Situs inversus totalis (SIT) is a rare congenital condition characterized by a complete mirror-image transposition of the thoracic and abdominal viscera, wherein the heart, liver, spleen, and other organs occupy positions opposite to their usual locations [1, 2]. The incidence of SIT has been estimated to range between 1 in 5,000 and 1 in 20,000 live births [1], with no distinct gender or ethnic predilection. Although the condition is typically asymptomatic and often detected incidentally during imaging or surgical procedures, it may pose significant diagnostic and interventional challenges due to the reversal of normal anatomical landmarks. From a clinical perspective, patients with SIT generally lead normal lives unless associated with other congenital anomalies, such as Kartagener’s syndrome or structural cardiac defects [3]. However, when biliary pathology such as choledocholithiasis arises, the reversed orientation of the biliary tract complicates both diagnosis and endoscopic management. Conventional endoscopic techniques rely heavily on anatomical familiarity, and thus, in SIT, the operator must adapt to a mirror-image configuration of the duodenum and ampulla of Vater [3, 4]. Endoscopic retrograde cholangiopancreatography (ERCP), which remains the standard therapeutic approach for biliary obstruction, becomes technically demanding in these patients. The altered anatomy challenges the endoscopist’s spatial orientation, particularly in identifying and cannulating the major papilla, which appears on the opposite side of the duodenal wall compared to normal anatomy. This may necessitate adjustments in patient positioning, scope manipulation, and sometimes even procedural strategy. In a large multicenter study, the incidence of SIT among patients undergoing ERCP was found to be exceptionally low- approximately 0.02%, accounting for only 14 of 65,838 procedures performed over a 10-year period [5]. Given the rarity of this condition, literature on ERCP in SIT remains sparse and is largely limited to individual case reports or small series [6, 7]. These reports emphasize the need for careful pre-procedural planning, modified endoscopic techniques, and flexibility in patient positioning to achieve successful outcomes. The current case series presents three patients with SIT who underwent ERCP for choledocholithiasis, illustrating the diverse technical adaptations employed, the challenges encountered during cannulation and stone extraction, and the eventual clinical outcomes achieved. By detailing these experiences, the series aims to contribute to the limited existing body of evidence and to provide practical insights for endoscopists managing similar cases in the future.

Case 1 A 59-year-old female known to have Situs Inversus Totalis (SIT) presented with progressive jaundice, dark urine, pale stools, and intermittent right upper quadrant abdominal pain over the past two weeks. On examination, she was icteric with mild tenderness in the left upper quadrant, consistent with the mirror-image anatomy of SIT. Laboratory investigations revealed elevated serum bilirubin (total 6.8 mg/dL, direct 4.9 mg/dL) and raised cholestatic enzymes (ALP, GGT), suggesting obstructive jaundice. Ultrasonography (USG) demonstrated a dilated common bile duct (CBD) and multiple echogenic foci consistent with choledocholithiasis. Magnetic Resonance Cholangiopancreatography (MRCP) confirmed the presence of CBD stones with proximal ductal dilatation and a normal intrahepatic biliary system. Given these findings, an Endoscopic Retrograde Cholangiopancreatography (ERCP) was planned. Considering the patient’s mirror-image anatomy, the procedure was performed in the supine position to optimize endoscope maneuverability. The endoscopist adapted hand and scope movements in a reversed orientation, opposite to the conventional anatomical direction. After careful orientation, selective CBD cannulation was achieved successfully. Endoscopic sphincterotomy was performed, and complete stone clearance was achieved using a combination of balloon sweeps and retrieval baskets. A 7 Fr × 7 cm plastic biliary stent was placed temporarily to ensure adequate bile drainage and to prevent post-procedural complications. The patient’s symptoms and biochemical parameters improved gradually. She later underwent laparoscopic cholecystectomy under reversed port placement, adapted for SIT anatomy. The stent was removed after six weeks, and the patient remained asymptomatic at follow-up. Case 2 A 36-year-old female with Situs Inversus Totalis presented with jaundice, pruritus, and upper abdominal discomfort for ten days. Physical examination revealed mild icterus and tenderness in the left upper abdomen. Laboratory evaluation showed elevated bilirubin and liver enzymes, consistent with obstructive