Abdominal pain
Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues.
Common causes of pain in the abdomen include gastroenteritis and irritable bowel syndrome. About 15% of people have a more serious underlying condition such as appendicitis, leaking or ruptured abdominal aortic aneurysm, diverticulitis, or ectopic pregnancy. In a third of cases the exact cause is unclear.Given that a variety of diseases can cause some form of abdominal pain, a systematic approach to the examination of a person and the formulation of a differential diagnosis remains important.

Differential diagnosis
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%). More common in those who are older, ischemic colitis, mesenteric ischemia, and abdominal aortic aneurysms are other serious causes.

Acute abdominal pain
Acute abdomen can be defined as severe, persistent abdominal pain of sudden onset that is likely to require surgical intervention to treat its cause. The pain may frequently be associated with nausea and vomiting, abdominal distention, fever and signs of shock. One of the most common conditions associated with acute abdominal pain is acute appendicitis.

Selected causes
Traumatic: blunt or perforating trauma to the stomach, bowel, spleen, liver, or kidney
Inflammatory:
Infections such as appendicitis, cholecystitis, pancreatitis, pyelonephritis, Peritonitis, pelvic inflammatory disease, hepatitis, mesenteric adenitis, or a subdiaphragmatic abscess
Perforation of a peptic ulcer, a diverticulum, or the caecum
Complications of inflammatory bowel disease such as Crohns disease or ulcerative colitis
Mechanical:
Small bowel obstruction secondary to adhesions caused by previous surgeries, intussusception, hernias, benign or malignant neoplasms
Large bowel obstruction caused by colorectal cancer, inflammatory bowel disease, volvulus, fecal impaction or hernia
Vascular: occlusive intestinal ischemia, usually caused by thromboembolism of the superior mesenteric artery

By system
A more extensive list includes the following:
Gastrointestinal
GI tract
Inflammatory: gastroenteritis, appendicitis, gastritis, esophagitis, diverticulitis, Crohns disease, ulcerative colitis, microscopic colitis
Obstruction: hernia, intussusception, volvulus, post-surgical adhesions, tumors, severe constipation, hemorrhoids
Vascular: embolism, thrombosis, hemorrhage, sickle cell disease, abdominal angina, blood vessel compression (such as celiac artery compression syndrome), superior mesenteric artery syndrome, postural orthostatic tachycardia syndrome
Digestive: peptic ulcer, lactose intolerance, celiac disease, food allergies, indigestion
Glands
Bile system
Inflammatory: cholecystitis, cholangitis
Obstruction: cholelithiasis, tumours
Liver
Inflammatory: hepatitis, liver abscess
Pancreatic
Inflammatory: pancreatitis
Renal and urological
Inflammation: pyelonephritis, bladder infection
Obstruction: kidney stones, urolithiasis, urinary retention, tumours
Vascular: left renal vein entrapment
Gynaecological or obstetric
Inflammatory: pelvic inflammatory disease
Mechanical: ovarian torsion
Endocrinological: menstruation, Mittelschmerz
Tumors: endometriosis, fibroids, ovarian cyst, ovarian cancer
Pregnancy: ruptured ectopic pregnancy, threatened abortion
Abdominal wall
muscle strain or trauma
muscular infection
neurogenic pain: herpes zoster, radiculitis in Lyme disease, abdominal cutaneous nerve entrapment syndrome (ACNES), tabes dorsalis
Referred pain
from the thorax: pneumonia, pulmonary embolism, ischemic heart disease, pericarditis
from the spine: radiculitis
from the genitals: testicular torsion
Metabolic disturbance
uremia, diabetic ketoacidosis, porphyria, C1-esterase inhibitor deficiency, adrenal insufficiency, lead poisoning, black widow spider bite, narcotic withdrawal
Blood vessels
aortic dissection, abdominal aortic aneurysm
Immune system
sarcoidosis
vasculitis
familial Mediterranean fever
Idiopathic
irritable bowel syndrome (IBS)(affecting up to 20% of the population, IBS is the most common cause of recurrent and intermittent abdominal pain)

