S4489 Navigating the Diagnostic Complexities of Post-Appendectomy Chronic Abdominal Pain

Introduction: Chronic abdominal pain following an appendectomy occurs in 20-25% of patients, with 30-40% of undiagnosed cases attributed to functional gastrointestinal disorders (FGIDs) or disorders of gut-brain interaction (DGBI). This case study highlights the diagnostic challenges, focusing on issues such as neuroendocrine dysfunction, central sensitization, and complications related to opioid use for abdominal pain. Case Description: A 21-year-old man presented with a 5-year history of suprapubic and right lower quadrant pain. He started experiencing pain after a laparoscopic appendectomy (2019). His pain persisted after adhesiolysis (2020). Additionally, he reported a 25 lb weight loss, nighttime urinary urgency, and burning pain when passing stools. Octreotide scans, magnetic resonance imaging enterography, and endoscopies ruled out the presence of inflammatory bowel disease (IBD) and neuroendocrine tumors. Other notable findings included transient bladder distension with post-void residual volume of 453 ml, unconfirmed secondary adrenal insufficiency diagnosed via adrenocorticotropic hormone stimulation test (2023), and stool calprotectin level of 114 µg/g. Hydrocortisone caused exogenous Cushingoid features and weight gain. Hydromorphone used for pain management caused dependency issues, while amitriptyline and gabapentin provided minimal pain relief. Anxiety and a high score on the Pain Catastrophizing Scale (41), worsened by unfulfilled athletic aspirations. Discussion: Persistent symptoms following adhesiolysis (2020) align with FGID criteria, Rome IV, suggesting visceral hypersensitivity and central sensitization. Despite normal colonoscopy findings, transiently elevated calprotectin levels (<150 µg/g) suggest “IBD-like” phenotypes within FGID spectra. Also, chronic opioid use has the potential to cause adrenal insufficiency and worsened visceral pain via glucocorticoid-mediated nociceptive dysregulation. Furthermore, hydromorphone >50 MME/day is likely contributing to dependency and hyperalgesia as it exceeds Centers for Disease Control and Prevention guidelines. Since poor pain processing is often associated with high pain catastrophizing, cognitive behavioral therapy (CBT) is crucial. However, inaccessibility leads to its non-implementation. Thus, a multidisciplinary approach involving opioid deprescribing, adrenal axis monitoring, and CBT is required for managing chronic postsurgical pain. The hormonal dysregulation, central sensitization, and maladaptive cognition interplay indicate significant gaps in chronic pain models, underscoring the need for holistic care.