ERCP has been well established for the management of biliary and pancreatic disorders. Although ERCP is a relatively safe procedure, complications cannot be avoided in the performance of endoscopic procedures. It is important to recognize the adverse events and the risk factors to minimize the severity of complications. The potential complications of stone extraction involve pancreatitis, haemorrhage, infection and perforation, with a total incidence rate of approximately 5% [1, 2]. The rate of haemorrhage after ERCP has been reported to be as low as 1.3%, and the rate of post-ERCP cholangitis is 1% or less. As shown by multivariate analysis, definitive risk factors for post-ERCP bleeding includes coagulopathy, anti-coagulation within 72 h of sphincterotomy, cholangitis before ERCP, bleeding during initial sphincterotomy and lower ERCP volume. Other possible risk factors include cirrhosis, dilated common bile duct, papillary stenosis, precut sphincterotomy and common bile duct stone. Although But the reason for post-ERCP biliary bleeding leading to biliary obstruction is rarehasn’t be described, we seek to analysis the risk factor and attract clinicians’ attention to the differential diagnosis of post-ERCP obstruction.

After reviewing the literature in PubMed between 1985 and 2016, four cases of biliary blood clot caused by stone extraction have been reported [3–6] (Table 1). In 1997 [3], Mosenkis BN first reported post-ERCP cholangitis caused by a biliary blood clot. Due to slow emptying of contrast material, endoscopic sphincterotomy (EST) (2 mm) was performed during the initial procedure. However, their patient returned due to cholangitis after 3 days. A clot as large as the entire CBD was extracted after a further ERCP, and she recovered 1 week later. In 1999 [4], Aftab Ala observed a 4-mm stone at the ampulla with non-dilated CBD in the patient’s first cholangiography. To retrieve the stone, a 5-mm long EST was performed. The patient returned 4 days later with cholangitis and bleeding (haemoglobin 4.8 g/dL). ERCP was repeated 9 days after the initial ERCP, and a 3.5 cm blood clot was retrieved. The patient recovered after 3 weeks. In 2012 [5], Ergül B reported a 61-year-old woman’s ERCP completed with EST and biliary stent placement due to the difficulty in contrast agent drainage. She developed cholangitis on the next day. A markedly dilated biliary tree was noted on ultrasonographic examination, and an emergency ERCP was performed again. She recovered well after 3 days. In 2013 [6], the initial ERCP in Maroy B’s study reported a 12-mm diameter stone above the pancreas. The intrapancreatic bile duct was only 7 mm. To extract the stone, a balloon was dilated to 13 mm. The patient developed pancreatitis and angiocholitis with septicaemia in the following days. Immediate plastic stenting through a clot did not stop multisystemic failure and multiple liver abscesses. He finally recovered after 2 months of hospitalization.

All the five cases including ours had post-ERCP cholangitis due to a blood clot in the CBD. We found that the blood clot in the CBD was caused by delayed bleeding after ERCP with a time interval varying from 24 h to 4 days. Extraction of the stone from the common bile duct should explain the haemorrhage. Therefore, as illustrated in the summary of previously reported cases, ERCP with sphincterotomy is considered a definite risk factor for bleeding. Four of five cases reported EST in the initial procedure, but EST does not appear to be related to the length of the incision [7].

The mechanism by which haemobilia leads to a blood clot remains uncertain. After analysis of the five cases, including ours, we found that all the patients exhibited the common characteristic of slow bile drainage. Maroy’s case [6] presented an intrapancreatic bile duct with a greater stone above the pancreas. Ergul’s patient [5] had a blunt end of the CBD at the level of the ampulla of Vater. Mosenkis and Aftab presented mild dilation or even normal CBD [3, 4]. In our case, the end of the CBD was relatively narrow during the ERCP procedure. Due to stenosis at the distal end of the bile duct, bile and blood may empty slowly. Sandblom demonstrated that blood and bile do not mix with each other in the context of minor and slow bleeding. Solid clots subsequently form, which can lead obstructions [8]. Therefore, stenosis of the outflow tract may be conducive to the solidification of blood clots.

In contrast to bile duct obstructions caused by stones, obstructions caused by blood clots could be entirely attributed to their long oval shape and soft, dense, and elastic characteristics. Instead of completely removing the blood clot, Maroy inserted a plastic bile duct stent across the clot. Thus, inadequate drainage might be responsible for the patient’s delayed recovery.

Additionally, the time interval for the further ERCP will determine the severity of the complications. The sooner the treatment is performed, the quicker the patient will recover. Otherwise, complications might be more severe or even fatal. Ergül B’s post-ERCP cholangitis was noted the next day. The patient recovered well and was discharged 3 days after an emergency ERCP. In contrast, Aftab Ala’s ERCP was repeated 9 days after the initial procedure, and the patient recovered after 3 weeks.

In conclusion,delayed bleeding after ERCP cannot be avoided. Careful and gentle handling is necessary during the ERCP procedure. If the patient exhibits poor bile drainage due to anatomical factors, the use of endoscopic biliary stenting or ENBD to ensure continued biliary drainage is necessary. The diagnosis of blood clot is based on clinical and laboratory data, particularly imaging. Repeated ERCP is often necessary and effective.