QuestionSBA
QuestionChoice
Once an ectopic pregnancy has been ruled out, this patient's history is strongly suggestive of appendicitis. An abdominal CT scan can be a valuable investigation, particularly in patients with a longer history of pain or a palpable mass in the right iliac fossa (where there may be concern of an appendicular abscess or underlying malignancy), as well as in cases where a previous ultrasound has been indeterminate. However, it is important to remember that appendicitis can also be a clinical diagnosis and many patients go straight to theatre without any confirmatory imaging
33330
c
Computed tomography (CT) abdomen
QuestionChoice
An erect CXR can play a role in assessment of patients presenting with acute abdominal pain – if the x-ray demonstrates pneumoperitoneum (air under the diaphragm) this is in keeping with a perforated viscus. However, this finding is not that sensitive - many cases of perforation occur in the absence of any identifiable pneumoperitoneum. There are other more valuable investigations at the stage of the patient's assessment
33329
b
Erect chest x-ray (CXR)
QuestionChoice
This would play an important role in determining the severity of any infection, as well as the patient's response to any antibiotic treatment. However, this is a relatively non-specific test and there are other more urgent considerations to be addressed, particularly the patient's pregnancy status
33331
d
Blood tests for inflammatory markers
QuestionChoice
In women of child-bearing age a urine pregnancy test should be prioritised to rule out the possibility of an ectopic pregnancy. This is a priority in early stages of patient assessment as the rupture of an ectopic is a surgical emergency, with high levels of mortality if not rapidly identified and treated. Additionally, it would be important to know about a viable pregnancy too, as this may alter the plan for further investigation and treatment of the pain
33328
a
Urinary beta-HCG
QuestionChoice
Once an ectopic pregnancy has been ruled out, this patient's history is strongly suggestive of appendicitis. An abdominal ultrasound is an important diagnostic investigation in appendicitis, particularly if there are concerns regarding radiation dose for the patient, i.e. in pregnancy or childhood/for young adults. However, it is important to remember that appendicitis can also be a clinical diagnosis and many patients go straight to theatre without any confirmatory imaging
33332
e
Abdominal ultrasound
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
6666
A 23-year-old female presents to the emergency department with severe abdominal pain. This started 24 hours ago and was generalised in location but has now become markedly worse overnight, alongside migration of the pain to be more focussed in her right iliac fossa. She also reports some associated nausea, but no vomiting.

Which of the following is the next best step in the management of this patient?
a