jaundice. Abdominal ultrasound revealed a dilated CBD (12 mm) with evidence of distal obstruction. An ERCP was undertaken with the patient in the left lateral position, which is typically preferred for routine cases. However, due to the mirror-image anatomy of the biliary system, endoscopic orientation proved technically challenging. The papilla appeared on the opposite side, requiring reversed manipulation of the duodenoscope and accessories. Despite several attempts, repeated pancreatic duct (PD) cannulation occurred inadvertently. To prevent procedure-induced pancreatitis, a prophylactic PD stent (5 Fr) was placed. Subsequently, needle-knife sphincterotomy was performed to facilitate bile duct access, following which successful CBD cannulation was achieved. Balloon sweeps retrieved several pigment stones; however, complete clearance could not be achieved due to a large residual stone burden. A plastic biliary stent was therefore inserted to ensure adequate drainage and relieve obstruction. The patient’s jaundice gradually improved post-ERCP. Given the incomplete clearance, she underwent laparoscopic common bile duct exploration (LCBDE) after optimization. The residual stones were completely removed, and intraoperative cholangiography confirmed ductal clearance. The postoperative period was uneventful, and the patient remained well at the three-month follow-up with normalized liver function tests. Case 3 A 60-year-old male with known Situs Inversus Totalis presented with obstructive jaundice, loss of appetite, and episodic epigastric pain radiating to the back. On physical examination, there was mild tenderness in the left upper quadrant and a palpable gallbladder. Laboratory tests revealed direct hyperbilirubinemia and elevated serum transaminases. Ultrasound and MRCP confirmed choledocholithiasis with a dilated CBD (13 mm) and no intrahepatic biliary dilatation. An ERCP was planned to relieve the obstruction. The procedure was initially attempted in the supine position to facilitate scope orientation. However, due to difficulty in aligning the papilla and maintaining a stable endoscopic position, positional adjustments were required during the procedure- transitioning from supine to left lateral and then back to supine. These changes helped optimize visualization and access to the papilla. Once the anatomy was clearly identified, selective CBD cannulation was achieved. A standard sphincterotomy was performed, followed by balloon extraction of multiple small stones. To maintain bile drainage and minimize post-procedural edema, a temporary biliary stent was placed. The patient tolerated the procedure well, with marked improvement in symptoms and laboratory parameters over the next week. Subsequently, a laparoscopic cholecystectomy was performed using a modified port placement to accommodate the reversed anatomy. The biliary stent was removed endoscopically six weeks later. The patient’s postoperative recovery was smooth, and he remained asymptomatic on follow-up ERCP Procedure Description ERCP was performed under general anesthesia with endotracheal intubation, as a prolonged procedure was anticipated. The supine position was chosen as the default; two procedures were completed in the supine position, while one was performed in the left lateral position. Endoscopic and fluoroscopic monitors were placed at the patient’s head end, and the endoscopist stood on the left side of the table, as per standard practice. The pharynx, esophagus, and gastroesophageal junction were traversed in the standard manner. In the stomach, a special maneuver was required: the duodenoscope was rotated 180° counterclockwise, advanced into the antrum, and then into the first part of the duodenum (D1). A further rotation allowed smooth entry into the second part (D2). This was followed by temporary detachment of the scope from the processor, straightening of the scope to reduce looping, and subsequent reattachment before continuing. In D2, scope stability remained challenging; therefore, the assistant was instructed to assist in maintaining scope stability. The papillary orifice was visualized between the 1-3 o’clock positions. All procedures were performed with a standard therapeutic duodenoscope and accessories. Wire-guided cannulation was used as the primary technique. In cases with repeated pancreatic duct (PD) cannulation, prophylactic PD stenting was performed. Precut sphincterotomy over the PD stent facilitated selective CBD cannulation when required. Balloon catheters were used for stone retrieval, and plastic biliary stents (10 cm × 7F DPT) were placed in all three patients. Prophylactic rectal indomethacin was administered in all cases during the initial ERCP. All procedures were performed by an experienced endoscopist with independent experience of more than 2,500 ERCPs.

