How Hard Is the CST Exam? What NBSTSA's Pass Rates and Outline Show

The CST is a passable exam that a sizable minority of first-time candidates fail. NBSTSA's certification data puts the 2025 national first-time pass rate at 68.6%, and the rate stayed between 68.6% and 71.8% in every year from 2021 to 2025 (as checked on October 25, 2026). What makes it hard is less any one topic than the mix of breadth across surgical specialties, application-style questions, and a fixed 4-hour clock.

NBSTSA first-time CST pass rates, 2021 to 2025

NBSTSA publishes national CST statistics in its certification data file:

Three things are worth knowing before you read too much into these numbers:

• About 3 in 10 first-time candidates did not pass in 2025. That is Passy arithmetic: 100% minus 68.6% is 31.4%.
• The pass mark changed during this period. NBSTSA's 2019 standard setting had set 102 correct out of 150; the current standard of 98 out of 150 has applied since January 1, 2024. Even with the lower count, 2025 had the lowest first-time rate of the five years. The CST passing score guide explains how both numbers were set.
• These are group figures. They describe everyone who tested that year, not your own chances, and NBSTSA does not publish a repeat-taker pass rate in this file.

If breadth is what worries you, see how full CST prep spreads its planned questions across the three subject areas before you decide how to study.

Why NBSTSA calls the CST a broad exam

NBSTSA's prepare page says the CST covers a wide range of surgical topics and is not limited to one specialty or subject area. Its page for educators goes further: students will need to know specialties they may not have experienced during their clinical rotations, and one night of studying will not get them through.

The outline shows how wide that is. Anatomy and Physiology alone lists 14 body systems, from cardiovascular and genitourinary to ophthalmic and otorhinolaryngology, and asks for both the anatomy and the physiology of each as they relate to the surgical procedure. Across all eight sub-areas the outline has more than 100 task lines. The CST content outline guide breaks down how many scored questions each sub-area carries.

CST questions test application, not only recall

NBSTSA's exam development guide says items are classified at two levels:

• Recall questions ask, in effect, "What is X?" They test memory of facts, procedures and principles.
• Application questions ask, "Given the following information about Y, what is X?" They test judgment about the best action in a situation.

NBSTSA states that its goal is to "minimize or control" the number of recall items so the exam is not overly rudimentary. In CST terms, knowing that a torn or damp pack is no longer sterile is recall; deciding what to do when you find one halfway through opening a set, with the surgeon waiting, is application. NBSTSA also tells item writers to avoid regional instrument names, so the name your hospital uses may not be the one on the screen.

This is where a flashcard-only plan falls short. Flashcards carry the recall load, but scenario practice is what builds the judgment the exam emphasizes. The CST prep page shows how practice is planned by subject area at launch, with an explanation for every answer.

Pacing the CST: 175 questions in 4 hours, and breaks cost time

The exam has 175 multiple-choice questions in 4 hours. That is about 82 seconds per question (Passy arithmetic: 240 minutes divided by 175). Two rules on NBSTSA's On Test Day page make pacing harder than the average suggests:

1. Breaks are allowed at any time, but the clock keeps running. Break time does not extend your exam, and you cannot leave the building during a break.
2. After a break, you may not return to previously answered questions. NBSTSA's FAQ puts it the same way: once you leave a question, you cannot return to it after a break.

The practical consequence: if you plan to take a break, finish reviewing the questions you want to revisit before you stand up.

Twenty-five of the 175 questions are unscored pretest items, randomly distributed through the exam. You cannot tell which ones they are, so treat every question as if it counts.

Claims about CST difficulty that do not match NBSTSA

Search results for the CST still repeat figures that NBSTSA's current pages contradict:

A failed attempt is not the end of the road. If it happens, the free CST retake planner turns the areas that felt hardest into a week-by-week plan.

How to judge whether you are ready for the CST

No tool, official or not, can tell you that you will pass. These checks can show where you stand:

• NBSTSA's free Study Evaluation. The Study Evaluation form has you rate yourself from 1 (very knowledgeable) to 5 (not knowledgeable) on each of the eight sub-areas. NBSTSA says the areas you rate 3, 4 or 5 are the ones to review most.
• NBSTSA's own practice tests. As checked on October 25, 2026, PSI's NBSTSA store sells two CST self-assessment forms, A and B, at $40 each. NBSTSA's new Practice Exam Hub, a $75, 150-question timed practice exam, is still marked "Coming soon" on its prepare page.
• Free Passy practice. The 20 free CST practice questions show where your reasoning breaks, with an explanation for every option. Twenty original items cannot predict whether you would reach 98 of 150, and they do not claim to.

If your checks point to weak sub-areas, a plan helps more than extra hours. The free CST study planner weights your days by NBSTSA's three subject areas, and you can compare the planned CST access periods and what each will include; checkout is not open yet.