Rofo
DOI: 10.1055/a-2594-7579
Abdomen

Enteral Contrast Administration in Abdominal Computed Tomography: Status Quo in Germany

Article in several languages: English | deutsch
Jan-Christoph Stadelmann
1   Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany (Ringgold ID: RIN9177)
,
Lars Grenacher
2   Imaging and Prevention Center, Conradia Radiology Munich, Munich, Germany
,
Markus S Juchems
3   Diagnostic and Interventional Radiology, Hospital Konstanz, Konstanz, Germany
,
Till Kaireit
1   Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany (Ringgold ID: RIN9177)
,
Guido Kukuk
4   Department of Radiology, Hospital Graubünden, Chur, Switzerland
,
Thomas Lauenstein
5   Department of Radiology, Hospital Düsseldorf, Düsseldorf, Germany
,
Andreas G. Schreyer
6   Institute for Diagnostic and Interventional Radiology, Brandenburg Medical School Theodor Fontane, Brandenburg a.d. Havel, Germany (Ringgold ID: RIN477107)
,
Johannes Wessling
7   Department of Radiology, Clemenshospital Münster, Münster, Germany
,
1   Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany (Ringgold ID: RIN9177)
› Author Affiliations
 

Abstract

Purpose

In an online survey conducted by the Gastrointestinal and Abdominal Imaging Working Group of the German Radiological Society (DRG), the current state regarding enteral contrast administration in computed tomography (CT) of the abdomen in Germany was established and critically evaluated. The results of the survey are intended to serve as a basis for expert recommendations on enteral contrast administration in abdominal CT.

Materials and methods

DRG members were invited to take part in the online survey by email, newsletter, and via the DRG online portal. The survey was available for 70 days. It comprised 61 questions on enteral contrast administration in various clinical scenarios, with an average operation approximately 10 to 15 minutes. The results were analyzed using descriptive statistical methods.

Results

1,001 radiologists completed the survey. Of the participants, 67% worked in a hospital and 33% in private practice or a medical care center. Furthermore, 52% of the participants were senior physicians or board-certified radiologists. Enteral contrast administration is being performed selectively for various indications, but with considerable differences in technique and regularity. A lack of substantial diagnostic gain, as well as time-related or organizational factors, were the main reasons cited against enteral contrast administration.

Conclusion

The results of the survey demonstrate a heterogeneous, selective, and indication-specific implementation of enteral contrast administration. There are considerable differences regarding technical implementation and realization. There is a strong desire for generally applicable recommendations along with their integration in respective SOPs.

Key Points

  • Enteral contrast administration in abdominal CT is being performed very heterogeneously.

  • Guidelines lack specifications regarding enteral contrast administration.

  • There is a strong desire for recommendations and their implementation in relevant SOPs.

Citation Format

  • Stadelmann J, Grenacher L, Juchems MS et al. Enteral Contrast Administration in Abdominal Computed Tomography: Status Quo in Germany. Rofo 2025; DOI 10.1055/a-2594-7579


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Introduction

Computed tomography (CT) of the abdomen is an established diagnostic procedure, and it covers a very wide range of indications. It is often the imaging modality of choice in both acute and elective diagnostics. Historically, abdominal CT scans were almost always performed after additional administration of enteral contrast media (CM) to improve the diagnostic value of the examination [1]. Thanks to technical developments alongside improvements in image quality in recent decades, the indications for enteral contrast have changed and are now obsolete (and partly even counterproductive) for many clinical questions [2] [3].

In Germany, medical care guidelines (particularly guidelines from the Association of Scientific Medical Societies (AWMF)) provide the basis for efficient and indication-appropriate diagnostics and therapy for specific clinical diseases or questions. These guidelines are intended to support decision-making in clinical practice and ensure that current evidence-based medical standards are observed [4]. However, technical details regarding the specific implementation of imaging diagnostics are rarely included (neither in national nor international recommendations). This also includes the possible additional application of enteral CM, which is only addressed in exceptional cases, e.g. in corresponding AWMF guidelines [5].

