Acute Surgical Presentations — MCQs
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A 43-year-old man presents with a 36-hour history of progressively worsening right iliac fossa pain, fever (38.9°C), and vomiting. Initial management with IV antibiotics was commenced 24 hours ago. He now develops sudden worsening of pain with more generalized peritonism. CT abdomen shows a perforated appendix with a 6cm abscess in the right iliac fossa, some free fluid in the pelvis, but no generalized free air or faecal contamination. He is haemodynamically stable. What is the most appropriate management strategy?
What is the primary indication for using Gastrografin (water-soluble contrast) follow-through study in the management of adhesional small bowel obstruction?
A 61-year-old woman presents with a 6-hour history of sudden onset severe central abdominal pain and one episode of vomiting. She has a background of atrial fibrillation for which she takes apixaban, but admits to missing several doses recently. On examination, she appears unwell with a temperature of 37.8°C, heart rate 98 bpm irregularly irregular, and blood pressure 125/78 mmHg. Her abdomen is soft with diffuse tenderness but no guarding. Bowel sounds are present. Blood tests show: WCC 19.3 × 10⁹/L, lactate 5.6 mmol/L, amylase 110 U/L. What is the most likely diagnosis?
What is the pathophysiological mechanism by which pneumoperitoneum occurs following colonoscopic perforation compared to spontaneous perforation of a gastric ulcer?
A 52-year-old man with Crohn's disease presents with a 48-hour history of severe cramping abdominal pain, vomiting, and absolute constipation. He has had multiple previous episodes of subacute obstruction managed conservatively. CT abdomen shows dilated small bowel loops measuring up to 5 cm with a transition point in the terminal ileum, where there is marked wall thickening and surrounding fat stranding. No free fluid or free air is identified. What is the most appropriate management?
A 78-year-old man with known colorectal carcinoma presents with a 5-day history of progressive abdominal distension, colicky pain, and absolute constipation. Plain abdominal radiograph shows marked dilatation of the caecum measuring 13 cm in diameter with proximal colonic distension. Distal to the splenic flexure, the colon appears decompressed. He is haemodynamically stable with no signs of peritonism. What is the most appropriate immediate management strategy?
A 35-year-old woman who is 28 weeks pregnant presents with a 12-hour history of right-sided abdominal pain, nausea, and fever. She is unable to lie on her right side due to pain. On examination, there is tenderness in the right flank region and right upper quadrant. Temperature is 38.2°C. Urinalysis shows 2+ leucocytes but is nitrite negative. Blood tests show WCC 16.5 × 10⁹/L (neutrophils 14.2), CRP 85 mg/L. What is the most likely diagnosis?
A 66-year-old man undergoes emergency laparotomy for perforated sigmoid diverticulitis. During surgery, purulent peritonitis with faecal contamination is found. He has a history of chronic obstructive pulmonary disease and takes prednisolone 10mg daily. His intra-operative lactate is 4.2 mmol/L and he required vasopressor support. According to the Hinchey classification, this represents Hinchey grade IV disease. What is the most appropriate surgical management?
What is the characteristic feature that distinguishes mechanical bowel obstruction from paralytic ileus on plain abdominal radiograph?
A 45-year-old woman presents with a 6-hour history of sudden onset severe epigastric pain. She has a history of recurrent peptic ulcer disease and takes omeprazole irregularly. On examination, her abdomen is rigid with guarding and rebound tenderness. An erect chest radiograph is performed but shows no free air under the diaphragm. Serum amylase is 180 U/L (normal <100 U/L). What is the most appropriate next investigation?
Acute Surgical Presentations UK Medical PG Practice Questions and MCQs
Question 91: A 43-year-old man presents with a 36-hour history of progressively worsening right iliac fossa pain, fever (38.9°C), and vomiting. Initial management with IV antibiotics was commenced 24 hours ago. He now develops sudden worsening of pain with more generalized peritonism. CT abdomen shows a perforated appendix with a 6cm abscess in the right iliac fossa, some free fluid in the pelvis, but no generalized free air or faecal contamination. He is haemodynamically stable. What is the most appropriate management strategy?
