Left upper quadrant pain has one of the broadest differentials of any abdominal pain location, spanning everything from splenic emergencies and stomach ulcers to kidney stones and musculoskeletal problems. It is also the least common site for abdominal pain and the hardest to evaluate on physical exam, with reportedly the lowest agreement between clinicians examining the same patient.1Journal of the American College of Radiology. ACR Appropriateness Criteria® Acute Left Upper Quadrant Pain That combination of rarity and diagnostic difficulty means the workup often demands imaging, and the list of possible culprits is longer than you might expect.
Why This Location Is Hard to Pin Down
The left upper quadrant (LUQ) sits beneath the lower ribs on the left side and houses the spleen, the tail of the pancreas, the stomach, the splenic flexure of the colon, and part of the left kidney. Pain felt here can originate from any of those structures. But LUQ pain can also be referred from somewhere else entirely, including the heart, left lung, or diaphragm.2Journal of the American College of Radiology. ACR Appropriateness Criteria® Acute Left Upper Quadrant Pain That overlap between local and referred sources is a big part of what makes the differential diagnosis so wide.
Physical examination findings in the LUQ are also less reliable than in, say, the right lower quadrant, where tenderness at McBurney’s point reliably points toward appendicitis. In the LUQ, there is no single exam finding that narrows the field nearly as well. Clinicians tend to rely heavily on the clinical context: your medical history, associated symptoms, and vital signs often do more work than palpation of the abdomen.
Splenic Conditions
The spleen dominates the LUQ differential. It sits just under the diaphragm on the left side, tucked behind the lower ribs, and when something goes wrong with it, LUQ pain is the hallmark symptom. The major splenic diagnoses to consider include infarction, rupture, abscess, and marked enlargement from various causes.
Splenic Infarction
Splenic infarction occurs when blood flow to part of the spleen is cut off, causing tissue to die. The pain is usually sudden and sharp, often radiating to the left shoulder. In a 10-year study at an academic hospital, the single largest cause was cardiogenic embolism, accounting for about two thirds of cases. Most of those patients had structural heart disease and atrial fibrillation, though atrial fibrillation had not always been documented before the infarction occurred.3PubMed Central. Acute Splenic Infarction at an Academic General Hospital Over 10 Years Other causes in that series included autoimmune disease and infection, each responsible for about one in eight cases. Roughly a quarter of patients had no previously known condition that would predispose them to a splenic infarct, and in most of those, the infarction itself led to a new diagnosis such as antiphospholipid syndrome or unsuspected heart valve disease.4PubMed Central. Acute Splenic Infarction at an Academic General Hospital Over 10 Years
A larger study found that splenic infarction is actually associated with a wider range of underlying conditions than these traditional categories suggest, and that atherosclerosis of the celiac or splenic arteries may be an underappreciated contributor.5JAMA Internal Medicine. Assessment of Clinical Conditions Associated With Splenic Infarction in Adult Patients Blood cancers, particularly lymphoma, can also trigger infarction through a different mechanism: the malignant tissue inside the spleen grows so fast it outstrips its own blood supply, or abnormal cells clog the veins draining the organ.6PubMed Central. Left lower quadrant pain: an unlikely diagnosis in a case of acute abdomen
Splenic Rupture
Splenic rupture is the most immediately life-threatening splenic diagnosis. Trauma is the classic cause, but spontaneous (atraumatic) rupture occurs too, and it is easy to miss because clinicians may not consider it without a history of injury. The classic presentation includes LUQ pain, abdominal guarding, and dropping blood pressure, but not every patient checks all those boxes. Left shoulder pain from diaphragmatic irritation, known as Kehr’s sign, appears in roughly half of atraumatic rupture cases.7PubMed Central. Spontaneous splenic rupture: A rare life-threatening condition; Diagnosed early and managed successfully When it is absent, the diagnosis can be delayed, which is why clinicians are urged to maintain a high level of suspicion for any patient with isolated left-sided abdominal pain and hemodynamic instability.8PubMed Central. Spontaneous splenic rupture: A rare life-threatening condition; Diagnosed early and managed successfully
Splenic Abscess
Splenic abscesses are uncommon but dangerous. They can develop after bloodstream infections seeding the spleen, or within areas of prior infarction that become infected. The pain tends to be more persistent and dull than the sudden onset of infarction or rupture, and fever is a prominent feature. Kehr’s sign, that referred left shoulder pain, was originally described by the German surgeon Hans Kehr and can also appear with abscess, since any fluid or pus irritating the diaphragm activates the same referred-pain pathway through the phrenic nerve.9PubMed. Traditional Kehr’s sign: Left shoulder pain related to splenic abscess
Stomach and Bowel Causes
The stomach sits partly in the LUQ, and the splenic flexure of the colon curves through it. Gastritis and peptic ulcer disease are among the most common non-splenic causes of LUQ pain, particularly when the ulcer or inflammation is on the greater curvature of the stomach or involves the body or fundus rather than the more typical antral or duodenal locations. The pain from gastritis or ulcers often has a burning quality, worsens with eating or on an empty stomach (depending on the location), and can be associated with nausea.