Endoscopic retrograde cholangiopancreatography (ERCP) in patients with Situs Inversus Totalis (SIT) is inherently challenging due to the mirror-image transposition of thoracoabdominal organs [2, 5, 6, 8]. This anatomical reversal alters the usual orientation of the duodenum and ampulla of Vater, making identification of the major papilla and execution of standard endoscopic maneuvers significantly more difficult. The endoscopist must adapt hand movements, scope rotation, and accessory handling in a way that is opposite to conventional anatomy, which increases procedural complexity and the risk of complications if not performed carefully. Patient positioning plays a crucial role in overcoming these challenges [7, 8]. While the prone position is standard for routine ERCP, our case series demonstrates that left lateral and supine positions can be equally effective, particularly in SIT patients [9]. These positions help align the papilla in a more familiar orientation relative to the endoscope, thereby facilitating selective cannulation. By optimizing scope trajectory and reducing torque in the duodenum, these modified positions improve access to the biliary tree and can reduce procedure time. Our observations are consistent with a multicenter study that reported higher cannulation success rates (90.9% vs. 66.7%) and fewer adverse events when modified positions were employed compared to the conventional prone approach [5]. In addition to positioning, special maneuvering within the first part of the duodenum (D1) was occasionally required to overcome the challenges posed by reversed anatomy. In our cases, temporarily detaching the endoscope from the processor, straightening it to reduce looping, and then reattaching it enabled smoother progression to the second part of the duodenum (D2) and improved visualization of the papilla. Although rarely described in the literature, this technique proved crucial in achieving selective CBD cannulation in our series. In one patient where conventional cannulation was unsuccessful due to repeated pancreatic duct (PD) entry, a precut sphincterotomy over a prophylactic PD stent was safely performed [10, 11]. This approach stabilized the papilla, minimized the risk of inadvertent pancreatic injury, and provided a controlled pathway for biliary access. Our experience supports the use of precut over PD stents as a safe and effective rescue technique in patients with SIT undergoing ERCP, echoing prior reports that recommend this method in complex or anatomically challenging cases [1, 2, 5-8, 12]. Overall, ERCP in SIT can be performed safely and effectively with careful modifications in patient positioning, scope handling, and use of adjunctive maneuvers. In our series, 100% selective CBD cannulation was achieved, and no post-procedural pancreatitis or other complications occurred. These outcomes are consistent with previously published data, including Ding et al., who reported no post-ERCP pancreatitis in a series of 14 SIT patients undergoing ERCP [5]. The absence of adverse events in our experience further reinforces that, with adequate expertise and procedural adaptations, ERCP in SIT can be executed safely and with outcomes comparable to those in patients with normal anatomy. Limitations This report is limited by the small sample size and single-center experience, which restricts generalizability. The absence of long-term follow-up data limits assessment of delayed complications or recurrence. Nevertheless, our series adds to the scarce literature on ERCP in SIT and emphasizes practical technical modifications that can aid endoscopists in similar cases. Future multicenter registries and prospective studies are needed to validate these findings, compare different positioning strategies, and develop standardized procedural guidelines for ERCP in SIT.

ERCP in patients with situs inversus totalis is technically challenging but feasible. Modified positioning (supine or left lateral), specialized duodenal maneuvers including temporary scope detachment, and PD stent–assisted precut sphincterotomy are effective strategies to improve safety and success. These adaptations reinforce ERCP as an effective therapeutic option in SIT.

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