In everyday clinical practice, the lack of clear recommendations for or against enteral CM application in abdominal CT scans regularly leads to uncertainty on the part of referring colleagues as well as radiologists. Lengthy discussions are often the result. In addition, scientific studies on this topic are frequently outdated and the underlying evidence is somewhat limited [6]. Doing something “because we’ve always done it this way” or “because the referring colleague wants it” is neither keeping up with the times nor should it be the focus of patient-oriented diagnostics.

Through its online survey, the Gastrointestinal and Abdominal Diagnostics Working Group of the German Radiological Society (DRG) aims to capture the existing status quo of clinical practice regarding enteral contrast in abdominal CT scans in German-speaking countries, to identify possible gaps in implementing guidelines, and to derive future recommendation needs. In the process, the results of this survey combined with an extensive literature review are intended to provide the basis for expert recommendations on enteral contrast administration for a variety of clinical questions, which will be published in a subsequent position paper. The following article provides the results of the online survey and critically analyzes them according to subtopic. Existing guideline recommendations, if available, are appended to the survey results and compared accordingly in the discussion section.


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Materials and Methods

In preparation for the online survey, the board of the Gastrointestinal and Abdominal Diagnostics Working Group identified technical aspects and clinically relevant indications for abdominal CT, with particular emphasis placed on preparatory enteral contrast. Based on this information, we created a questionnaire using the Surveymonkey web tool (www.surveymonkey.com) [7]. The DRG made this online questionnaire available to all its members via email, newsletter, and the DRG INTERNET portal. The survey was posted online on February 2, 2024, and was available for 70 days until April 12, 2024. The anonymized survey was divided into eight sections for respondents to provide information about their clinical background and their use of enteral contrast agent in abdominal CT, in general, as well as for specific clinical questions. The survey contained a total of 61 questions, consisting of 51 single-choice questions, 9 multiple-choice questions, and a final open question for comments and remarks. Estimated completion time was approximately 10 to 15 minutes. The full questionnaire is provided in Supplementary Tab. 1.

For the evaluation, we used the implemented Surveymonkey tools. Additional statistical analysis using descriptive methods was performed using Excel (Excel: mac 2023, version 16.78, Microsoft, WA, USA) and Prism 7.0 (GraphPad Software Inc., San Diego, USA).


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Results

A total of 1,001 participants completed the survey and were therefore included in the evaluation. Respondents did not have to answer all 61 questions; individual questions could be skipped. In the following results sections, the absolute number of responding participants is therefore given as the defined population.

General background information on the survey participants (1,001 responses)

33.2% (n=333) of the respondents stated that they work as a practicing physician in a medical office or medical care center, while 66.8% (n=668) work primarily as a physician in a hospital ([Fig. 1]). The surveyed number of beds of radiologists working in clinical settings showed that the majority of 74.8% (n=564) work in hospitals with fewer than 1,000 beds, and only 25.2% (n=190) work in hospitals with more than 1,000 beds. The majority of the participating radiologists were not in management positions. Only 13.8% were part-owners or owners of a medical office (n=138), 10.3% were chief physicians (n=103), and 8.7% (n=87) worked in senior physician positions. Specialist physicians were the largest group of respondents, with 27.3% (n=273), followed by senior physicians with 24.8% (n=248), and physicians in training with 15.2% (n=152).

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Fig. 1 Professional environment of all participants. Out of the 1,001 participants, 33.2% worked in a medical office or medical care center, 66.8% in a hospital.

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General aspects of performing enteral contrast in CT (924 responses)

The survey shows that the majority of respondents generally perform enteral contrast during abdominal CT scans. 56.5% (n=522) reported administering enteral CM in less than half of these scans, while 43.5% (n=402) used it in 50 to 100% of cases. In this context, enteral contrast (oral/rectal/combined) is usually performed depending on the exact clinical question (74.8% of participants). Selective, indication-dependent enteral CM administration for specific clinical questions is favored by over 90% (n=859) of participants.

