Acute abdomen is a term used to describe the sudden onset of severe abdominal pain that requires urgent medical attention. It is often a symptom of a serious underlying condition, many of which require surgical intervention to prevent life-threatening complications. For healthcare professionals, quickly establishing a differential diagnosis for acute abdomen based on the location and characteristics of abdominal pain is crucial for prompt and effective patient management. This article serves as a comprehensive Acute Abdomen Abdominal Pain Differential Diagnosis Chart, guiding clinicians through potential causes categorized by pain location, and is designed to be a valuable resource for medical professionals seeking to refine their diagnostic approach to this critical condition.
The causes of abdominal pain in acute abdomen can be broadly categorized into surgical, gynecological/obstetrical, and medical etiologies. When assessing a patient presenting with acute abdomen, considering the location of the pain is a fundamental first step. However, it is essential to remember that pain can radiate or shift, and conditions in adjacent regions should always be considered in the differential diagnosis. Furthermore, the abdominal wall itself can be a source of pain, and pain may even originate from areas above the diaphragm, mimicking abdominal pathology.
This guide focuses on differentiating causes of acute abdomen based on pain localization, offering a structured approach to diagnosis. For a deeper understanding of medical causes of abdominal pain, please refer to specialized resources.
Differential Diagnosis by Pain Location
Generalized Abdominal Pain with Tenderness and Rigidity
This presentation suggests widespread peritonitis and is a surgical emergency. Consider the following:
- Perforated Peptic Ulcer: Rupture of a gastric or duodenal ulcer leading to spillage of gastric contents into the peritoneum.
- Perforation of Other Intra-abdominal Organs: Includes rupture of the appendix, colon, gallbladder, or any other hollow viscus.
- AAA Rupture (Abdominal Aortic Aneurysm Rupture): Life-threatening hemorrhage from a ruptured aneurysm, often presenting with back and abdominal pain.
- Aortic Dissection: Tear in the inner layer of the aorta, which can extend into the abdomen and mimic acute abdomen.
- Pancreatitis: Severe inflammation of the pancreas, which can become generalized in severe cases.
- Ectopic Pregnancy: Ruptured ectopic pregnancy leading to intra-abdominal bleeding in women of reproductive age.
- Ischemic Gut (Mesenteric Ischemia): Reduced blood flow to the intestines, leading to tissue death and potential perforation.
Central/ Peri-umbilical Pain without Abdominal Signs
Pain in the central abdomen or around the umbilicus, without significant physical examination findings initially, can be challenging. Potential causes include:
- Acute Small Bowel Ischemia: Early stages may present with pain out of proportion to physical findings.
- Acute Appendicitis: Early appendicitis pain often starts as peri-umbilical before localizing to the right iliac fossa.
- Acute Small Bowel Obstruction: Blockage of the small intestine, causing distention and pain.
- Acute Pancreatitis: Can present with central abdominal pain initially.
- Testicular Torsion: While primarily groin pain, it can sometimes manifest as referred peri-umbilical pain, especially in younger males.
- Medical Causes of Abdominal Pain: Consider non-surgical causes that may present with central abdominal pain.
Epigastric Pain
Pain located in the upper central abdomen, below the ribs. Differential diagnosis includes:
Gastrointestinal Causes:
- Gastritis: Inflammation of the stomach lining.
- Peptic Ulcer Disease: Ulcers in the stomach or duodenum.
- Reflux Esophagitis (GERD): Heartburn and acid reflux, severe cases can mimic acute pain.
- Pancreatitis: Inflammation of the pancreas, commonly presenting with epigastric pain radiating to the back.
- Gastric Cancer and Pancreatic Cancer: Malignancies may present with persistent epigastric pain.
- Boerhaave Syndrome (Esophageal Rupture): Spontaneous rupture of the esophagus, a surgical emergency, often with severe chest and epigastric pain.
- Dyspepsia (Indigestion): Upper abdominal discomfort, often related to eating.
- Irritable Bowel Syndrome (IBS): Chronic condition causing abdominal pain, bloating, and altered bowel habits; acute exacerbations can mimic acute abdomen.
Pain from Nearby Areas:
- Abdominal: Pain radiating from central or right upper quadrant regions.
