A 43-year-old man with no previous medical history presents with a 24-hour history of severe periumbilical pain that has now localised to the right iliac fossa. He has vomited three times. On examination, temperature 38.2°C, heart rate 92 bpm, blood pressure 128/78 mmHg. There is tenderness and guarding in the right iliac fossa with positive Rovsing's sign. Bloods: WCC 14.2 × 10⁹/L, CRP 85 mg/L. His Alvarado score is calculated as 8. What is the most appropriate next step in management?
Q22
A 51-year-old woman with known Crohn's disease (terminal ileum involvement, on adalimumab maintenance therapy) presents with a 72-hour history of worsening right iliac fossa pain, fever (38.4°C), and vomiting. She has not opened her bowels for 48 hours. Examination reveals a tender mass in the right iliac fossa. CT abdomen shows a 6 cm inflammatory phlegmon involving the terminal ileum and caecum with localised abscess formation but no free perforation. There is proximal small bowel dilatation to 3.5 cm. After initial resuscitation and IV antibiotics, what is the most appropriate next management step?
Q23
A 76-year-old man with end-stage COPD (FEV1 35% predicted), ischaemic heart disease (previous MI 2 years ago), and chronic kidney disease stage 4 presents with a 12-hour history of sudden onset severe generalised abdominal pain. Examination shows a rigid, silent abdomen with generalised peritonism. He is tachycardic (118 bpm), hypotensive (88/54 mmHg), and in respiratory distress. Bloods: WCC 18.5 × 10⁹/L, lactate 5.2 mmol/L, creatinine 285 μmol/L, urea 24 mmol/L. CT shows widespread pneumoperitoneum with a 15 mm anterior gastric perforation. After initial resuscitation, what scoring system would best predict his peri-operative mortality risk?
Q24
A 62-year-old man undergoes CT abdomen for suspected large bowel obstruction. The radiologist reports a 'whirl sign' at the level of the hepatic flexure with associated proximal colonic dilatation. What does this radiological finding indicate?
Q25
A 38-year-old woman who is 34 weeks pregnant presents with sudden onset severe right upper quadrant pain radiating to the right shoulder. She reports nausea and has vomited twice. On examination, temperature 38.1°C, heart rate 105 bpm, blood pressure 145/95 mmHg. She has marked tenderness in the right upper quadrant with a positive Murphy's sign. Bloods: WCC 15.8 × 10⁹/L, Hb 118 g/L, platelets 95 × 10⁹/L, ALT 280 U/L, bilirubin 45 μmol/L, ALP 420 U/L. Ultrasound shows gallbladder wall thickening (5 mm), multiple gallstones, and pericholecystic fluid. What is the most appropriate management?
Q26
A 68-year-old woman presents with a 4-day history of colicky lower abdominal pain, progressive distension, and absolute constipation. She has a background of previous sigmoid diverticulitis treated conservatively 18 months ago. Examination reveals a grossly distended, tympanic abdomen with diffuse tenderness but no peritonism. Plain abdominal radiograph shows a massively dilated loop of large bowel arising from the pelvis with the apex in the right upper quadrant, measuring 12 cm in diameter. No small bowel dilatation is seen. What is the definitive management after initial resuscitation?
Q27
A 55-year-old man undergoes emergency laparotomy for perforated duodenal ulcer. During the procedure, a 7 mm anterior duodenal perforation is identified. The surrounding tissue appears healthy with minimal contamination, and the perforation has been present for less than 12 hours based on history. The patient has no history of previous peptic ulcer disease or long-term PPI use. He is haemodynamically stable. What is the most appropriate surgical management?
Q28
What is the mechanism by which pneumoperitoneum is best detected on an erect chest radiograph in cases of gastrointestinal perforation?
Q29
A 72-year-old man with a history of chronic atrial fibrillation (on apixaban), hypertension, and previous myocardial infarction presents with a 10-hour history of sudden onset severe periumbilical pain followed by passage of dark red blood per rectum 2 hours ago. The pain has paradoxically improved over the last 3 hours but he remains unwell. On examination, temperature 37.8°C, heart rate 110 bpm irregularly irregular, blood pressure 105/65 mmHg. His abdomen is diffusely tender but soft without guarding. Bloods: Hb 132 g/L, WCC 16.2 × 10⁹/L, lactate 4.8 mmol/L, CRP 28 mg/L. What is the most likely diagnosis?
