Acute Surgical Presentations — MCQs
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A 28-year-old man presents with a 14-hour history of right iliac fossa pain. Initial examination reveals tenderness at McBurney's point. Four hours later, the pain becomes generalized with board-like rigidity across the whole abdomen. Heart rate is 125 bpm and temperature 38.7°C. What pathophysiological change best explains this clinical progression?
A 67-year-old man with known gallstone disease presents with a 48-hour history of right upper quadrant pain, fever (39.1°C), and confusion. Examination reveals jaundice, right upper quadrant tenderness, and hypotension (85/50 mmHg). Blood tests show: bilirubin 95 μmol/L, ALP 450 U/L, ALT 180 U/L, WCC 19 × 10⁹/L, CRP 285 mg/L. What is the most appropriate initial management strategy?
A 39-year-old woman presents with a 6-hour history of sudden onset severe epigastric pain radiating to the back. She admits to consuming 60 units of alcohol per week. Amylase is 1200 U/L (normal <100). Her observations show: BP 100/70 mmHg, HR 110 bpm, temperature 37.8°C, oxygen saturation 94% on air. Blood tests reveal: calcium 1.95 mmol/L, glucose 12.5 mmol/L, urea 9.5 mmol/L, WCC 18 × 10⁹/L, CRP 180 mg/L. Using the Glasgow scoring system, what is this patient's predicted mortality risk in the first 48 hours?
A 75-year-old man presents with a 12-hour history of severe generalized abdominal pain. He has a background of poorly controlled type 2 diabetes and ischaemic heart disease. On examination, he is tachycardic (120 bpm) and hypotensive (95/60 mmHg). The abdomen is diffusely tender with guarding. Laboratory investigations show WCC 22 × 10⁹/L, lactate 6.5 mmol/L, and amylase 150 U/L. CT scan demonstrates pneumatosis intestinalis and portal venous gas. What is the most likely diagnosis?
A 61-year-old woman with no previous abdominal surgery presents with a 5-day history of progressive abdominal distension, absolute constipation, and vomiting. She has a history of chronic laxative use. Examination reveals a grossly distended, tympanic abdomen. Abdominal X-ray shows a markedly dilated loop of bowel arising from the left lower quadrant, forming an inverted U-shape extending into the right upper quadrant. What is the most likely diagnosis?
Which of the following mechanisms best explains the pathophysiology of pneumoperitoneum following hollow viscus perforation?
A 46-year-old woman presents with a 24-hour history of severe, constant right iliac fossa pain. She reports nausea and anorexia. On examination, temperature is 38.2°C, tenderness in the right iliac fossa with guarding is present. White cell count is 16.5 × 10⁹/L. CT scan shows an inflamed appendix with surrounding fat stranding but no abscess or perforation. What is the most appropriate definitive management?
A 54-year-old man with a history of previous abdominal surgery presents with a 36-hour history of colicky abdominal pain, vomiting, and absolute constipation. Examination reveals a distended abdomen with tinkling bowel sounds. Abdominal X-ray shows dilated loops of small bowel with valvulae conniventes visible. Which initial management approach is most appropriate?
A 47-year-old man with alcoholic cirrhosis develops sudden onset severe abdominal pain and fever. He has tense ascites. Examination shows generalized abdominal tenderness without rebound. Ascitic tap shows: WCC 850 cells/μL with 75% neutrophils, protein 18 g/L, glucose 2.1 mmol/L, pH 7.28, amylase 35 U/L. Blood cultures are pending. What is the most appropriate immediate management?
A 68-year-old man presents with sudden onset severe abdominal pain and bloody diarrhoea for 4 hours. He has atrial fibrillation but stopped his warfarin 3 weeks ago. Examination shows moderate abdominal tenderness in the left iliac fossa without peritonism. CT shows thickening of the sigmoid and descending colon wall with surrounding fat stranding. The superior mesenteric artery and coeliac axis are patent. What is the most likely diagnosis?