- A. Immediate open appendicectomy with drainage
- B. CT-guided percutaneous drainage of abscess with continued antibiotics (Correct Answer)
- C. Continue IV antibiotics alone for a further 48 hours
- D. Emergency laparoscopic appendicectomy
- E. Immediate laparotomy with peritoneal lavage
Explanation: ***CT-guided percutaneous drainage of abscess with continued antibiotics*** - For a hemodynamically stable patient with a large (**>3-5 cm**) localized **appendiceal abscess**, percutaneous drainage is the preferred therapy to achieve source control while avoiding the high morbidity of surgery in an inflamed field. - This conservative approach avoids complications like **inadvertent bowel injury** or **fistula formation** which are common during immediate surgery for an established phlegmon or abscess. *Immediate open appendicectomy with drainage* - Operating during the acute inflammatory phase of an abscess is technically difficult because of **adhesions** and distorted anatomy, leading to higher rates of **ileal resection**. - This approach is generally reserved for patients who fail conservative management or show signs of **sepsis** despite treatment. *Continue IV antibiotics alone for a further 48 hours* - While antibiotics are essential, a **6cm abscess** is unlikely to resolve with pharmacological treatment alone and requires mechanical drainage for effective source control. - Relying solely on antibiotics in the face of worsening pain and a large collection increases the risk of **secondary rupture** or systemic decline. *Emergency laparoscopic appendicectomy* - Although laparoscopy is the standard for simple appendicitis, it is associated with a higher risk of **fecal fistula** and **wound infection** when an organized abscess is present. - The current clinical stability of the patient favors a **step-up approach** (drainage first) over high-risk emergency surgery. *Immediate laparotomy with peritoneal lavage* - Laparotomy and lavage are indicated for **generalized peritonitis** or fecal contamination, which are not present on this patient's CT scan. - Given the CT shows a **contained abscess** and the patient is stable, an invasive laparotomy is considered excessive and carries significant postoperative risks.
Question 92: What is the primary indication for using Gastrografin (water-soluble contrast) follow-through study in the management of adhesional small bowel obstruction?
- A. To definitively diagnose the exact anatomical location of adhesions
- B. To provide both diagnostic information about likelihood of resolution and therapeutic benefit through its hyperosmolar properties (Correct Answer)
- C. To identify whether the obstruction is complete or partial
- D. To exclude malignancy as the underlying cause
- E. To determine if surgical intervention is required within 6 hours
Explanation: ***To provide both diagnostic information about likelihood of resolution and therapeutic benefit through its hyperosmolar properties***- **Gastrografin** is hyperosmolar (1900 mOsm/L), drawing fluid into the bowel lumen, which increases the **pressure gradient** and can help overcome adhesional small bowel obstruction.- Diagnostically, the appearance of contrast in the **colon** within 4-24 hours is a strong predictor that the obstruction will resolve with **conservative management**.*To definitively diagnose the exact anatomical location of adhesions*- Adhesions themselves are typically **radiolucent** and cannot be directly visualized; their exact location is inferred rather than precisely diagnosed.- **CT scanning** with IV contrast is generally the preferred modality for precisely localizing the site and cause of small bowel obstruction.*To identify whether the obstruction is complete or partial*- While Gastrografin can demonstrate flow past an obstruction (indicating partial), its primary clinical utility in **adhesional SBO** is specifically to predict the success of non-operative treatment, not just the type of obstruction.- **Plain abdominal X-rays** and initial clinical evaluation often provide sufficient information to differentiate between complete and partial obstruction initially.*To exclude malignancy as the underlying cause*- Gastrografin follow-through provides limited detail for evaluating bowel wall thickening, masses, or lymphadenopathy that might suggest **malignancy**.- **Contrast-enhanced CT** is the definitive imaging modality for excluding malignancy as the cause of bowel obstruction.*To determine if surgical intervention is required within 6 hours*- The Gastrografin challenge is typically monitored over 24 hours, and decisions for surgical intervention in adhesional SBO are usually made after 48-72 hours of failed conservative management.- Urgent surgery within 6 hours is reserved for patients with clear signs of **strangulation**, ischemia, or **perforation**, conditions where Gastrografin is contraindicated.
