Pictorial essay

Rev. Argent. Radiol. 2015;79(2): 86-9486

IntroductionWhen intra-abdominal hemorraghe is suspected, ultraso-nography may be used as the initial method of evaluation, because its widespread availability and capacity for detecting free fluid in the abdomen. Computed tomography (CT) is the modality of choice because its speed and specificity to detect small amounts of intraabdominal blood, allowing identifica-tion of the source and cause of bleeding by identifying the sentinel clot1-3. Magnetic resonance (MR), has a high sensitiv-ity for characterization of blood at its various stages, but its role is been limited by its lower availability and higher cost, also is not useful for unstable patients because its longer time proceding1-3.Causes of abdominal bleeding are diverse and are summa-rized in table 1.The aim of this article is to review the various causes and im-aging findings of spontaneous abdominal bleeding that may help to establish a correct diagnosis and to provide guidance on the proper treatment.

Topic review

Signs of spontaneous abdominal bleedingOn unenhanced CT, bleeding has an attenuation of 35-45

Hounsfield units (HU) in the hyperacute stage and of over 60 HU in the acute stage (then decreasing over time). Clots tend to form near the site of bleeding, allowing the identification of the site of the hemorrhage (scentinel clot) surrounded by areas of lower attenuation. (fig. 1).

Spontaneous abdominal hemorrhage: imaging evaluation G. Espil, N. Larrañaga, N. Díaz Villarroel, A. Oyarzun, G. Matzke* and S. Kozima

Hospital General de Agudos Dr. Cosme Argerich, Ciudad Autónoma de Buenos Aires, Argentina

AbstractSpontaneous abdominal hemorrhage is defined as intra-abdominal hemorrhage from a non-traumatic cause. The clini-cal presentation of this condition is nonspecific, therefore the diagnosis is usually made on the basis of imaging findings. Imaging serves three basic purposes: detecting the presence of intra-abdominal hemorraghe, locating the source of bleeding and determining the presence or absence of active arterial extravasation.The causes of non traumatic intra-abdominal hemorraghe are diverse and can be classified according to the organ of origin in hepatic, splenic, pancreatic, adrenal, renal, gynecologic and obstetric, vascular, and soft tissue-related (perito-neal and muscular).© 2013 Sociedad Argentina de Radiología. Published by Elsevier Spain, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Keywords: Hemorrhage; Spontaneous; Clot; Sentinel.

Figure 1 Sentinel clot. Unenhanced CT in a 56-year-old pa-tient with cirrhosis and spontaneous rupture of hepatocellu-lar carcinoma: sentinel clot sign (arrowhead) and perihepatic free blood (arrow).

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On contrast-enhanced CT, the site of active bleeding may be occasionally depicted an area or foci of high attenuation, of 85 and 300 HU, suggestive of active hemorrhage. This find-ing may be indicative of the need for emergency emboliza-tion or surgery 1-3(fig. 2).Ultrasonography may be used as the initial method of evalua-tion for detecting intraabdominal fluid. Its may be hypoechoic or appear as a heterogeneous collection, with multiple hyperechoic areas surrounding solid organs or bowel loops. This finding play an important role, in making the diagnosis of spontaneous ab-dominal bleeding secondary to gynecologic causes.MRI is highly sensitive for detecting blood content at various stages, but it plays a limited role in the emergency setting.

Hepatic causes

Spontaneous hepatic hemorrhage is an uncommon disorder

Figure 2 Active bleeding. Thirty-eight year-old patient with coagulation abnormalities and spontaneous mesenteric bleed-ing: after contrast administration, the presence of a small area of hyperdense vessels suggests active bleeding (arrow).

Table 1: Causes of spontaneous abdominal hemorrhage according to the organ of origin.

Origin Causes

*Hepatic - Adenoma - Hepatocellular carcinoma (HCC) Others: metastasis, hemangioma or angiosarcoma - HELLP Syndrome

*Splenic - Infectious spontaneous rupture: cytomegalovirus and mononucleosis - Lymphoproliferative spontaneous rupture: lymphoma and leukemia - Rupture of focal tumors

* Renal - Angiomyolipoma - Renal cell carcinoma - Spontaneous bleeding (coagulopathy and vasculitis)

*Adrenal - Spontaneous bleeding - Tumors

*Pancreatic - Necrohemorrhagic pancreatitis - Rupture of peripancreatic pseudoaneurysm *Gynecologic - Rupture of hemorrhagic cyst - Rupture of endometrioma

*Obstetric - Rupture of ectopic pregnancy - HELLP Syndrome

*Vascular - Rupture of arterial aneurysm - Dissection - Wall hematomas - Vascular erosion by tumor, inflammation, vasculitis or cysts.

