Acute abdominal pain is the sudden onset of pain in the abdominal area that can vary in intensity and duration. This pain may arise from various conditions, ranging from mild and self-limiting to severe and life-threatening. Acute abdominal pain is a common reason for emergency department visits, accounting for 5% to 10% of cases annually.
Acute abdominal pain contrasts with chronic or recurrent abdominal pain, which persists over weeks to months and may come and go in episodes. Chronic pain is often associated with long-standing conditions like irritable bowel syndrome or inflammatory bowel disease, while acute pain is typically of sudden onset and suggests a new or rapidly progressing condition that may require urgent evaluation.
Anatomy of the abdomen
The abdomen houses several vital organs, each involved in digestion, excretion, or reproduction. Pain arising from these organs often localizes to specific regions of the abdomen depending on the organ involved but can also be referred to distant areas due to the complex innervation of the abdominal structures.
- Stomach: The stomach is located in the upper central part of the abdomen, just beneath the ribs. It is responsible for the digestion of food by secreting stomach acid and digestive enzymes. Conditions affecting the stomach, such as gastritis, peptic ulcer disease, or gastric cancer, typically cause pain in the upper middle abdomen (epigastric region). Pain may be described as burning or gnawing and can be worsened by eating or fasting.
- Liver and gallbladder: The liver occupies the upper right side of the abdomen and is essential for metabolism, detoxification, and bile production. The gallbladder, a small organ under the liver, stores bile for digestion. Liver inflammation (hepatitis) or gallbladder inflammation (cholecystitis) can result in pain in the right upper quadrant of the abdomen. Gallbladder pain may radiate to the right shoulder or back, especially after fatty meals, due to irritation of the diaphragm, which shares nerve pathways with the shoulder.
- Pancreas: The pancreas, located behind the stomach in the upper abdomen, plays a key role in regulating blood sugar and digesting food. Pancreatic inflammation (pancreatitis) typically causes severe pain in the upper abdomen that often radiates to the back. This pain is frequently described as deep and may worsen after eating or lying down.
- Small and large intestines: The small intestine spans the mid-abdomen and is responsible for nutrient absorption. The large intestine, or colon, surrounds the abdomen and is responsible for water absorption and stool formation. Conditions such as small bowel obstruction, Crohn’s disease, or diverticulitis can cause pain throughout the abdomen, depending on the location of the pathology. Small intestine pain is often diffuse, while pain from the large intestine is more localized, such as left lower quadrant pain in diverticulitis.
- Appendix: The appendix is a small, finger-like projection from the large intestine located in the lower right abdomen. Appendicitis, or inflammation of the appendix, often begins with generalized abdominal discomfort that localizes to the lower right quadrant as the inflammation progresses. Without treatment, the appendix may rupture, leading to severe pain and widespread peritonitis.
- Kidneys and bladder: The kidneys are located in the back of the abdomen on either side of the spine, and the bladder sits in the lower abdomen, just behind the pubic bone. Kidney stones can cause sharp, severe pain that starts in the flanks and radiates toward the groin. Bladder infections, on the other hand, may cause lower abdominal pain, often described as a pressure or cramping sensation.
- Uterus and ovaries: In females, the uterus and ovaries are in the lower abdomen. Pain from conditions such as ovarian cysts, pelvic inflammatory disease, or ectopic pregnancy is typically felt in the lower abdomen or pelvis. This pain may be sharp or cramping and is often associated with menstrual irregularities or vaginal bleeding.
What is referred pain?
Referred pain occurs when pain originating in one area of the body is perceived in another area. This phenomenon arises due to the shared nerve pathways between different regions. The abdominal organs are innervated by both visceral and somatic nerves. Visceral nerves detect pain, stretch, or distension from the organs, while somatic nerves detect pain from the skin, muscles, and joints. These nerves often converge at the same spinal cord level, which can cause the brain to misinterpret the source of the pain. For example, pain from the diaphragm, which is innervated by the phrenic nerve, is often referred to the shoulder because the phrenic nerve shares the same cervical spinal roots (C3–C5) as the nerves that supply sensation to the shoulder. Similarly, pain from the liver or gallbladder may be referred to the right shoulder or back due to shared innervation via the diaphragm.