By location
The location of abdominal pain can provide information about what may be causing the pain. The abdomen can be divided into four regions called quadrants. Locations and associated conditions include:
Diffuse
Peritonitis
Vascular: mesenteric ischemia, ischemic colitis, Henoch-Schonlein purpura, sickle cell disease, systemic lupus erythematosus, polyarteritis nodosa
Small bowel obstruction
Irritable bowel syndrome
Metabolic disorders: ketoacidosis, porphyria, familial Mediterranean fever, adrenal crisis
Epigastric
Heart: myocardial infarction, pericarditis
Stomach: gastritis, stomach ulcer, stomach cancer
Pancreas: pancreatitis, pancreatic cancer
Intestinal: duodenal ulcer, diverticulitis, appendicitis
Right upper quadrant
Liver: hepatomegaly, fatty liver, hepatitis, liver cancer, abscess
Gallbladder and biliary tract: inflammation, gallstones, worm infection, cholangitis
Colon: bowel obstruction, functional disorders, gas accumulation, spasm, inflammation, colon cancer
Other: pneumonia, Fitz-Hugh-Curtis syndrome
Left upper quadrant
Splenomegaly
Colon: bowel obstruction, functional disorders, gas accumulation, spasm, inflammation, colon cancer
Peri-umbilical (the area around the umbilicus, aka the belly button)
Appendicitis
Pancreatitis
Inferior myocardial infarction
Peptic ulcer
Diabetic ketoacidosis
Vascular: aortic dissection, aortic rupture
Bowel: mesenteric ischemia, Celiac disease, inflammation, intestinal spasm, functional disorders, small bowel obstruction
Lower abdominal pain
Diarrhea
Colitis
Crohns
Dysentery
Hernia
Right lower quadrant
Colon: intussusception, bowel obstruction, appendicitis (McBurneys point)
Renal: kidney stone (nephrolithiasis), pyelonephritis
Pelvic: cystitis, bladder stone, bladder cancer, pelvic inflammatory disease, pelvic pain syndrome
Gynecologic: endometriosis, intrauterine pregnancy, ectopic pregnancy, ovarian cyst, ovarian torsion, fibroid (leiomyoma), abscess, ovarian cancer, endometrial cancer
Left lower quadrant
Bowel: diverticulitis, sigmoid colon volvulus, bowel obstruction, gas accumulation, Toxic megacolon
Right low back pain
Liver: hepatomegaly
Kidney: kidney stone (nephrolithiasis), complicated urinary tract infection
Left low back pain
Spleen
Kidney: kidney stone (nephrolithiasis), complicated urinary tract infection
Low back pain
kidney pain (kidney stone, kidney cancer, hydronephrosis)
Ureteral stone pain

Pathophysiology
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. 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. The midgut contains portions of the duodenum (distal), cecum, appendix, ascending colon, and first half of the transverse colon. The hindgut contains the distal half of the transverse colon, descending colon, sigmoid colon, rectum, and superior anal canal.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. 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. 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.

Diagnosis
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:
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 patients past medical history, focusing on any prior issues or surgical procedures.
Clarifying the patients current medication regimen, including prescriptions, over-the-counter medications, and supplements.
Confirming the patients drug and food allergies.
Discussing with the patient any family history of disease processes, focusing on conditions that might resemble the patients 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 Carnetts sign to differentiate between visceral pain and pain originating in the muscles of the abdominal wall.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.Additional investigations that can aid diagnosis include:
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
ElectrocardiogramIf diagnosis remains unclear after history, examination, and basic investigations as above, then more advanced investigations may reveal a diagnosis. Such tests include:
Computed tomography of the abdomen/pelvis
Abdominal or pelvic ultrasound
Endoscopy and/or colonoscopy

Management
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. Treatment for abdominal pain includes analgesia, such as non-opioid (ketorolac) and opioid medications (morphine, fentanyl). Choice of analgesia is dependent on the cause of the pain, as ketorolac can worsen some intra-abdominal processes. 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. After addressing pain, there may be a role for antimicrobial treatment in some cases of abdominal pain. Butylscopolamine (Buscopan) is used to treat cramping abdominal pain with some success. Surgical management for causes of abdominal pain includes but is not limited to cholecystectomy, appendectomy, and exploratory laparotomy.

Emergencies
Below is a brief overview of abdominal pain emergencies.

Epidemiology
Abdominal pain is the reason about 3% of adults see their family physician. 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%.

References


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