Acute Surgical Presentations UK Medical PG Practice Questions and MCQs
Question 201: A 28-year-old man presents with a 14-hour history of right iliac fossa pain. Initial examination reveals tenderness at McBurney's point. Four hours later, the pain becomes generalized with board-like rigidity across the whole abdomen. Heart rate is 125 bpm and temperature 38.7°C. What pathophysiological change best explains this clinical progression?
- A. Extension of inflammatory process to involve the entire small bowel
- B. Development of paralytic ileus causing generalized abdominal distension
- C. Progression from localized visceral peritoneal inflammation to generalized parietal peritonitis (Correct Answer)
- D. Thrombosis of mesenteric vessels causing widespread intestinal ischaemia
- E. Bacterial translocation causing systemic inflammatory response syndrome
Explanation: ***Progression from localized visceral peritoneal inflammation to generalized parietal peritonitis***- The initial localized pain at **McBurney's point** is characteristic of **visceral peritoneum** irritation from an inflamed appendix.- The subsequent **generalized pain** with **board-like rigidity** signifies **appendiceal perforation** and widespread irritation of the somatically innervated **parietal peritoneum**, leading to peritonitis.*Extension of inflammatory process to involve the entire small bowel*- **Acute appendicitis** is a localized inflammation of the appendix, not typically involving diffuse inflammation of the entire **small bowel wall**.- While inflammation can spread locally, this option does not accurately describe the rapid progression to **generalized peritonitis** and muscular rigidity.*Development of paralytic ileus causing generalized abdominal distension*- **Paralytic ileus** can occur secondary to peritonitis, causing **abdominal distension** and decreased bowel sounds, but it does not directly cause **board-like rigidity**.- **Rigidity** is a direct sign of severe **parietal peritoneal irritation**, whereas ileus is a functional bowel impairment.*Thrombosis of mesenteric vessels causing widespread intestinal ischaemia*- **Acute mesenteric ischemia** typically presents with severe, diffuse abdominal pain that is often
Question 202: A 67-year-old man with known gallstone disease presents with a 48-hour history of right upper quadrant pain, fever (39.1°C), and confusion. Examination reveals jaundice, right upper quadrant tenderness, and hypotension (85/50 mmHg). Blood tests show: bilirubin 95 μmol/L, ALP 450 U/L, ALT 180 U/L, WCC 19 × 10⁹/L, CRP 285 mg/L. What is the most appropriate initial management strategy?
- A. Immediate laparoscopic cholecystectomy
- B. Fluid resuscitation, broad-spectrum antibiotics, and urgent ERCP within 24 hours (Correct Answer)
- C. Conservative management with antibiotics and interval cholecystectomy after 6 weeks
- D. Percutaneous cholecystostomy under radiological guidance
- E. Open cholecystectomy and common bile duct exploration
Explanation: ***Fluid resuscitation, broad-spectrum antibiotics, and urgent ERCP within 24 hours*** - This patient presents with **Reynolds' pentad** (fever, jaundice, RUQ pain, hypotension, and confusion), indicating severe **acute cholangitis** and septic shock. - Immediate management requires aggressive **circulatory support**, intravenous antibiotics, and **urgent biliary decompression** via ERCP to relieve the obstruction and source of sepsis. *Immediate laparoscopic cholecystectomy* - Performing surgery during an acute episode of **septic shock** and biliary obstruction significantly increases the risk of morbidity and mortality. - **ERCP** is the preferred initial modality for emergent biliary decompression, with cholecystectomy typically deferred until the patient's condition stabilizes. *Conservative management with antibiotics and interval cholecystectomy after 6 weeks* - While antibiotics are crucial, they are insufficient for **severe cholangitis** with systemic signs of sepsis (Grade III) without mechanical **biliary drainage**. - Delaying decompression in a hemodynamically unstable patient with **sepsis and altered mental status** would lead to rapid clinical deterioration and potential multi-organ failure. *Percutaneous cholecystostomy under radiological guidance* - This procedure is primarily indicated for draining the **gallbladder** in acute cholecystitis, especially in high-risk patients unsuitable for surgery, not for common bile duct obstruction. - For **common bile duct obstruction**, as seen in cholangitis, **ERCP** or percutaneous transhepatic cholangiography (PTC) are more effective as they directly target and decompress the **obstructed biliary tree**. *Open cholecystectomy and common bile duct exploration* - **Open surgery** is highly invasive and associated with significant morbidity and mortality in a patient who is hemodynamically unstable and in septic shock. - **Endoscopic decompression** via ERCP is a less invasive and highly effective primary approach for relieving **biliary obstruction** and managing severe cholangitis.