Question 93: A 61-year-old woman presents with a 6-hour history of sudden onset severe central abdominal pain and one episode of vomiting. She has a background of atrial fibrillation for which she takes apixaban, but admits to missing several doses recently. On examination, she appears unwell with a temperature of 37.8°C, heart rate 98 bpm irregularly irregular, and blood pressure 125/78 mmHg. Her abdomen is soft with diffuse tenderness but no guarding. Bowel sounds are present. Blood tests show: WCC 19.3 × 10⁹/L, lactate 5.6 mmol/L, amylase 110 U/L. What is the most likely diagnosis?
- A. Perforated peptic ulcer
- B. Acute mesenteric ischaemia (Correct Answer)
- C. Acute pancreatitis
- D. Ruptured abdominal aortic aneurysm
- E. Small bowel obstruction
Explanation: ***Acute mesenteric ischaemia***- This classic presentation involves sudden onset severe central abdominal **pain out of proportion to clinical findings**, evidenced by a soft abdomen despite high pain levels and metabolic distress.- Risk factors like **atrial fibrillation** (with missed anticoagulation doses) and an elevated **lactate** of 5.6 mmol/L strongly point to an **embolic event** causing bowel hypoxia.*Perforated peptic ulcer*- Typically presents with a **rigid abdomen** and signs of **peritonism** (guarding and rebound tenderness) due to stomach contents leaking into the peritoneum.- Diagnosis is usually confirmed by finding **pneumoperitoneum** (free air under the diaphragm) on an erect chest X-ray.*Acute pancreatitis*- While it causes severe epigastric pain and vomiting, the **amylase level** of 110 U/L is not high enough to meet the diagnostic threshold (usually >3 times the upper limit of normal).- Pain in pancreatitis is often relieved by **leaning forward** and is frequently associated with alcohol use or gallstones rather than atrial fibrillation.*Ruptured abdominal aortic aneurysm*- Classical presentation includes the triad of abdominal/back pain, **hypotension**, and a **pulsatile abdominal mass**.- This patient is **haemodynamically stable** with a BP of 125/78 mmHg, making a rupture less likely though it remains a critical differential.*Small bowel obstruction*- Usually presents with clinical features of **distension**, absolute constipation, and **tinkling bowel sounds**.- While it can cause elevated lactate if strangulated, the sudden onset in a patient with a known **embolic source** (AF) makes mesenteric ischaemia more likely.
Question 94: What is the pathophysiological mechanism by which pneumoperitoneum occurs following colonoscopic perforation compared to spontaneous perforation of a gastric ulcer?
