QuestionSBA
QuestionChoice
This patient appears to be having a flare of his ulcerative colitis, a barium enema would not be an appropriate investigation, and in fact may increase risk of bowel perforation
31971
d
Barium enema
QuestionChoice
A plain abdominal x-ray should first be conducted in this patient to investigate for toxic megacolon. The symptoms that he presents with are consistent with this
31968
a
Abdominal X-ray
QuestionChoice
Urgent endoscopy is not indicated in this patient at present, who appears to be having a flare of his ulcerative colitis. An urgent endoscopy may indicated in patients with haematemesis, melaena, or haemodynamic instability
31972
e
Urgent endoscopy
QuestionChoice
A CT abdomen/pelvis may be indicated later in his admission to look or any complications such as abscesses, but would first require an abdominal x-ray
31969
b
CT abdomen/pelvis
QuestionChoice
In this patient it is most important to investigate for toxic megacolon as they appear to be having a flare of their ulcerative colitis. An ultrasound abdomen would visualise investigate gallstones or free pelvic fluid
31970
c
Ultrasound abdomen
Concept
Chapter
# Summary

The acute abdomen, a common presentation in clinical practice, refers to the sudden onset of severe abdominal pain. It is often a medical and/or surgical emergency, requiring prompt evaluation and intervention. Causes of an acute abdomen can be divided into surgical and medical causes, and while investigations and management of these are specific to the underlying cause, there are broad principles which should always be followed. This section explores the diverse aetiologies and clinical manifestations of acute abdominal conditions, emphasising the importance of timely diagnosis and management. 

# Epidemiology

While prevalence varies geographically, acute abdomen accounts for a substantial proportion of emergency department admissions worldwide. A broad spectrum of age groups is affected, with appendicitis being more common in younger individuals, while conditions like diverticulitis and cholecystitis are prevalent in older populations. Additionally, comorbidities and lifestyle factors, including smoking and diet, may contribute to the incidence of acute abdominal conditions. 

# Differential Diagnosis

## Surgical Acute Abdomen

Here's a summary table with surgical differential diagnoses for each of the specified types of abdominal pain. It's important to note this is a guide and not all of these pathologies can only present with one type of pain, and there can be overlap with atypical presentations.


| Type of Abdominal Pain     | Surgical Differential Diagnoses                                    |
|-----------------------------|-----------------------------------------------------------------------|
| **Central Abdominal Pain** | - Mesenteric ischemia <br /> - Acute pancreatitis (complicated) <br /> - Aortic dissection <br /> - Appendicitis <br /> - Intestinal obstruction <br /> - Perforated viscus <br /> - Abdominal wall hernia (strangulated) <br /> - Ruptured AAA |
| **Epigastric Pain**        | - Acute pancreatitis (complicated) <br /> - Perforated peptic ulcer <br /> - Cholecystitis (with gallbladder perforation) <br /> - Gastro-oesophageal perforation <br /> - Aortic dissection <br /> - Abdominal aortic aneurysm (AAA) <br /> - Gastric or duodenal ulcer (complicated) |
| **Left Upper Quadrant Pain** | - Gastrointestinal perforation <br /> - Left-sided diverticulitis <br /> - Left renal pathology (e.g. abscess) <br /> - Perforated gastric or duodenal ulcer <br /> - Abdominal aortic aneurysm (AAA) <br /> - Spleen-related conditions (e.g. splenic infarction, rupture, abscess) <br /> - Gastric or duodenal ulcers (complicated) |
| **Left Iliac Fossa Pain**   | - Diverticulitis (complicated) <br /> - Gynecological emergencies (e.g. ovarian torsion, ovarian cyst rupture, ectopic pregnancy) <br /> - Left ureteral stone (with obstruction) <br /> - Ulcerative colitis <br /> - Perforated sigmoid diverticulitis <br /> - Ischaemic colitis (left-sided) <br /> - Left renal pathology (e.g. abscess) <br /> - Ileocecal tuberculosis (rare) <br /> - Sigmoid volvulus <br /> - Left-sided appendicitis (rare) |
| **Right Upper Quadrant Pain** | - Acute cholecystitis <br /> - Biliary colic <br /> - Ascending cholangitis <br /> - Perforated peptic ulcer (anterior) <br /> - Liver pathology (e.g. hepatic abscess) <br /> - Right renal pathology (e.g. abscess) <br /> - Right-sided diaphragmatic hernia (e.g. Morgagni hernia) <br /> - Subphrenic abscess <br /> - Appendicitis (retrocecal) |
| **Right Iliac Fossa Pain**  | - Appendicitis <br /> - Caecal diverticulitis (rarely) <br /> - Right-sided gynecological emergencies (e.g. ovarian torsion, ovarian cyst rupture, ectopic pregnancy) <br /> - Right ureteral stone (with obstruction) <br /> - Ileocecal tuberculosis (rarely) <br /> - Right renal pathology (e.g. infarction, abscess) <br /> - Gastrointestinal perforation (e.g. perforated appendicitis) <br /> - Crohn's disease (terminal ileitis) |
| **Suprapubic Pain**         | - Acute appendicitis (atypical presentation) <br /> - Diverticulitis (with involvement of sigmoid) <br /> - Bladder pathology (e.g. bladder rupture) <br /> - Right ureteral stone (with lower migration) <br /> - Urethral pathology (e.g. urethral diverticulum) <br /> - Colonic pathology (e.g. ischaemic colitis) <br /> - Testicular torsion <br /> - Inguinal hernia (rare) <br /> - Pubic osteomyelitis (rare) |