*Soft tissues -Hematoma in the psoas -Hematoma in the rectus sheath - Mesenteric hematoma

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due to the rupture of a tumor or, less frequently to the HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count). Adenoma and hepatocellular carcinoma (HCC) have the highest incidence of spontaneous rupture. Adenoma usually occurs in women receiving oral contraceptives, and its complication should be suspected in the presence of hemorrhagic tumor and subcap-sular hematoma, or blood in the peritoneal cavity (fig. 3)4.Rupture of the HCC occurs in cirrhotic patients, mainly in exophytic or peripherally located tumors (fig. 4) with discon-tinuity of the hepatic surface, presence of blood in the sub-capsular region or peritoneal cavity5. Rarely, a hemangioma

may rupture after hepatic trauma5. Bleeding has also been reported in association with hypervascular metastases and angiosarcomas.The HELLP syndrome is a serious variant of preeclampsia that may be associated with necrosis and hepatic infarctions, as well as with intrahepatic or subcapsular hematomas6 (fig. 5).

Splenic causes

Spontaneous splenic rupture may occur in association with severe or massive splenomegaly due to hematologic malig-nancies (such as lymphoma or acute leukemia) and infectious causes (like mononucleosis and infection by cytomegalovirus [CMV])7 CT shows an enlarged spleen with perisplenic blood and the sentinel clot sign within the spleen (fig. 6).Less frequently, some splenic tumors (mestastases, heman-gioma and angiosarcoma) may be complicated by bleeding. In these cases, imaging scans show a focal lesion associated with intratumoral and perisplenic blood (fig. 7).

Renal causes

Renal tumors, such as renal cell carcinomas (RCC) and an-giomyolipoma (AML) may complicate and cause spontaneous bleeding into the subcapsular and perinephric space. Diagno-sis of complicated AML is based on the identification of gross fat in the tumoral lesion (fig. 8). RCC appears as a solid hy-pervascular lesion with blood content (fig. 9) and rarefaction of adjacent fat. If the tumor is too small, it may remain occult within the hematoma and be overlooked (for this reason, it is important to monitor progress of the lesion).

Figure 3 Complication of hepatic adenoma with bleeding in a 35-year-old woman with acute abdominal pain and a de-crease in hematocrit levels.

Figure 4 Spontaneous rupture of hepatocellular carcinoma in a patient with chronic liver disease. (a) Contrast-enhanced CT and (b) T2-weighted MRI. Note the peripheral location of the tumor and the free blood content towards the peritoneum (arrows).

a b

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Figure 5 HELLP syndrome in a pregnant 27-year old woman with abdominal pain and a decrease in hematocrit levles. (a) Unen-hanced CT shows a large acute hepatic subcapsular hematoma. (b) CT slices at the level of the pelvis show a pregnant uterus.

a b

Figure 6 Spontaneous splenic rupture in a patient with acute lymphoblastic leukemia and splenomegaly. (a) Unenhanced CT shows the sentinel clot sign (arrow), while (b and c) intravenous contrast-enhanced CT shows a hypodense intrasplenic lesion, hemoperitoneum and a small focus of active bleeding (arrow in b).

a c

b

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Figure 7 Spontaneous rupture of splenic hemangioma in a 54-year-old woman with acute abdominal pain. (a and b) Intravenous contrast-enhanced CT shows a hypervascular nodular lesion in the upper region of the spleen (arrow in a) and a large perisplenic hematoma (arrow in b).

a b

Figure 8 Sponatenous rupture of renal angiomyolipom in a 40-year-old female patient with tuberous sclerosis. Contrast-enhanced CT shows bilateral angiomyolipomas with the sen-tinel clot sign (arrow) and a site of active bleeding (arrow-head) in the right kidney.

Figure 9 Renal cell carcinoma with sarcomatoid transformation in a 39-year-old woman who presents with pain of 3 days dura-tion and a decrease in hematocrit levels. (a) Unenhanced CT scan shows a large left renal mass with internal bleeding and (b) T1-weighted MRI in the same patient shows the blood content of the tumor at different stages.

a b

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Less frequently, subcapsular or perinephric hematomas oc-cur in association with coagulopathy or vasculitis (fig. 10), as such as Wegener’s disease or polyarteritis nodosa, and they may cause acute blood hypertension by parenchymal com-pression (known as Page kidney)8,9.

Adrenal causes

Spontaneous adrenal hematomas may occur in association with anticoagulation therapy, sepsis, severe stress and hema-tologic or idiopathic disease. CT shows enlarged hyperdense adrenal gland with no changes in density after intravenous administration of contrast material (fig. 11). Some tumors, such as metastases, adrenal carcinoma and lymphoma (fig. 12) may occasionally bleed10.

Pancreatic causes

Pancreatic necrosis occurs in 20% of acute pancreatitis and it is associated with hemorrhagic changes affecting the pan-creatic parenchyma and neighboring tissues. The bleeding is usually small in volume and self-limited, but marked hemor-rhage can occur (fig. 13).Formation of a peripancreatic pseudoaneurysm in the splenic or gastroduodenal artery may occur in 10% of cases. Rupture and bleeding can occur into the peritoneum, adjacent hollow organs, or pancreatic duct (hemosuccus pancreaticus)11.