- A. Colonoscopic perforation releases gas under pressure whereas gastric perforation releases gas at atmospheric pressure (Correct Answer)
- B. Colonoscopic perforation causes immediate massive pneumoperitoneum whereas gastric perforation causes delayed gradual accumulation
- C. Both mechanisms are identical and produce equivalent volumes of free intraperitoneal air
- D. Colonoscopic perforation releases nitrogen-based insufflation gas whereas gastric perforation releases swallowed air and gastric gas
- E. Gastric perforation causes greater pneumoperitoneum because of higher intragastric pressure
Explanation: ***Colonoscopic perforation releases gas under pressure whereas gastric perforation releases gas at atmospheric pressure*** - During colonoscopy, **active insufflation** (using air or CO2) creates **positive pressure** to distend the lumen, forcing a large volume of gas into the peritoneum immediately upon injury. - Spontaneous **gastric ulcer perforation** relies on the passive release of swallowed air and gastric gases, which occur at approximately **atmospheric pressure**, typically resulting in a different rate of accumulation. *Colonoscopic perforation causes immediate massive pneumoperitoneum whereas gastric perforation causes delayed gradual accumulation* - While colonoscopic perforation is often immediate, the **volume** is determined by the **pressure gradient** rather than just a simplistic time delay. - Gastric perforations can also present acutely depending on the **size of the defect**, but they lack the external **mechanical driving force** of an insufflator. *Both mechanisms are identical and produce equivalent volumes of free intraperitoneal air* - The mechanisms are distinct because one involves **iatrogenic positive pressure** while the other involves **pathological wall erosion** under normal physiological pressures. - The volume of air in colonoscopic injuries is usually **significantly larger** due to the continuous flow of gas from the endoscopy tower. *Colonoscopic perforation releases nitrogen-based insufflation gas whereas gastric perforation releases swallowed air and gastric gas* - Modern colonoscopy often uses **CO2 insufflation** because it is absorbed faster, not necessarily nitrogen-based room air. - The **chemical composition** of the gas is less clinically significant for the initial pathophysiology than the **pressure** at which it enters the cavity. *Gastric perforation causes greater pneumoperitoneum because of higher intragastric pressure* - This is incorrect as **intragastric pressure** is typically low, whereas colonoscopic insufflation pressures can reach **20-40 mmHg**. - Consequently, colonoscopic injuries generally lead to **larger volumes** of free air more rapidly than spontaneous upper GI perforations.
Question 95: A 52-year-old man with Crohn's disease presents with a 48-hour history of severe cramping abdominal pain, vomiting, and absolute constipation. He has had multiple previous episodes of subacute obstruction managed conservatively. CT abdomen shows dilated small bowel loops measuring up to 5 cm with a transition point in the terminal ileum, where there is marked wall thickening and surrounding fat stranding. No free fluid or free air is identified. What is the most appropriate management?
- A. Immediate surgical resection of the diseased segment
- B. Conservative management with IV fluids, nasogastric decompression, and bowel rest (Correct Answer)
- C. Water-soluble contrast follow-through study
- D. High-dose IV corticosteroids
- E. Emergency balloon dilatation of the stricture
Explanation: ***Conservative management with IV fluids, nasogastric decompression, and bowel rest***- Initial management for **small bowel obstruction** in Crohn's disease is trial of conservative therapy, as many episodes represent **inflammatory edema** rather than fixed fibrous strictures.- **Supportive care** with hydration and decompression often resolves the acute presentation, allowing for later evaluation of the underlying Crohn's activity and long-term medical optimization.*Immediate surgical resection of the diseased segment*- Surgery is not the first-line treatment unless there are signs of **ischaemia, perforation**, or **strangulation**, which are currently absent on the patient's CT scan.- A conservative approach is preferred in **Crohn's disease** to avoid multiple resections and the subsequent risk of **short bowel syndrome**.*Water-soluble contrast follow-through study*- While contrast studies can be used to predict the success of non-operative management, the 5 cm **dilated loops** and absolute constipation require immediate **NG decompression** and stabilization first.- This study serves as a **prognostic tool** rather than the primary therapeutic intervention for acute bowel obstruction.*High-dose IV corticosteroids*- Although corticosteroids can reduce **inflammatory swelling** in Crohn's, they are an adjunct to, rather than a replacement for, immediate **nasogastric decompression** and fluid resuscitation.- Giving steroids without ensuring adequate **bowel decompression** and fluid balance could mask worsening clinical signs in a patient with acute obstruction.*Emergency balloon dilatation of the stricture*- **Endoscopic balloon dilatation** is contraindicated in the setting of acute obstruction with active **peri-enteric inflammation** and fat stranding due to the high risk of perforation.- This procedure is typically reserved for **short, fibrotic strictures** identified during a stable, elective setting rather than emergency management.
