COMAT Surgery Exam V2 | COMAT Surgery | Q&A
with Rationale (COMAT Surgery Exam) | National
Board of Osteopathic Medical Examiners (NBOME)
1. A 45-year-old female presents to the emergency department with acute right upper
quadrant pain that radiates to her right scapula. She reports nausea and one episode of
vomiting. Physical examination reveals tenderness in the right upper quadrant and an
inspiratory arrest upon deep palpation. Which of the following is the most appropriate initial
diagnostic study?
A. Hepatobiliary iminodiacetic acid (HIDA) scan
B. Right upper quadrant ultrasound
C. Abdominal Computed Tomography (CT) with contrast
D. Endoscopic retrograde cholangiopancreatography (ERCP)
Correct Answer: B
Explanation: Abdominal ultrasound is the initial study of choice for suspected acute
cholecystitis due to its high sensitivity and lack of radiation. The presence of gallstones,
gallbladder wall thickening, and pericholecystic fluid are hallmark findings. While a HIDA
scan is the most sensitive test, it is typically reserved for cases where ultrasound results
are equivocal.
,2. A 22-year-old male presents with a 12-hour history of periumbilical pain that has now
shifted to the right lower quadrant. He reports anorexia and a low-grade fever. On
examination, there is rebound tenderness at McBurney’s point. What is the most likely
pathophysiologic mechanism for this patient’s condition?
A. Obstruction of the appendiceal lumen
B. Viral infection of the mesenteric lymph nodes
C. Twisting of the spermatic cord
D. Autoimmune inflammation of the terminal ileum
Correct Answer: A
Explanation: Acute appendicitis is most commonly caused by obstruction of the
appendiceal lumen, often by a fecalith in adults or lymphoid hyperplasia in children. This
obstruction leads to increased intraluminal pressure, ischemia, and subsequent bacterial
overgrowth. Recognizing the progression from visceral (periumbilical) to parietal (RLQ)
pain is critical for clinical diagnosis.
3. A 68-year-old male smoker with a history of hypertension presents with sudden onset,
severe ‘tearing’ back pain. His blood pressure is 90/60 mmHg, and a pulsatile abdominal mass
is palpable. Which of the following is the most immediate priority in this patient’s
management?
A. Perform an urgent abdominal ultrasound
B. Emergent surgical consultation and transfer to the OR
,C. Obtain a CT angiogram of the chest and abdomen
D. Administer intravenous beta-blockers
Correct Answer: B
Explanation: A ruptured abdominal aortic aneurysm (AAA) is a surgical emergency
characterized by the triad of pain, hypotension, and a pulsatile mass. In an unstable patient,
diagnostic imaging should not delay definitive operative or endovascular repair. A common
pitfall is wasting time with a CT scan when the patient’s hemodynamic status requires
immediate intervention.
4. A 55-year-old male undergoes a total colectomy for ulcerative colitis. On postoperative day
2, he develops a fever of 38.5°C (101.3°F). His lungs are clear to auscultation, and his surgical
incision is clean. What is the most likely cause of his fever?
A. Wound infection
B. Deep vein thrombosis
C. Atelectasis
D. Urinary tract infection
Correct Answer: C
Explanation: Atelectasis is the most common cause of fever in the first 24-48 hours
postoperatively (the ‘Wind’ of the 5 W’s). Management focuses on incentive spirometry,
early ambulation, and adequate pain control to allow for deep breathing. Surgeons must
, distinguish early inflammatory fevers from later infectious causes like pneumonia or
wound infections.
5. A 30-year-old male is brought to the trauma bay after a motor vehicle accident. He is
tachypneic and cyanotic. Examination reveals absent breath sounds on the right, tracheal
deviation to the left, and distended neck veins. What is the next step in management?
A. Obtain an immediate chest X-ray
B. Intubate the patient
C. Needle thoracostomy in the second intercostal space
D. Perform a focused assessment with sonography for trauma (FAST)
Correct Answer: C
Explanation: This patient presents with classic signs of a tension pneumothorax, which is
a clinical diagnosis. Immediate needle decompression is required to relieve the pressure
before obtaining a chest X-ray. Failure to act quickly can lead to cardiovascular collapse due
to decreased venous return to the heart.
6. A 60-year-old male with a 40-pack-year smoking history presents with crampy leg pain that
occurs after walking two blocks and is relieved by rest. His ankle-brachial index (ABI) is 0.6.
Which of the following is the most appropriate first-line medical therapy?