- Cardiac: Myocardial infarction (heart attack), especially inferior MI, can present as epigastric pain; pleuritis (inflammation of the pleura) can refer pain.
- Pulmonary: Pneumonia, pleurisy in the lower lobes can cause referred epigastric pain.
Right Hypochondrium/ Upper Quadrant Pain
Pain in the right upper abdomen, below the ribs on the right side.
Gallbladder and Biliary Tract:
- Biliary Colic: Pain caused by gallstones temporarily blocking the bile duct.
- Cholecystitis: Inflammation of the gallbladder, usually due to gallstones.
- Cholangitis: Infection of the bile ducts, a serious condition often associated with jaundice and fever.
Liver:
- Hepatitis: Inflammation of the liver, often viral or alcoholic.
- Hepatomegaly: Liver enlargement, for example, due to congestive heart failure, causing stretching of the liver capsule and RUQ pain.
- Hemorrhage into Hepatic Tumor: Bleeding within a liver tumor.
- Liver Trauma: Injury to the liver.
- Hepatic or Subdiaphragmatic Abscess: Collection of pus in or around the liver or below the diaphragm.
- Fitz-Hugh-Curtis Syndrome (Perihepatitis): Inflammation of the liver capsule associated with Pelvic Inflammatory Disease (PID) in women.
- Pre-eclampsia and HELLP Syndrome: Pregnancy-related conditions that can cause RUQ pain due to liver involvement.
Other Gastrointestinal:
- Appendicitis with High Appendix: In pregnancy or individuals with anatomical variations, the appendix may be located higher in the abdomen, causing RUQ pain.
- Perforated or Penetrating Duodenal Ulcer: Can present in the RUQ if the perforation is anterior or lateral.
- Colon Cancer (Right-sided): Cancer in the ascending colon.
Pain from Nearby Areas:
- Abdominal: Pain radiating from epigastric, central, right lower quadrant, flank (loin), or groin regions.
- Right Lower Lobe Pneumonia, Pleurisy, or Other Lung Disease: Referred pain from the chest.
- Subphrenic Abscess: Abscess below the diaphragm.
- Acute Pyelonephritis (Right Kidney): Kidney infection can cause flank pain radiating to the RUQ.
Left Hypochondrium/ Upper Quadrant Pain
Pain in the left upper abdomen, below the ribs on the left side.
- Pancreatitis: While often epigastric, can also present in the LUQ.
- Subphrenic Abscess (Left): Abscess below the left diaphragm.
- Diverticulitis (Sigmoid Colon): Although typically LIF pain, sigmoid diverticulitis can sometimes extend to the LUQ.
- Ruptured Spleen: Trauma or certain medical conditions can lead to splenic rupture.
- Acute Pyelonephritis (Left Kidney): Kidney infection causing flank pain radiating to the LUQ.
- Leaking Aneurysm of the Splenic Artery: Rare but life-threatening.
- Acute Gastric Distention: Severe stomach bloating.
Right Iliac Fossa Pain (RIF)
Pain in the right lower abdomen. This is classically associated with appendicitis.
Gastrointestinal:
- Appendicitis: Inflammation of the appendix, the most common cause of RIF pain.
- Crohn’s Disease: Inflammatory bowel disease, particularly ileitis, can cause RIF pain.
- Inflamed Meckel Diverticulum: A congenital outpouching of the small intestine that can become inflamed.
- Cholecystitis with Low Gallbladder: Rarely, a gallbladder located low in the abdomen can cause RIF pain.
- Mesenteric Adenitis: Inflammation of mesenteric lymph nodes, often in children, mimicking appendicitis.
- Epiploic Appendagitis: Inflammation of small, fat-filled sacs attached to the colon.
- Colon Cancer (Right-sided): Cancer of the ascending colon or cecum.
- Constipation: Severe constipation can cause abdominal pain in various locations, including the RIF.
- Irritable Bowel Syndrome (IBS): Can cause pain in any abdominal region.
Reproductive (Female):
- Ectopic Pregnancy: Ruptured ectopic pregnancy can cause RIF pain and bleeding.
- Acute Ovarian Event: Ovarian cyst rupture, hemorrhage, or torsion.
- Mittelschmerz (Ovulation Pain): Mid-cycle pain associated with ovulation.
