Intended for healthcare professionals

Student Practical skills

Interpreting abdominal radiographs

BMJ 2012; 345 doi: https://doi.org/10.1136/sbmj.e5375 (Published 13 September 2012) Cite this as: BMJ 2012;345:e5375
  1. Jen-Jou Wong, specialist registrar1,
  2. Latifa Patel, foundation year 1 doctor2,
  3. John Curtis, consultant3
  1. 1Royal Liverpool University Hospital, Merseycare NHS Trust, UK
  2. 2Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, UK
  3. 3Department of Radiology, Aintree University Hospital, Liverpool, UK

Understanding the large variations in normal anatomy will lead to more confident interpretation

The abdominal radiograph can be difficult to interpret, and it is often given less teaching time than its more popular sibling, the chest radiograph. This is despite its being the third most commonly requested radiological investigation, after chest and extremity radiographs. Competence in the interpretation of abdominal films is needed, given their ubiquity in surgical specialties and the need for doctors to request and interpret these films while on call or in the emergency department.

Normal abdominal radiographs

Abdominal radiographs can display a wide variety of normal presentations, so familiarity with these is important (fig 1). It is also important to compare the radiograph with previous films, if they are available, to note any progression or detection of pathology.

Fig 1 Normal anatomy. A—hemidiaphragms/lung bases; B—vertebrae; C—liver; D—iliac crests; E—bladder; F—sacroiliac joint; G—head of femur; H—acetabulum; I—superior pubic ramus; J—normal bowel gas. Other structures that may be seen include the outline of the kidneys, psoas muscles, and spleen; these are not obvious on this radiograph.

Technical features of the abdominal plain film

Sex

Important anatomical variations between males and females—that is, sexual organs—can give rise to sex specific pathologies. A wider pelvic girdle is also specific to female anatomy.

Field of view

The film should encompass the lung bases and the hemidiaphragms superiorly and up to just below the pubic and the inguinal canals inferiorly. Depending on the size of the patient and the cassette being used, a radiograph with an adequate field of view can be spread over two images.

Penetration

Cases of extreme underpenetration or overpenetration might lead to difficulty diagnosing free air in the abdominal cavity. A well penetrated film will also increase the chances of identifying abdominal cavity structures, which rely on subtle differences in soft tissue density (the internal organs are often surrounded by fat), as …

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