Question 203: A 39-year-old woman presents with a 6-hour history of sudden onset severe epigastric pain radiating to the back. She admits to consuming 60 units of alcohol per week. Amylase is 1200 U/L (normal <100). Her observations show: BP 100/70 mmHg, HR 110 bpm, temperature 37.8°C, oxygen saturation 94% on air. Blood tests reveal: calcium 1.95 mmol/L, glucose 12.5 mmol/L, urea 9.5 mmol/L, WCC 18 × 10⁹/L, CRP 180 mg/L. Using the Glasgow scoring system, what is this patient's predicted mortality risk in the first 48 hours?
- A. Less than 1% (0 or 1 criteria met)
- B. Approximately 1-5% (2 criteria met)
- C. Approximately 10-15% (3 criteria met) (Correct Answer)
- D. Approximately 40% (4 criteria met)
- E. Greater than 50% (5 or more criteria met)
Explanation: ***Approximately 10-15% (3 criteria met)*** - This patient scores **3 points** on the **Glasgow (Imrie) Scale** based on **WCC >15 x 10⁹/L** (18), **Glucose >10 mmol/L** (12.5), and **Calcium <2.0 mmol/L** (1.95). - A score of **3 or more** signifies **severe acute pancreatitis**, which correlates with a predicted mortality risk of approximately **10-15%**. *Less than 1% (0 or 1 criteria met)* - This score indicates **mild pancreatitis** where the probability of developing organ failure or local complications is very low. - The presence of **leukocytosis**, **hyperglycemia**, and **hypocalcemia** in this patient clearly exceeds this mild threshold. *Approximately 1-5% (2 criteria met)* - A score of **2 points** still generally classifies the event as **mild-to-moderate** rather than severe pancreatitis. - Since the patient meets **three separate criteria** (WCC, Glucose, Calcium), this category underestimates the clinical severity and risk. *Approximately 40% (4 criteria met)* - This level of mortality is associated with a score of **4 points**, indicating very high risk and likely **multisystem involvement**. - Although the patient is ill, she does not meet other criteria like **Age >55**, **Urea >16 mmol/L**, or low **Albumin** to reach this total. *Greater than 50% (5 or more criteria met)* - A mortality rate exceeding 50% is reserved for patients with a Glasgow score of **5 or higher**, representing extreme severity. - This patient lacks the necessary number of systemic inflammatory markers or biochemical derangements to reach this critical threshold.
Question 204: A 75-year-old man presents with a 12-hour history of severe generalized abdominal pain. He has a background of poorly controlled type 2 diabetes and ischaemic heart disease. On examination, he is tachycardic (120 bpm) and hypotensive (95/60 mmHg). The abdomen is diffusely tender with guarding. Laboratory investigations show WCC 22 × 10⁹/L, lactate 6.5 mmol/L, and amylase 150 U/L. CT scan demonstrates pneumatosis intestinalis and portal venous gas. What is the most likely diagnosis?
