Plain Abdominal Radiograph In patients presenting with acute abdominal pain ,plain film remain one of the most valuable initial investigations. The main purpose of the plain radiograph is to : establish a diagnosis Decide : whether or not a patient with acute abdominal pain needs an operation Should be performed immediately or whether time can be spent resuscitating or performing other investigations to confirm the diagnosis .
INTERPRETATION OF THE PFA There are some basic rules regarding interpretation of the PFA Name It is always important to ensure that the correct radiograph for the correct patient is being viewed. Sex Some pathological processes may be commoner in either one of the sexes. Obviously the genitourinary tracts also differ. Age Old or young? Different pathological processes may vary between those of different ages.
Date of investigation Many radiographs may be present in the patients ‘X-ray bag’ and it is important that the appropriate radiograph is being viewed. Previous radiographs are helpful for comparison. Marker The right or left side should be labeled on the plain abdominal film. Position A supine AP (anteroposterior) film is usually obtained. suspected bowel obstruction an erect abdominal film can be helpful Occasionally LT lateral decubitus views may be performed to show intraperitoneal free air. Having completed these steps, it is now possible to systematically interpret the abdominal film.
1 Gas in caecum 2 Gas in descending colon 3 Gas in stomach 4 Gastric rugal folds 5 Twelfth rib 6 Right kidney 7 L2 vertebra 8 Liver 9 Transverse process of L1 10 Right psoas muscle 11 Left psoas muscle 12 Head of femur 13 Pubic symphysis 14 Right sacro-iliac joint
The formation of a radiographic image depends on the structure & size of the organs within the abdomen.
Gas which absorbs least X-rays appears black or dark grey.
Fat is usually seen as dark grey lines.
Soft tissues appear very light grey with large soft tissue masses appearing almost white.
Calcification which absorbs most X-rays appears white.
Main purpose of horizontal beam is to detect air fluid levels & free intraperitoneal gas. Relatively large amounts of gas normally present in the stomach & colon; only a small amount is usually seen in the SI. Short air fluid levels in the SI & LI are normal. Abnormal AFL when they are numerous/ bowel is dilated
May be present Absent Solid faeces 50 mm+ 30-50 mm. Diameter of loop Large Small Radius of curvature of loops Peripheral Central Distribution of loops Few Many Number of loops Absent Present in jejunum Vavulae connventes Present Absent Haustra Large bowel Small bowel