Positive CM in the form of water-soluble iodine compounds is preferred by the majority of respondents for both oral (66.1%) and rectal (80.6%) contrast filling ([Fig. 2]). The reasons given for using an enteral CM in CT scans (multiple selections allowed) were, in particular, a substantial diagnostic gain (69.6%) and pressure from or request by the referring physician (30.6%) ([Fig. 3]). On the other hand, the decision not to use enteral contrast (multiple selections allowed) is justified primarily by a lack of substantial diagnostic gain (73.3%), as well as time (44.8%) and organizational (34.2%) obstacles ([Fig. 3]). Based on additional comments from participants, it can also be deduced that rectal CM application, in particular, is rarely carried out or is unusual in a medical office. Medical office or hospital-internal SOPs for the regulated use of enteral CM are available to 54.6% of the radiologists surveyed. 85.6% of participants feel confident or very confident determining the indication for use of enteral CM.

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Fig. 2 Preferred enteral contrast agents. Positive contrast agents are preferred for oral as well as rectal contrast filling, with water-soluble iodine compounds leading the way.
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Fig. 3 Reasons for (a) or against (b) enteral contrast administration in abdominal CT (multiple answers possible).

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Enteral contrast for specific clinical questions

Primary staging and follow-up of tumors of the upper gastrointestinal tract (875 responses):
The frequency of performing enteral contrast administration in CT scans of the upper gastrointestinal tract for primary staging or follow-up varies considerably among respondents. 33.8% (n=296) stated that they only use enteral CM in a maximum of 25% of scans. In contrast, 50.7% (n=444) applied enteral CM in more than 75% of the scans. In the majority of cases, CM application is purely oral (80.7%; n=706) and less frequently combined oral and rectal administration or purely rectal contrast administration (8.8%). Positive CM in the form of water-soluble iodine compounds is used by 48%, while water is used as a neutral CM by 34.2% of respondents. The same applies to the follow-up of patients with known tumors of the upper gastrointestinal tract ([Table 1]).

Table 1 Enteral contrast application with CT for staging of upper gastrointestinal tract tumors.

Primary staging

Follow-up exam

GIST = gastrointestinal stromal tumor; HCC = hepatocellular carcinoma; CCA = cholangiocarcinoma

Esophageal carcinoma

75.5%

73.8%

Gastric carcinoma

80%

78.4%

GIST

65.8%

64.7%

Pancreatic carcinoma

64.5%

62.4%

Duodenal carcinoma

75.1%

73.4%

HCC, CCA

30.2%

29.1%

Recommendations from national guidelines:
Current AWMF guidelines only contain specifications for the use of enteral CM in individual cases during CT staging scans and follow-up exams of the upper gastrointestinal tract. According to the S3 guideline for the diagnosis and treatment of squamous cell carcinomas and adenocarcinomas of the esophagus, CT should be performed, including oral negative CM, which improves T-staging due to wall distension. The so-called “hydro technique” with 1 to 1.5 liters of water and simultaneous spasmolysis is recommended [8]. A similar recommendation can be found in the S3 guideline on gastric cancer or carcinomas of the esophagogastric junction. In patients with curative therapy, the CT scan for gastric distension should be performed using oral CM or water, and should be combined with intravenous contrast administration. Here, too, the “hydro-technique” should be used. This leads to improved differentiation of local findings in diagnostics, and makes it easier to visualize infiltration or differentiation from neighboring organs [5]. The guidelines for gastrointestinal stromal tumor (GIST), exocrine pancreatic carcinoma, hepatocellular carcinoma (HCC), or cholangiocarcinoma (CCA) do not contain specific recommendations regarding the use of enteral CM [9] [10] [11].

