Common Causes of Acute Abdominal Pain
The diagnosis and treatment of acute abdominal pain is a collaborative effort, often starting in the emergency department (ED). Over 50% of complaints presenting to the ED are related to acute pain, with abdominal pain accounting for 7% of all ED visits.1-2
Pain is now recognized as the fifth vital sign, along with blood pressure, pulse, respiratory rate, and temperature. As a vital sign, it allows physicians to monitor changes in a patient’s condition and better evaluate the clinical picture.3 However, the best way to manage acute pain in the ED remains controversial. One school of thought calls for minimal pain management until a diagnosis has been made and surgery ruled out.4,5 According to the other school of thought, undertreatment of pain can hamper recovery and decrease patient satisfaction.6,7 Recent studies of patients receiving tramadol preoperatively, however, have shown that its use does not affect decision-making.8 In addition, early administration of potent analgesics, such as morphine, have also been shown to reduce pain but not to hamper diagnosis.9,10
The problem of the undertreatment of pain is more pronounced in the pediatric and elderly populations. In one study, pediatric patients were shown to be less likely to receive analgesics than adults.11 One reason that children are undertreated is the myth that children, especially infants, do not feel pain the same way that adults do.12 Another reason is physicians’ fear of opioid side effects, such as oversedation, respiratory depression, hypotension, and addiction. Lastly, many physicians are not comfortable with the pharmacokinetics and dosing of opioid medications in the pediatric population, especially in the ED.13,14 Not only is dosing during the ED stay problematic, children often are discharged with inadequate doses of analgesic medication.13 Older adults face similar problems—receiving inadequate analgesia and waiting significantly longer than younger adults before their pain is addressed.15
This article will discuss the most common acute abdominal conditions treated in the ED.
When a patient presents to the ED with abdominal pain, one of the primary considerations is the differentiation of the most dangerous diagnoses from non-emergency causes (Table 1).16 Taking a thorough medical history is critical because trauma to a certain area and/or a certain progression of symptoms makes some diagnoses more likely than others. Conditions such as acute mesenteric ischemia lead to significant morbidity and mortality and requires early diagnosis and intervention.17
Location, Location, Location
The location of the pain corresponds to different anatomical structures. For example, back pain usually indicates a retroperitoneal source of abdominal pain. The bladder, distal colon, and pelvic organs refer pain to the suprapubic region. The small bowel, appendix, and midgut structures often convey a periumbilical pain.18 Pain from the stomach, pancreas, liver, and gallbladder often will convey an epigastric pain.19 The location and timing of the pain, whether the pain is relieved by eating, and other information gleaned from a patient history are just some of the clues that ED physicians use to diagnose and treat abdominal pain.
Abdominal Pain Conditions
Some of the most common causes of abdominal pain are appendicitis, gastroesophageal reflux disease (GERD), pancreatitis, gallbladder disease, diverticulitis, and small bowel obstruction.
Appendicitis is the most common abdominal-related emergency seen in the ER, as well as the most common reason to have urgent surgery. There are 250,000 appendectomies performed in the United States every year.20,21 The diagnosis of appendicitis needs to be made quickly because the risk for rupture or perforation increases significantly after 36 hours from the onset of symptoms.22
The typical presentation of appendicitis includes a patient complaining of periumbilical, colicky pain that worsens during the first 24 hours. The pain then localizes to the right lower quadrant of the abdomen and sharpens in intensity. This migration of pain is the most consistent finding for appendicitis.23,24
Yet the misdiagnosis of appendicitis remains a problem.25 Laboratory values indicating an inflammatory response may help with the diagnosis. Loss of appetite is present in more than two-thirds of patients. However, in the elderly, loss of appetite is much less common, present in only one-third of older patients.26
In addition to a physical examination and laboratory results, imaging techniques are helpful with the differential diagnosis. Computed tomography (CT) scanning has been shown to have a greater sensitivity than ultrasound in detecting appendicitis, but the positive predictive values of the 2 are similar, and ultrasound is a good first-line technique.27,28 Although appendicitis is the most common reason to undergo surgery due to right lower quadrant pain, there are many other ailments that can mimic or confuse the picture, including diverticulitis, mesenteric inflammation, Crohn’s disease, infectious enterocolitis, endometriosis, ectopic pregnancy, and intussusception, to name a few.29
When the patient arrives in the ED, morphine is a great choice to reduce the pain without hindering the diagnosis of appendicitis; it has a long history of use with good outcomes.30
GERD is a common complaint affecting 7% of the US population daily and up to 40% monthly.31,32 In addition to the typical symptoms of GERD (heartburn and regurgitation), other presenting symptoms may include sour taste in the throat, cough, asthma, and stenosis (trouble swallowing).33 Data suggests that GERD may account for between 25% and 55% of the cases of non-cardiac chest pain presenting to physicians.34 This, however, should not lead physicians to dismiss chest pain as GERD. Patients with cardiac disease and angina may have symptoms similar to those of GERD, and they may even feel relief after treatment with proton pump inhibitors (PPIs) or histamine-2 (H2-receptor blockers).35 Therefore, the ER physician needs to rule out cardiac and more serious causes of chest pain in patients presenting with GERD, especially in elderly patients.36
As for many other medical conditions, the treatment for GERD begins with lifestyle modifications including not eating for 2 to 3 hours before bedtime, elevating the head of the bed, quitting smoking, losing weight, and eating a low-fat diet. Avoiding foods such as chocolate, mint, and onions, as well as beverages such as alcohol, tea, and soda, also is helpful.