ABCRS common mistakes
ABCRS · Understand the traps and how to avoid them.
When a rectal cancer vignette gives a mid-rectal tumor, choosing low anterior resection without first staging with pelvic MRI and assessing the mesorectal margin and sphincter complex, then committing to a sphincter-preserving plan the tumor cannot support.
Candidates anchor on 'avoid a stoma' and jump to the operation before completing locoregional staging, so they skip the CRM and intersphincteric assessment that determines feasibility.
What to do instead
For every rectal cancer item, write out stage (T, N, EMVI, CRM distance, tumor height) before selecting an operation; only then decide neoadjuvant therapy and procedure.
Treating a cecal or ascending colon cancer with obstruction as an automatic indication for subtotal colectomy rather than considering resection with primary anastomosis or staged approaches based on hemodynamic and nutritional status.
The 'obstructed right colon = subtotal colectomy' heuristic is overlearned and applied without weighing patient stability, contamination, and bowel viability.
What to do instead
State the decision variables explicitly (stability, peritoneal contamination, bowel quality, comorbidity) and match the operation to them rather than to tumor location alone.
In an acute severe ulcerative colitis vignette, continuing maximal medical therapy or ordering a colonoscopy before deciding on rescue therapy or surgery.
Candidates focus on confirming the diagnosis and forget that day-3 response criteria and the risk of toxic megacolon/perforation drive management.
What to do instead
Memorize the acute severe colitis pathway: limit endoscopy to flexible sigmoidoscopy, assess response by day 3 (stool frequency, CRP, albumin), and move to rescue infliximab or colectomy if failing.
Choosing a straight ileoanal anastomosis or omitting mucosectomy considerations in a patient with indeterminate colitis or Crohn's-like features, instead of recognizing that IPAA is contraindicated when Crohn's disease cannot be excluded.
Candidates equate 'UC refractory to medical therapy' with 'IPAA' and overlook the diagnostic uncertainty that changes the operation.
What to do instead
Before selecting IPAA, explicitly confirm the diagnosis (clinical, endoscopic, histologic, serologic) and name the alternative (completion proctocolectomy with end ileostomy) when Crohn's is possible.
In a patient with a thrombosed external hemorrhoid presenting acutely, recommending excision without first distinguishing it from a strangulated internal hemorrhoid or perianal abscess, and without checking timing relative to symptom onset.
Candidates pattern-match 'painful perianal lump' to hemorrhoid and skip the differential and the 48-72 hour window that guides excision versus conservative care.
What to do instead
For every acute anorectal pain item, list the differential (thrombosed external hemorrhoid, strangulated internal hemorrhoid, abscess, fissure, fistula) and state the time since onset before choosing intervention.
Managing a high transsphincteric or suprasphincteric fistula with fistulotomy rather than sphincter-preserving options (seton, LIFT, advancement flap), or failing to assess continence and prior sphincter surgery first.
Candidates default to the simplest definitive operation and underestimate the risk of incontinence from dividing significant sphincter muscle.
What to do instead
Classify the fistula by Parks type and measure the proportion of sphincter involved; if more than roughly a third of the external sphincter is involved, select a sphincter-preserving strategy and justify it.
In fecal incontinence evaluation, proceeding to surgery without objective testing (endoanal ultrasound, manometry, pudendal nerve assessment) and without a trial of conservative therapy.
Candidates want to name the definitive operation and skip the stepwise workup that determines whether a sphincter defect exists and is repairable.
What to do instead
Always order the workup sequence first (history/diary, exam, manometry, ultrasound, consider MRI or pudendal studies), then match therapy to the identified defect.
In a trauma or emergency vignette with a hemodynamically unstable patient and a positive FAST, ordering CT imaging before laparotomy.
Candidates reflexively complete the diagnostic workup and forget that instability plus positive FAST mandates immediate operative control.
What to do instead
Use the stability-first rule: unstable plus positive FAST or peritonitis goes to the operating room; CT is reserved for stable patients.
Failing to address the physiologic and nutritional preparation for a high-risk colorectal operation (e.g., not correcting severe anemia, malnutrition, or steroid stress dosing) before elective surgery.
Candidates concentrate on the technical operation and skip the perioperative optimization that the exam tests through comorbidity-laden vignettes.
What to do instead
For each elective case, list modifiable risk factors (nutrition, anemia, glycemic control, smoking, steroid coverage, VTE prophylaxis) and state the specific correction before surgery.
In a laparoscopic converted-to-open case or a robotic rectal case, describing the approach without addressing the specific technical pitfalls (ureteral identification, splenic flexure mobilization, anastomotic perfusion assessment, conversion triggers).
Candidates answer at the level of 'laparoscopic is fine' and miss the intraoperative decision points the question is testing.
What to do instead
For minimally invasive items, explicitly state the critical view steps (ureter, gonadal vessels, mesenteric planes), the perfusion check, and the criteria for conversion.
Accepting a study's conclusion without checking whether the design supports it (e.g., treating a retrospective cohort's association as causal, or ignoring confidence intervals and absolute versus relative risk).
Candidates read the abstract conclusion and skip the methods appraisal that the question is designed to test.
What to do instead
For every research item, identify design, bias, effect size with CI, and whether the stated conclusion follows; answer the methodology question before the clinical one.
In an ethics vignette involving an incompetent or incapacitated patient, choosing treatment based on family preference or clinician judgment without identifying the appropriate surrogate and the standard (substituted judgment versus best interests).
Candidates focus on the clinical urgency and skip the decision-making framework the question is testing.
What to do instead
Name the decision-maker, the applicable standard, and whether advance directives exist before selecting an option; default to the patient's previously expressed wishes when known.