USMLE Step 3: Preparing for Computer-Based Case Simulations

USMLE Step 3 represents the final hurdle in the long series of board exams required to obtain a license to practice medicine in the US.

USMLE Step 3 Structure

Step 3 is a two-day, 17-hour exam, making it more than twice as long as Step 1. Step 3 includes at least 100 more multiple choice questions (MCQs) than Step 1 as well as Computer-based Case Simulations (CCS).  The CCS cases are the most striking difference between Step 3 and the other USMLE Step exams. Many interns and residents are quite anxious about knowing exactly what they can expect on the CCS cases.


Exam Test items Total testing time
USMLE Step 1 322 MCQs 8 hours
USMLE Step 2 CK 350 MCQs 9 hours
USMLE Step 3 454 MCQs + 13 CCS cases 17 hours


Understanding the USMLE Step 3 CCS

The CCS tests your management of a series of virtual patients to demonstrate your readiness to assume independent responsibility for patient care.

Each CCS case is allotted a maximum of either 10 or 20 minutes of “real time.” However, the cases can cover weeks or months of “simulated time,” during which you may be expected to move the patient from emergency department to inpatient ward to home.

You are responsible for ordering everythingfor your patient: lab tests, x-rays, procedures, medications, IV fluids, etc. In addition to diagnosing and treating your patient’s presenting problem, you may also be responsible for providing necessary preventive measures and counseling.

Knowing how and when to advance the clock of simulated time is vital to working through the cases efficiently

Scoring the USMLE Step 3 CCS

The USMLE is tight-lipped about how CCS cases are scored, but efficient management is definitely one of the concepts being evaluated.  Unlike multiple choice questions in which there is a single best answer, there is often more than one way to approach a CCS patient.

You are expected to order certain tests and treatments for each case. Failure to order these required elements (or failure to order them in a timely fashion) will result in a lower score. Likewise, you can lower your score by ordering inappropriate or unnecessarily dangerous tests and treatments. Some tests/treatments may neither hurt nor help your score.

The official Step 3 content description says, “Seemingly correct management decisions made in a suboptimal or incorrect sequence or after a delay in simulated time may receive little or no credit.” In other words, if you take too long to start treatment, or if you order things out of sequence, your score will suffer.

The best strategy, according to the official USMLE documentation, is to balance efficiency with thoroughness based on your clinical judgment. Be as efficient as possible, but be as thorough as you need to be.

Preparing for the USMLE Step 3 CCS

The single most important preparation for the CCS cases is to become extremely familiar with the practice software before test day. The practice software posted on includes a short tutorial and several practice cases that can be completed in as little as an hour or two. Within that time, you should feel very comfortable with entering orders, viewing results and advancing the clock in the CCS software.

Doctors In Training is here to help you clear the last hurdle of your board exams. Click here for more information about the Doctors In Training Step 3 Review Course.

About DIT Advising Team

The Doctors In Training Student Advising Team offers many advisory services including the following: customizing individual study plans for USMLE Step 1/ COMLEX Level 1 or USMLE Step 2 CK/ COMLEX Level 2, advising students with respect to combating everyday stress and test anxiety and preparing students for the residency application process.


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