- Pelvic Inflammatory Disease (PID): Infection of the female reproductive organs.
- Endometriosis: Condition where tissue similar to the uterine lining grows outside the uterus.
Reproductive (Male):
- Seminal Vesiculitis: Inflammation of the seminal vesicles.
- Undescended Testicle Pathology: Problems with an undescended testicle.
Urinary:
- Renal Colic: Kidney stones passing through the ureter.
- Urinary Tract Infection (UTI): Though typically suprapubic, can sometimes present with RIF pain.
Pain from Nearby Areas:
- Abdominal: Pain radiating from RUQ, central abdomen, or groin.
- Hip Pathology: Hip joint problems can refer pain to the RIF.
- Psoas Abscess: Abscess in the psoas muscle.
- Rectus Sheath Hematoma: Bleeding within the rectus abdominis muscle.
- Right Lower Lobe Pneumonia: Referred pain.
Left Iliac Fossa Pain (LIF)
Pain in the left lower abdomen.
Gastrointestinal:
- Diverticulitis: Inflammation or infection of diverticula in the colon, most commonly in the sigmoid colon, causing LIF pain.
- Colitis: Inflammation of the colon, such as ulcerative colitis or infectious colitis.
- Colon Cancer (Left-sided): Cancer in the descending or sigmoid colon.
- Constipation: Impacted stool in the sigmoid colon.
- Irritable Bowel Syndrome (IBS): Can cause pain in any abdominal region.
Reproductive (Female):
- Ectopic Pregnancy: Ruptured ectopic pregnancy.
- Acute Ovarian Event: Ovarian cyst rupture, hemorrhage, or torsion.
- Mittelschmerz (Ovulation Pain): Mid-cycle pain.
- Pelvic Inflammatory Disease (PID): Infection of the female reproductive organs.
- Endometriosis:
Reproductive (Male):
- Seminal Vesiculitis:
- Undescended Testicle Pathology:
Urinary:
- Renal Colic: Kidney stones.
- Urinary Tract Infection (UTI):
Pain from Nearby Areas:
- Abdominal: Pain radiating from LUQ, central abdomen, or groin.
- Hip Pathology:
- Psoas Abscess:
- Rectus Sheath Hematoma:
- Left Lower Lobe Pneumonia:
Suprapubic Pain
Pain in the lower central abdomen, above the pubic bone.
- Urinary Retention: Inability to urinate, causing bladder distention.
- Cystitis: Bladder infection.
- Uterine in Origin: PID, uterine fibroids, menstruation, or other gynecological conditions.
- Origin from RIF and/or LIF causes: Pain from lower quadrant conditions can sometimes be felt suprapubically.
Loin Pain (Flank Pain)
Pain in the side of the abdomen, between the ribs and hip.
Renal Tract:
- Infection (Pyelonephritis): Kidney infection.
- Obstruction (Renal Colic): Kidney stones blocking the ureter.
- Renal Carcinoma: Kidney cancer.
- Renal Vein Thrombosis: Blood clot in the renal vein.
- Polycystic Kidney Disease: Genetic disorder causing cysts in the kidneys, hemorrhage or rupture of cysts can cause acute pain.
- Adrenal Hemorrhage: Bleeding into the adrenal gland.
Other:
- Retroperitoneal Hemorrhage: Bleeding behind the peritoneum.
- Retroperitoneal Infection: Infection in the retroperitoneal space.
- Vertebral Pathology: Spinal problems referring pain to the flank.
Groin Pain
Pain in the area where the thigh meets the abdomen.
- Renal Calculi: Kidney stones moving down the ureter.
- Scrotal Pain: Testicular torsion, epididymo-orchitis (inflammation of the epididymis and testicle), trauma.
- Inguinal Hernia: Protrusion of abdominal contents through the inguinal canal.
- Hip Pathology: Hip joint problems.
- Pelvic Fracture: Fracture of the pelvic bones.
This acute abdomen abdominal pain differential diagnosis chart is intended as a quick reference guide and not a substitute for thorough clinical evaluation. Always consider the patient’s history, physical examination findings, and relevant investigations to reach an accurate diagnosis and initiate appropriate management. Prompt recognition and management of acute abdomen are critical in minimizing morbidity and mortality.
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