Question 96: A 78-year-old man with known colorectal carcinoma presents with a 5-day history of progressive abdominal distension, colicky pain, and absolute constipation. Plain abdominal radiograph shows marked dilatation of the caecum measuring 13 cm in diameter with proximal colonic distension. Distal to the splenic flexure, the colon appears decompressed. He is haemodynamically stable with no signs of peritonism. What is the most appropriate immediate management strategy?
- A. Emergency right hemicolectomy
- B. Emergency Hartmann's procedure
- C. Insertion of self-expanding metal stent (SEMS) followed by elective resection
- D. Caecostomy tube placement (Correct Answer)
- E. Endoscopic decompression
Explanation: ***Caecostomy tube placement*** - A **caecal diameter > 12 cm** indicates an imminent risk of **perforation** due to Laplace’s law; a caecostomy provides rapid, minimally invasive decompression to prevent rupture. - It serves as a **temporizing measure** in a hemodynamically stable patient, allowing for stabilization and further staging before definitive oncological surgery. *Emergency right hemicolectomy* - This procedure is indicated for **caecal or right-sided tumors**, whereas the imaging suggests an obstruction distal to the **splenic flexure**. - Primary resection in an unprepared, obstructed bowel carries significantly higher **morbidity and mortality** compared to staged procedures. *Emergency Hartmann's procedure* - This is typically reserved for patients with **peritonitis** or perforated sigmoid cancer, which this patient does not currently exhibit. - Performing a major resection in the acute phase of **large bowel obstruction** is associated with higher complication rates than elective resection after decompression. *Insertion of self-expanding metal stent (SEMS) followed by elective resection* - While **SEMS** is a valid bridge to surgery for distal obstructions, it is technically challenging if the lesion is at the **splenic flexure** or more proximal. - In the setting of severe **caecal dilatation (13 cm)**, the risk of perforation during or immediately after the procedure is a concern compared to direct decompression. *Endoscopic decompression* - This technique is primarily used for **colonic pseudo-obstruction (Ogilvie's syndrome)** rather than mechanical obstruction from a malignancy. - Attempting endoscopic decompression in a **mechanical obstruction** is likely to be ineffective and increases the risk of iatrogenic bowel perforation.
Question 97: A 35-year-old woman who is 28 weeks pregnant presents with a 12-hour history of right-sided abdominal pain, nausea, and fever. She is unable to lie on her right side due to pain. On examination, there is tenderness in the right flank region and right upper quadrant. Temperature is 38.2°C. Urinalysis shows 2+ leucocytes but is nitrite negative. Blood tests show WCC 16.5 × 10⁹/L (neutrophils 14.2), CRP 85 mg/L. What is the most likely diagnosis?
- A. Acute appendicitis (Correct Answer)
- B. Acute cholecystitis
- C. Pyelonephritis
- D. Placental abruption
- E. Preterm labour
Explanation: ***Acute appendicitis***- In the second and third trimesters of pregnancy, the enlarging uterus displaces the appendix **superiorly and laterally**, often leading to pain in the **right upper quadrant (RUQ)** or **right flank** rather than the right iliac fossa.- It is the most common **non-obstetric surgical emergency** in pregnancy; the inability to lie on the right side and the presence of **fever and neutrophilia** strongly support this diagnosis.*Acute cholecystitis*- While it presents with RUQ pain and fever, it is typically associated with **fatty food intolerance** and specific clinical signs like **Murphy's sign**, which are not mentioned here.- The localized pain in the flank is less common for gallbladder disease compared to the displaced appendix in late pregnancy.*Pyelonephritis*- This condition usually presents with **costovertebral angle tenderness** and significant urinary symptoms; however, the **nitrite-negative** urinalysis makes this less likely.- Although leucocytes are present, they can be a non-specific finding or due to **appendiceal irritation** of the ureter.*Placental abruption*- Characterized by **painful vaginal bleeding** and a rigid, "woody" uterus, which are absent in this clinical vignette.- It is an obstetric emergency that typically presents with signs of **fetal distress** or maternal hemodynamic instability rather than localized flank tenderness and fever.*Preterm labour*- Presents with **regular uterine contractions** that lead to progressive **cervical effacement and dilation**, which are not described in this patient.- Unlike appendicitis, it does not typically cause localized RUQ/flank tenderness or high inflammatory markers like an **elevated CRP** and neutrophilia.