## Medical Acute Abdomen

Unless otherwise specified, these causes can often present with very generalised abdominal pain which is often poorly localised.

-   Myocardial infarction (especially inferior MI which can present with epigastric pain)
-   Pericarditis
-   Pulmonary embolism
-   Gastroenteritis
-   Pneumonia (left/right lower lobes)
-   Mesenteric adenitis
-   Vasculitis (such as Henoch-Schonlein purpura)
-   Diabetic ketoacidosis
-   Addison's disease
-   Hypercalcaemia
-   Acute intermittent porphyria
-   Abdominal migraine
-   Irritable bowel syndrome
-   UTI and urinary retention (often suprapubic pain)
-   Sickle cell crisis

# Investigations

### Bedside
- Blood glucose and ketones 
- Urine (urine dip, cultures and **pregnancy test in all females of childbearing age**
- Stool (culture, faecal calprotectin), FIT testing in primary care (less urgent in acute setting)
- ECG (looking for ischaemic changes)

### Blood tests
- VBG (raised lactate may indicate ischaemia, metabolic disturbances can be indicative of several medical causes such as DKA, addison's disease and hypercalcaemia)
- FBC (anaemia may indicate haemorrhage, underlying malignancy; raised infection markers), CRP, U+E, LFTs, coagulation profile and group and save (especially if surgical intervention is likely), amylase/lipase, beta-HCG, troponin/d-dimer **(if indicated)**, blood cultures
- Less urgent blood tests include tumour markers (CEA, CA 19-9)

### Imaging
- AXR +/- erect CXR (to assess for pneumoperitoneum and perforation)
- USS of abdomen/renal tract/pelvis/testes
- CT abdomen pelvis/urinary tract, CT angiogram (if ischaemia/AAA rupture suspected)
- MRI may be indicated if e.g. looking for abscesses
- MRCP (gallstones)
- Endoscopy - OGD/colonoscopy/flexible sigmoidoscopy which may also be therapeutic

# Management

Though specific management strategies will depend on the underyling cause (see separate sections on each differential diagnosis), here are broad principles which will be applicable to the majority of the above differentials:

- Conservative management - IV fluids +/- NG tube insertion ('drip and suck'), analgesia, anti-emetics, anti-spasmodics (such as hyoscine butylbromide), nutritional support (e.g. pabrinex)
- Medical management - oral/IV antibiotics if suspected infectious cause, PPI (e.g. omeprazole)
- Surgical management - may include but not limited to: endoscopy, ERCP, laparoscopic intervention.


# NICE Guidelines

NICE CKS Summaries:

- [Acute pancreatitis](https://cks.nice.org.uk/topics/pancreatitis-acute/)
- [Diverticular disease](https://cks.nice.org.uk/topics/diverticular-disease/)
- [Appendicitis](https://cks.nice.org.uk/topics/appendicitis/)
- [Ectopic pregnancy](https://cks.nice.org.uk/topics/ectopic-pregnancy/)
- [Cholecystitis](https://cks.nice.org.uk/topics/cholecystitis-acute/)
- [Gallstones](https://cks.nice.org.uk/topics/gallstones/)
- [Crohn's disease](https://cks.nice.org.uk/topics/crohns-disease/)
- [Ulcerative colitis](https://cks.nice.org.uk/topics/ulcerative-colitis/)


3269
5407
Acute Abdomen
Topic
7
General Surgery
6394
A 30 year old man with a past medical history of ulcerative colitis presents to the accident and emergency department. They report that they have been passing approximately six blood-stained stools per day. He denies nausea or vomiting at present.

Their observations are as follows:

- Respiratory rate: 18 breaths per minute
- Saturations: 99% on air
- Heart rate: 105 beats per minute
- Blood pressure: 110/85mmHg
- Temperature: 38.2 degrees Celsius

On examination, their abdomen is mildly distended with mild generalised tenderness. Bowel sounds are present.

Which of the following investigations should be first conducted in this patient?
a