Situs ambiguous (SA) is a rare genetic defect in embryogenesis characterised by failure
to generate normal left-right asymmetry, leading to a spectrum of abnormalities. This
anatomical variation creates additional challenges when performing endoscopic intervention.
We present the case of 65-year-old with SA who was admitted with cholangitis. Imaging
confirmed large bile duct stones and unconventional anatomy with a right-sided stomach,
third part of duodenum crossing the midline and a central liver. She underwent ERCP
with cholangioscopy, electrohydraulic lithotripsy (EHL) and ultimately complete bile
duct clearance, negating the need for surgical intervention [1]
[2].
She was sedated with propofol/remifentanil with anaesthetist support. The ampulla
appeared relatively more proximal in the duodenum and in a 1 o'clock position rather
than the more conventional 11 o'clock. Maintaining a stable scope position was the
largest challenge and only achieved with a second operator applying significant clockwise
torque. When the duodenoscope position was threatened with falling back, stability
was regained with additional clockwise torque and downward tip angulation.
Review of imaging with GI radiologists greatly assisted procedural planning. Patient
consent should include discussion of the additional complexity and the risk of a prolonged
procedure. The procedure should be optimised by ensuring adequate deep sedation/anaesthetic
as well as sufficient time allocation and consideration of a second operator. A gastroscope
was initially used to assess anatomy and technical factors. We have demonstrated that
clearance of large bile duct stones using EHL is achievable in patients with SA.
