Crossing the In-Between

The ultrasound screen flickered in the dim procedure room.

JM held the probe with both hands, afraid it might escape him. On the monitor, the vessel appeared a dark circle, collapsing each time he pressed too hard. The angiocath rested above skin. Around us, the room grew quiet, the way rooms do when something is about to succeed or fail.

“Try again.”

My voice sounded steadier than I felt.

The vessel flattened again under the probe. JM lifted slightly. It filled back with blood. The needle tip crept forward, then disappeared from view as if it was a magic trick.

I watched the screen closely, wondering whether I understood this well enough to teach it. For a moment I was paralyzed, sensing him and the others hovering with their eyes, waiting for instruction.

From my first day of residency, I was drawn to teaching. I found quiet joy in moments when confusion gave way to recognition, or when a face brightened as a concept finally clicked. Richard Feynman was often quoted as saying, “Understanding something means being able to explain it simply.” That idea followed me, yet teaching rarely felt like mastery.

My transition from learner to educator was not marked by a degree, a promotion, or a ceremony.¹ One day, a question crossed the room and landed my way while everyone waited for an answer. In that moment, I felt a sense of insecurity; teaching while still learning often meant making a choice based on the flip of a coin—expose your own gaps in understanding, or allow a learner’s confusion to grow.

A mentor once showed me how to navigate this tension. One afternoon when I was still a student, he pulled our team aside between admissions and placed the ultrasound probe over a patient’s arm as he guided the needle forward.

The needle vanished from the screen.

He stopped.

“Why does this keep happening?” he asked, glancing at the monitor.

No one answered.

He adjusted the probe again. The vessel remained clear, a dark circle in the center of the screen, but the needle flickered in and out of sight like a faulty signal.

“I’m going to admit something,” he said. “I know how to place the line, but I’ve never fully understood why the needle keeps on disappearing like that.”

He pressed the probe down and rocked it back and forth.

“Something about the angle,” he said. “But the physics of it… I’m not entirely sure.” Then he looked around the group.

“Does anyone know?”

One of the medical students raised her hand.

“I think it’s the angle between the ultrasound beam and the needle,” she said. “Ultrasound only shows structures that reflect the beam back to the probe. If the needle is too steep, the sound waves bounce away instead of returning, which is why it disappears.”

The attending paused.

“That… actually makes sense.”

He handed her the probe.

“Show us!”

She tilted the probe ever so slightly. The bright line of the needle tip suddenly appeared on the screen.

“There,” she said. “If the needle lines up with the beam, you see it!”

The attending stepped back and watched her demonstration with the same attention the rest of us gave the monitor.

Weeks later during another procedure, he stood beside the bed while an intern struggled to track the needle on the screen.

“Flatten your angle slightly,” he said.

The intern adjusted. The needle reappeared.

“There you go!”

He then paused and smiled.

“I learned this from a student a few weeks ago. If the angle is too steep, the ultrasound beam reflects away from the probe and the needle disappears.”

That moment stayed with me, the way knowledge moved across the room from student to teacher and then back again. Watching my attending learn openly made me realize teaching can happen at any level and can long begin before certainty.

Now, when a student hesitates with the probe, I realize the same reluctance in myself.

Do I know this well enough to teach it?

Yet I begin anyway.

“Look at the vessel,” I said. “See how it collapses? That tells you it’s a vein.”

JM adjusted the probe. The vessel steadied.

“Now flatten the needle tip and keep it aligned with the probe at about 90 degrees.”

The vessel collapsed as JM pressed too hard, then filled again as he steadied his hand. As he flattened the angle, the needle came back into view beneath the probe. The needle advanced in sight. A flash of blood appeared, and relief softened the room. The line was in.

What lingered was not only his success, but the realization that somewhere between guiding the needle and watching the vessel fill on the screen, my understanding of teaching had shifted.

I once imagined a clear line between the learner and the educator. Standing beside the bed that day, it was no longer clear where one began and the other ended. Hesitation once holding me back shapes how I learn and teach today.

Perhaps this is the paradox of being a learner-educator: to learn, one must remain uncertain; to teach, one must be willing to step into the in-between.

Author Notes

Disclosure: AI was not used in writing this article.