Ansa pancreatica is a reversed S-shaped pancreatic duct arising from the main pancreatic duct of Wirsung and ending at or near the minor duodenal papilla. Described for the first time in 1961, it is a rare anatomic variant of the pancreatic ducts system and is characterized by the absence of the accessory duct of Santorini. It probably serves as a counter measure after the accessory duct obliteration, in order to maintain sufficient pancreatic juice drainage. The literature concerning ansa pancreatica seems to be rather poor, compared to other anatomic variants and congenital anomalies of the pancreatic ducts. We tried to define the ansa pancreatica incidence among general population and highlight the possible differences between different populations, and to define its possible correlation with pancreatitis. The existing data correlate ansa pancreatica with recurrent acute pancreatitis and pancreatitis in alcoholics. Despite the lack of extended data, ansa pancreatica is a rare anatomic variant, proven to play an important role in certain clinical conditions

Dimitrios, Filippou

Panagiotis, Skandalakis

Sotirios, Kympouris

Firenze University Press: E-Journals

IJAE 
Vo l .  124,  n .  1:  79 - 8 6 ,  2019
© 2019 Firenze University Press 
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ITALIAN JOURNAL OF ANATOMY AND EMBRYOLOGY
DOI: 10.13128/IJAE-25472
* Corresponding author. E-mail: sotiriskympouris@hotmail.com
Review - Basic and Applied Anatomy
Ansa pancreatica. Review of the literature
Kympouris Sotirios*, Filippou Dimitrios, Skandalakis Panagiotis
Department of Anatomy and Surgical Anatomy, Medical School, National and Kapodestrian University of 
Athens, Athens, Greece
Abstract
Ansa pancreatica is a reversed S-shaped pancreatic duct arising from the main pancreatic duct of 
Wirsung and ending at or near the minor duodenal papilla. Described for the first time in 1961, 
it is a rare anatomic variant of the pancreatic ducts system and is characterized by the absence of 
the accessory duct of Santorini. It probably serves as a counter measure after the accessory duct 
obliteration, in order to maintain sufficient pancreatic juice drainage. The literature concerning 
ansa pancreatica seems to be rather poor, compared to other anatomic variants and congenital 
anomalies of the pancreatic ducts. We tried to define the ansa pancreatica incidence among gener-
al population and highlight the possible differences between different populations, and to define 
its possible correlation with pancreatitis. The existing data correlate ansa pancreatica with recur-
rent acute pancreatitis and pancreatitis in alcoholics. Despite the lack of extended data, ansa pan-
creatica is a rare anatomic variant, proven to play an important role in certain clinical conditions.
Key words
Ansa pancreatica, pancreatitis, pancreas, anatomy of pancreas, pancreatic ducts.
Introduction
Various congenital anomalies and anatomic variants of the pancreas and the pan-
creatic duct patterns have been described in the literature (Lehman, 2000; Türkvatan 
et al., 2013). These conditions have been highlighted and studied, especially since 
magnetic resonance cholangiopacreatography (MRCP) and endoscopic retrograde 
cholangiopacreatography (ERCP) play a substantial role in the diagnosis, treatment 
and follow up of pancreaticobiliary diseases.
Developmental malformations and anatomic variants of the pancreas and the pan-
creatic ducts include: variations in the course of the main pancreatic duct (sigmoid, 
descending, loop etc.), variations of the configuration, duplication anomalies, anoma-
lous pancreaticobiliary ductal junction, pancreas divisum (fusion related), annular 
pancreas (migration related), ectopic pancreatic tissue, pancreatic agenesis or hypo-
plasia of the dorsal pancreas or accessory pancreatic lobe (Türkvatan et al., 2013).
Ansa pancreatica (Fig. 1) is a very rare fusion related pancreatic duct variation, in 
which the duct of Santorini forms a reversed S shape and connects with a side branch 
of the duct of Wirsung (Mortele et al., 2006). It was first described by Dawson and 
Langman (1961) in an anatomical and radiological study of cadaveric subjects. This 
condition has been proposed as a potential cause of pancreatitis, especially in alcohol-
ics (Tanaka et al., 1991, 1992).
80 Kympouris Sotirios, Filippou Dimitrios, Skandalakis Panagiotis
The aim of this paper is to review the literature about the prevalence of ansa pan-
creatica and put emphasis on the potential clinical implications of such a rare pancre-
atic duct anatomic variation.
Materials and methods
Pubmed and journals outside Pubmed were searched in the internet using ansa 
pancreatica as a search term. The literature found was rather poor and heterogenous, 
so no exclusion criteria were set, as it was tried to include as much information as 
possible concerning ansa pancreatica. Approximately twenty papers were found on 
the whole.
Results