Q30
A 45-year-old man with no significant past medical history presents with a 6-hour history of severe epigastric pain that came on suddenly while he was lifting heavy boxes at work. The pain is sharp, constant, and radiates to both shoulders. He reports one episode of vomiting. On examination, his temperature is 37.2°C, heart rate 98 bpm, blood pressure 135/85 mmHg. His abdomen is rigid with generalised tenderness and absent bowel sounds. An erect chest radiograph shows no free gas under the diaphragm. What is the most appropriate next investigation?
Acute Surgical Presentations UK Medical PG Practice Questions and MCQs
Question 21: A 43-year-old man with no previous medical history presents with a 24-hour history of severe periumbilical pain that has now localised to the right iliac fossa. He has vomited three times. On examination, temperature 38.2°C, heart rate 92 bpm, blood pressure 128/78 mmHg. There is tenderness and guarding in the right iliac fossa with positive Rovsing's sign. Bloods: WCC 14.2 × 10⁹/L, CRP 85 mg/L. His Alvarado score is calculated as 8. What is the most appropriate next step in management?
A. Proceed directly to diagnostic laparoscopy (Correct Answer)
B. CT abdomen and pelvis with IV contrast
C. Ultrasound of right iliac fossa
D. Admit for active observation with repeat clinical assessment in 6-8 hours
E. MRI abdomen and pelvis
Explanation: ***Proceed directly to diagnostic laparoscopy***
- This patient has classic signs of **acute appendicitis**, including **migratory periumbilical pain** localizing to the **right iliac fossa**, **guarding**, **positive Rovsing's sign**, **fever**, and **leukocytosis**. An **Alvarado score of 8** indicates a very high probability.
- In stable male patients with such a definitive clinical picture and high Alvarado score, **diagnostic laparoscopy** is the most appropriate next step, as it can confirm the diagnosis and proceed directly to appendectomy, preventing delays and complications like **perforation**.
*CT abdomen and pelvis with IV contrast*
- While highly accurate, **CT imaging** is generally reserved for cases of **diagnostic uncertainty** (e.g., Alvarado score 5-6) or atypical presentations, especially in women to rule out gynecological causes.
- For a patient with an **Alvarado score of 8** and classic symptoms, the **pre-test probability** is so high that CT is unlikely to alter management and exposes the patient to unnecessary **radiation** and potential **delay** to surgery.
*Ultrasound of right iliac fossa*
- **Ultrasound** is often the first-line imaging for appendicitis in **children** and **pregnant women** to avoid radiation, but its sensitivity in adults is generally lower than CT and is highly **operator-dependent**.
- Given the strong clinical evidence and high Alvarado score, an ultrasound would likely not provide additional diagnostic clarity sufficient to change the immediate surgical plan and could **delay definitive treatment**.
*Admit for active observation with repeat clinical assessment in 6-8 hours*
- **Active observation** is typically appropriate for patients with **indeterminate clinical findings** or intermediate Alvarado scores (e.g., 3-6) where the diagnosis is not yet clear.
- Delaying surgery in a patient with an Alvarado score of 8 and signs of **peritoneal irritation** (guarding, Rovsing's) significantly increases the risk of **appendiceal perforation** and subsequent peritonitis.
*MRI abdomen and pelvis*
- **MRI** is a highly sensitive imaging modality primarily indicated for appendicitis diagnosis in **pregnant patients** when ultrasound results are inconclusive, as it avoids radiation.
- For a non-pregnant adult male with a clear clinical picture of appendicitis, MRI is **expensive**, **time-consuming**, and **less readily available** than other options, making it an impractical initial step.
Question 22: A 51-year-old woman with known Crohn's disease (terminal ileum involvement, on adalimumab maintenance therapy) presents with a 72-hour history of worsening right iliac fossa pain, fever (38.4°C), and vomiting. She has not opened her bowels for 48 hours. Examination reveals a tender mass in the right iliac fossa. CT abdomen shows a 6 cm inflammatory phlegmon involving the terminal ileum and caecum with localised abscess formation but no free perforation. There is proximal small bowel dilatation to 3.5 cm. After initial resuscitation and IV antibiotics, what is the most appropriate next management step?