Primary staging and follow-up of tumors of the lower gastrointestinal tract (843 responses):
Almost half (48.1%) of the participants used enteral contrast administration in more than 75% of the CT scans performed for initial staging or follow-up of tumors of the lower gastrointestinal tract ([Table 2]). Enteral contrast is mostly administered only orally (41%), less frequently combined orally and rectally (29.1%), or only rectally (12%). Positive CM, especially water-soluble iodine compounds (60.7%) are preferred, followed by water (16.8%).

Table 2 Enteral contrast application with CT for staging of lower gastrointestinal tract tumors.

Primary staging

Follow-up exam

GIST = gastrointestinal stromal tumor

Carcinoma of the small intestine (excluding duodenum)

59.2%

60%

GIST

55.8%

55.4%

Colon carcinoma

71.2%

68.7%

Rectal carcinoma

71.1%

70.2%

Malignant tumors of non-solid organs

52%

51.3%

Recommendations from national guidelines:
Existing national guidelines on tumors of the lower gastrointestinal tract do not currently contain any specific recommendations regarding enteral CMp administration during abdominal CT.

Non-traumatic acute/unclear abdomen (806 responses):
In the context of CT of the unclear, acute abdomen, enteral CM application is usually very restrictive. The majority of respondents (57.6%) perform these tests only rarely (in less than 25% of scans), with small variations in different suspected clinical diagnoses ([Fig. 4]). If enteral contrast is used, positive CMs with water-soluble iodine compounds are preferred in various clinical scenarios (on average in 72% of cases).

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Fig. 4 Enteral contrast application in abdominal CT for different clinical questions or suspected diagnoses, respectively.

Recommendations from national guidelines:
No generally applicable AWMF guideline exists for diagnostics of the acute, non-traumatic abdomen. The S1 guideline for appendicitis recommends against oral contrast administration, as this would not improve the diagnosis in non-obese patients and children [12]. The guideline on diverticular disease or diverticulitis describes the “status quo” with regard to technical implementation in the background text, noting that most clinics currently perform the examination using intravenous and oral positive contrast with diluted iodine-containing CM. In addition, rectal contrast with water-soluble CM is recommended to better assess the rectum and sigmoid colon. However, this recommendation also includes a note that some recent studies have dispensed with intravenous and oral or rectal contrast media administration, which has produced the same diagnostic results. Nevertheless, the level of evidence from these studies is currently not considered sufficient. As a result, a re-evaluation of the literature is recommended in the years ahead [13].

Traumatic acute abdomen (798 responses):
Enteral CM application during CT imaging of the acute traumatic abdomen is not generally performed (85.1% of participants; [Fig. 4]). However, up to 10.2% of respondents stated that they would carry out or consider supplemental enteral contrast administration in individual cases, mostly orally and with water-soluble iodine compounds (65%).

Recommendations from national guidelines:
The S3 guideline for polytrauma and the treatment of severely injured patients states that a multi-slice spiral CT should generally be performed for diagnostics of intra-abdominal injuries after abdominal trauma. If a practical implementation of oral or rectal contrast would be possible, it could be used to better visualize intestinal injuries. There is no concrete recommendation as to which CM should be used [14].

Chronic inflammatory bowel diseases (788 responses):
As part of the CT for the diagnosis of Crohn’s disease or ulcerative colitis, the majority of respondents regularly perform (i.e. in more than 75% of scans) enteral contrast administration (Crohn’s disease: 57% or ulcerative colitis: 54.8%; [Fig. 4]). Enteral CM application is primarily oral (in 56.4%), and combined oral and rectal is used less frequently (22.1%). Mainly water-soluble iodine compounds (55.2%) are used, and less frequently water (17.6%) and mannitol or methylcellulose (17.9%).

