The "acute abdomen" refers to a patient who suddenly becomes unwell, presenting with a painful abdomen. It is a presentation all medical students and foundation doctors should know about, as it is the most common emergency presentation in surgery. The abdomen includes a number of organs of which any could be responsible for the pain. The way to approach these patients is no different to any other; a relevant history and a focussed examination will guide you in the right direction with your management.

Common causes of abdominal pain

    • appendicitis
    • pancreatitis
    • gallstones
    • intestinal obstruction (adhesions, hernias, gallstone, etc)
    • renal calculi
    • diverticulitis
    • peptic ulcer disease
    • inflammatory bowel disease
    • non-specific abdominal pain

                   

                  Female causes

                  • ectopic pregnancy
                  • miscarriage
                  • ruptured ovarian cyst

                   

                      Male causes

                    • testicular torsion

                     

                       

                      Thinking outside the box...

                      Some medical conditions can also masquerade as an acute abdomen, a few to watch out for are shown below.

                      • inferior MI
                      • lower lobe pneumonia
                      • hyperglycaemia
                      • hypercalcaemia

                       

                      Areas of the abdomen

                      Shown in the diagram are the areas of the abdomen, and the most likely underlying pathology.

                      Areas of the abdomen showing the sites of pain

                      History

                       

                      Taking a relevant history is always the first step. Having a structure is a good idea, as it means you won't get lost. You will need to know what sections are particularly significant to the presentation, in order to gather relevant information, and so that you don't waste any time!

                      Knowing typical presentations of common causes of abdominal pain will help to keep you on track, and remind you of anything you might have forgotten. A few of these are shown in the list on the right.

                      It is worth remembering that you are more likely to see strange presentations of the common causes than text book presentations of rare diseases.

                      Shown on the left is a break down of the history structure, and the relevant areas that should be covered for an acute abdomen.

                       

                      Presenting complaint

                      • Patient's own words

                      History of presenting complaint

                      • Pain (use mnemonic e.g. SOCRATES)

                      Past medical and surgical history

                      • Previous abdominal pain (if so, is it the same?)
                      • Previous diagnosis of inflammatory bowel disease (flare up?)
                      • Previous abdominal surgery (think adhesions leading to obstruction)
                      • Diabetes or heart disease (cover the unusual presentations)
                      • Any other significant illness that required hospitalisation or led to long term medication

                       Drug history

                      • Document all medications (if they need admitting then they still need to receive their medication)
                      • Consider adverse reactions/side-effects (NSAIDs leading to peptic ulcer, opiates causing constipation)
                      • Important - if the patient will require surgery, you must find out if they are on any anti-coagulant medications

                      Social History

                      • Alcohol intake (pancreatitis)
                      • Diet (fatty foods exacerbate gallstones)
                      • Support at home (may need help after an operation)

                      Family History

                      • Cancers
                      • Inflammatory bowel disease

                      Systems review

                      • Cover all systems, especially genitourinary

                       

                       

                          Examination

                          From the history you should already have formulated differential diagnoses. The examination will then allow you to narrow it down further to guide any investigations.

                           

                          Inspection

                          • pallor (due to intra-abdominal bleeding)
                          • sweating (pyrexic or hypotensive)
                          • restless (colic type pain)
                          • motionless (peritonitis - movement exacerbates pain)
                          • leaning forward (may relieve pain from retroperitoneal structures)
                          • scars from previous surgery
                          • evidence of hernia 

                           

                          Palpation

                          Always start at the point furthest away from the pain. The aim of palpation is to find the area specifically involved with the pain. Guarding is a response of the muscle tensing in the immediate area of the pain. Peritonitis will feel rigid, from contraction of the abdominal muscles.

                           

                          Percussion

                          Useful for distinguishing the character of any lumps and bumps. It may also produce rebound tenderness.

                           

                          Auscultation

                          High pitched, or tinkling, bowel sounds indicate an obstruction. The absence of them could indicate peritonitis or an ileus.

                           

                          Genitalia, Hernial orifices and Rectal examination

                          Full examination of these areas would be carried out on patients with an acute abdomen. Be sure to mention you would ideally like to perform these examinations in the OSCEs.

                           

                          Investigations

                          The next steps of management should be guided by your history and examination. Investigations should be specific to your patient and their presentation, not just a generic set of procedures.

                           

                          Blood tests

                          • Full blood count will show up any anaemia or white cell abnormality. 
                          • Urea and electrolytes will show renal function, and can be relevant of the patient is going to have an anaesthetic. 
                          • Liver function tests should be ordered if there are signs of liver failure or you suspect gallbladder disease.
                          • Amylase is a useful marker for pancreatitis, although it can be raised due to other pathology.
                          • Group and save should be performed if their is any likelihood that a operation will be needed.

                           

                          Urine can be tested with a dipstick, if anything abnormal is seen then a sample shoud be sent for microscopy and culture.

                           

                          Imaging

                          • Erect chest x-ray (CXR) - can be used to show subphrenic gas, a mark of perforation. It may also show consolidation in lower lobe pneumonia.
                          • Abdominal x-ray (AXR) - can be used to show free gas as well, but also distended bowel from obstruction or stones in the kidney or gallbladder. (N.B. gallstones will only be picked up 10% of the time)
                          • Ultrasound - may also be used to visualise most of the organs in the abdomen, retroperitoneal structures are harder because they are behind so many other organs.
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