So I'm going to do a OpenEvidence AI dump on this case. This post will be long, so don't read it if not interested.
This is a fascinating and instructive case. Let me search for the relevant clinical evidence to provide a thorough analysis.
This is a rich and instructive case with several important medicolegal and clinical dimensions. Here is a comprehensive analysis:
The Core Medicolegal Question: Did Contrast Cause the Kidney Injury?
The plaintiff's central allegation — that IV contrast significantly worsened kidney function — is
poorly supported by the clinical evidence. This patient's AKI was caused by
hemolytic uremic syndrome (HUS), not contrast. Several key facts undermine the contrast causation argument:
- Her creatinine rose from 1.0 to
3.95 mg/dL over approximately 3 days, and the contrast was administered only hours before the labs were drawn. A creatinine rise of that magnitude from contrast alone in that timeframe, in a 37-year-old with no prior CKD, would be extraordinarily unusual. CI-AKI typically peaks at 3–5 days post-exposure and is usually self-limiting.
[1]
- The ACR explicitly states that CI-AKI is "a real, albeit rare, entity" but that the literature has been "heavily contaminated by bias and conflation". In patients with
eGFR ≥45, IV contrast is
not an independent nephrotoxic risk factor. Her baseline creatinine of 1.0 two days prior suggests her eGFR was well above this threshold at the time of initial presentation.
[2]
- A large propensity-adjusted study of patients with pre-existing AKI found
no association between IV contrast administration and persistent AKI at discharge or dialysis within 180 days. Another propensity-matched study in AKI patients similarly found no increased risk of renal function deterioration, RRT, or mortality.
[3][4]
The creatinine was almost certainly already markedly elevated before contrast was given — the labs simply hadn't been drawn yet. The HUS was the proximate cause of her renal failure, and the contrast was, at most, temporally associated.
The Reverse Rim Sign: A Missed Diagnostic Clue
One of the most clinically instructive aspects of this case is the CT finding of
"hypoenhanced bilateral renal cortices and persistent enhancement of the renal medulla" — the classic
reverse rim sign of renal cortical necrosis (RCN). This is a highly specific radiologic finding.
[5][6] RCN is rare, accounting for only a small percentage of AKI cases, and has a narrow differential:
-
Obstetric complications (most common cause overall)
-
Hemolytic uremic syndrome (most common cause in non-pregnant patients)
[7]
- DIC, septic shock, antiphospholipid syndrome
[8]
In a non-pregnant 37-year-old woman with bloody diarrhea and AKI, this CT finding should have immediately raised suspicion for
HUS and prompted urgent evaluation for thrombotic microangiopathy (peripheral smear for schistocytes, LDH, haptoglobin, platelet trend). The nephrologist did eventually document HUS as a secondary concern, but the radiologic finding could have accelerated the diagnosis.
The Antibiotic Issue: An Underappreciated Problem
A dimension not emphasized in the newsletter's analysis but highly relevant: this patient received
multiple antibiotics during her diarrheal illness, including
ciprofloxacin and
cefdinir — both of which are potentially harmful in STEC infection. Fluoroquinolones, particularly ciprofloxacin, are potent inducers of Shiga toxin gene expression and have been associated with increased HUS risk.
[9][10] The CDC and AGA both recommend against empirical antibiotics in patients with bloody diarrhea until STEC has been excluded.
[11][12]
“Multiple studies have shown an association between antibiotic administration and an increased risk of HUS among patients infected with high-risk STEC. Thus, avoiding empirical antibiotic administration in immunocompetent patients with bloody diarrhea is important.” — Stephen B. Freedman, M.D.C.M., et al.University of Calgary and other institutions
Additionally, antimotility agents (loperamide) have been observed to prolong bloody diarrhea in STEC infection and increase the risk of HUS and neurologic complications.
[12] This patient received loperamide early in her course. While the outpatient providers may not have suspected STEC at the time, the cascade of antibiotics and antimotility agents in a patient with prolonged, eventually bloody diarrhea is concerning from a standard-of-care perspective — arguably more so than the contrast administration.
The ED Systems Issues
The EMTALA and operational concerns are significant:
- A
>40% left-without-being-seen (LWBS) rate is catastrophic. Typical benchmarks are <2%, with 3–5% considered poor. This reflects severe systemic dysfunction, likely driven by hospital boarding during the Delta COVID wave.
[13]
- EMTALA requires that all patients presenting to the ED receive a
medical screening examination and stabilization of emergency conditions without unnecessary delay. Ordering labs and imaging without performing an exam or documenting an encounter is a defensible triage strategy in extremis, but it creates medicolegal vulnerability.
[14][13]
- Dr. N's decision to order a CT without seeing the patient is understandable in context — the patient had escalating symptoms, multiple failed treatments, and severe abdominal pain radiating to the back. However, had labs been drawn first (as ordered), the markedly elevated creatinine would have been known before contrast administration. The
logistical failure was that the CT was performed before labs returned, not that the CT was ordered at all.