Recommendations from national guidelines:
According to the guideline on Crohn’s disease, MR enterography should be preferred over CT for small bowel diagnostics due to radiation exposure while offering comparable sensitivity. CT enterography can be used in emergency situations, but the form of enteral contrast administration is not specified [15].

Postoperative complication diagnostics (772 responses):
In the CT diagnosis of postoperative complications, two main approaches emerge with regard to supplementary enteral CM administration. 46.4% of participants reported using enteral CM in 50% or fewer of CT scans, while 53.6% used enteral CM in more than half of the corresponding CT scans. Variations in the application method exist, particularly in cases of suspected postoperative fistula or leakage (oral: 63.1%; rectal: 45%; combined oral and rectal: 47.3%; via a GI tube: 46.1%; via a stoma: 45%). 92.3% of respondents primarily use positive CM with water-soluble iodine compounds. Similar results are available when using CT to check postoperative anastomosis. If other clinical issues (e.g. bleeding, ileus, or transit disorder) are in the foreground, most participants do not use additional enteral CM application ([Fig. 4]).

Recommendations from national guidelines:
The guideline literature in Germany is very limited with regard to diagnostics of postoperative complications. In the S3 guideline for the perioperative management of GIST, the treatment of postoperative paralytic ileus recommends against the use of osmotically effective X-ray contrast media such as Gastrografin [16].


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Discussion

The present study by the DRG’s Gastrointestinal and Abdominal Diagnostics Working Group is intended to present the current status of enteral CM application in the context of CT diagnostics of the abdomen in Germany. With a total of 1,001 participants from radiological colleagues in hospitals and medical offices, we consider this survey to be representative. The high level of participation also confirms the strong interest in the topic and its clinical relevance in everyday radiology practice. We therefore wish to thank all of the survey participants.

Overall, it can be summarized that for most colleagues, selective, indication-dependent enteral contrast is the main focus, but on the other hand, there are sometimes considerable differences in the technical implementation and execution. Compared to historical patient cohorts, routine enteral CM application is increasingly being omitted as part of abdominal CT, particularly in acute cases. Exceptions are staging scans and follow-up exams in patients with tumor diseases, who are regularly administered enteral CM, primarily orally in the form of water-soluble iodine compounds or water.

In the diagnosis of tumors of the upper gastrointestinal tract, the survey shows that oral CM administration continues to play an important role. This approach is consistent with current guideline recommendations ([Table 3]) and is comparable with the results of an older survey from 2016 [17]. The somewhat restrictive use of enteral CM in other tumor entities investigated may be due to the lack of clear recommendations in guidelines. The results are correspondingly heterogeneous with regard to the type of enteral contrast administration and the substances used.

Table 3 Current existing guideline recommendations regarding enteral contrast administration with CT in relation to various clinical questions.

Recommendations based on current guidelines

GIST = gastrointestinal stromal tumor

Esophageal carcinoma [8]

CT including oral, negative CM, “hydro-technique” (1–1.5l water) under spasmolysis

Gastric carcinoma [5]

CT including oral CM or water, “hydro-technique” with i.v. contrasting

Appendicitis [12]

CT without oral CM in non-obese children and adults

Diverticulitis, diverticular disease [13]

CT including oral, positive CM (and, if necessary, rectal), water-soluble contrast agent with i.v. contrasting

Abdominal trauma [14]

CT including oral or rectal CM, if practically possible

Crohn’s disease [15]

CT enterography only in exceptional situations

Postoperative paralytic ileus in GIST [16]

Avoid osmotically effective X-ray contrast media

In acute diagnostics of abdominal complaints, enteral CM is generally applied very cautiously. This is certainly also due to the time-critical diagnostics of the often clinically severely impaired patients, in combination with limited diagnostic value added [18]. There is one exception with regard to the diagnosis of diverticulitis, where 60% of respondents perform CT after enteral CM administration, although there are significant differences with regard to the type of application (oral, rectal, or combined). This only partially reflects the current recommendations in the corresponding AWMF guideline, and it is certainly due, in part, to the increasing number of studies demonstrating that enteral CM application can be avoided while maintaining the same diagnostic quality [19] [20].