A. Continue conservative management with antibiotics and immunosuppression cessation, plan interval surgery in 6-8 weeks
B. Emergency ileocaecal resection with primary anastomosis
C. CT-guided percutaneous drainage of abscess, continue medical therapy, interval surgery after 6-8 weeks (Correct Answer)
D. Emergency right hemicolectomy with end ileostomy formation
E. Urgent colonoscopy and stricture dilatation
Explanation: ***CT-guided percutaneous drainage of abscess, continue medical therapy, interval surgery after 6-8 weeks***
- For a **Crohn's-related intra-abdominal abscess** larger than 3-4 cm, especially one of **6 cm**, a **step-up approach** with percutaneous drainage is the preferred initial management to control sepsis and source of infection.
- This strategy allows for resolution of acute inflammation, **nutritional optimization**, potential tapering of immunosuppression (adalimumab), and reduces the risks associated with **emergency surgery** by converting it to an elective procedure with lower morbidity.
*Continue conservative management with antibiotics and immunosuppression cessation, plan interval surgery in 6-8 weeks*
- While antibiotics are initiated, a **6 cm intra-abdominal abscess** typically requires **mechanical drainage** in addition to antibiotics for effective source control; antibiotics alone are often insufficient for large abscesses.
- Delaying drainage of a significant abscess puts the patient at continued risk of **sepsis**, treatment failure, and potential deterioration, rather than achieving effective stabilization for planned interval surgery.
*Emergency ileocaecal resection with primary anastomosis*
- Performing a **primary anastomosis** in a patient with active sepsis, significant inflammation, potential malnutrition, and recent **biologic therapy (adalimumab)** carries a very **high risk of anastomotic leak** and surgical complications.
- Emergency surgery with resection is generally reserved for complications such as **free perforation**, generalized peritonitis, or complete bowel obstruction refractory to medical management, which are not the primary issues here (localized abscess, no free perforation).
*Emergency right hemicolectomy with end ileostomy formation*
- Although an **end ileostomy** can be safer than primary anastomosis in an emergency, immediate radical resection is not typically indicated for a **localized, drainable abscess** without signs of generalized peritonitis or intractable obstruction.
- The goal is to avoid emergency surgery if possible; an elective, controlled **interval surgery** after abscess drainage and patient optimization is associated with better outcomes than an emergent stoma formation.
*Urgent colonoscopy and stricture dilatation*
- **Colonoscopy** is generally **contraindicated** in the presence of an acute **inflammatory phlegmon** and associated **intra-abdominal abscess** due to the significant risk of **bowel perforation**.
- **Stricture dilatation** is appropriate for short, fibrotic strictures but not for an **inflammatory phlegmon** or extrinsic compression by an abscess, which require addressing the infection and inflammation first.
Question 23: A 76-year-old man with end-stage COPD (FEV1 35% predicted), ischaemic heart disease (previous MI 2 years ago), and chronic kidney disease stage 4 presents with a 12-hour history of sudden onset severe generalised abdominal pain. Examination shows a rigid, silent abdomen with generalised peritonism. He is tachycardic (118 bpm), hypotensive (88/54 mmHg), and in respiratory distress. Bloods: WCC 18.5 × 10⁹/L, lactate 5.2 mmol/L, creatinine 285 μmol/L, urea 24 mmol/L. CT shows widespread pneumoperitoneum with a 15 mm anterior gastric perforation. After initial resuscitation, what scoring system would best predict his peri-operative mortality risk?
A. APACHE II score
B. P-POSSUM (Portsmouth Physiological and Operative Severity Score for Enumeration of Mortality) (Correct Answer)
C. ASA (American Society of Anesthesiologists) physical status classification
D. Boey score for perforated peptic ulcer
E. Mannheim Peritonitis Index
Explanation: ***P-POSSUM (Portsmouth Physiological and Operative Severity Score for Enumeration of Mortality)***
- **P-POSSUM** is specifically validated for predicting **peri-operative mortality** in general surgery, incorporating 12 physiological and 6 operative variables to provide a surgical risk percentage.
