From the Guidelines
Xanthochromia is a critical diagnostic marker for subarachnoid hemorrhage, characterized by the yellowish discoloration of cerebrospinal fluid (CSF) due to the breakdown of red blood cells and release of hemoglobin, which is then converted to bilirubin. This condition is significant in distinguishing between a traumatic lumbar puncture and a true subarachnoid hemorrhage, as noted in the 2023 guideline for the management of patients with aneurysmal subarachnoid hemorrhage 1. The development of xanthochromia typically occurs 2-12 hours after bleeding and may persist for up to two weeks. Some key points about xanthochromia include:
- It is a vital marker in the evaluation of patients with suspected subarachnoid hemorrhage, especially when CT imaging is negative but clinical suspicion remains high 1.
- Laboratory detection methods include visual inspection and spectrophotometry, with spectrophotometry being more sensitive, as reported by Walton et al with a sensitivity of 100% and specificity of 95.2% 1.
- The American College of Emergency Physicians recommends CTA or LP as the next diagnostic study if noncontrast head CT is inconclusive in a patient with a high suspicion for SAH, highlighting the importance of xanthochromia evaluation in LP 1. In clinical practice, the presence of xanthochromia is a strong indicator of subarachnoid hemorrhage, and its detection is crucial for prompt and effective management of this life-threatening condition, as emphasized by the American Heart Association/American Stroke Association guideline 1.
From the Research
Definition of Xanthochromia
- Xanthochromia refers to the yellow discoloration of cerebrospinal fluid (CSF) caused by hemoglobin catabolism 2, 3, 4.
- It is most commonly associated with subarachnoid hemorrhage (SAH), but other etiologies must be considered when initial imaging is unremarkable 2.
Causes of Xanthochromia
- Subarachnoid hemorrhage (SAH) is a serious neurological event associated with high morbidity and mortality, and xanthochromia is often used to diagnose SAH 3.
- However, xanthochromia can also be observed in traumatic lumbar puncture (LP) 4, and in cases of mixed etiology involving partial mechanical obstruction of CSF flow and a subclinical viral process 2.
- Other causes of xanthochromia include infectious, inflammatory, and structural causes, which should be considered in the differential diagnosis when SAH is excluded 2.
Diagnosis of Xanthochromia
- Spectrophotometry of CSF for xanthochromia is a sensitive and specific test for diagnosing SAH, with a diagnostic sensitivity of 100% and a diagnostic specificity of 98.5% 3.
- Visual inspection of CSF supernatant for xanthochromia lacks the sensitivity necessary to reliably exclude the diagnosis of SAH, with a sensitivity of 47.3% 5.
- Incorporating CSF red cell count (RCC) with xanthochromia can improve diagnostic accuracy, reducing false positive tests and inconclusive tests 6.
Clinical Significance of Xanthochromia
- Xanthochromia is an important diagnostic tool in the evaluation of patients with suspected SAH, and can help to identify patients who require further imaging or treatment 3, 6.
- However, the positive yield of xanthochromia is low, and it identified only 6% of all SAH diagnosed in one study 6.
- The use of xanthochromia in the diagnosis of SAH should be considered in the context of other clinical and radiological findings, and should be interpreted with caution in cases of traumatic LP or other potential causes of xanthochromia 4, 5.