Question 98: A 66-year-old man undergoes emergency laparotomy for perforated sigmoid diverticulitis. During surgery, purulent peritonitis with faecal contamination is found. He has a history of chronic obstructive pulmonary disease and takes prednisolone 10mg daily. His intra-operative lactate is 4.2 mmol/L and he required vasopressor support. According to the Hinchey classification, this represents Hinchey grade IV disease. What is the most appropriate surgical management?
- A. Primary resection with end-to-end anastomosis
- B. Hartmann's procedure (resection with end colostomy and rectal stump) (Correct Answer)
- C. Laparoscopic peritoneal lavage and drainage only
- D. Oversewing of perforation with omental patch
- E. Resection with primary anastomosis and defunctioning loop ileostomy
Explanation: ***Hartmann's procedure (resection with end colostomy and rectal stump)***- **Hinchey grade IV** disease (fecal peritonitis) combined with hemodynamic instability, **high lactate**, and chronic **steroid use** makes a primary anastomosis extremely dangerous due to the high risk of **anastomotic leak**.- This procedure remains the gold standard for high-risk patients with **fecal contamination** and compromised physiological status, as it removes the source of sepsis while avoiding a precarious internal connection. *Primary resection with end-to-end anastomosis*- This approach is typically reserved for hemodynamically stable patients with **less severe contamination** (e.g., Hinchey grade I or II) and no significant comorbidities impacting wound healing.- In the presence of **vasopressor support**, **fecal peritonitis**, and **immunosuppression**, a primary anastomosis is contraindicated due to an unacceptably high risk of dehiscence. *Laparoscopic peritoneal lavage and drainage only*- While sometimes debated for selected cases of **purulent peritonitis (Hinchey III)**, it is strictly inadequate and associated with high mortality for **fecal peritonitis (Hinchey IV)**.- This method fails to remove the diseased segment of bowel and the source of gross fecal contamination, leading to persistent sepsis. *Oversewing of perforation with omental patch*- This technique is primarily used for **perforated peptic ulcers**, where the perforation is typically a discrete, localized defect in an otherwise healthy organ.- It is not appropriate for **perforated diverticulitis**, which involves diseased, inflamed, and often friable bowel, making simple oversewing ineffective for reliable source control. *Resection with primary anastomosis and defunctioning loop ileostomy*- This option attempts to protect an anastomosis with a diverting stoma but still involves creating an internal anastomosis in a highly contaminated and systemically unwell patient.- Even with a defunctioning stoma, the risk of **pelvic sepsis** from a contained anastomotic leak remains high in this critically ill, immunosuppressed patient, making it less safe than a Hartmann's.
Question 99: What is the characteristic feature that distinguishes mechanical bowel obstruction from paralytic ileus on plain abdominal radiograph?
