Peritoneal blood tends to collect near the source of bleeding initially, and then spills into dependent portions of the peritoneal cavity. Ultrasound evaluation of these dependent recesses, listed in Table 26–2, can reveal the presence of hemoperitoneum.
TABLE 26–2Recesses of the Abdominal Cavity |Favorite Table|Download (.pdf) TABLE 26–2Recesses of the Abdominal Cavity
|Recess ||Location ||Comments |
|Morison’s pouch ||Hepatorenal recess ||Most dependent recess of upper abdomen and most common site of blood collection seen on CT scan |
|Perihepatic space ||Right subphrenic || |
|Perisplenic space ||Left subphrenic || |
|Paracolic gutters ||Lateral to ascending and descending colon ||Blood frequently tracks down root of mesentery to right paracolic gutter |
|Pelvis || ||Adjacent to urinary bladder |
FAST examination of the abdomen typically includes three intra-abdominal views: (1) Morison’s pouch, (2) the perisplenic space, and (3) the pelvis, as well as a transverse subxiphoid cardiac view. Blood and fluid appear as a black space between two organs (Figures 26–1, 26–2, and 26–3).
Positive FAST examination in the right upper quadrant view. Free fluid (FF) is seen as a dark stripe in the hepatorenal recess, consistent with hemoperitoneum.
Positive FAST examination in the right upper quadrant view, with free fluid (FF) in Morison’s pouch.
Ultrasound of grade III splenic laceration, with free fluid (FF) and a parenchymal hematoma (H).
The appearance of blood in the peritoneal cavity by CT depends on the site of bleeding, duration of extravasation, and whether it is clotted or lysed. Immediately after hemorrhage, blood has the same attenuation as intravascular blood. Free blood (Figure 26–4) has Hounsfield units (HU) of 30 to 45, whereas clotted blood (Figure 26–5) has HU of 50 to 100, depending on density of clot.5 Clotted blood in the peritoneal cavity will begin to lyse rapidly, and attenuation will decrease within several days. Failure of this change to occur may indicate ongoing hemorrhage. Active arterial hemorrhage is indicated by focal or diffuse high-attenuation of areas of extravasated blood (HU 80–370) and can even be isodense with the abdominal aorta (Figures 26–6 and 26–7).
CT scan depicting recent retroperitoneal hemorrhage (arrows).
Pelvic hematoma (arrow). Note the low attenuation, comparable in density to the adjacent bladder (B). The rim enhancement of this collection is also indicative of a more chronic, organized process.
High-grade splenic injury with active extravasation of contrast (arrow), indicative of ongoing bleeding. Note that the contrast appears bright white, the same attenuation as the aorta (A).
High-grade liver injury. Note the active extravasation (solid arrow), as well as copious free intraperitoneal blood (dashed arrow).
Other CT signs seen with intraperitoneal hemorrhage are presented in Table 26–3 (Figures 26–8 and 26–9).
TABLE 26–3CT Scan Findings of Intra-abdominal Hemorrhage |Favorite Table|Download (.pdf) TABLE 26–3CT Scan Findings of Intra-abdominal Hemorrhage
|CT Sign ||Description ||Comments |
|Hematocrit effect ||Layering of serous fluid on dependent clot ||Indicates fresh blood within a hematoma (Figure 26–8) |
|Sentinel clot ||Localized collection of high-attenuation clotted blood ||Sensitive sign of visceral injury, useful for more subtle injuries |
|Contrast “blush” ||Focal jet of extravasated contrast ||Indicates active, vigorous arterial hemorrhage (Figures 26–6 and 26–7) |
|Pseudoaneurysm ||Well-circumscribed, large vascular enhancement within parenchyma ||Hematoma contained within parenchyma |
|Signs of hypovolemia ||Flattened aorta or inferior vena cava, or abnormal intensity of contrast enhancement of bowel or kidney ||Signs of hypovolemia may support diagnosis of hemorrhage (Figure 26–9) |
Hematocrit effect. Intraperitoneal hematoma, with serous fluid (solid arrow) layering atop higher-attenuation clot (dashed arrow). The patient has an open abdominal wound, and the bilateral stranding of the abdominal wall is anasarca.
(A) Patient in hemorrhagic shock after sustaining a high-grade liver injury. Note the slit-like caliber of the inferior vena cava (red arrow), consistent with profound hypovolemia. (B) Same patient, postoperative weeks later and fully resuscitated. Note the normal, full caliber of the vena cava (red arrow). Organized hematoma can be seen in the right perinephric space (white arrow).
CT scan is 98% sensitive for detecting blunt splenic injury. Injury can be seen as hematomas or lacerations and has been classified by the American Association for the Surgery of Trauma (AAST), 1994 revision,6 as illustrated in Table 26–4.