Gynecologic and obstetric causes

Rupture of a hemorrhagic cyst or rupture of an ectopic preg-nancy are the most common causes of spontaneous abdominal bleeding in women of childbearing age. These conditions may have similar clinical and imaging features, but the key differen-tiating finding is the increased beta-human chorionic gonado-tropin (hCG) in ectopic pregnancy. On ultrasonography, they appear as complex adnexal cystic mass or images with dense content and free fluid in the pelvis extending to the rest of the abdomen (fig. 14). CT may confirm the existence of adnexal blood content and free fluid (fig.15). Diagnosis of complicated ectopic pregnancy may be definitively established upon visual-ization of adnexal ring on ultrasound or by the presence of a ring-enhancing mass on contrast-enhanced CT12,13.Very rarely endometriomas or other cysts may be complicated by intracavitary bleeding. In addition, another cause of spon-taneous abdominal bleeding is the HELLP syndrome (previ-ously described).

Figure 10 Spontaneous subcapsuar perinephric hematoma on unenhanced CT in a patient with Wegener’s disease who pres-ents with pain and acute onset hypertension (Page kidney).

Figure 11 Right adrenal hematoma in a 67-year-old man on anticoagulation therapy who developed abdominal pain and suspected ruptured aortic aneurysm. (a) Enlargement and in-creased density of right adrenal gland. (b and c) Unenhanced and contrast-enhanced measurement of HU shows no en-hancement: this finding is suggestive of hematoma.

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a b

Figure 12 Bilateral adrenal hematoma in a patient with Burkitt lymphoma who developed acute abdominal pain. (a) Unen-hanced CT shows an enlargement of both adrenal glands with internal density (suggestive of hemorrhage). (b) T2-weighted STIR MRI differentiates a liquid area and a solid area in both glands. (c and d). Unenhanced and gadolinium-enhanced T1-weighted images identify posterior hemorrhagic areas, with no enhancement and at different stages of blood (arrows), and an anterior solid area that enhances with contrast (arrowheads).

c d

Figure 13 Necro hemorrhagic pancreatitis in a 35-year-old male patient. Unenhanced CT shows large hematoma in the region of the head and neck of pancreas.

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Vascular causes

Arterial bleeding may be due to rupture of an abnormally dilated vessel or a vessel of normal size with weakened walls. These causes include aneurysm, pseudoaneurysm, arterial dissection, wall hematomas or erosion of a vessel by an adja-cent mass, inflammatory disorders, vasculitis or cysts.The most common cause of vascular bleeding is a ruptured ab-dominal aortic aneurysm, followed by ruptured aneurysms of iliac, splenic and hepatic arteries. CT shows active bleeding, ret-roperitoneal hematoma and loss of wall continuity (fig. 16)14-19.

Soft tissues

Hematoma of the iliopsoas muscle or the rectus sheath may be found in association with coagulopathy, vasculitis or un-known etiology14. CT shows an enlargement and increased density of the muscle (figs. 17 and 18).Hematoma of the rectus sheath may extend extraperitoneally towards the pelvis below the linea alba and be misdiagnosed as pelvic masses (fig. 18); while a spontaneous mesenteric he-matoma may be misdiagnosed as adenomegaly or tumor mass, hence the importance of follow-up of the lesion (fig. 19).

Figure 14 Acute rupture of ectopic pregnancy in a 25-year-old woman with signs of shock and increased levels of the beta sub-unit of human chorionic gonadotropin in blood. Ultrasonography (a) in axial view of the uterus and (b) longitudinal view of the kidney shows a hyperechogenic right complex adnexal mass and particulate fluid in the pelvis and Morrison’s pouch.

a b

Figure 15 Complication of an adnexal cyst in a 25-year-old woman with acute sudden-onset pain. (a and b) Unenhanced and contrast-enhanced CT shows blood content in the pelvis and adenexal cysts (one of them, on the left side, with blood-fluid level). Surgery confirmed complicated endometriotic cyst.

a b

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Figure 16 Ruptured abdominal aorta aneurysm. Contrast-en-hanced CT shows typical signs: discontinuity of the aortic wall (arrow), contrast extravasation (arrowhead) and retroperito-neal hematoma (asterisk).

Figure 17 Hematoma of the rectus sheath in a patient on anticoagulation therapy. (a) Unenhanced CT shows hematoma with a hematocrit effect in the rectus sheath on the left side, extending contralaterally and extraperitoneally towards the right pelvis below the linea alba. (b) Ultrasonography of the same patient showing a complex fluid mass on the right pelvis that was initially misdiagnosed as adnexal blastoma.

a b

Figure 18 Hematoma of the right psoas in a patient with abnormal coagulation factors. Unenhanced CT shows en-largement of the right psoas muscle with a hematocrit effect (cellular-fluid level).

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Conclusion

Diagnosis of spontaneous abdominal bleeding is mainly based on radiologic findings. For this reason, the imaging specialist should be able to recognize its signs and be aware of the various causes that may originate such bleeding.

Conflicts of interestThe authors declare no conflicts of interest, except for Dr. Kozima who declares a possible conflict of interest as mem-ber of the Executive Committee of SAR.

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Figure 19 Mesenteric hematoma in a 45-year-old patient with renal transplant, and acute abdomen. CT without in-travenous contrast shows a hemorrhagic foci at the center of the abdominal mesentery with rarefaction of neighboring fat. Follow-up CT scans showed complete resolution of the lesion.