NBME Clinical Mastery Series with Answers (Offline) Surgery: Form 4

1) Enemas • Enema → washout of hard stools/constipation in the bowel

2) Size of the abnormality • Larger AV fistula → ↑ venous return → high cardiac output heart failure

3) Increased scrotal temperature • Stasis of venous blood → ↑ temp → damage to sperm

4) Refuse to proceed with the operation

• Non maleficence

5) Carotid plaque • Cholesterol emboli that lodge into the retinal artery usually originate from an ulcerated atheromatous plaque within the carotid arteries (Hollenhorst plaque)

6) Hypovolemic • ↓ Cardiac index, ↓ pulm arterial pressure, ↓ PCWP, ↑ SVR = hypovolemic shock

• Anaphylactic shock: ↓ SVR, ↑ cardiac index

• Cardiogenic shock: ↓ cardiac index, ↑ PCWP

• Septic shock: ↓ SVR, ↑ cardiac index

7) Tension pneumothorax

• Typical scenario after insertion of central line (iatrogenic pneumothorax is a common complication)

• Decreased breath sounds, JVD, shortness of breath

8) Gastrin

• Zollinger-Ellison syndrome (gastrinoma) • ↑ gastrin → ↑ acid levels → erosion of of mucosa/vessels → hematemesis

9) Slipped capital femoral epiphysis • Displaced epiphysis relative to femoral neck → hip/knee pain with limp

• Common in obese pre-teens

10) Toxic synovitis

• Toxic synovitis = transient synovitis

• Common cause of hip pain and limping in children following a viral infection (cold or diarrhea)

11) Removal of the percutaneous intravenous catheter after completion of piperacillin and tazobactam therapy

• Patient had line in for 6 weeks (way over his 14 day abx course) → bacteremia → infective endocarditis

• PIC lines → ↑ risk for catheter-associated bloodstream infections

12) Penile cancer • Elderly uncircumcised man with ulcer growing in size over 6 months • Having foreskin (lack of circumcision) acts as a nidus for infection/inflammation

13) Esophagogastroduodenoscopy • Endoscopy can confirm diagnosis of hiatal hernia and rule out malignancy (patient has red flag symptoms/history)

14) Arteriography with runoff

• Popliteal artery aneurysm → acute limb ischemia due to thrombosis of aneurysm or acute thromboembolism

• Runoff = visualization of vessels beyond the occlusion

15) Ulcerative colitis • High ALP + narrow bile ducts = Primary sclerosing cholangitis (PSC)

• PSC is associated with UC

16) Administration of heparin

• Patient has a pulmonary embolism

• Starting anticoagulation in a hemodynamically stable patients 48-72 hours after surgery is generally safe and wont increase the risk of bleeding

17) Asbestos • Pleural effusion with extensive soft tissue densities (pleural plaques)

• Mesothelioma = bloody pleural effusion

18) Transfusion of packed red blood cells

• Macroangiopathic anemia due to mechanical shearing → schistocytes → replace with pRBCs

• No thrombocytopenia (like in TTP), thus no need for whole blood

19) Enteral tube feedings • Jejunostomy should be used for enteral feedings (more patient autonomy, less expensive, and less adverse reactions in comparison to TPN)

20) No further testing is indicated • Mass with central scar (characteristic feature) = focal nodular hyperplasia

• Managed conservatively - no malignant potential

21) Ruptured intracerebral aneurysm

• HTN + bradycardia = signs of ↑ ICP

• Rupture of aneurysm → abrupt change in ICP (other options wouldn’t cause an abrupt change)

22) Ruptured abdominal aortic aneurysm • Hypotension and Sudden collapse with lower back pain

23) Intraductal papilloma • Bloody nipple discharge with no palpable masses

24) Increased pulmonary vascular resistance • Holosystolic murmur indicates the VSD wasn’t successfully repaired

• VSD with Eisenmenger syndrome

25) Adhesions • History of surgery with symptoms of bowel obstruction - most commonly due to adhesions

26) Oxycodone therapy

• Severe cancer pain awakening the patient from sleep should be treated with long acting opioids (etc. fentanyl patch, oxycodone) + short acting opioids for breakthrough pain (etc. morphine)