- It is superior for this patient as it accounts for both his **severe comorbidities** (COPD, IHD, CKD) and the **acute surgical severity** (peritoneal soiling and emergency status).
*APACHE II score*
- This scoring system is primarily designed for patients in the **intensive care unit (ICU)** to predict hospital mortality based on physiological derangement within the first 24 hours.
- While accurate for general critical illness, it is not a specific **peri-operative tool** and requires data like **arterial blood gas** (PaO2) which may not be immediately available pre-operatively.
*ASA (American Society of Anesthesiologists) physical status classification*
- The **ASA classification** is a subjective grading of a patient's **pre-operative physical status** (e.g., this patient would be Grade 4E).
- Although it correlates with risk, it is a **qualitative tool** rather than a precise mathematical predictor of mortality compared to P-POSSUM.
*Boey score for perforated peptic ulcer*
- The **Boey score** specifically predicts outcomes for **perforated peptic ulcers** using three criteria: major medical illness, preoperative shock, and duration of perforation >24 hours.
- While relevant to the diagnosis, it is less comprehensive than P-POSSUM for capturing the full extent of this patient's **multi-system physiological compromise**.
*Mannheim Peritonitis Index*
- This index is used to predict the prognosis of patients with **secondary peritonitis** based on factors like age, sex, organ failure, and characteristics of the peritoneal fluid.
- It focuses heavily on the **intra-abdominal pathology** and is less effective at integrating complex **cardiorespiratory comorbidities** for surgical risk stratification.
Question 24: A 62-year-old man undergoes CT abdomen for suspected large bowel obstruction. The radiologist reports a 'whirl sign' at the level of the hepatic flexure with associated proximal colonic dilatation. What does this radiological finding indicate?
A. Caecal volvulus with twisting of the mesentery and vessels (Correct Answer)
B. Intussusception with telescoping of proximal bowel into distal segment
C. Closed loop small bowel obstruction with rotated mesenteric vessels
D. Internal hernia with herniation through a mesenteric defect
E. Adhesional band causing focal constriction of the hepatic flexure
Explanation: ***Caecal volvulus with twisting of the mesentery and vessels***- The **'whirl sign'** on CT is pathognomonic for a volvulus, representing the spiral appearance of **mesenteric vessels** and fat as they rotate around the vascular pedicle.- Finding this sign at the **hepatic flexure** in a patient with large bowel obstruction confirms a **caecal volvulus**, often seen in patients with a mobile caecum due to poor embryological fixation.*Intussusception with telescoping of proximal bowel into distal segment*- This typically presents with a **'target sign'** or **'pseudokidney sign'** on CT, where layers of bowel wall are seen within the lumen.- It does not involve a **torsion of vessels** around a central axis, making the whirl sign an incorrect descriptor for this pathology.*Closed loop small bowel obstruction with rotated mesenteric vessels*- While a whirl sign can occur in small bowel volvulus, the clinical finding of **proximal colonic dilatation** points specifically to a large bowel issue like caecal volvulus.- Small bowel obstructions characteristically show dilated loops with **valvulae conniventes**, whereas this case identifies an obstruction at the level of the colon.*Internal hernia with herniation through a mesenteric defect*- Internal hernias can cause a whirl sign, but they typically involve **displaced small bowel loops** into unusual compartments like the lesser sac.- The specific location at the **hepatic flexure** and the resulting large bowel obstruction pattern fits a primary colonic rotation rather than a hernia.*Adhesional band causing focal constriction of the hepatic flexure*- Adhesions are the most common cause of obstruction but typically show a **'transition point'** without the characteristic vascular spiraling of the whirl sign.- **Adhesional bands** cause external compression and kink the bowel rather than inducing a **360-degree rotation** of the mesentery.
Question 25: A 38-year-old woman who is 34 weeks pregnant presents with sudden onset severe right upper quadrant pain radiating to the right shoulder. She reports nausea and has vomited twice. On examination, temperature 38.1°C, heart rate 105 bpm, blood pressure 145/95 mmHg. She has marked tenderness in the right upper quadrant with a positive Murphy's sign. Bloods: WCC 15.8 × 10⁹/L, Hb 118 g/L, platelets 95 × 10⁹/L, ALT 280 U/L, bilirubin 45 μmol/L, ALP 420 U/L. Ultrasound shows gallbladder wall thickening (5 mm), multiple gallstones, and pericholecystic fluid. What is the most appropriate management?