There are a few anatomic, radiologic and clinical studies in the literature concen-
trating on the pancreatic ductal patterns but only a recent one, to the author’s knowl-
edge, focuses on ansa pancreatica (Hayashi et al., 2016). The studies are based either 
on anatomic-cadaveric examination or MRCP-ERCP reports. In the study of Daw-
son and Langman (1961), where ansa pancreatica was originally described, this duct 
Figure 1. (A) Common pancreatic ductal anatomy with dominant Wirsung duct (black arrow) (B) Ansa pan-
creatica (red duct) arising from and passing in front of the main pancreatic duct
81Ansa pancreatica
variation was found in 17% of the subjects (21/120 cases). It was an anatomic study 
based on fresh specimens, enhanced by the injection of a contrast medium and radio-
graphic imaging. In 66% of the cases with ansa pancreatica, this duct was obliterated 
at its junction with the duodenum, despite a visible minor papilla. 
Using dye injection during ERCP and interpreting dynamic images, Kamisawa et 
al. (1998) reported an incidence of 13.6% in 213 patients with diagnosed or suspected 
pancreaticobiliary disease. The incidence of an impervious minor papilla in these cas-
es was almost 80%, even higher than reported Dawson and Langman (1961). 
These reported high values of incidence of ansa pancreatica are in dispute with 
studies based on MRCP imaging (Table 1.).
In a Turkish population based, retrospective study of 1158 MRCPs of people with 
suspected biliary or pancreatic disease, the ansa pancreatica incidence was found to 
be 1.2% (Adibelli et al., 2016). This study tried to establish the connection between 
pancreatic ducts variations and the modified for MRCP Cambridge classification sys-
tem of chronic pancreatitis (Choueiri et al, 2010). In the results, ansa pancreatica was 
associated with higher score and thus, might be considered a relevant factor to the 
onset of chronic pancreatitis (Adibelli et al., 2016).
Another retrospective, Italian population study based on the interpretation of 300 
dynamic MRCPs (before and after secretin administration) of patients with suspect-
ed or known pancreatic disease, resulted in an incidence of 1% for ansa pancreatica 
(3/300) (Liessi et al., 2010). A cadaveric study of the pancreatic ductal system of 50 
subjects in an Indian population in 2017 revealed a 2% incidence rate of ansa pancre-
atica (Narayanan and Shabna, 2017).
Ansa pancreatica has also been associated, in case reports, with idiopathic acute 
pancreatitis (Bhasin et al., 2006), acute pancreatitis (Jarrar et al., 2013) and pancreatitis 
complicated with walled off pancreatic necrosis (Jagielski et al., 2017). According to 
Ishii et al., (1998) approximately 7% of patients with ansa pancreatica present with at 
least an episode of acute pancreatitis.
Table 1. Studies reporting ansa pancreatica incidence.
Authors/Date Subjects examined
Methods of 
examination Country
Incidence of 
ansa pancre-
atica
Langman and Dawson (1961) 120
Cadaveric and 
radiologic Canada 17%
Kamisawa et al. (1998) 213 ERCP Japan 13.6%
Adibelli et al.(2016) 1158 MRCP Turkey 1.2%
Hayashi et al. (2016) 660 MRCP Japan 1.2%
Narayanan and Shabna C. (2017) 50 Cadaveric India 2%
Liessi et al. (2010) 300
MRCP after 
secretin 
injection
Italy 1%
ERCP: endoscopic retrograde cholangiopacreatography
MRCP: magnetic resonance cholangiopacreatography
82 Kympouris Sotirios, Filippou Dimitrios, Skandalakis Panagiotis
In 2016, the first attempt to determine the non-biased prevalence of ansa pancre-
atica and its correlation with pancreatitis was made, with a retrospective study based 
on a Japanese population (Hayashi et al., 2016). 663 community based subjects and 85 
subjects with episode of acute pancreatitis (of which 18 with recurrent pancreatitis) 
underwent medical examination, blood tests and examination by magnetic resonance 
imaging-MRCP. The accessory pancreatic duct was clearly visualized in 587 case in 
the community group and in 73 cases in the pancreatitis group (not statistically sig-
nificant difference). The ansa pancreatica incidence was 0.85% in community group 
subjects, 1.81% (1/55) in patients with single episode of pancreatitis and 11.1% (2/18) 
in patients with recurrent acute pancreatitis. In this study, a statistically significant 
correlation between ansa pancreatica and the onset of acute recurrent pancreatitis was 
established. Ansa pancreatica was also found to be more prevalent in patients with 
alcoholic pancreatitis, but no exact and significant correlation could be achieved.
Among all the studies found, either based on cadaveric examination, radiograph-
ic evaluation (ERCP-MRCP) or a combination of methods, no statistically significant 
connection was detected between ansa pancreatica and the demographic characteris-
tics of the subjects examined.
Discussion
During fetal life, the two pancreatic buds (ventral and dorsal) along with their 
respective ductal systems, fuse in order to form the adult pancreas. This happens by 