What is the most common cause of acute (sudden) abdominal pain in adults?
Acute appendicitis
One of the most common causes of acute abdominal pain in adults is acute appendicitis. This condition occurs when the appendix, a small tube connected to the large intestine, becomes inflamed due to obstruction of its lumen. This obstruction can result from fecal matter, lymphoid hyperplasia, or a foreign body, leading to increased pressure within the appendix, bacterial overgrowth, and subsequent inflammation. As the condition progresses, the appendix may perforate, releasing its contents into the abdominal cavity, which can result in peritonitis, a potentially life-threatening infection.
Appendicitis typically affects individuals between the ages of 10 and 30, though it can occur at any age. The pain usually begins as vague discomfort around the navel before localizing to the lower right quadrant of the abdomen within hours. Patients often experience nausea, vomiting, fever, and loss of appetite. Key diagnostic clues include tenderness at McBurney’s point, a positive rebound tenderness test, and elevated white blood cell counts on laboratory tests. Imaging such as ultrasound or CT scan can confirm the diagnosis. The treatment for acute appendicitis is surgical removal of the appendix, known as an appendectomy. While antibiotics alone may be considered in selected cases, surgery remains the gold standard treatment to prevent complications such as rupture and sepsis.
Other common causes of acute (sudden) abdominal pain in adults
Cholecystitis
Cholecystitis is inflammation of the gallbladder, usually caused by gallstones obstructing the cystic duct. This blockage results in bile buildup, increased pressure, and subsequent inflammation. The condition is more common in middle-aged adults and women, particularly those who are overweight or have a history of rapid weight loss. Patients with cholecystitis experience severe pain in the right upper quadrant of the abdomen, which may radiate to the right shoulder or back. The pain typically worsens after consuming fatty foods. In severe cases, associated symptoms include nausea, vomiting, fever, and jaundice. The diagnosis is confirmed through imaging, usually an ultrasound, which may show a thickened gallbladder wall and gallstones. Treatment often involves surgical removal of the gallbladder (cholecystectomy), though in some cases, conservative management with antibiotics may be appropriate.
Pancreatitis
Pancreatitis refers to inflammation of the pancreas, an organ responsible for producing digestive enzymes and regulating blood sugar. The most common causes of pancreatitis are gallstones and chronic alcohol consumption. This condition is characterized by sudden, severe upper abdominal pain that often radiates to the back. The pain is typically worse after eating and may improve when leaning forward. Nausea, vomiting, and fever are common accompanying symptoms. The diagnosis is made based on elevated levels of pancreatic enzymes (amylase and lipase) in the blood, along with imaging such as CT scans or MRIs to assess the severity of the inflammation. Management includes supportive care with IV fluids, pain relief, and treatment of the underlying cause.
Diverticulitis
Diverticulitis occurs when small pouches, called diverticula, that form in the walls of the colon become inflamed or infected. It primarily affects older adults, particularly those over 50. The most common symptom is sharp pain in the lower left quadrant of the abdomen, often accompanied by fever, nausea, and changes in bowel habits such as constipation or diarrhea. Diagnosis is typically confirmed through a CT scan that shows an inflamed diverticula. Treatment for mild cases includes antibiotics and a temporary liquid diet. In contrast, more severe cases may require hospitalization and, in some instances, surgery to remove the affected part of the colon.
