From the Guidelines
Murphy's sign is a clinical manifestation of acute cholecystitis, resulting from the inflammation of the gallbladder wall, which becomes edematous and hypersensitive due to obstruction of the cystic duct by gallstones. The pathophysiology behind Murphy's sign involves the release of prostaglandins, cytokines, and other inflammatory mediators that sensitize pain receptors in the gallbladder wall 1. When the gallbladder is inflamed, its wall becomes irritated, and when mechanical pressure is applied during the examination, nociceptors are stimulated, resulting in the characteristic pain response.
The clinical significance of Murphy's sign is highlighted in the 2020 World Society of Emergency Surgery guidelines for the diagnosis and treatment of acute calculus cholecystitis, which suggests using a combination of detailed history, complete clinical examination, laboratory tests, and imaging investigations for diagnosis 1. The guidelines also mention that Murphy's sign has a positive likelihood ratio of 2.8, although the 95% confidence intervals included 1.0, indicating some uncertainty in its diagnostic accuracy 1.
Some key points to consider in the pathophysiology of Murphy's sign include:
- Inflammation of the gallbladder wall due to obstruction of the cystic duct by gallstones
- Release of inflammatory mediators that sensitize pain receptors in the gallbladder wall
- Irritation of the visceral peritoneum covering the gallbladder
- Stimulation of nociceptors during mechanical pressure applied during the examination
- Characteristic pain response resulting from the sudden contact between the inflamed gallbladder and the examiner's fingers during inspiration.
It is essential to note that while Murphy's sign is highly specific for acute cholecystitis, its absence does not rule out the diagnosis, especially if the patient has received pain medication prior to imaging 1. Ultrasound remains the initial test of choice for imaging patients with suspected acute cholecystitis, despite cholescintigraphy having higher sensitivity and specificity 1.
From the Research
Pathophysiology of Murphy's Sign
The pathophysiology behind Murphy's sign is related to the inflammation of the gallbladder, which is a characteristic of acute cholecystitis.
- The sonographic Murphy sign is defined as the presence of maximal tenderness elicited by direct pressure of the transducer over a sonographically localized gallbladder 2.
- This tenderness is caused by the inflammation of the gallbladder, which irritates the surrounding nerves and causes pain 3.
- The presence of Murphy's sign is a useful indicator of acute cholecystitis, with a reported prevalence of more than 95% in patients with this condition 2.
- However, the absence of Murphy's sign does not rule out acute cholecystitis, especially in elderly patients or those with gangrenous cholecystitis 2, 4.
Clinical Relevance
The clinical relevance of Murphy's sign lies in its ability to aid in the diagnosis of acute cholecystitis.
- The sonographic Murphy sign has been shown to have a high sensitivity and specificity in diagnosing acute cholecystitis, with a predictive value of a positive sign of 72.5% and a predictive value of a negative sign of 90.5% 5.
- Combining the sonographic Murphy sign with clinical parameters such as patient age, sex, and white blood cell count can effectively stratify patients into risk groups for acute cholecystitis 6.
- However, the interpretation of Murphy's sign should be cautious in elderly patients, as the presentation of acute abdomen can differ from that in younger patients 4.