NBME Surgery Form 1 - Answers & Explanations

Updated: Nov 16, 2019

1) Needle-localized open biopsy • Percutaneous core biopsy, localization with needle and surgically sampling, is preferred for evaluation of microcalcifications • Fine-needle aspiration is inadequate as it may miss the cancer cells

2) Clostridium perfringens • Crepitus = gas-forming = clostridium

3) Lack of normal joint sensation • Neuropathic (Charcot) arthropathy

4) Avascular necrosis of the femoral head • Legg-Calvé-Perthes disease • Common in males between 5-8 years old

5) Low-dose heparin prophylaxis • Heparin is best choice for pre-surgical VTE prophylaxis because it has a short half-life (~45 mins) and is easily reversed with protamine sulfate

6) Cardiogenic shock • SOB, JVD, hypotension, hepatomegaly, ST elevation in anterior leads

7) Surgical decompression • Compartment syndrome

• Paresthesia and pain on passive stretch are early sxs

8) Fat embolism • Associated with long bone fractures and liposuction • Triad: Neurologic dysfunction, petechial rash (usually in axilla), respiratory distress (hypoxemia)

• Therapy is supportive

9) Melanoma • Subungual hematoma, unlike melanoma, will gradually clear as the nail heals

• Subungual hematoma will form a transverse groove across the surface as the nail heals

10) Testicular tumor • Young age, painless progressive enlargement over 8 months = cancer

• Hydrocele and Spermatocele both transilluminate • Epididymitis is painful

11) Appropriate in view of the medical necessity to remove the inflamed appendix

• Acutely inflamed appendix is a medical emergency and therefore doesn’t require consent

12) Ruptured spleen • Kehr sign: referred pain in shoulder due to irritants (eg, blood) in the peritoneal cavity • Kehr sign in the left shoulder is a classic sxs of a ruptured spleen

13) Rapid infusion of 0.9% saline

• Patient is unstable

14) Sphenopalatine artery • Sphenopalatine artery is the MCC of posterior nosebleeds • 90% of nosebleeds are anteriorly located at Kiesselbach’s plexus

15) Ovarian adenocarcinoma

• Nulligravid → uninterrupted menstrual cycles (follicular rupture and tissue damage) → ↑ risk of ovarian cancer

• Advanced ovarian cancer → peritoneal seeding and inflammation → ascites

• Meigs syndrome: triad of ovarian fibroma, ascites, and pleural effusion

16) Increase positive end-expiratory pressure

• Normal PO2 is between 80-10

• FiO2 and PEEP determine PO2; TV and RR determine CO2

17) Slipped capital femoral epiphysis

• Classically presents in teens/pre-teens that are obese or above 90th percentile in weight

18) Incision and drainage of the lesion

• Abscesses must be drained

19) Increased serum aldosterone concentration

• Renin increases on the affected side due to ↓ blood supply → ↑ aldosterone

• Blood supply to unaffected side is normal, so no need to release renin

20) Proctocolectomy with an ileoanal reservoir

• Prophylactic colectomy is the best long-term management in FAP because 100% of cases will eventually progress to CRC

• FAP patients should be screened with a colonoscopy every year starting at age 10-12

21) 15 L of lactated Ringer solution

• Parkland formula: 4 x weight in kg x % area

• 4 x 75 x 50 = 15000 ml = 15L

22) Epidural hematoma • The middle meningeal artery runs underneath the pterion, the weak region of the skull where the frontal, parietal, temporal, and sphenoid bones join together

• Traumatic blows to this area classically cause an epidural hematoma

23) Aortic arteriography

• Mild tenderness over the chest and a ‘somewhat’ widened mediastinum warrant an aortic arteriography

• If the patient had presented with “tearing chest pain radiating to the back” and a widened mediastinum following a MVC, then an immediate thoracotomy would be indicated

24) Carotid duplex ultrasonography

• B/L carotid bruits indicate stenosis in the carotids → compromised blood flow → cerebral ischemia → TIA

• Carotid U/S should be performed to determine the level of stenosis and the corresponding treatment