A. Immediate laparoscopic cholecystectomy (Correct Answer)
B. ERCP with sphincterotomy and stone extraction
C. Conservative management with IV antibiotics and plan interval cholecystectomy postpartum
D. Ultrasound-guided percutaneous cholecystostomy
E. Emergency open cholecystectomy via midline laparotomy
Explanation: ***Immediate laparoscopic cholecystectomy***
- The patient presents with clear clinical signs and ultrasound findings of **acute cholecystitis** (RUQ pain, fever, positive Murphy's sign, gallbladder wall thickening, gallstones). Current guidelines advocate for **laparoscopic cholecystectomy** as the definitive treatment, even in the **third trimester** of pregnancy, to prevent recurrent attacks and potential fetal complications.
- Laparoscopic surgery in late pregnancy is considered safe with specific modifications, such as **open (Hassan) entry**, **left lateral tilt** to prevent aortocaval compression, and **low-pressure insufflation**, making it the preferred approach over conservative management or open surgery.
*ERCP with sphincterotomy and stone extraction*
- **ERCP** is primarily indicated for **choledocholithiasis** (common bile duct stones) or **ascending cholangitis**, typically presenting with significant **jaundice** or severe obstruction, which is not the primary diagnosis here.
- Although the patient has some deranged LFTs, the ultrasound findings prominently point to **acute inflammation of the gallbladder** itself rather than primary common bile duct obstruction as the urgent issue, making cholecystectomy more appropriate initially.
*Conservative management with IV antibiotics and plan interval cholecystectomy postpartum*
- **Conservative management** of acute cholecystitis during pregnancy is associated with a high rate of **recurrence** (up to 60%) during the same pregnancy, potentially leading to increased risks of **preterm labor** and **fetal distress**.
- Delaying definitive surgical treatment increases the risk of complications such as **gallbladder gangrene** or **perforation**, especially in a patient already showing systemic inflammatory response.
*Ultrasound-guided percutaneous cholecystostomy*
- This procedure is a temporizing measure primarily reserved for **critically ill** or **unstable patients** who are unfit for general anesthesia or definitive surgical intervention due to severe comorbidities.
- While the patient is acutely unwell and pregnant, she is not described as being so unstable as to preclude eventual definitive surgical management, which offers a cure rather than just symptom relief.
*Emergency open cholecystectomy via midline laparotomy*
- **Laparoscopic cholecystectomy** is the preferred surgical approach over open surgery in pregnancy due to its **minimally invasive** nature, leading to less maternal morbidity, reduced postoperative pain, and shorter recovery times.
- An **open cholecystectomy** carries higher risks of wound complications and greater physiological stress, which is generally avoided in pregnancy unless laparoscopic techniques are not feasible or fail.
Question 26: A 68-year-old woman presents with a 4-day history of colicky lower abdominal pain, progressive distension, and absolute constipation. She has a background of previous sigmoid diverticulitis treated conservatively 18 months ago. Examination reveals a grossly distended, tympanic abdomen with diffuse tenderness but no peritonism. Plain abdominal radiograph shows a massively dilated loop of large bowel arising from the pelvis with the apex in the right upper quadrant, measuring 12 cm in diameter. No small bowel dilatation is seen. What is the definitive management after initial resuscitation?
A. Urgent colonoscopic decompression followed by elective sigmoid resection (Correct Answer)
B. Emergency Hartmann's procedure
C. Emergency sigmoid colectomy with primary anastomosis
D. Percutaneous colonic decompression tube insertion
E. Conservative management with flatus tube and bowel rest
Explanation: ***Urgent colonoscopic decompression followed by elective sigmoid resection***
- The clinical presentation with **colicky abdominal pain**, **distension**, **absolute constipation**, and the characteristic **coffee-bean sign** on X-ray (massively dilated loop from pelvis to right upper quadrant) is highly indicative of **sigmoid volvulus**. In the absence of **peritonism** or signs of **ischemia**, endoscopic decompression is the initial treatment to untwist the bowel.