- A. Presence of fluid levels throughout the small and large bowel with gaseous distension of the rectum
- B. Differential air-fluid levels with absence of gas in the distal bowel beyond the point of obstruction (Correct Answer)
- C. Centrally located dilated bowel loops measuring greater than 6 cm in diameter
- D. Thickened bowel wall with thumb-printing appearance
- E. Presence of pneumatosis intestinalis in the bowel wall
Explanation: ***Differential air-fluid levels with absence of gas in the distal bowel beyond the point of obstruction*** - In **mechanical bowel obstruction**, the key feature is a **transition point** where bowel is dilated proximal to the blockage and **collapsed** or devoid of gas distal to it. - **Differential (stair-step) air-fluid levels** (multiple levels at different heights within the same loop of bowel) are highly suggestive of mechanical obstruction rather than ileus. *Presence of fluid levels throughout the small and large bowel with gaseous distension of the rectum* - This describes **paralytic ileus**, where there is a global failure of peristalsis leading to uniform gas distribution including the **rectum** and sigmoid. - In ileus, air-fluid levels are typically at the **same horizontal level** within a single loop, rather than being differential. *Centrally located dilated bowel loops measuring greater than 6 cm in diameter* - While **central loops** and a diameter >3 cm indicate **small bowel dilation**, 6 cm is often used as a threshold for the **colon** (except the caecum which is >9 cm). - Dilation alone does not reliably distinguish between mechanical obstruction and ileus as both can present with significant **luminal distension**. *Thickened bowel wall with thumb-printing appearance* - **Thumb-printing** is a sign of **submucosal edema** or hemorrhage, most commonly seen in **ischemic colitis** or severe inflammatory bowel disease. - It is not a primary diagnostic feature used to differentiate mechanical obstruction from a functional paralytic ileus. *Presence of pneumatosis intestinalis in the bowel wall* - **Pneumatosis intestinalis** (gas within the bowel wall) is a sign of **intestinal ischemia** or necrosis and represents a surgical emergency. - While it can be a complication of high-grade mechanical obstruction, it is not the standard feature used to distinguish patterns of **simple obstruction** from ileus.
Question 100: A 45-year-old woman presents with a 6-hour history of sudden onset severe epigastric pain. She has a history of recurrent peptic ulcer disease and takes omeprazole irregularly. On examination, her abdomen is rigid with guarding and rebound tenderness. An erect chest radiograph is performed but shows no free air under the diaphragm. Serum amylase is 180 U/L (normal <100 U/L). What is the most appropriate next investigation?
- A. Repeat erect chest radiograph after 6 hours
- B. CT abdomen and pelvis with IV contrast (Correct Answer)
- C. Abdominal ultrasound
- D. Diagnostic peritoneal lavage
- E. Upper GI endoscopy
Explanation: ***CT abdomen and pelvis with IV contrast***- This is the **gold standard** for diagnosing a suspected **perforated viscus** when plain radiographs are negative, as it is highly sensitive to small amounts of **pneumoperitoneum**.- It helps localize the site of perforation and can rule out other acute pathologies like **acute pancreatitis** or mesenteric ischemia in a patient with a **rigid abdomen**.*Repeat erect chest radiograph after 6 hours*- Delaying diagnosis in a patient with clinical **peritonitis** is dangerous and can lead to increased morbidity and **septic shock**.- Up to 30% of perforations do not show air on initial **erect chest X-ray**, so a repeat is unlikely to provide superior diagnostic clarity over a CT scan.*Abdominal ultrasound*- While useful for **biliary pathology**, ultrasound is limited by bowel gas and is much less reliable than CT for detecting **intraperitoneal free air**.- It cannot adequately assess the retroperitoneum or the extent of contamination in the setting of a **perforated peptic ulcer**.*Diagnostic peritoneal lavage*- This procedure has largely been replaced by modern imaging like **FAST** and **CT scans** and is rarely indicated in nontraumatic surgical emergencies.- It is an invasive procedure that does not provide information regarding the **cause or site** of the perforation.*Upper GI endoscopy*- Endoscopy is strictly **contraindicated** when there is a clinical suspicion of perforation as air insufflation can worsen the **pneumoperitoneum** and tension.- It can exacerbate the leakage of gastric contents into the **peritoneal cavity**, increasing the risk of chemical and bacterial peritonitis.
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