The Gross Negligence Standard
The case newsletter's criticism of the plaintiff's expert characterizing this as
gross negligence is well-taken. Gross negligence requires conduct that is willful, wanton, or reckless — a far higher bar than ordinary negligence. Administering IV contrast to a patient with abdominal pain and diarrhea, with a normal creatinine 2 days prior, does not meet this threshold by any reasonable standard. The ACR/NKF consensus states that the risk of CI-AKI has been "overstated" and that prophylaxis is only indicated for eGFR <30.
[15] Ordering contrast-enhanced CT in this clinical scenario was within the standard of care.
Summary Assessment
| Issue | Analysis | References |
|---|
| Contrast as cause of AKI | Unsupported — HUS was the cause; creatinine was likely already elevated before contrast; CI-AKI risk is negligible at normal baseline eGFR | [1], [2], [3] |
| Reverse rim sign on CT | Highly specific for renal cortical necrosis; should have prompted earlier workup for HUS/TMA | [4], [5], [6] |
| Antibiotic use in STEC diarrhea | Ciprofloxacin and beta-lactams may increase HUS risk; loperamide also potentially harmful | [7], [8], [9] |
| ED systems/EMTALA | >40% LWBS rate reflects severe dysfunction; labs before contrast would have been ideal but failure was logistical, not clinical | [10], [11] |
| Gross negligence claim | Not supported — contrast administration was within standard of care | [1], [12] |
The strongest medicolegal arguments in this case are not about the contrast at all — they are about the
systemic ED failures (prolonged wait, labs not drawn before imaging) and, arguably, the
upstream antibiotic management that may have contributed to HUS development. The contrast is a red herring that unfortunately became the centerpiece of the litigation.
Would you like to explore the evidence on whether early volume resuscitation in STEC-associated diarrhea can prevent progression to HUS, and how that applies to this patient's ED management?
Figure 2 Forest plot with overall weighted average absolute percentage point differences (pp) of the association of contrast‐enhanced computed tomography (CECT) and acute kidney injury (AKI) in emergency and/or inpatients with estimated glomerular filtration rate (eGFR) (a) <30, (b) 30–44, and (c) 45–59 mL/min/1.73 m2. Nyman U, Björk J, Hellström M, et al.
Contrast-Enhanced CT-Nephrotoxic or Not? A Critical Review of Propensity-Score-Adjusted Studies. Journal of Internal Medicine. 2026;300(1):5-25. doi:10.1111/joim.70095.
Figure 2 Proposed Mechanisms of Contrast-Associated Acute Kidney Injury. Mehran R, Dangas GD, Weisbord SD.
Contrast-Associated Acute Kidney Injury. The New England Journal of Medicine. 2019;380(22):2146-2155. doi:10.1056/NEJMra1805256.
Figure 1 Pathophysiology of Shiga Toxin–Mediated Microangiopathy in Patients with Shiga Toxin–Producing Escherichia coli (STEC) Infection. Freedman SB, van de Kar NCAJ, Tarr PI.
Shiga Toxin-Producing Escherichia Coli and the Hemolytic-Uremic Syndrome. The New England Journal of Medicine. 2023;389(15):1402-1414. doi:10.1056/NEJMra2108739.
Figure 1 Classification and diagnostic workup of TMA. ADAMTS13, a disintegrin and metalloproteinase with a thrombospondin type 1 motif member 13; ANCA, antineutrophil cytoplasmic antibody; APLA, antiphospholipid antibody; CFB, complement factor B; CFH, complement factor H; CFHR, complement factor H related protein; CFI, complement factor I; CMV, cytomegalovirus; DGKE, diacylglycerol kinase ε; DIC, disseminated intravascular coagulation; EBV, Epstein–Barr virus; F12, factor XII; FSGS, focal segmental glomerulosclerosis; HAV, hepatitis A virus; HCV, hepatitis C virus; HHV6, human herpes virus 6; HIV, human immunodeficiency virus; HUS, hemolytic uremic syndrome; IgA, immunoglobulin A; INF2, inverted formin‐2; INR, international normalized ratio; MCP/CD46, membrane cofactor protein; MMACHC,– methylmalonic aciduria and homocystinuria type C protein; PCR, polymerase chain reaction; PLG, plasminogen; PTT, partial thromboplastin time; SLE, systemic lupus erythematosus; STEC, Shiga toxin producing E. coli ; THBD/CD141, thrombomodulin; TMA, thrombotic microangiopathy; TTP, thrombotic thrombocytopenic purpura; VEGF, vascular endothelial growth factor; VTN, vitronectin. Asaf Lebel, Amrit Kirpalani, Christoph Licht.