Gastroenteritis
Gastroenteritis, commonly known as stomach flu, is an infection of the stomach and intestines caused by viruses or bacteria. Symptoms include sudden onset of abdominal cramps, diarrhea, vomiting, and fever. The condition affects people of all ages and is typically self-limiting, lasting a few days. Diagnosis is often clinical, based on the characteristic symptoms and a history of recent exposure to contaminated food or water. Treatment focuses on rehydration, either orally or intravenously in severe cases, and symptomatic relief with medications such as antiemetics or antidiarrheals.
Peptic ulcer disease
Peptic ulcer disease occurs when ulcers develop in the lining of the stomach or the first part of the small intestine (duodenum) due to the corrosive effects of stomach acid. The most common cause is infection with Helicobacter pylori bacteria, though chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) can also contribute. Patients typically present with burning pain in the upper abdomen, often worse on an empty stomach and relieved by eating or taking antacids. Diagnosis is confirmed through endoscopy or testing for H. pylori. Treatment involves proton pump inhibitors to reduce acid production, antibiotics for H. pylori, and avoidance of NSAIDs.
Kidney stones
Kidney stones are solid masses formed from crystals originating in the kidneys and can cause severe pain as they pass through the urinary tract. The pain, often described as excruciating and cramping, typically begins in the back or flanks and may radiate to the lower abdomen and groin as the stone moves. Nausea, vomiting, and blood in the urine are common associated symptoms. Diagnosis is confirmed through imaging, usually a CT scan. Treatment includes pain management, increased fluid intake to help pass the stone, and, in some cases, surgical intervention.
Ectopic pregnancy
An ectopic pregnancy occurs when a fertilized egg implants outside the uterus, most commonly in the fallopian tube. This condition can cause severe lower abdominal pain and vaginal bleeding in women of reproductive age. If the fallopian tube ruptures, it can lead to life-threatening internal bleeding. Diagnosis is based on a positive pregnancy test along with ultrasound findings that show no intrauterine pregnancy. Immediate surgical intervention is often required to remove the ectopic tissue and prevent complications.
Urinary tract infection (UTI)
Urinary tract infections (UTIs) occur when bacteria enter the urinary tract, causing inflammation and pain. They are more common in women and typically cause pain or pressure in the lower abdomen, burning during urination, and frequent urges to urinate. Diagnosis is confirmed through a urine test that shows the presence of bacteria and white blood cells. Treatment involves antibiotics, and symptoms usually resolve within a few days of starting treatment.
Hernia
A hernia occurs when part of an organ or tissue protrudes through a weak spot in the abdominal wall. Hernias can cause localized pain and discomfort, especially during physical activity or straining. The pain is often relieved by lying down. Diagnosis is made through physical examination, and surgical repair is often necessary to prevent complications such as strangulation of the protruding tissue.
Less common but important causes of acute (sudden) abdominal pain in adults
Acute myocardial infarction (heart attack)
Though typically associated with chest pain, an acute myocardial infarction can also present with epigastric pain, especially in older adults or individuals with diabetes. The pain may be mistaken for indigestion or gastritis, often associated with nausea, vomiting, sweating, and shortness of breath. Diagnosis is confirmed through an electrocardiogram (ECG) and blood tests for cardiac enzymes. Immediate treatment with medications to restore blood flow, such as aspirin or thrombolytics, or emergency angioplasty, is required.
Aortic dissection
Aortic dissection is a life-threatening condition where the inner layer of the aorta, the large blood vessel branching off the heart, tears. This can cause sudden, severe chest or abdominal pain that radiates to the back. Risk factors include hypertension, connective tissue disorders, and a history of cardiovascular disease. Diagnosis is confirmed through imaging, such as CT or MRI angiography. Immediate surgical repair is often required to prevent rupture and death.
Mesenteric ischemia
Mesenteric ischemia occurs when blood flow to the intestines is reduced due to a blockage or narrowing of the mesenteric arteries. This condition causes sudden, severe abdominal pain, often described as “out of proportion” to physical findings. It is most common in older adults with a history of cardiovascular disease. Diagnosis is confirmed through imaging, and treatment may involve surgical intervention to restore blood flow or medications to dissolve the clot.
