients presenting to the emergency department with abdominal pain may receive a "GI cocktail" that includes an antacid (examples include omeprazole, ranitidine, magnesium hydroxide, and calcium chloride) and lidocaine.[16] After addressing pain, there may be a role for antimicrobial treatment in some cases of abdominal pain.[16] Butylscopolamine (Buscopan) is used to treat cramping abdominal pain with some success.[17] Surgical management for causes of abdominal pain includes but is not limited to cholecystectomy, appendectomy, and exploratory laparotomy.

Abdominal pain is the reason about 3% of adults see their family physician.[2] Rates of emergency department (ED) visits in the United States for abdominal pain increased 18% from 2006 through to 2011. This was the largest increase out of 20 common conditions seen in the ED. The rate of ED use for nausea and vomiting also increased 18%.[19]