- Due to the **high recurrence rate** of sigmoid volvulus after successful endoscopic decompression, an **elective sigmoid resection** is necessary to provide definitive management and prevent future episodes, typically performed during the same admission.
*Emergency Hartmann's procedure*
- This procedure is generally reserved for cases of **sigmoid volvulus** with evidence of **bowel ischemia**, **gangrene**, **perforation**, or **peritonitis**, as it involves resecting the affected segment and forming a colostomy.
- The patient's presentation specifically states **no peritonism**, making this overly aggressive as an initial step when decompression is possible.
*Emergency sigmoid colectomy with primary anastomosis*
- Performing an **emergency primary anastomosis** on an acutely obstructed and often **edematous bowel** carries a significantly higher risk of **anastomotic leak** compared to elective surgery on a prepared bowel.
- While it might be considered in some emergency scenarios if the bowel is viable and conditions are optimal, the preferred staged approach for sigmoid volvulus without peritonitis is decompression first, followed by elective resection.
*Percutaneous colonic decompression tube insertion*
- This method is not a standard or commonly accepted definitive management for **sigmoid volvulus**.
- It carries a significant risk of **bowel injury**, **peritoneal contamination**, and is less effective at detorsing the volvulus compared to colonoscopy.
*Conservative management with flatus tube and bowel rest*
- While a **flatus tube** can sometimes aid in partial decompression, it does not effectively address the **mechanical twisting** of the bowel in **sigmoid volvulus** and is far less reliable than colonoscopic decompression.
- Furthermore, **conservative management alone** does not prevent the almost certain **recurrence** of sigmoid volvulus, which requires surgical intervention.
Question 27: A 55-year-old man undergoes emergency laparotomy for perforated duodenal ulcer. During the procedure, a 7 mm anterior duodenal perforation is identified. The surrounding tissue appears healthy with minimal contamination, and the perforation has been present for less than 12 hours based on history. The patient has no history of previous peptic ulcer disease or long-term PPI use. He is haemodynamically stable. What is the most appropriate surgical management?
A. Simple omental patch repair (Graham patch) with peritoneal lavage (Correct Answer)
B. Wide local excision of ulcer with primary closure
C. Truncal vagotomy and pyloroplasty
D. Antrectomy with Billroth II reconstruction
E. Omental patch with highly selective vagotomy
Explanation: ***Simple omental patch repair (Graham patch) with peritoneal lavage***- This is the **gold standard** for perforated duodenal ulcers presented within **24 hours**, as it provides a secure closure with **minimal morbidity**.- Since the advent of **PPI therapy** and **H. pylori eradication**, definitive acid-reducing surgeries are rarely indicated during the emergency phase.*Wide local excision of ulcer with primary closure*- Primary closure alone is associated with a high risk of **leakage** and **dehiscence** due to the tension on the friable duodenal tissues.- **Omental transposition** (the Graham patch) is necessary to provide a **vascularized seal** and bolster the repair site.*Truncal vagotomy and pyloroplasty*- This is a **definitive surgery** that was common in the pre-PPI era but is now avoided in acute settings due to increased **operative time** and potential for long-term **post-vagotomy syndromes**.- It is generally unnecessary for a patient with no prior history of **chronic peptic ulcer disease** who can be managed medically post-operatively.*Antrectomy with Billroth II reconstruction*- This is a major **resectional procedure** that carries a significantly higher risk of **postoperative complications** and mortality in an emergency setting.- It is usually reserved for **giant ulcers** (>2cm) or cases where the duodenum cannot be safely closed, which does not apply to this **7 mm perforation**.*Omental patch with highly selective vagotomy*- Highly selective vagotomy requires a **stable patient** and significant surgical expertise, but it adds unnecessary **surgical risk** without clear benefit over medical management.- Current management focuses on **addressing the perforation** first and managing the underlying cause (like **H. pylori**) medically later.
Question 28: What is the mechanism by which pneumoperitoneum is best detected on an erect chest radiograph in cases of gastrointestinal perforation?