• Acetaminophen treats mild cancer pain

• Codeine treats moderate cancer pain

27) Debridement and application of a sterile dressing to the open wound

• Shouldn’t close any dirty/infected wounds - closure, grafting or a flap would just incubate the bacteria

• Should cover gram (+) and anaerobes using amoxicillin and clavulanate

28) Immediate surgical exploration of the upper abdomen

• Free air under diaphragm = perforated viscus → Ex-Lap

29) Impaired cough mechanism • Cough threshold is raised after surgery and mucociliary escalator may be inhibited by ET intubation

30) X-ray of the cervical spine

• ABCDE primary survey - must evaluate cervical spine to ensure airway isn’t/wont become compromised

• Abdomen is non tender, lungs are clear to auscultation and CXR is normal - no need for further abdominal or chest imaging

31) Phosphorus • Hyperparathyroidism → hypercalcemia, bone resorption, and ↑ excretion of phosphorus

32) Meckel diverticulum • Pertechnetate scan uptake by heterotypic gastric mucosa

33) Chronic lymphocytic thyroiditis (Hashimoto disease) • Antibodies against thyroid peroxidase (antimicrosomal) and thyroglobulin

34) Sigmoidoscopy-guided placement of a rectal tube • Sigmoidoscopy to untwist the sigmoid volvulus • Rectal tube is left in to ↓ chance of recurrence in the acute setting

35) Reexcision of the biopsy site • Positive margins → reexcision (must remove cancer before proceeding with adjuvant therapy)

36) Pyoderma gangrenosum • Associated with inflammatory bowel disease

• Sharply demarcated ulcer with purulent base

37) Stricture of the distal esophagus • Dysphagia for solids not liquids = mechanical rather than motor problem

• 6 years of GERD → stricture

38) Overproduction of bilirubin

• 10 units of blood will lead to extreme amounts of RBC breakdown

• Direct:Indirect bilirubin ratio is 1:1 indicating that the problem does not have to do with excretion

39) Clostridium difficile infection • Hospitalized patient taking antibiotics and PPI with fever and abdominal pain

• Pseudomembranes = patchy white mucosa

40) Intubation with hyperventilation • GCS < 8 → intubate and hyperventilate • Hyperventilation washes out the CO2 → cerebral vasoconstriction → ↓ ICP

41) Complete small-bowel obstruction • Adhesions from hysterectomy (previous surgery), active bowel sounds in rush with abdominal cramps, constipation = SBO obstruction

42) Direct pressure to the bleeding laceration

• Direct pressure to stop bleeding

• Closed reduction can be delayed up to 72 hours in presence of more severe injuries

• Don’t need transfusion at the moment since the patient is stable (SBP > 100) on crystalloids

43) Laparotomy • Free air under diaphragm = perforated viscus → Ex-Lap

44) Rupture of the bladder

• Bladder dome rupture → urine leakage (→ anuria) → chemical peritonitis → lower abdominal pain

• Next step: cystourethrogram

45) Spironolactone therapy

• Bilateral adrenal hyperplasia is treated with medication (mineralcorticoid receptor antagonists)

• Unilateral adrenal hyperplasia is surgically removed

46) Lung abscess • Hospitalized patient on ventilation → ↑ risk of aspiration (→ abscess) • A supine, hospitalized patient aspirates to the right upper lobe (dependent portion)

47) Sitz bath • Sitz bath → ↑ blood flow to area of fissure → promotes/accelerates healing

48) Hypomagnesemia • Alcoholic → poor nutrition → ↑ risk of hypomagnesemia • Profound magnesium depletion → ↓ PTH release → hypocalcemia

49) Streptococcus pyogenes (group A) • Group A strep is the MCC of erysipelas • Red, tender painful plaque with sharply demarcated edges

50) Biopsy of the mass • Squamous cell carcinoma (SCC) of the anus is more common in HIV+

○ There is higher prevalence of high-risk anal HPV strains and anal cancer in HIV+ patients

○ There is a close relationship between HPV and SCC • Dx: biopsy • Tx: Nigro chemoradiation protocol followed by surgery

The NBME Clinical Mastery Series conclude following areas: