Case Presentation: An 81 year-old female with a history of CAD, diverticulitis, and GERD presented with abdominal pain. She denied any nausea or vomiting and had no associated stool changes or weight loss. On exam, the patient was afebrile with tenderness in the epigastrum and right upper quadrant without guarding or rebound tenderness. Laboratory studies were unremarkable. Her initial workup included an abdominal ultrasound which was unremarkable. A follow up CT abdomen revealed a possible 6 mm stone in the common bile duct. Due to the patient’s persistent abdominal pain, she underwent an ERCP which revealed biliary sludge. The patient ultimately underwent stent placement in the common bile duct in an attempt to improve her pain. Laboratory studies post-procedure revealed normal LFTs and lipase. However, the patient continued to have persistent abdominal pain and subsequently underwent a CTA abdomen, which was negative for ischemia or acute pathology. Upon further investigation, the patient’s physical exam was positive for Carnett’s sign, indicating abdominal tenderness after tension of the abdominal wall, raising suspicion for musculoskeletal causes of her abdominal pain. The patient then underwent two trigger point injections to the abdominal wall with an anesthetic/corticosteroid combination of 0.25% bupivacaine with 2 mg dexamethasone, which provided significant improvement in her abdominal pain. The patient was able to be discharged post-injection without further pain or adverse events.
Discussion: The prevalence of abdominal wall pain is unknown, although it may account for approximately 10% of patients with chronic idiopathic abdominal pain. The most common cause of abdominal wall pain appears to be entrapment of an anterior cutaneous branch of a thoracic intercostal nerve. Carnett’s sign, which is a finding on physical examination in which abdominal tenderness is elicited with tension of the abdominal wall using certain actions such as lifting the head or flexing the legs, is a helpful diagnostic tool, especially when incorporated with early exclusion of a parietal source of the pain. Accurately placed anesthetic/corticosteroid injections have been found to provide substantial pain relief to more than 75% of patients, often for prolonged periods. These trigger point injections also serve as confirmatory tests for diagnosing the abdominal wall as the source of the pain, with a very small probability of missing visceral disease.
Conclusions: For patients with physical exam findings concerning for abdominal wall pain and a negative workup for visceral causes of the pain, trigger point injections of anesthetic/corticosteroid should be considered both for confirming the diagnosis of abdominal wall pain as well as for management.