- A. Perforated duodenal ulcer with severe peritonitis
- B. Acute mesenteric ischaemia with bowel infarction (Correct Answer)
- C. Severe acute pancreatitis with infected necrosis
- D. Perforated sigmoid diverticulitis with faecal peritonitis
- E. Ruptured abdominal aortic aneurysm
Explanation: ***Acute mesenteric ischaemia with bowel infarction***- The presence of **pneumatosis intestinalis** (gas within the bowel wall) and **portal venous gas** on CT scan are highly specific findings indicating transmural bowel necrosis.- The patient's severe generalized abdominal pain, shock, high **lactate** (6.5 mmol/L), and risk factors like **ischaemic heart disease** are classic for this life-threatening condition.*Perforated duodenal ulcer with severe peritonitis*- This condition typically results in **pneumoperitoneum** (free air in the abdominal cavity), which is distinct from pneumatosis intestinalis or portal venous gas.- While it causes severe peritonitis and shock, the specific CT findings of gas within the bowel wall and portal system are not characteristic.*Severe acute pancreatitis with infected necrosis*- The **amylase** level of 150 U/L is not sufficiently elevated (typically >3x upper limit of normal) to diagnose acute pancreatitis.- **Pneumatosis intestinalis** and **portal venous gas** are not characteristic CT findings for pancreatitis, which would typically show pancreatic inflammation or fluid collections.*Perforated sigmoid diverticulitis with faecal peritonitis*- This condition would likely present with localized abdominal pain (often left lower quadrant) progressing to peritonitis and **pneumoperitoneum** on imaging.- The CT findings of diffuse **pneumatosis intestinalis** and **portal venous gas** are not typical for isolated perforated diverticulitis but rather for widespread bowel ischaemia.*Ruptured abdominal aortic aneurysm*- A ruptured AAA presents with sudden severe pain (often radiating to the back) and **hypovolemic shock**, but CT would reveal a **retroperitoneal hematoma**.- This diagnosis does not account for the presence of **pneumatosis intestinalis** or **portal venous gas**, which are specific indicators of bowel necrosis.
Question 205: A 61-year-old woman with no previous abdominal surgery presents with a 5-day history of progressive abdominal distension, absolute constipation, and vomiting. She has a history of chronic laxative use. Examination reveals a grossly distended, tympanic abdomen. Abdominal X-ray shows a markedly dilated loop of bowel arising from the left lower quadrant, forming an inverted U-shape extending into the right upper quadrant. What is the most likely diagnosis?
- A. Caecal volvulus
- B. Sigmoid volvulus (Correct Answer)
- C. Small bowel obstruction due to adhesions
- D. Large bowel obstruction secondary to colorectal carcinoma
- E. Ogilvie's syndrome (acute colonic pseudo-obstruction)
Explanation: ***Sigmoid volvulus*** - The patient's presentation with progressive abdominal distension, absolute constipation, vomiting, and a grossly distended, tympanic abdomen are classic symptoms of **large bowel obstruction**. - The abdominal X-ray finding of a markedly dilated loop of bowel forming an **inverted U-shape** (often described as a **coffee bean sign**) arising from the **left lower quadrant** and extending into the right upper quadrant is highly characteristic of **sigmoid volvulus**. **Chronic laxative use** is a known risk factor. *Caecal volvulus* - While also a form of volvulus, **caecal volvulus** typically presents radiologically with the dilated loop's apex in the **right upper quadrant** or mid-abdomen, and it often has a more **kidney bean shape** rather than an inverted U. - It often affects **younger individuals** and is associated with incomplete fixation of the caecum, which is not suggested by the patient's age (61) or history. *Small bowel obstruction due to adhesions* - **Adhesions** are a common cause of small bowel obstruction, but the patient's history states **no previous abdominal surgery**, making adhesions highly unlikely. - Small bowel obstruction typically shows **multiple dilated loops of small bowel** with **valvulae conniventes** on X-ray, and generally less pronounced isolated distension than described for this patient. *Large bowel obstruction secondary to colorectal carcinoma* - While **colorectal carcinoma** is a common cause of large bowel obstruction, it typically has a more **gradual onset** of symptoms and would show a **transition point** on imaging, often with visible **haustral markings** proximal to the obstruction. - The X-ray finding of a single, markedly dilated, **inverted U-shaped loop** is specific to a volvulus, not typically seen with a stenotic lesion from a tumor. *Ogilvie's syndrome (acute colonic pseudo-obstruction)* - **Ogilvie's syndrome** is characterized by massive acute colonic dilatation without a mechanical obstruction, often precipitated by serious illness, trauma, or surgery. - While it causes distension, the X-ray usually shows **diffuse colonic dilatation**, including the caecum and right colon, without the specific, localized, **inverted U-shaped loop** characteristic of a sigmoid volvulus.
Question 206: Which of the following mechanisms best explains the pathophysiology of pneumoperitoneum following hollow viscus perforation?
