Traumatic Injury
Trauma can be either blunt force or sharp penetrating trauma. Common mechanisms include high speed road traffic accidents, falls from height and assault. Both blunt and penetrating trauma types can cause solid organ, bowel and mesenteric injuries. In high energy trauma, a whole body (head/neck/chest/abdo/pelvis) trauma series CT with two phases of contrast enhancement is usually done. Injuries to the liver, kidneys and spleen are associated with rib injuries. There may be a laceration with associated haematoma, with extension to involve the vessels at the hilum of the organ. There may also be active bleeding which would require emergent surgery or interventional radiology input to embolise the bleeding vessel.
Appearance: Disruption in continuity of the organ cortex, associated soft tissue injury, haematoma, contrast extravasation indicating active bleeding.
Gas in Peritoneum
Causes of gas/air within intra- or retroperitoneal spaces:
- Perforation – of hollow viscus (usually duodenum or sigmoid)
- Recent laparoscopic surgery – from CO2 insufflation
Appearance: Free air within the peritoneum. Location of the air depends on the segment of perforated bowel i.e. intra- or retro-peritoneal. Air can extend into other spaces e.g. pneumomediastinum. Perforation of the rectum – air in mesorectum (mesentery surrounding rectum).
Gas in Bladder
Causes of gas within the urinary bladder:
- Catheterisation – recent or current
- Fistula – between bladder and bowel
A fistula would allow infecting organisms to easily colonise the bladder leading to frequent UTIs and pyelonephritis.
Appearance: Gas within the bladder, forming an air-fluid level with the urine inside the bladder.
Abdominal Aortic Aneurysm
Focal dilatation of the abdominal aorta. Two-thirds of patients with ruptured AAAs die before reaching hospital. Of those who make it to emergency surgery, half die. Ultrasound used for diagnosis and screening. CT used for suspected leak, but this must not delay emergency surgery.
Screening for AAA is offered to all men when they turn 65. It is a quick ultrasound scan to measure the abdominal aorta, done in the community.
- If the test is negative (< 3 cm), there will be no further recall scans, unlike other screening programmes
- If the test is positive (> 3 cm), further action depends on the diameter of the aneurysm: 3.0 – 4.4 cm = repeat in 1 year; 4.5 – 5.4 cm = repeat in 3 months; > 5.5 cm = immediate referral to vascular surgeons to consider elective repair
Appearance: Aneurysm wall usually calcified. If ruptured, free blood (higher density than fluid e.g. in stomach/GB) with possible contrast leak. Mural thrombus common, seen as circumferential low density area.
Gynaecology
The preferred modality for initial diagnosis of a suspected gynaecological pathology is ultrasound (transabdominal or transvaginal).
Uterine fibroids can be very large and cause pain if they degenerate. Endometriosis may present as ovarian masses, partially cystic, or as deposits anywhere within the abdominal cavity.
Gynaecologic malignancies are staged with MRI & CT. Ovarian cancer tends to present late, frequently with spread to the peritoneum and omentum by diagnosis.
A ‘Krukenberg tumour’ refers to a metastatic deposit in the ovary which originated from a primary elsewhere within the peritoneal cavity.
Appearance: Uterine fibroids can calcify and are seen as rounded masses with calcific rims. MRI can show the blood within endometriotic deposits on ovaries and the rectovaginal space.
Peritoneal and Omental Disease
Soft tissue nodularity and thickening of the omentum and peritoneum can be seen in either metastatic disease (usually from gastric, pancreatic, colonic or ovarian carcinomas) or from infections such as tuberculosis. There may also be nodularity on the serosal surface of the bowel, and in metastatic disease in particular, the bowel may become encased in widespread malignant tissue. Ultrasound or CT guidance can be used to biopsy the omentum to identify the primary source.
Appearance: Nodular thickening of omentum deep to abdominal wall (“cake”) and peritoneal nodularity. Necrotic lymph nodes are a feature of TB.
Ascites
Ascites is seen in chronic liver disease, heart failure and abdominopelvic malignancies. It presents as abdominal distension.
It can be seen easily on ultrasound and CT.
Ultrasound guided paracentesis/drainage can be carried out. A sample of ascitic fluid can be obtained for laboratory testing.
Appearance: Depending on the quantity, it is usually seen as fluid around the liver and spleen, surrounding the bowel, and in the pelvic cavity. It travels to dependent locations, i.e. the left and right paracolic gutters (folds of peritoneum) posteriorly.