asymmetric rotation of the duodenum and a 180 degree counterclockwise rotation 
of the ventral pancreatic bud. The ventral duct will fuse with the dorsal duct in the 
cephalic portion of the pancreas and give birth to the main pancreatic duct of Wir-
sung that drains at the major duodenal papilla. The majority of the pancreatic juice 
drainage will happen through this duct. The dorsal duct system will form the acces-
sory pancreatic duct of Santorini, which drains into the duodenum through the minor 
papilla (Fig. 2) (Flati and Andrén-Sandberg , 2002).
Kamisawa et al. (1997) reported a 59% of healthy subjects with an impervious 
minor papilla, while Dawson and Langman (1961) reported a very high propor-
tion (80-90%) of patent accessory ducts in fetuses and infants. Taking these data into 
account might lead to the conclusion that minor papilla obliteration happens later in 
adult life.
Ansa pancreatica is an anatomic variant of the pancreatic ductal system, character-
ized by a blocked minor papilla in the majority of cases (Dawson and Langman, 1961; 
Kamisawa et al., 1998), along with obliteration of the accessory duct at the extrem-
ity near its junction with the main pancreatic duct. The accessory duct is replaced by 
a hook shaped duct which serves as a communication between ventral and dorsal 
duct systems. This duct is formed by the proximal part of the dorsal duct, the lower 
branch of the ventral duct and the lower branch of the dorsal duct (Fig. 3). It ends 
at or near the minor papilla. It is merely a hypothesis that this procedure serves as a 
counterweight to the accessory duct or minor papilla obliteration, in order not to dis-
turb pancreatic drainage.
The verification of the actual anatomy of the pancreatic ducts has been made pos-
sible since ERCP has entered everyday medical practice. MRCP serves as an equally 
83Ansa pancreatica
accurate tool (Bret et al., 1996; Bülow et al., 2014), with the advantage of not being 
invasive. However, in MRCP, ansa pancreatica is often depicted as a faint duct, com-
pared to ERCP. This can be probably explained because of the absence of an injected 
radiologic agent that results into higher intraductal pressure (Tamura et al., 2006). 
The magnetic resonance imaging before and after the administration of secretin and 
the design and conduction of retrospective studies might be a good idea in order to 
inspect and perhaps increase MRCP’s sensitivity in detecting pancreatic ductal varia-
tions, such as ansa pancreatica.
The studies found in the literature describing the incidence of ansa pancreatica 
are few and equivocal (Table 1). More and larger studies are needed, even in healthy 
individuals, in order to accurately determine ansa pancreatica incidence. Interestingly, 
no difference was found between men and women, however race might be impor-
tant. A remarkable deviance in results was noticed between studies based on different 
national groups.
Throughout the literature, several case reports and studies have proposed the 
connection between ansa pancreatica and pancreatitis. Only recently, solid statisti-
cally significant evidence has been provided to support this correlation (Hayashi et 
al., 2016). Not only this, but also a relationship between alcohol, ansa pancreatica 
and pancreatitis has been highlighted. This study might be a great motive for new, 
anatomic based studies of alcoholic pancreatitis. It is also a big question, whether all 
individuals with pancreatitis should undergo pancreatic ductal anatomy examination 
Figure 2. Embryologic development of the pancreas and the pancreatic ducts. HB: hepatic bud; GB: gallblad-
der; VPB: ventral pancreatic bud; DPB: dorsal pancreatic bud; CBD: common bile duct.
84 Kympouris Sotirios, Filippou Dimitrios, Skandalakis Panagiotis
with either ERCP or MRCP, as anatomic variants of pancreatic ducts are in the major-
ity of cases asymptomatic and undiagnosed (Lehman, 2000).
It is indisputable that further studies of randomized nature are needed, in order 
to more precisely define the exact risk of pancreaticobiliary disease occurrence, in 
patients with this rare pancreatic duct anatomic variant. Physicians and especially 
surgeons often come across with anatomic variations that either are asymptomatic or 
cause pathology. Ansa pancreatica is a bold example of how aberrant anatomy could 
predispose to certain pathologic conditions. Firm knowledge of common and variant 
anatomy is a formidable tool in the hands of physicians, irrespectively to their spe-
cialty or expertise.
Aknowledgments
The author would like to declare no conflict of interest and also thank Tzigkou-
naki Aikaterini for her valuable help.
Figure 3. (A) Formation of ansa pancreatica, dashed line: obliterated accessory duct, (B) Ansa pancreatica 
formed, red component: lower branch of ventral duct, green component: lower branch of dorsal duct, black 
component: proximal accessory duct, yellow duct: common bile duct
85Ansa pancreatica
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