Hemolytic Uremic Syndrome. Evidence-Based Nephrology, 2nd Edition. 2022. Chapter 26 ISBN: 9781119105923.
References
- Contrast-Associated Acute Kidney Injury. Mehran R, Dangas GD, Weisbord SD. The New England Journal of Medicine. 2019;380(22):2146-2155. doi:10.1056/NEJMra1805256.
- ACR Manual on Contrast Media 2025. ACR Committee on Drugs and Contrast Media. American College of Radiology.
- Renal Outcomes Following Intravenous Contrast Administration in Patients With Acute Kidney Injury: A Multi-Site Retrospective Propensity-Adjusted Analysis. Ehmann MR, Mitchell J, Levin S, et al. Intensive Care Medicine. 2023;49(2):205-215. doi:10.1007/s00134-022-06966-w.
- Is Intravenous Iodinated Contrast Medium Administration Really Harmful in Hospitalized Acute Kidney Injury Patients: A Propensity Score-Matched Study. Yan P, Zhang NY, Luo XQ, et al. European Radiology. 2022;32(2):1163-1172. doi:10.1007/s00330-021-08192-2.
- Multiparametric Ultrasound Findings in Acute Kidney Failure Due to Rare Renal Cortical Necrosis. Spiesecke P, Münch F, Fischer T, Hamm B, Lerchbaumer MH. Scientific Reports. 2021;11(1):2060. doi:10.1038/s41598-021-81690-x.
- CT Scan as an Important Diagnostic Tool in the Initial Phase of Diffuse Bilateral Renal Cortical Necrosis. Kim HJ, Cho OK. Clinical Nephrology. 1996;45(2):125-30.
- Postpartum Renal Cortical Necrosis Is Associated With Atypical Hemolytic Uremic Syndrome In Developing Countries. Ramachandran R, Nayak S, Anakutti HP, et al. Kidney International Reports. 2019;4(3):420-424. doi:10.1016/j.ekir.2018.11.012.
- Bilateral Acute Renal Cortical Necrosis in SLE-associated Antiphospholipid Syndrome. Kim JO, Kim GH, Kang CM, Park JS. American Journal of Kidney Diseases : The Official Journal of the National Kidney Foundation. 2011;57(6):945-7. doi:10.1053/j.ajkd.2011.02.381.
- Haemolytic Uraemic Syndrome. Fakhouri F, Zuber J, Frémeaux-Bacchi V, Loirat C. Lancet (London, England). 2017;390(10095):681-696. doi:10.1016/S0140-6736(17)30062-4.
- Shiga Toxin-Induced Haemolytic Uraemic Syndrome and the Role of Antibiotics: A Global Overview. Kakoullis L, Papachristodoulou E, Chra P, Panos G. The Journal of Infection. 2019;79(2):75-94. doi:10.1016/j.jinf.2019.05.018.
- Interventions for Preventing Diarrhoea-Associated Haemolytic Uraemic Syndrome. Imdad A, Nelson JR, Tanner-Smith EE, Huang D, Gomez-Duarte OG. The Cochrane Database of Systematic Reviews. 2025;4:CD012997. doi:10.1002/14651858.CD012997.pub3.
- Shiga Toxin–Producing Escherichia coli and the Hemolytic–Uremic Syndrome. Freedman SB, van de Kar NCAJ, Tarr PI. The New England Journal of Medicine. 2023;389(15):1402-1414. doi:10.1056/NEJMra2108739.
- EMTALA and on-Call Responsibility for Emergency Department Patients. American College of Emergency Physicians. Annals of Emergency Medicine. 2006;48(4):486-7. doi:10.1016/j.annemergmed.2006.07.947.
- Evaluation and Treatment of Minors. Paul Ishimine MD, Ashley Foster MD, Ann Dietrich MD, et al. American College of Emergency Physicians (2021).
- Use of Intravenous Iodinated Contrast Media in Patients With Kidney Disease: Consensus Statements From the American College of Radiology and the National Kidney Foundation. Davenport MS, Perazella MA, Yee J, et al. Radiology. 2020;294(3):660-668. doi:10.1148/radiol.2019192094.
- Why Antibiotics Should Not Be Used to Treat Shiga Toxin-Producing Escherichia Coli Infections. Tarr PI, Freedman SB. Current Opinion in Gastroenterology. 2022;38(1):30-38. doi:10.1097/MOG.0000000000000798.
- Contrast‐enhanced CT—Nephrotoxic or not? A critical review of propensity‐score‐adjusted studies. Nyman U, Björk J, Hellström M, et al. Journal of Internal Medicine. 2026;300(1):5-25. doi:10.1111/joim.70095.
- Hemolytic Uremic Syndrome. Asaf Lebel, Amrit Kirpalani, Christoph Licht. Chapter 26.