A perforated gastric ulcer is the emergency scenario here. When the wall of the stomach breaks down completely, gastric contents spill into the peritoneal cavity, causing sudden, severe pain that often starts in the epigastrium or LUQ before becoming diffuse as peritonitis sets in. The patient looks acutely ill, and the abdomen becomes rigid.
Conditions affecting the splenic flexure of the colon, including diverticulitis, ischemic colitis, and inflammatory bowel disease flares, can also produce LUQ pain. Left-sided diverticulitis is classically associated with the left lower quadrant, but when the diverticula are in the splenic flexure or the transverse colon, the pain shifts upward. Ischemic colitis affecting the splenic flexure (a watershed zone with relatively tenuous blood supply) can present with LUQ pain accompanied by bloody diarrhea.
Kidney and Urinary Tract Problems
The left kidney sits in the retroperitoneum behind the LUQ, and kidney stones passing through the left ureter are a well-known cause of pain felt in this area. The pain from a kidney stone typically has a colicky, wave-like quality, and it often radiates from the flank around to the front and down into the groin. But not all renal pain follows that textbook pattern, and a stone lodged in the upper ureter or at the ureteropelvic junction can produce pain perceived mainly in the LUQ.
Emergency physicians increasingly use point-of-care ultrasound to check for hydronephrosis (swelling of the kidney from backed-up urine) as an indicator of obstruction. This approach has a sensitivity in the range of roughly 70 to 83% for detecting hydronephrosis, which is similar to formal radiology-performed ultrasound.10PubMed Central. My patient has abdominal and flank pain: Identifying renal causes Beyond stones, pyelonephritis (kidney infection) and renal infarction can both produce LUQ and flank pain. Pyelonephritis usually comes with fever, chills, and painful urination. Renal infarction is rarer and presents more like splenic infarction: sudden flank or LUQ pain in a patient with a cardiac source of emboli or a clotting disorder.
Vascular Emergencies
Two vascular diagnoses deserve mention because, although uncommon, they are potentially fatal if missed. The first is splenic artery aneurysm, the third most common abdominal aneurysm. Most are small and asymptomatic, discovered incidentally on imaging done for other reasons. When they rupture, though, the presentation is dramatic: sudden, severe LUQ pain and rapid hemodynamic collapse. One documented case involved a large aneurysm measuring about 33 by 30 millimeters that ruptured and produced a massive hematoma, requiring emergency surgery and removal of the spleen.11PubMed Central. Spontaneous rupture of a large splenic artery aneurysm in a 59-year-old male patient with pemphigus vulgaris
The second is mesenteric ischemia affecting the vessels that supply the left side of the gut. Acute mesenteric ischemia classically produces pain that is “out of proportion” to the physical exam findings: the patient is in agony, but the abdomen initially feels relatively soft and nontender. This disconnect is an important clue. Chronic mesenteric ischemia, by contrast, causes postprandial pain (pain after eating) and weight loss, and is sometimes confused with peptic ulcer disease.
Sickle Cell Disease and Other Blood Disorders
Sickle cell disease (SCD) adds an entire layer of complexity to LUQ pain. People with SCD can experience vaso-occlusive crises that produce diffuse abdominal pain, and this pain can localize to the LUQ.12Journal of Clinical Gastroenterology. Abdominal Pain in Children With Sickle Cell Disease But they are also at risk for acute splenic sequestration, a condition in which sickled red blood cells become trapped in the spleen, causing it to swell rapidly. This is an emergency, especially in children, because large volumes of blood can pool in the spleen, leading to severe anemia and cardiovascular collapse.13Journal of Clinical Gastroenterology. Abdominal Pain in Children With Sickle Cell Disease Adults with SCD can also develop acute splenic sequestration, though it is less common since repeated sickling episodes in childhood often cause the spleen to scar and shrink (a process called autosplenectomy).14PubMed. Rescue splenic artery embolization in an adult patient of sickle cell disease presented with acute splenic sequestration crisis
Distinguishing between a vaso-occlusive crisis (painful but typically managed with hydration and pain control) and splenic sequestration or another surgical emergency is a real clinical challenge. Vaso-occlusive pain in SCD is considered a diagnosis of exclusion for abdominal complaints, meaning clinicians need to rule out the dangerous possibilities first.15Journal of Clinical Gastroenterology. Abdominal Pain in Children With Sickle Cell Disease
Other hematologic conditions associated with LUQ pain include leukemias and lymphomas that enlarge the spleen, myeloproliferative disorders, and conditions causing portal hypertension with splenomegaly. The enlarged spleen itself may cause a dragging, heavy discomfort in the LUQ even without infarction or rupture.