TABLE 26–4AAST Splenic Injury Grading Scale |Favorite Table|Download (.pdf) TABLE 26–4AAST Splenic Injury Grading Scale
|Grade ||Type ||Injury Description |
|I || |
Subcapsular, <10% surface area
Capsular tear, <1-cm parenchymal depth
|II || |
Subcapsular, 10%–50% surface area
Intraparenchymal, <5-cm diameter
1- to 3-cm parenchymal depth not involving a parenchymal vessel
|III || |
Subcapsular, >50% surface area or expanding
Ruptured subcapsular or parenchymal hematoma
Intraparenchymal hematoma >5 cm or expanding
>3-cm parenchymal depth or involving trabecular vessels
|IV ||Laceration ||Laceration of segmental or hilar vessels producing major devascularization (>25% of spleen) |
|V || |
Completely shattered spleen
Hilar vascular injury with devascularized spleen
Splenic infarcts can be seen following devascularization injuries to the spleen and are seen as wedge-shaped areas of the parenchyma that extend to the capsule. CT findings of ongoing hemorrhage are a contrast “blush,” pseudoaneurysm, or an arteriovenous fistula and generally require intervention, either by angiography and embolization or operative splenorrhaphy or splenectomy. Early intervention increases the likelihood of splenic salvage7 (Figures 26–10, 26–11, 26–12, 26–13, and 26–14).
(A) Axial and (B) coronal CT views depicting grade I splenic injury. Arrows point to small subcapsular hematoma.
(A & B) Examples of grade II splenic injury.
(A–C) Examples of grade III splenic injury. Note that the degree of hematoma can be impressive (B) without classification beyond grade III, given the integrity of the splenic vessels with intact perfusion.
Grade IV splenic laceration, with devitalization of >25% of the parenchyma.
(A & B) Grade V splenic injury, or “shattered spleen.” Note the significant hematoma, devascularization, and in (A), active extravasation.
A liver injury grading scale has been developed by the AAST for CT findings after blunt abdominal trauma. CT findings are similar to injuries seen in splenic trauma and include hematomas, lacerations, and vascular injuries (Table 26–5).
TABLE 26–5AAST Liver Injury Grading Scale |Favorite Table|Download (.pdf) TABLE 26–5AAST Liver Injury Grading Scale
|Grade ||Type ||Injury Description |
|I || |
Subcapsular, <10% surface area
Capsular tear, <1-cm depth
|II || |
Subcapsular, 10%–50% surface area or intraparenchymal <10-cm diameter
Capsular tear, 1- to 3-cm depth, <10-cm length
|III || |
Subcapsular, >50% surface area, or ruptured with active bleeding or intraparenchymal >10-cm diameter
Capsular tear, >3-cm depth
|IV || |
Ruptured intraparenchymal with active bleeding
Parenchymal disruption involving 25%–75% hepatic lobes or 1–3 Couinaud segments (within one lobe)
|V || |
Parenchymal disruption involving >75% hepatic lobe or >3 Couinaud segments (within one lobe)
Juxtahepatic venous injuries (IVC, major hepatic vein)
|VI ||Vascular ||Hepatic avulsion |
The right lobe of the liver, particularly the posterior segment, is the most frequently injured portion because of its volume and position relative to the spine and ribs.8 Connection to the undersurface of the diaphragm by coronary ligaments also contributes to right lobe injury. Left lobe injuries are usually due to direct blows and have a higher association with injuries to the pancreas, duodenum, and transverse colon. Lacerations commonly follow the hepatic or portal venous vasculature and can extend to the capsule, in the so-called “bear claw” pattern. If the capsule is violated, hemoperitoneum can occur. Lacerations that extend between lobes devascularize some segments. Deep lacerations between segments also have an increased likelihood of bile duct injury and associated biloma or hemobilia, though this is rarely detectable on initial CT scan. Bile collections typically have attenuation of 0 HU (Figures 26–15, 26–16, 26–17, and 26–18).
(A) Axial and (B) sagittal views of grade I–II liver injury, with small laceration (A, white arrow) and subcapsular hematoma (B, red arrow).
Grade III liver injury with large subcapsular hematoma and hemoperitoneum.
Grade IV liver injury with active extravasation (solid arrow) and hemoperitoneum (dashed arrow).
Grade V liver injury with obliteration of the right hepatic lobe, active extravasation (solid arrow), and hemoperitoneum (dashed arrow).
Rectus sheath hematomas are uncommon. A grading scale has been developed,9 and predicts need for surgery and provides management advice (Table 26–6 and Figure 26–19).
TABLE 26–6Grading Scale for Rectus Sheath Hematomas |Favorite Table|Download (.pdf) TABLE 26–6Grading Scale for Rectus Sheath Hematomas
|Grade ||Description ||Management |
|1 ||Intramuscular ||Usually none |
|2 ||Blood between rectus and transversalis fascia ||Admit to hospital, transfuse as needed |
|3 ||Intraperitoneal extension ||Admit to hospital, transfuse as needed, may need intravascular embolization or, occasionally operation |
Non-contrast abdominal CT scan, with fullness of the right rectus muscle consistent with hematoma (arrow).
Retroperitoneal hematoma appears on CT as a discrete collection of fluid in the retroperitoneal space that displaces peritoneal structures medially and anteriorly. These hematomas may demonstrate active extravasation. If the hematoma ruptures, there may be significant stranding and free fluid indicative of hemoperitoneum (Figure 26–20).
Hematoma of the left iliacus muscle (arrow) in the setting of anticoagulation. Note the displacement of the pelvic neurovascular structures. This patient required operative decompression for femoral nerve deficits. Her symptoms resolved postoperatively.