- A. Release of gastric acid causing tissue necrosis and gas formation
- B. Bacterial fermentation producing carbon dioxide in the peritoneal cavity
- C. Direct escape of luminal gas through the perforation into the peritoneal cavity (Correct Answer)
- D. Chemical peritonitis leading to secondary gas production by inflammatory cells
- E. Paralytic ileus causing retrograde gas migration through the bowel wall
Explanation: ***Direct escape of luminal gas through the perforation into the peritoneal cavity*** - **Pneumoperitoneum** is primarily caused by the physical movement of **intraluminal gases** (such as swallowed air) escaping through a breach in the gut wall. - This gas typically collects under the **diaphragm** on an erect chest X-ray, serving as a hallmark sign of a **perforated hollow viscus**. *Release of gastric acid causing tissue necrosis and gas formation* - While **gastric acid** causes immediate **chemical peritonitis** and tissue damage, it does not generate gas as a byproduct of the corrosive process. - The gas seen in these cases is already present in the **gastric lumen** and is released when the wall integrity is lost. *Bacterial fermentation producing carbon dioxide in the peritoneal cavity* - Although **bacterial flora** are released during perforation, the rapid onset of pneumoperitoneum is due to **mechanical escape** of air rather than the slow process of fermentation. - Fermentation may contribute to later stages of **septic peritonitis**, but it is not the primary mechanism behind the initial free air seen on imaging. *Chemical peritonitis leading to secondary gas production by inflammatory cells* - **Inflammatory cells** responding to chemical irritants release cytokines and enzymes, but they do not produce **bulk gas** volumes sufficient to cause radiographically visible pneumoperitoneum. - Chemical peritonitis is a result of the leakage of **digestive enzymes** and acid, not the cause of the gas accumulation itself. *Paralytic ileus causing retrograde gas migration through the bowel wall* - **Paralytic ileus** causes bowel loops to distend with gas, but the gas remains trapped within the **bowel lumen** unless a physical perforation occurs. - **Transmural migration** of gas without a macroscopic perforation (pneumatosis intestinalis) is a distinct and much rarer clinical phenomenon than hollow viscus rupture.
Question 207: A 46-year-old woman presents with a 24-hour history of severe, constant right iliac fossa pain. She reports nausea and anorexia. On examination, temperature is 38.2°C, tenderness in the right iliac fossa with guarding is present. White cell count is 16.5 × 10⁹/L. CT scan shows an inflamed appendix with surrounding fat stranding but no abscess or perforation. What is the most appropriate definitive management?
- A. Intravenous antibiotics alone for 48 hours
- B. Laparoscopic appendicectomy within 24 hours (Correct Answer)
- C. Interval appendicectomy after 6-8 weeks
- D. Percutaneous drainage under ultrasound guidance
- E. Conservative management with antibiotics and interval appendicectomy only if symptoms recur
Explanation: ***Laparoscopic appendicectomy within 24 hours***- For **acute uncomplicated appendicitis**, as seen with an inflamed appendix and no abscess or perforation, **surgical removal** is the definitive and most appropriate management.- **Laparoscopic appendicectomy** is the preferred approach due to its benefits, including reduced postoperative pain, shorter hospital stay, and faster recovery compared to open surgery.*Intravenous antibiotics alone for 48 hours*- While **antibiotics** can be used in some cases of uncomplicated appendicitis, they are associated with a **higher risk of recurrence** or treatment failure, leading to a need for surgery later.- **Surgical appendicectomy** remains the gold standard for definitive management of acute appendicitis in otherwise fit patients to prevent complications and recurrence.*Interval appendicectomy after 6-8 weeks*- This management strategy is typically reserved for cases where an **appendix mass** or **phlegmon** has been managed conservatively, and inflammation needs to subside.- Since the CT scan shows an acutely inflamed appendix without a mass or abscess, **delaying surgery** for 6-8 weeks is unnecessary and increases the risk of **perforation**.*Percutaneous drainage under ultrasound guidance*- **Percutaneous drainage** is indicated for the management of a **localized appendix abscess**, particularly larger ones (e.g., >3cm), to drain the collection.- The CT scan explicitly stated **no abscess** or perforation, making percutaneous drainage inappropriate for this patient's condition.*Conservative management with antibiotics and interval appendicectomy only if symptoms recur*- **Conservative management** with antibiotics as a primary approach is associated with a higher rate of **treatment failure** and recurrence compared to immediate surgical intervention.- This approach is not the **definitive management** for acute uncomplicated appendicitis, as immediate appendicectomy offers a permanent cure and prevents future episodes.
