Cholelithiasis is a commonly encountered clinical disorder in both emergency and out-patient clinics [7]. The prevalence of CBD stones coexisting with gallstones is estimated to range from 8 to 15% before the age of 60 years to up to 60% in the older population [8]. Also, compared to male patients, females are twice as likely to have coexisting CBD stones [9].
Abdominal ultrasound can accurately show gall bladder stones but has poor sensitivity in the diagnosis of choledocholithiasis [10]. However, sonographic detection of multiple small gall bladder calculi can be predictive for simultaneous small CBD stones [10]. Such sonographic predictive value of choledocholithiasis is 4-fold higher with multiple calculi less than 5 mm in opposing to larger and solitary stones [11]. Of note, sonographic detection of dilated CBD more than 7 mm can be highly indicative of biliary obstruction either calcular or non-calcular [12]. The ultrasound findings in the present case were in support of both presence of CBD stones mostly small ones and biliary obstruction.
Normal serum levels of liver function tests have shown to have a negative predictive value (NPV) for complicated CBD stones as high as 98% and people with normal liver function tests would not be subjects for further investigations [13]. In contrary to sonographic findings, in this case, normal liver testing along with clinical data were strongly arguing against complicated CBD stones and deterring performing further intervention. However, it was theorized that a slow process of marked dilatation of the CBD may serve as a blunting reservoir for the elevation of liver testing parameters and this might explain the lack of complications in this case despite ERC documentation of such a quantity of small-sized choledocholithiasis [14]. Also, such significant CBD dilatation with the migration of innumerable stones from the gall bladder may induce some proximal pressure effect and consequent mild dilatation of the proximal biliary channels.
Likewise, in the present case, such a small size of the stones might be associated with spontaneous peaceful passage of numerous stones and prolonged asymptomatic history in this case.
ERCP is a positioned technique in the management of CBD stones and has been considered the gold standard in the diagnosis and treatment of suspected CBD stones [3]. Reportedly, magnetic resonance cholangiography (MRC) can identify up to 91% of biliary stones, but small calculi less than 5 mm can be shown in only 71% of cases [15]. In this case, the diagnosis of CBD stones has been achieved by ERCP while MRCP has failed to show any filling defects.
According to the American Society for Gastrointestinal Endoscopy (ASGE) practice guidelines to assign risk stratification of choledocholithiasis, dilated CBD to 6 mm and more (11 mm in our case) was considered a strong predictor of CBD stones [16]. It is generally recommended that CBD stones have to be removed even in asymptomatic individuals because of the serious sequelae and associated mortality [17]. Therefore, ERCP has been the favored and attentive management in this case.
The last point to be explained in this elderly patient who expressed disinterest in doing further laboratory investigations is the pigment black stones in absence of overt hemolytic disorder, the non-cirrhotic liver, and the in situ gall bladder. Her complete blood picture shows moderate anemia, low mean corpuscular volume (MCV), increased mean corpuscular volume concentration (MCHC), and mildly raised red cell width (RDW). All these parameters combined with the late-onset black choledocholithiasis can be explained in view of an occult hemolytic disorder intermittently causing repeated undiagnosed hemolytic attacks and in the long term inducing these intensely black pigment stones in our elderly patient [18, 19]. As her sonography showed a normal-sized spleen, the possibility that a trait of either sickle cell disease or beta thalassemia can be dominating [18]. Certainly, a combined iron deficiency anemia can be suggested due to poor appetite or bad iron utilization and may engage in the development of such a picture of moderate rather than mild anemia.
As evidently clear in this case, the lack of bacterial cholangitis is the typical setting to form black rather than brown pigment stones [2]. Additionally, a gall bladder hypo-contractility in such an elderly patient could represent a synergistic pathophysiological background for her non-overt hemolysis-related black calculi [20].
