abdominal pain is a common medical complaint while acute abdomen is a term used when there is a rapid onset of severe abdominal pain that can indicate a life-threatening underlying cause there are many different causes of an acute abdomen therefore it is important to focus on the urgent causes that need immediate intervention firstly we have peritonitis which refers to inflammation of the peritoneum the lining of the peritoneal cavity in cases where this is generalized and involves most of the abdomen it is called generalized peritonitis peritonitic patients can quickly deteriorate and the peritoneum is a large cavity that can hold several liters of fluid and that combined with a significant inflammatory response means that patients can quickly become hypovolemic and enter shock additionally infection is extremely common as the contents of many organs are not sterile this generates an infective source that can quickly become septic shock the most common cause is a perforation of one of the abdominal organs primarily a bowel obstruction peptic ulcer disease diverticular disease or inflammatory bowel disease acute abdomen generated by a bleed is also an emergency bleeding must be kept in the differential in this case it may be overlooked as the bleeding is not visible externally in many cases examples include the rupture of an abdominal aortic aneurysm a ruptured ectopic pregnancy trauma or a bleeding peptic ulcer these patients will often require immediate surgical intervention ischemic bowel is also an emergency characterized by pain that is disproportionately more severe than the clinical picture the other causes can be divided by category including inflammatory such as acute cholecystitis pancreatitis or appendicitis other gynecological causes such as a rupture of an ovarian cyst or ovarian torsion infections are another cause featuring intra-abdominal abscesses which pose a risk of developing peritonitis there are also urological causes such as pyelonephritis renal stones or testicular torsion and other causes include a vaso-occlusive crisis in sickle cell disease and diabetic ketoacidosis in terms of the diagnosis the clinical history and physical exam will greatly help in narrowing down the possible causes of the acute abdomen mnemonics such as socrates are useful in gathering a comprehensive history of the pain the sight of the pain can guide us towards an underlying cause right upper quadrant pain can indicate gallstone disease acute hepatitis or even pneumonia as well as in some instances urotericolic or pyelonephritis left upper quadrant pain can also suggest many of these pathologies and in bowel ischemia can also be a focus of pain as the splenic flexure is a watershed area bear in mind that pain in the epigastric region may also include these conditions as well as peptic ulcer disease pancreatitis or even in some cases myocardial infarction pain in the right lower quadrant may indicate appendicitis note that appendicitis pain can also depend on the position of the appendix in that particular patient as well as gynecological issues such as a rupture of an ovarian cyst ovarian torsion or an ectopic pregnancy others include inguinal hernias or a ureteric stone the left lower quadrant may also have similar conditions this time including diverticular disease in the western world diviticulitis is more common on the left side however in the asian population it is more common to have it on the right side pain in the periumbilical region may be more indicative of an abdominal aortic aneurysm a bowel obstruction or the early stages of appendicitis if there is pain diffusely across the abdomen this may be more suggestive of ischemia or peritonitis we then look at the onset of the pain a longer standing pain that has worsened can be suggestive of peptic ulcer disease or if there are previous episodes of a similar pain that could indicate gallstone disease or diverticular disease the character of the pain also varies by condition for example a cramping colicky pain may point towards renal colic or an obstruction while aortic dissection is more likely to be a sudden sharp pain in addition to the sight the pain may also radiate to other places typical examples include from the right upper quadrant to the right scapula in gallstone disease around the upper abdomen and back like a belt in acute pancreatitis a progression from the peri umbilical region to the right iliac fossa in acute appendicitis and from the flank to the groin or loin to groin in renal stones associated symptoms can provide clues on the severity for example the presence of nausea and vomiting any fevers or rigors changes in bowel habits or even the presence of shortness of breath the t is for timing for example a correlation with food may indicate gallstone disease or peptic ulcer disease we then have e which is for the exacerbating or relieving factors in peritonitis small movements can exacerbate the pain causing the patient to lie still while in renal colic these patients are often continuously moving because they cannot find a comfortable position the last s is for severity and typically a pain score out of 10 is asked for but also remember to ask for the severity at its worst and at the time of the examination to gauge any fluctuations and to help guide the need for analgesia it is also beneficial to ask whether the pain has been generally improving or worsening to go alongside the history a physical exam can help narrow down the causes following the look listen and feel method a general inspection of the patient can be performed are they well colored or pale are they struggling to breathe are they in visible pain are there any abdominal scars that may indicate previous surgery therefore predisposing to an obstruction is there any abdominal discoloration or bruising or even abdominal distension when listening to the chest and abdomen are the breath sounds and heart sounds present normal are there any bowel sounds the bowel sounds may be absent in patients with a perforation peritonitis or the later stages of an obstruction or may be tinkling in the case of an early obstruction next comes palpation a diffuse tenderness with a rigid abdomen with guarding or rebound tenderness may point towards peritonitis but we may also look for any lumps that may indicate a hernia as the underlying cause we can also look for murphy's sign which is where palpation of the liver when asking the patient to breathe in causes a sharp cessation in inspiration when the liver or gallbladder comes into contact with a palpating hand this may indicate acute cholecystitis percussion may also be done which if painful may indicate peritoneal inflammation but it can also be done to look for dullness in the abdomen which may indicate underlying fluid or it may be tympanic indicating air it's important to remember that the vital signs are crucial with indicators such as hypotension and tachycardia potentially pointing towards a patient who is critically unwell and possibly shocked or septic lab values are useful such as the hemoglobin count white blood cells electrolytes and further inflammatory markers like crp other labs may also be useful such as the amylase levels however you may not have time to wait for all the lab values to come back therefore it's very useful to get a blood gas done which gives some of the other values we mentioned as an immediate result but crucially also contains lactate which can be a marker for tissue hypoxia or poor perfusion if it is raised and will help to determine how urgent the case is it is likely that imaging will also be required with plain abdominal x-ray being the fastest which may suggest findings such as an obstruction or the loss of the psoas shadow in the presence of an abdominal aortic aneurysm an erect chest x-ray may be done to look for air under the diaphragm which would indicate a perforation but a ct of the abdomen and pelvis is the imaging modality that is done most commonly when evaluating for causes of generalized abdominal pain ultrasound is also useful it may evaluate the gallbladder and biliary system it can do a fast scan for the presence of free fluid in the abdomen or the pericardium as well as being able to look for the rupture of an ectopic pregnancy or ovarian torsion the treatment and management of patients with an acute abdomen will vary depending on the underlying cause however there are some general principles that may be followed for example close monitoring of the vital signs oxygen if necessary intravenous access and initiation of fluid or even blood if necessary in most cases aggressive fluid management is tolerated but in cases such as a rupture of an abdominal aneurysm too much fluid can exacerbate the bleeding and in patients with comorbidities they may quickly become overloaded fluid intake and output should also be undertaken and broad-spectrum antibiotics should be considered if the patient has a suspected infection or perforation a pregnancy test should also be done if the female is of child bearing age analgesia and anti-metic agents may also be prescribed and patients with acute abdomens should generally be kept nil by mouth in case they require surgery then a surgical review of the patient should also be requested to determine the need for immediate operative management or even exploratory surgery