In the context of diagnostics and follow-up for chronic inflammatory bowel diseases, and in line with current guideline recommendations, CT diagnostics and CT enterography play a subordinate role. In postoperative complication diagnostics, the survey results suggest that there are certain scenarios in which the use of enteral CM appears beneficial. Above all, this includes the diagnosis of leakages, fistulas, or clarification of anastomotic insufficiency. The majority of respondents consistently stated that they prefer positive CM in the form of water-soluble iodine compounds. Even though there are no specific national guideline recommendations in this regard, there are studies that attest to the added value provided by enteral CM administration in the above-mentioned situations [21] [22].

In summary, the survey responses paint a very heterogeneous picture of enteral CM application in virtually all of the questions. This is certainly also due to a lack of recommendations (whether for or against) in relevant guidelines. In addition, there is often a lack of internal departmental or practice-specific SOPs that could serve as guidelines, especially for younger physicians, in their everyday radiology work. Pressure from referring colleagues and also habit still seem to play a role in how examinations are conducted. It would therefore be desirable, as many survey participants stated, to implement cross-departmental recommendations based on evidence or consensus.

In response to this feedback, the results of this survey will serve as a basis for recommendations on enteral contrast administration in abdominal CT. Selective, indication-dependent enteral contrast administration will be the focus, including an algorithm developed as a decision-making tool for use in everyday clinical practice. Alongside a critical evaluation of the evidence available and taking into account (inter)national guideline recommendations, the Gastrointestinal and Abdominal Diagnostics Working Group plans to publish these recommendations soon in a subsequent position paper.


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Conflict of Interest

The authors declare that they have no conflict of interest.

Acknowledgement

Die AG Gastrointestinal- und Abdominaldiagnostik bedankt sich herzlich bei allen Kolleginnen und Kollegen für die sehr rege Teilnahme an dieser Umfrage und die zahlreichen Kommentare.


Correspondence

Medical Doctor Kristina Imeen Ringe
Department of Diagnostic and Interventional Radiology, Hannover Medical School
Carl-Neuberg Strasse 1
30625 Hannover
Germany   

Publication History

Received: 27 February 2025

Accepted after revision: 10 April 2025

Article published online:
21 May 2025

© 2025. Thieme. All rights reserved.

Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany


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Fig. 1 Professional environment of all participants. Out of the 1,001 participants, 33.2% worked in a medical office or medical care center, 66.8% in a hospital.
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Fig. 2 Preferred enteral contrast agents. Positive contrast agents are preferred for oral as well as rectal contrast filling, with water-soluble iodine compounds leading the way.
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Fig. 3 Reasons for (a) or against (b) enteral contrast administration in abdominal CT (multiple answers possible).
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Fig. 4 Enteral contrast application in abdominal CT for different clinical questions or suspected diagnoses, respectively.
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Abb. 1 Radiologisches Umfeld aller an der Umfrage Teilnehmenden. Von den 1001 Teilnehmenden waren 33,2% in der Niederlassung bzw. in einem MZV (Medizinisches Versorgungszentrum) tätig, 66,8% in einem Krankenhaus.
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Abb. 2 Präferierte Substanzen zur enteralen Kontrastierung. Sowohl für die orale als auch rektale Kontrastierung werden positive Kontrastmittel bevorzugt eingesetzt, allen voran wasserlösliche Jodverbindungen.
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Abb. 3 Gründe für (a) bzw. gegen (b) die Applikation enteraler Kontrastmittel im Rahmen von abdominellen CT-Untersuchungen (Mehrfachauswahl möglich).
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Abb. 4 Enterale KM-Applikation im Rahmen der abdominellen CT-Diagnostik bei verschiedenen klinischen Fragestellungen bzw. Verdachtsdiagnosen.