Today I posted my essay “Alice’s Guardian Angels” about a case of missed diagnosis of appendicitis. This is an appendix (!) documenting my chat with Chat GPT-4.
My prompt: "I need your help to determine a differential diagnosis. The patient is a 14 year old girl, previously healthy, who presents now with 3 days of diarrhea and fever, and one episode of vomiting just prior to being seen in the Emergency Department. On physical examination, her abdomen is diffusely tender. There is no right lower quadrant tenderness and Murphy's sign and other physical signs of appendicitis are negative. She is tachycardic, hypotensive and dehydrated. She has improved slightly with intravenous hydration. What is the differential diagnosis? Please rank the diagnoses in order of likelihood, and assign a percentage likelihood to each. What is the most likely diagnosis and how should we rule that possibility in or out? What is the most serious diagnosis and how should we rule that possibility in or out?"
ChatGPT-4 reply: "Certainly, the presentation suggests a gastrointestinal and potentially systemic illness in a previously healthy adolescent girl. Here's a differential diagnosis in order of likelihood, with estimated percentages based on the given clinical picture:
1. Infectious Gastroenteritis (45%):
- Caused by bacteria (e.g., Salmonella, Campylobacter, E. coli), viruses (e.g., Norovirus, Rotavirus), or parasites (e.g., Giardia, Entamoeba histolytica).
- Workup: Stool cultures, stool ova and parasites, and possibly a stool Clostridium difficile toxin test if recent antibiotic use. Empirical treatment can start in severe cases or those where specific pathogens are suspected.
2. Appendicitis (20%):
- Despite the absence of classic right lower quadrant pain, it still should be considered given the abdominal tenderness.
- Workup: Abdominal ultrasound or CT scan can confirm or exclude.
3. Pyelonephritis (10%):
- Kidney infection can present with abdominal pain, fever, and vomiting.
- Workup: Urinalysis and urine culture. Imaging if obstruction or abscess is suspected.
4. Pelvic Inflammatory Disease (PID, 10%):
- Infection of the female reproductive organs.
- Workup: Pelvic examination, cervical swabs, and possibly pelvic ultrasound.
5. Mesenteric Adenitis (5%):
- Swollen lymph nodes in the mesentery mimicking appendicitis.
- Workup: Often a clinical diagnosis, but imaging can help rule out other causes.
6. Intussusception (4%):
- Telescoping of one part of the bowel into another.
- Workup: Abdominal ultrasound.
7. Toxic Shock Syndrome (TSS, 3%):
- Caused by bacterial toxins, often associated with tampon use in menstruating females.
- Workup: Clinical criteria, blood cultures, and other supporting labs.
8. Other (3%):
- This includes conditions like diabetic ketoacidosis (though she's previously healthy), inflammatory bowel disease, pancreatitis, or even a rare presentation of an ectopic pregnancy (if she's sexually active).
- Workup: Dependent on the suspected condition; could include labs like amylase and lipase, blood glucose and ketones, or even a pregnancy test.
Most Likely Diagnosis: Infectious gastroenteritis is the most likely diagnosis due to its common presentation with diarrhea, fever, vomiting, and dehydration. A stool workup should be done to determine the causative pathogen.
Most Serious Diagnosis: Toxic Shock Syndrome (TSS) is among the most serious and life-threatening diagnoses on this list. Though its likelihood is lower, it can rapidly progress and become fatal. Given its association with tampon use in menstruating females and the systemic symptoms of hypotension and tachycardia, it's important to inquire about menstrual history and tampon use. A high index of suspicion and early treatment with broad-spectrum antibiotics are essential, even before definitive diagnosis, if TSS is suspected.
It's important to collaborate with a medical team and evaluate the patient comprehensively, using clinical judgment to prioritize investigations based on the clinical presentation and other findings."
My prompt: "Now I will tell you what happened next. The patient continued having fever and diffuse abdominal pain. She became increasingly septic. What diagnoses must be considered now, and what tests should be done? The family was very concerned. The patient is not sexually active."
ChatGPT-4 reply: "Given the progression of the patient's symptoms with increased sepsis, the differential diagnosis needs to be revisited, and certain diagnoses become more concerning:
1. Appendicitis with Perforation: Even though the initial presentation did not have the classic right lower quadrant tenderness, a perforated appendix can lead to diffuse peritonitis and sepsis.
- Workup: Abdominal CT scan to identify any perforation, abscess, or signs of inflammation around the appendix.
2. Pyelonephritis with Abscess or Urosepsis: If the kidney infection is not contained, it can lead to an abscess or even spread into the bloodstream.
- Workup: Urinalysis, urine culture, and renal ultrasound or CT scan.
3. Toxic Shock Syndrome (TSS): Even though she is not sexually active, there can be other causes for TSS beyond tampon use, such as skin infections or surgical wounds.
- Workup: Blood cultures, and tests for streptococcal or staphylococcal toxins. Clinical criteria remain important.
4. Mesenteric Adenitis with Secondary Infection: While typically benign, if the lymph nodes become secondarily infected, it could cause sepsis.
- Workup: Abdominal imaging, like CT scan or ultrasound.
5. Bowel Perforation from another cause: Other parts of the bowel, beyond the appendix, can perforate and lead to sepsis.
- Workup: Abdominal CT scan looking for free air or signs of inflammation.
6. Pelvic Inflammatory Disease (PID) with Abscess Formation: Even if not sexually active, it's not impossible (though very rare) for PID to occur.
- Workup: Pelvic ultrasound and possibly a diagnostic laparoscopy.
7. Intussusception with Bowel Necrosis: Continued intussusception can lead to bowel ischemia and necrosis.
- Workup: Abdominal ultrasound.
Given the severity of the clinical picture:
- Immediate Intervention: Broad-spectrum intravenous antibiotics should be initiated promptly, given the septic presentation.
- Supportive Care: Continued fluid resuscitation, monitoring in a critical care setting, and vasopressors if hypotension persists despite adequate fluid resuscitation.
- Further Workup: Depending on the clinical picture, lab tests to consider include complete blood count (CBC), blood cultures, lactic acid (indicative of tissue hypoperfusion in sepsis), comprehensive metabolic panel, and coagulation profile. Imaging like an abdominal CT scan can give a broad overview of many of the potential issues on the differential.
Given the acuity and potential for rapid deterioration in sepsis, prompt consultation with surgery and other relevant specialties is essential. The family should be kept informed throughout the process, ensuring they understand the severity and the steps being taken for diagnosis and management."