A. Warfarin
B. Cilostazol and a walking program
C. Urgent femoral-popliteal bypass
with Rationale (COMAT Surgery Exam) | National
Board of Osteopathic Medical Examiners (NBOME)
1. A 45-year-old female presents to the emergency department with acute right upper
quadrant pain that radiates to her right scapula. She reports nausea and one episode of
vomiting. Physical examination reveals tenderness in the right upper quadrant and an
inspiratory arrest upon deep palpation. Which of the following is the most appropriate initial
diagnostic study?
A. Hepatobiliary iminodiacetic acid (HIDA) scan
B. Right upper quadrant ultrasound
C. Abdominal Computed Tomography (CT) with contrast
D. Endoscopic retrograde cholangiopancreatography (ERCP)
Correct Answer: B
Explanation: Abdominal ultrasound is the initial study of choice for suspected acute
cholecystitis due to its high sensitivity and lack of radiation. The presence of gallstones,
gallbladder wall thickening, and pericholecystic fluid are hallmark findings. While a HIDA
scan is the most sensitive test, it is typically reserved for cases where ultrasound results
are equivocal.
,2. A 22-year-old male presents with a 12-hour history of periumbilical pain that has now
shifted to the right lower quadrant. He reports anorexia and a low-grade fever. On
examination, there is rebound tenderness at McBurney’s point. What is the most likely
pathophysiologic mechanism for this patient’s condition?
A. Obstruction of the appendiceal lumen
B. Viral infection of the mesenteric lymph nodes
C. Twisting of the spermatic cord
D. Autoimmune inflammation of the terminal ileum
Correct Answer: A
Explanation: Acute appendicitis is most commonly caused by obstruction of the
appendiceal lumen, often by a fecalith in adults or lymphoid hyperplasia in children. This
obstruction leads to increased intraluminal pressure, ischemia, and subsequent bacterial
overgrowth. Recognizing the progression from visceral (periumbilical) to parietal (RLQ)
pain is critical for clinical diagnosis.
3. A 68-year-old male smoker with a history of hypertension presents with sudden onset,
severe ‘tearing’ back pain. His blood pressure is 90/60 mmHg, and a pulsatile abdominal mass
is palpable. Which of the following is the most immediate priority in this patient’s
management?
A. Perform an urgent abdominal ultrasound
B. Emergent surgical consultation and transfer to the OR
,C. Obtain a CT angiogram of the chest and abdomen
D. Administer intravenous beta-blockers
Correct Answer: B
Explanation: A ruptured abdominal aortic aneurysm (AAA) is a surgical emergency
characterized by the triad of pain, hypotension, and a pulsatile mass. In an unstable patient,
diagnostic imaging should not delay definitive operative or endovascular repair. A common
pitfall is wasting time with a CT scan when the patient’s hemodynamic status requires
immediate intervention.
4. A 55-year-old male undergoes a total colectomy for ulcerative colitis. On postoperative day
2, he develops a fever of 38.5°C (101.3°F). His lungs are clear to auscultation, and his surgical
incision is clean. What is the most likely cause of his fever?
A. Wound infection
B. Deep vein thrombosis
C. Atelectasis
D. Urinary tract infection
Correct Answer: C
Explanation: Atelectasis is the most common cause of fever in the first 24-48 hours
postoperatively (the ‘Wind’ of the 5 W’s). Management focuses on incentive spirometry,
early ambulation, and adequate pain control to allow for deep breathing. Surgeons must
, distinguish early inflammatory fevers from later infectious causes like pneumonia or
wound infections.
5. A 30-year-old male is brought to the trauma bay after a motor vehicle accident. He is
tachypneic and cyanotic. Examination reveals absent breath sounds on the right, tracheal
deviation to the left, and distended neck veins. What is the next step in management?
A. Obtain an immediate chest X-ray
B. Intubate the patient
C. Needle thoracostomy in the second intercostal space
D. Perform a focused assessment with sonography for trauma (FAST)
Correct Answer: C
Explanation: This patient presents with classic signs of a tension pneumothorax, which is
a clinical diagnosis. Immediate needle decompression is required to relieve the pressure
before obtaining a chest X-ray. Failure to act quickly can lead to cardiovascular collapse due
to decreased venous return to the heart.
6. A 60-year-old male with a 40-pack-year smoking history presents with crampy leg pain that
occurs after walking two blocks and is relieved by rest. His ankle-brachial index (ABI) is 0.6.
Which of the following is the most appropriate first-line medical therapy?
A. Warfarin
B. Cilostazol and a walking program
C. Urgent femoral-popliteal bypass