A. Free air accumulates beneath the diaphragm due to negative intrathoracic pressure, appearing as a radiolucent crescent between the diaphragm and liver (Correct Answer)
B. Air-fluid levels form in the peritoneal cavity creating multiple radiolucent pockets throughout the abdomen
C. Gas within the bowel wall becomes visible as linear lucencies parallel to the bowel contour
D. Free air dissects along the mesentery creating a characteristic 'tree-like' branching pattern
E. Pneumoperitoneum causes generalised increased lucency of the abdominal cavity with loss of normal organ silhouettes
Explanation: ***Free air accumulates beneath the diaphragm due to negative intrathoracic pressure, appearing as a radiolucent crescent between the diaphragm and liver***
- In an **erect position**, free gas from a gastrointestinal perforation rises to the highest point in the abdominal cavity, which is beneath the **diaphragm**.
- On a chest radiograph, this appears as a **radiolucent crescent** of air, typically more visible on the right side between the **diaphragm** and the **liver**, which provides a distinct radiographic contrast.
*Air-fluid levels form in the peritoneal cavity creating multiple radiolucent pockets throughout the abdomen*
- **Air-fluid levels** are commonly seen in **bowel obstruction** (within bowel loops) or in localized fluid collections with gas, not as the primary sign of free pneumoperitoneum on an erect chest X-ray.
- While some air and fluid can coexist in perforation, the hallmark sign of free air is subdiaphragmatic gas, not multiple pockets within the general peritoneal cavity.
*Gas within the bowel wall becomes visible as linear lucencies parallel to the bowel contour*
- Linear lucencies within the bowel wall are indicative of **pneumatosis intestinalis**, a sign of **bowel ischemia**, infarction, or necrotizing enterocolitis.
- This represents gas trapped within the layers of the bowel wall itself, rather than free gas in the peritoneal cavity.
*Free air dissects along the mesentery creating a characteristic 'tree-like' branching pattern*
- A "tree-like" branching pattern of gas is characteristic of **portal venous gas** or **pneumobilia** (gas in the biliary tree), not free intraperitoneal air.
- **Mesenteric air** is usually a sign of advanced conditions like **mesenteric ischemia** and is distinct from free gas causing pneumoperitoneum.
*Pneumoperitoneum causes generalised increased lucency of the abdominal cavity with loss of normal organ silhouettes*
- While very large volumes of free air (e.g., the **football sign** on a supine film) can cause diffuse abdominal lucency, this is not the typical or best mechanism for detecting pneumoperitoneum on an **erect chest radiograph**.
- The loss of normal organ silhouettes is more commonly associated with the presence of **ascites** (fluid), which increases abdominal opacity, or with very diffuse free air on a supine film, making organs difficult to distinguish.
Question 29: A 72-year-old man with a history of chronic atrial fibrillation (on apixaban), hypertension, and previous myocardial infarction presents with a 10-hour history of sudden onset severe periumbilical pain followed by passage of dark red blood per rectum 2 hours ago. The pain has paradoxically improved over the last 3 hours but he remains unwell. On examination, temperature 37.8°C, heart rate 110 bpm irregularly irregular, blood pressure 105/65 mmHg. His abdomen is diffusely tender but soft without guarding. Bloods: Hb 132 g/L, WCC 16.2 × 10⁹/L, lactate 4.8 mmol/L, CRP 28 mg/L. What is the most likely diagnosis?
A. Ischaemic colitis
B. Perforated sigmoid diverticulitis
C. Acute mesenteric ischaemia (Correct Answer)
D. Strangulated small bowel obstruction
E. Ruptured abdominal aortic aneurysm
Explanation: ***Acute mesenteric ischaemia***
- This diagnosis is strongly suggested by the patient's history of **atrial fibrillation** (a source of emboli), **sudden onset severe periumbilical pain**, and the classic finding of **pain out of proportion to the physical examination** (diffusely tender but soft abdomen).
- The **paradoxical improvement in pain** combined with ongoing unwellness, **elevated lactate** (4.8 mmol/L), and passage of **dark red blood per rectum** are highly indicative of bowel infarction due to arterial occlusion.
*Ischaemic colitis*
- Typically presents with **left-sided abdominal pain** and bloody diarrhea, often less severe than described here, and is usually related to hypoperfusion rather than acute arterial occlusion.
