Approaching An `acute Abdomen`

The Acute Abdomen

An acute abdomen describes the feeling of sudden onset and extremely severe abdominal pain. There are a range of underlying causes which makes a thorough history taking and clinical examination imperative. Initially, we need to establish if a patient requires immediate surgical intervention or medical therapy. We begin assessing a patient by general inspection and looking at their observations.

Bleeding is a serious underlying cause requiring urgent intervention, the most severe cause being a rupture abdominal aortic aneurysm which requires intervention by the vascular team. Furthermore, other causes of bleeding include a perforated gastric ulcer, ruptured ectopic pregnancy and trauma. Medics should particularly pay attention to heart rate and blood pressure for tachycardia (fast heart rate) and hypotension (low blood pressure) as these signs indicate the patient is going into hypovolemic shock. Other clinical features include pale and clammy peripheries.

If a patient is lying completely still and they look very unwell, you should suspect a perforated viscus resulting in a generalised peritonitis which means inflammation of the peritoneum. Underlying causes include peptic ulceration, small or large bowel obstruction, diverticulitis and IBD. Other signs of peritonism on examination include: rigid abdomen with percussion tenderness, involuntary guarding, reduced or absent bowel sounds as well as tachycardia and potential hypotension.

If you come across a patient who has severe pain out of proportion to the clinical signs, then it is crucial to rule out bowel ischaemia. An ABG will show acidosis with a raised lactate patients will have a diffuse and constant pain so a definitive diagnosis can be made via a CT scan with IV contrast.

Lab tests are important to help reach a diagnosis, some useful ones include: urine dipstick, ABG, routine bloods (FBC, U+E`s, LFT`s, CRP, amylase etc), GS, blood cultures etc

Imaging: eCXR. ultrasound, CT imaging, ECG

Management usually depends on the underlying cause but the general plan involves intravenous access, nil-by-mouth, analgesia, antiemetics, imaging, VTE prophylaxis, urine dip, bloods etc. If critically unwell we can consider a catheter and NG tube. When commencing IV fluids it`s important to monitor fluid balance and urine output.