He paused, added the scans from two weeks ago, and placed them side by side, highlighting the contrast. "But this is different; this is an infectious aneurysm. Bacteria attach to the blood vessel walls, causing localized inflammation. The blood vessel wall is damaged by the inflammation, which is why it bulges out. It’s not like inflating a balloon; it’s more like it’s rotted out."

Zhaxi stared at the two scans, slowly forming a picture in his mind.

Yang Ping continued, "You use antibiotics to kill the bacteria, the inflammation subsides, the blood vessel wall repairs itself, and the aneurysm naturally disappears. It’s like when you cut your hand; if it doesn’t get infected, it heals on its own."

Zhaxi was stunned; he never thought an aneurysm could "heal" like this.

Doctor Meng sighed beside him, "Professor Yang, the day you first came for the consultation, you asked me if the infection indicators had been checked. At the time, I thought you were overthinking. Now that I think about it, it was my lack of experience."

Yang Ping shook his head and said calmly, "It’s not that you lack experience; you just trust the test results too much. A negative blood culture doesn’t mean there’s no infection. The infection could be hiding in the intestinal tract, the teeth, the sinuses, or even in places you can’t see. The job of a clinical doctor is to uncover these hidden things."

"Professor Yang is impressive. We learned something real today by following Professor Yang’s lead. Aren’t you taking notes?" Director Tian saw Zhaxi taking notes and immediately urged Doctor Meng to do the same.

He glanced at his watch and said, "Let’s go and check on the patient."

Zhaxi followed Yang Ping to the ward, his mind still churning. In Changdu, how many "idiopathic" diagnoses had he seen? Headaches with no discernible cause were labeled idiopathic headaches; brain hemorrhages with no cause were called idiopathic brain hemorrhages; aneurysms with unidentified origins were termed idiopathic aneurysms. The word "idiopathic" seemed to cover up all issues, as if the diagnosis was complete.

But now he realized, "idiopathic" wasn’t the end of a diagnosis; it was the starting point for further thought.

In the ward, the patient looked much better than two weeks ago. His face had color; his eye sockets weren’t as hollow, and he was leaning against the headboard, talking with his wife. Seeing Yang Ping enter, he immediately sat up straight.

"Professor Yang!" His voice was much stronger than two weeks ago. "Doctor Meng just came by and said my aneurysm is gone. Is that true?"

Yang Ping walked over, picked up the scans from the bedside table, and held them up for him to see. "Take a look yourself."

The patient stared at the scans for a long time but couldn’t make anything out, though he trusted Yang Ping’s words. His lips trembled a bit, unable to speak.

His wife was already in tears beside him. She took out a tissue from her bag, wiped her eyes, and choked on her words, "Professor Yang, thank you, truly thank you. These past two weeks, I’ve been on edge every day, just fearing that thing would suddenly burst. I couldn’t sleep at night; I sat by his bed watching him, scared that something would happen. But now, I can finally sleep peacefully."

Yang Ping waved his hand, his tone calm, "No need to thank me. This kind of case is actually very misleading, and I almost got fooled by it. Fortunately, Director Tian and Doctor Meng were very meticulous, providing me with many clues, which allowed us to solve it. If it weren’t for their thorough groundwork, I couldn’t have uncovered it. So, thank them. You eat four pieces of bread and get full; I was just the last piece, the tenth."

The woman wiped her tears, both crying and laughing, "Thank you, Director Tian, thank you, Doctor Meng."

Director Tian and Doctor Meng felt a bit embarrassed, accepting praise without achievement, and just nodded slightly.

Yang Ping added, "However, I must clarify: though the aneurysm has disappeared, the intestinal tract issue isn’t completely resolved. Clostridium difficile infections are prone to recurrence. After discharge, you must continue the medication and have regular check-ups. Be careful with your diet, eat less greasy food, and consume more digestible items. If diarrhea occurs again, return to the hospital immediately."

The patient nodded repeatedly, "Got it, got it!"

Yang Ping asked a few more questions, checked the nervous system, confirmed everything was normal, and then turned to leave.

Zhaxi suddenly mustered the courage to ask, "Professor Yang, can I ask the patient a few questions?"

Yang Ping glanced at him and nodded.

Zhaxi walked to the bedside and asked, "You mentioned starting to have diarrhea six months ago. Did you visit any hospitals or take any medication?"

The patient thought for a moment and said, "I did, went to several hospitals; they all said it was irritable bowel syndrome. They prescribed probiotics and montmorillonite powder, but it didn’t help. Later, a doctor prescribed some antibiotics, and after a few days, the diarrhea worsened."

Zhaxi was intrigued, "Worsened?"

"Yes!" the patient confirmed, "Initially, it was once or twice a day, and after taking the antibiotic, it became four or five times a day. I thought it was the drug’s problem, so I stopped."

Zhaxi nodded and asked, "When you had a fever, did you have any blood work done?"

The patient said, "Yes, they said the white blood cell count was high, indicating inflammation, which is why I was given antibiotics."

Zhaxi noted all this in his notebook and asked, "In the past six months, have you eaten any unusual foods or traveled far?"

The patient shook his head, "No! Just a regular diet and no extensive travel."

Zhaxi asked a few more questions and, feeling satisfied, thanked him.

The patient was especially cooperative, responding patiently and in detail to whatever Zhaxi inquired, afraid of leaving anything out.

As they left the ward, Yang Ping asked Zhaxi, "What are you hoping to prove by asking these questions?"

Zhaxi replied, "I want to figure out how he contracted Clostridium difficile. Was it because antibiotics disrupted the intestinal flora, allowing Clostridium difficile to grow?"

Yang Ping nodded, "That’s a good line of thinking, and then?"

Zhaxi thought for a moment and said, "Then I can write a case report. This kind of brain artery aneurysm caused by Clostridium difficile infection hasn’t been reported in domestic literature as far as I’ve looked."

Yang Ping gave him a look with a hint of surprise and approval. "You checked the literature?"

Zhaxi nodded, somewhat sheepishly, "Last time, you mentioned that the chain of evidence was missing a link, so I went back to search and read all the literature on Clostridium difficile infectious aneurysms. I found about ten papers, mostly foreign, with only a review article in China."

Yang Ping was silent for two seconds, then said, "Then write it up, and I’ll help you revise it. Remember, your knowledge and experience should weave into a net. This net takes time to weave, not something done in a day or two."

Zhaxi didn’t expect Yang Ping would offer to help him revise the paper. In Changdu, he had written several case reports, all rejected, and then he stopped writing.

"Thank you, Professor Yang." His voice was slightly strained.

Yang Ping waved and walked toward the elevator. After taking a couple of steps, he stopped, turned back, and said, "Remember, that case report must be carefully written. Review more literature and strive to thoroughly understand this disease with a single case."

Zhaxi nodded vigorously, "I will write it well."

That afternoon, Zhaxi sat in his dorm, staring blankly at his notebook. He had a lot to write about: medical history, physical examination, lab results, imaging data, treatment course, literature review; each part needed clarity, and every detail had to be accurate.

He opened his computer, created a new Word document, and typed the title: "A Case of Clostridium Difficile Infection Complicated by Infectious Intracranial Aneurysm."

Then he got stuck.

How to start? How to describe the chief complaint? How to organize the medical history? The case reports he wrote in Changdu were all formulaic, just filling in a template. But this time was different, with Yang Ping offering to revise it; it had to be written earnestly and thoroughly.

He pondered for a long time but couldn’t type a single word.