Musculoskeletal Mimics
Not all LUQ pain comes from inside the abdominal cavity. The chest wall and lower ribs can produce pain that feels abdominal. Slipping rib syndrome is one underrecognized culprit. It involves hypermobility of the lower “floating” ribs (ribs 8 through 12), which are not directly anchored to the breastbone. When the cartilaginous attachments between these ribs loosen, the ribs can shift and irritate the intercostal nerves, producing sharp pain in the lower chest and upper abdomen that waxes and wanes and worsens with certain movements.16PubMed Central. Slipping Rib Syndrome in a Female Adult with Longstanding Intractable Upper Abdominal Pain
Costochondritis, muscle strains of the abdominal wall or intercostal muscles, and herpes zoster (shingles) affecting the thoracic dermatomes can all mimic intra-abdominal pathology in the LUQ. These diagnoses are often considered late in the workup, after imaging has excluded the more dangerous possibilities. A key distinguishing feature is that musculoskeletal pain tends to be reproducible with palpation of the chest wall or specific movements, while pain from intra-abdominal organs usually is not.
Iatrogenic and Post-Procedural Causes
LUQ pain developing after a recent medical procedure should raise a specific red flag: splenic injury. The spleen can be damaged during colonoscopy because the instrument passes near it at the splenic flexure, and traction or torque on the colon can tear splenic tissue or disrupt adhesions between the colon and the splenic capsule. This is a rare complication, but the presentation can be delayed by hours or even days after an otherwise uneventful procedure.17Journal of Surgery and Medicine. Rare case of delayed splenic injury post colonoscopy in a regional hospital The delayed timing makes it easy to miss the connection.
Other procedures that can injure the spleen include upper abdominal surgery, cardiac surgery (because of the proximity of the spleen to the operative field), and even extracorporeal shock wave lithotripsy used to break up kidney stones on the left side. Patients presenting with new LUQ pain or pleuritic chest pain after any of these procedures should be evaluated with imaging to rule out a subcapsular hematoma or active bleeding.18Journal of Surgery and Medicine. Rare case of delayed splenic injury post colonoscopy in a regional hospital
How Clinicians Approach the Workup
Given the breadth of the differential, imaging plays a central role. CT with intravenous contrast is the primary modality for evaluating acute LUQ pain.19PubMed. Evaluating Patients with Left Upper Quadrant Pain It can identify splenic infarction, abscess, rupture, free fluid, bowel pathology, kidney stones, vascular abnormalities, and many other causes in a single scan. Ultrasound is sometimes used as a first-line tool, particularly in pregnant patients and children, and is useful for assessing the spleen and kidneys quickly at the bedside.
In children, the approach to abdominal pain imaging is tailored differently. Ultrasound tends to be the preferred initial study because it avoids radiation, and the differential itself shifts: common pediatric causes such as intussusception, mesenteric lymphadenitis, and constipation are considered alongside the adult diagnoses.20Pediatric Annals. Imaging of Acute Abdominal Pain in the Pediatric Population For children with sickle cell disease, the threshold for imaging is particularly low because the consequences of missing splenic sequestration or other surgical emergencies are so high.
Beyond imaging, laboratory tests help narrow the differential. A complete blood count can reveal anemia (suggesting bleeding or sequestration), elevated white cells (suggesting infection or infarction), or abnormal platelet counts. A lipase level screens for pancreatitis. A urinalysis checks for blood or infection pointing to a renal cause. Lactate levels and lactate dehydrogenase can be elevated in ischemic conditions, including both splenic and mesenteric infarction. In patients with suspected splenic infarction and no obvious predisposing condition, a hypercoagulability workup and echocardiogram are often part of the evaluation, since the infarction itself may be the first sign of an undiagnosed clotting disorder or heart valve problem.21PubMed Central. Acute Splenic Infarction at an Academic General Hospital Over 10 Years
Parasitic Infections of the Spleen
In parts of the world where certain parasitic infections are common, splenic involvement should be on the differential. Hydatid disease, caused by the tapeworm Echinococcus granulosus, most commonly affects the liver, but in rare cases, cysts form primarily in the spleen. The most common presentation of a primary splenic hydatid cyst is discomfort and pain in the LUQ.22The Korean Journal of Parasitology. Two Cases of Primary Splenic Hydatid Cyst in Greece These cysts grow slowly, and pain tends to be a gradual, dull ache rather than the sudden sharpness of an infarction or rupture. Imaging typically reveals a well-defined cystic structure in the spleen, sometimes with characteristic internal features like daughter cysts or calcification of the wall. Travel history to endemic areas (parts of the Mediterranean, Middle East, Central Asia, sub-Saharan Africa, and South America) is the clinical clue that prompts consideration of this diagnosis. Treatment usually involves surgery combined with anti-parasitic medication, and rupture of a hydatid cyst, whether spontaneous or surgical, carries a risk of anaphylaxis from release of cyst fluid into the peritoneum.