Intestinal obstruction
Intestinal obstruction is a blockage that prevents the normal passage of contents through the intestines. The most common causes include adhesions from previous surgeries, hernias, and tumors. Patients present with diffuse abdominal pain, vomiting, abdominal distension, and the inability to pass gas or have a bowel movement. Diagnosis is made through imaging, typically an abdominal X-ray or CT scan. Treatment depends on the cause but often involves hospitalization, nasogastric tube insertion to relieve pressure, and sometimes surgery to remove the obstruction.
Perforated peptic ulcer
A perforated peptic ulcer occurs when an ulcer in the stomach or duodenum erodes through the organ’s wall, causing the contents to leak into the abdominal cavity. This results in sudden, severe abdominal pain, often accompanied by signs of shock such as low blood pressure and a rapid heart rate. Diagnosis is confirmed through imaging, which may show free air under the diaphragm. Emergency surgery is required to close the perforation and prevent peritonitis.
Adrenal crisis
An adrenal crisis occurs when the adrenal glands, which produce hormones such as cortisol, fail to produce enough hormones in response to stress. This condition can cause severe abdominal pain, vomiting, low blood pressure, and confusion. It is most common in individuals with adrenal insufficiency or those on long-term steroid therapy. Diagnosis is confirmed through blood tests showing low cortisol levels, and treatment involves immediate administration of corticosteroids and supportive care.
Ovarian torsion
Ovarian torsion occurs when the ovary twists around its supporting ligaments, cutting off its blood supply. This condition causes sudden, severe lower abdominal pain, often accompanied by nausea and vomiting. It is most common in women of reproductive age and may be associated with ovarian cysts. Diagnosis is confirmed through ultrasound, and prompt surgical intervention is required to untwist the ovary and restore blood flow.
Pneumonia (lower lobe)
Lower lobe pneumonia, particularly on the right side, can sometimes present as abdominal pain due to irritation of the diaphragm. Patients typically have fever, cough, difficulty breathing, and abdominal discomfort. A chest X-ray showing consolidation in the affected lung confirms the diagnosis. Treatment involves antibiotics and supportive care.
Sickle cell crisis
Individuals with sickle cell disease can experience episodes of severe abdominal pain during a sickle cell crisis. This occurs when sickled red blood cells block blood flow to the organs, causing ischemia and pain. The pain is often diffuse and may be accompanied by fever, fatigue, and jaundice. Diagnosis is based on the patient’s history and blood tests showing sickled cells. Treatment involves pain management, hydration, and sometimes blood transfusions.
Toxic megacolon
Toxic megacolon is a severe complication of inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease, in which the colon becomes dilated and inflamed. Patients present with sudden, severe abdominal pain, fever, and a distended abdomen. Diagnosis is confirmed through imaging, and treatment typically involves IV steroids, antibiotics, and sometimes emergency surgery to remove the affected portion of the colon.
Advice for patients
Adults experiencing acute abdominal pain should seek medical attention if the pain is severe, persistent, or associated with concerning symptoms such as fever, vomiting, chest pain, difficulty breathing, blood in the stool, or signs of shock (e.g., dizziness or fainting). Urgent care is necessary for conditions such as appendicitis, cholecystitis, or pancreatitis, as delaying treatment can lead to serious complications. It is also crucial to seek immediate medical attention if there is a sudden change in the nature of the pain, such as worsening intensity, or if the pain is accompanied by symptoms such as shortness of breath, severe back pain, or signs of internal bleeding.
Summary
Acute abdominal pain is a common symptom that can be caused by a wide variety of conditions. Appendicitis is among the most common causes, but other potential diagnoses include cholecystitis, pancreatitis, diverticulitis, and more. Some less common but serious conditions, such as aortic dissection or mesenteric ischemia, must also be considered in the differential diagnosis. Early identification and treatment are essential to improving outcomes and preventing complications.