- While it can cause bloody stools, the **diffuse periumbilical pain** and exceptionally high **lactate** are more characteristic of acute mesenteric ischaemia affecting the small bowel.
*Perforated sigmoid diverticulitis*
- This condition would typically manifest with **localized left lower quadrant pain**, **peritoneal signs** like guarding and rebound tenderness, and potentially fever and leukocytosis, which contrasts with the soft abdomen.
- It is unlikely to cause the **sudden onset severe periumbilical pain** followed by improvement and diffuse tenderness described, and imaging would reveal **pneumoperitoneum**.
*Strangulated small bowel obstruction*
- This condition presents with features of obstruction such as **vomiting**, **abdominal distension**, and altered bowel habits, which are not primary complaints in this case.
- While strangulation can cause bowel ischemia and elevated lactate, the absence of obstructive symptoms and the strong embolic risk factor point away from this as the initial primary diagnosis.
*Ruptured abdominal aortic aneurysm*
- A ruptured AAA typically presents with a triad of **hypotension**, severe **back or flank pain**, and a **pulsatile abdominal mass**.
- While the patient is hypotensive and in pain, the absence of a pulsatile mass and the presence of significant **dark red blood per rectum** make mesenteric ischaemia a more fitting diagnosis.
Question 30: A 45-year-old man with no significant past medical history presents with a 6-hour history of severe epigastric pain that came on suddenly while he was lifting heavy boxes at work. The pain is sharp, constant, and radiates to both shoulders. He reports one episode of vomiting. On examination, his temperature is 37.2°C, heart rate 98 bpm, blood pressure 135/85 mmHg. His abdomen is rigid with generalised tenderness and absent bowel sounds. An erect chest radiograph shows no free gas under the diaphragm. What is the most appropriate next investigation?
A. CT abdomen and pelvis with oral and IV contrast (Correct Answer)
B. Upper GI endoscopy
C. Abdominal ultrasound
D. Contrast swallow study with water-soluble contrast
E. Diagnostic peritoneal lavage
Explanation: ***CT abdomen and pelvis with oral and IV contrast***
- This patient presents with classic signs of **perforated peptic ulcer**, including sudden-onset severe **epigastric pain**, **shoulder radiation** due to diaphragmatic irritation, and a **rigid abdomen** consistent with peritonitis.
- Although the erect chest radiograph was negative for free gas, **CT imaging** is the **gold standard** investigation, offering superior sensitivity (near 100%) for detecting **extraluminal gas** and identifying the precise site of perforation, which is crucial for surgical planning.
*Upper GI endoscopy*
- **Upper GI endoscopy** is **contraindicated** in suspected gastrointestinal perforation because the **insufflation of air** during the procedure can worsen the perforation and increase the spread of contamination, exacerbating peritonitis.
- It is primarily a diagnostic and therapeutic tool for non-perforated conditions and should be avoided in the setting of an **acute surgical abdomen** where perforation is suspected.
*Abdominal ultrasound*
- **Abdominal ultrasound** has limited diagnostic value for detecting **hollow viscus perforation** or **pneumoperitoneum** due to the technical challenges posed by overlying bowel gas and its poor sensitivity for free air.
- While useful for other acute abdominal conditions like **cholecystitis** or appendicitis, it is not the appropriate initial investigation for suspected perforation and **peritonitis**.
*Contrast swallow study with water-soluble contrast*
- A **contrast swallow study** can identify a leak, but it is generally **less sensitive** and provides less comprehensive information about the entire abdominal cavity compared to a **CT scan**.
- Performing this study can significantly delay definitive surgical management for a **perforated viscus**, which is a time-sensitive emergency, and may be challenging in a patient with severe pain.
*Diagnostic peritoneal lavage*
- **Diagnostic peritoneal lavage (DPL)** is an invasive procedure that has largely been **replaced** by modern imaging techniques like **CT scans** and **FAST exams** in the assessment of acute abdominal conditions.
- While it can detect **intraperitoneal fluid** or blood, it does not pinpoint the site of perforation or directly visualize **free gas**, making it less specific for diagnosing a **perforated hollow viscus** in this context.
