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NBME Surgery Form 4 - Answers & Explanations

Updated: Feb 25, 2020

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


• 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

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29) Impaired cough mechanism • Cough threshold is raised after surgery and mucociliary escalator may be inhibited by ET intubation I think that you got the objective wrong. She has Parkinson's, which is associated with impaired cough mechanism (hence the patients have repeted aspiration pneumonias). Therefore the vomiting led to aspiration, which in turn led to pneumonitis


Folasade Fakoya
Folasade Fakoya
Feb 29, 2020

Wow this is quite helpful.Thanks very much.Can you pls upload Form 5 n 6 explanations


did form 5 answers ever get completed? i can't find answers anywhere on the internet... did nbme crack down?


Oct 25, 2019



Jordan Abrams
Jordan Abrams
Oct 03, 2019

We're currently looking for medical students to help us write explanations for these new NBME forms. If you're interested please contact us via

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