Question 208: A 54-year-old man with a history of previous abdominal surgery presents with a 36-hour history of colicky abdominal pain, vomiting, and absolute constipation. Examination reveals a distended abdomen with tinkling bowel sounds. Abdominal X-ray shows dilated loops of small bowel with valvulae conniventes visible. Which initial management approach is most appropriate?
- A. Immediate laparotomy
- B. Conservative management with nasogastric decompression, intravenous fluids, and close monitoring (Correct Answer)
- C. Colonoscopy for decompression
- D. Water-soluble contrast enema
- E. CT abdomen followed by immediate surgery
Explanation: ***Conservative management with nasogastric decompression, intravenous fluids, and close monitoring***- In a patient with a history of prior abdominal surgery presenting with **colicky abdominal pain**, **vomiting**, and **absolute constipation**, and radiological evidence of dilated small bowel loops without signs of **peritonitis** or **strangulation**, **conservative management** is the initial approach.- This involves **nasogastric decompression** (to relieve distension and vomiting), **intravenous fluids** (to correct fluid and electrolyte imbalances), and **close monitoring** for signs of improvement or deterioration. Approximately 70-80% of adhesive small bowel obstructions resolve with this management. *Immediate laparotomy*- This invasive approach is reserved for patients showing signs of **bowel ischemia**, **perforation**, or **strangulation**, such as fever, tachycardia, localized tenderness, guarding, rebound tenderness, or signs of systemic toxicity.- Without these alarming features, immediate surgery carries the risk of further **adhesion formation** and is not the first-line management for uncomplicated adhesive small bowel obstruction.*Colonoscopy for decompression*- **Colonoscopy** is primarily used to decompress or diagnose issues in the **large bowel**, such as sigmoid volvulus or large bowel obstruction.- The presence of **valvulae conniventes** on X-ray confirms small bowel dilation, making colonoscopy an ineffective intervention for this type of obstruction.*Water-soluble contrast enema*- A **water-soluble contrast enema** is used to evaluate the **colon** and rectum, primarily for distal large bowel obstructions or structural abnormalities of the colon.- It is not indicated for the diagnosis or management of a **small bowel obstruction**, especially when the likely cause is adhesions from previous surgery. A Gastrografin swallow (oral contrast) may be used diagnostically and therapeutically for SBO.*CT abdomen followed by immediate surgery*- A **CT abdomen** is the gold standard for diagnosing the cause and location of small bowel obstruction and ruling out **strangulation**.- However, even with CT confirmation, **immediate surgery** is only indicated if signs of strangulation, ischemia, or perforation are present; otherwise, **conservative management** is typically initiated first.
Question 209: A 47-year-old man with alcoholic cirrhosis develops sudden onset severe abdominal pain and fever. He has tense ascites. Examination shows generalized abdominal tenderness without rebound. Ascitic tap shows: WCC 850 cells/μL with 75% neutrophils, protein 18 g/L, glucose 2.1 mmol/L, pH 7.28, amylase 35 U/L. Blood cultures are pending. What is the most appropriate immediate management?
- A. IV cefotaxime and albumin infusion (Correct Answer)
- B. Emergency laparotomy to exclude perforation
- C. Diagnostic paracentesis repeated in 24 hours
- D. CT abdomen with oral and IV contrast
- E. IV metronidazole and ciprofloxacin
Explanation: ***IV cefotaxime and albumin infusion***- The patient has **Spontaneous Bacterial Peritonitis (SBP)**, confirmed by an ascitic **neutrophil count >250 cells/μL** (850 x 0.75 = 638 cells/μL), requiring immediate **third-generation cephalosporins**.- High-dose **intravenous albumin** is critical to reduce the risk of **hepatorenal syndrome** and mortality in patients with SBP and cirrhosis.*Emergency laparotomy to exclude perforation*- SBP is a **medical emergency**, not a surgical one; the absence of **rebound tenderness** and a low ascitic protein make secondary peritonitis less likely.- Surgery is contraindicated unless **secondary peritonitis** is proven by imaging or multiple organisms on culture, as it carries high mortality in cirrhotics.*Diagnostic paracentesis repeated in 24 hours*- Delaying treatment for a repeat tap is inappropriate when the **absolute neutrophil count (ANC)** already exceeds the diagnostic threshold for SBP.- Immediate antibiotic administration is necessary to prevent **sepsis** and clinical deterioration.*CT abdomen with oral and IV contrast*- The diagnosis of SBP is made via **ascitic fluid analysis**, making immediate cross-sectional imaging unnecessary for the primary diagnosis.- **IV contrast** carries a high risk of inducing **acute kidney injury** (contrast-induced nephropathy) in patients with advanced cirrhosis and ascites.*IV metronidazole and ciprofloxacin*- **Cefotaxime** is the gold standard for SBP; **ciprofloxacin** is typically reserved for prophylaxis or as a second-line option if cephalosporins are contraindicated.- **Metronidazole** is unnecessary as SBP is usually caused by **Gram-negative aerobes** (like E. coli) rather than anaerobes.
Question 210: A 68-year-old man presents with sudden onset severe abdominal pain and bloody diarrhoea for 4 hours. He has atrial fibrillation but stopped his warfarin 3 weeks ago. Examination shows moderate abdominal tenderness in the left iliac fossa without peritonism. CT shows thickening of the sigmoid and descending colon wall with surrounding fat stranding. The superior mesenteric artery and coeliac axis are patent. What is the most likely diagnosis?
- A. Ischaemic colitis (Correct Answer)
- B. Acute diverticulitis
- C. Inferior mesenteric artery thrombosis
- D. Infective colitis
- E. Acute mesenteric ischaemia
Explanation: ***Ischaemic colitis*** - Sudden onset **abdominal pain** and **bloody diarrhoea** in an elderly patient with **atrial fibrillation** (a risk factor for emboli) who has stopped anticoagulation strongly suggests a vascular event. - CT findings of **wall thickening** and **fat stranding** specifically in the **left colon** (sigmoid and descending colon, which are **watershed areas**) with **patent major mesenteric arteries** are characteristic of ischaemic colitis, often caused by transient hypoperfusion or small vessel disease. *Acute diverticulitis* - While it causes **left iliac fossa pain**, acute diverticulitis typically presents with **fever**, leukocytosis, and altered bowel habits, usually without acute, severe **bloody diarrhoea**. - CT would show **diverticula** with localized inflammation, pericolic fat stranding, or abscess formation around a diverticulum, rather than diffuse wall thickening of a long segment of the colon. *Inferior mesenteric artery thrombosis* - Although thrombosis of the **inferior mesenteric artery (IMA)** would affect the left colon, the CT scan explicitly states that the **major mesenteric arteries are patent**. - Ischaemic colitis is more commonly due to **non-occlusive mesenteric ischaemia** or microvascular disease affecting watershed areas, rather than a large vessel occlusive event like IMA thrombosis. *Infective colitis* - The **sudden onset** (4 hours), **severe pain**, and history of **atrial fibrillation** with recent warfarin cessation strongly point towards a vascular etiology rather than an infection. - While infective colitis can cause bloody diarrhoea, the specific involvement of **watershed areas** of the colon on CT and the prominent vascular risk factors make ischaemic colitis a more likely diagnosis. *Acute mesenteric ischaemia* - This term usually refers to **small bowel ischaemia**, typically caused by occlusion of the **Superior Mesenteric Artery (SMA)**, leading to **pain out of proportion to examination**. - The patient's symptoms are localized to the **large bowel**, and the CT scan clearly states that the **SMA and coeliac axis are patent**, ruling out a major occlusive event affecting the small bowel.
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