Hemoabdomen & Hemoperitoneum: Abdominal Bleeding in Cats
Dr. Douglas Brum
Hemoperitoneum is a potentially life-threatening situation. The peritoneal or abdominal cavity is potentially a large space that can contain a significant volume of blood. If a large amount of blood is lost into this space, the abdominal musculature is stretched and abdominal distension becomes evident. Abdominal distension may cause discomfort or pain, leading to agitation and stress. Severe hemoperitoneum may cause pressure on the diaphragm, which may impede breathing. Trauma. The most common traumatic injury causing a hemoperitoneum occurs when a car has hit an animal. Severe abdominal trauma may cause a rapid death if the blood loss is profound. Most of the time, bleeding occurs more slowly and there is time to seek veterinary care. The spleen and liver are the internal organs most commonly traumatized, leading to hemoperitoneum. Less commonly, the bladder or kidneys may hemorrhage into the abdomen, but such injury is usually also associated with uroabdomen (urine within the peritoneal cavity). The bleeding that occurs may be mild or severe, but in most cases will stop without intervention. Other causes of trauma include gunshot and knife wounds.
Rapid blood loss into the abdomen may lead to a decrease in blood pressure and tissue perfusion: This can cause shock. As blood continues to be lost, the decrease in circulating red blood cells results in anemia. Pale mucus membranes are often seen. If veterinary care is not immediately available, rapid blood loss may cause death. Slower blood loss is more common, allowing owners more time to seek veterinary attention.
Chronic (long standing) or intermittent blood loss usually occurs more slowly and more subtle clinical signs are present. If the blood loss is slow, the body can reabsorb (auto transfuse) some of the free blood in the abdomen. Thus, animals may only have a small amount of blood in the abdominal cavity at any one time. Such animals may not present as an emergency, but they still have a serious underlying disease process. In these cases, appreciating the existence of hemoperitoneum is critical for proper case management.
If the cat has normal clotting parameters, bleeding into the abdomen will oftentimes stop on its own. Blood clots form that stop the bleeding. Sometimes, cats collapse because of acute blood loss, and then spontaneously recover because of the body's compensatory mechanisms. These animals may appear pale and weak initially but slowly become stronger and their mucus membranes become pinker. Owners may describe intermittent episodes of weakness followed by spontaneous recovery. However, blood clots can become dislodged, especially with increased movement or manipulations. If blood clots are dislodged, the bleeding may start again. In many cases of hemoperitoneum caused by abdominal trauma, bleeding stops on its own.
There are several causes of a hemoperitoneum. Probably the most common cause is trauma. A lacerated blood vessel within the abdomen or on the surface of an internal organ trauma may lead to rapid or slow bleeding, depending on the extent of organ or tissue damage. Outdoor cats are at significantly greater risk of hemoperitoneum than indoor cats. Younger cats are more likely to be traumatized and thus develop hemoperitoneum than older cats.
In young animals with a hemoperitoneum and no history of trauma, coagulopathy (bleeding disorder) should be suspected. In cats with a coagulopathy, bleeding into the peritoneum does not usually stop unless vitamin K or other therapy is initiated.
In older cats with a hemoperitoneum and no history of trauma, a bleeding abdominal tumor is often the cause. Bleeding tumors may cause rapid or chronic intermittent blood loss.
Specific causes of hemoperitoneum include:
Tumors. Tumors of the abdomen may erode a blood vessel or simply rupture, causing an acute bleed. Tumors located in the body wall or associated with abdominal organs may cause bleeding into the abdomen. The most common tumor to cause intra-abdominal bleeding is a hemangiosarcoma (a tumor of blood vessels). These tumors are aggressive and malignant and are commonly found on the spleen or liver. Hemangioma is the benign form, but it is not as commonly seen. Hemangiosarcoma is a very common tumor in dogs, though it is rare in cats. In cats, abdominal tumors usually involve the spleen, mesentery, liver, or gastrointestinal tract.
Hematomas. Hematomas are formed by broken blood vessels that cause blood to accumulate in a tissue or organ. They are a common cause of hemoperitoneum and are often associated with the spleen. Hematomas may be caused by previous trauma or more commonly nodular regeneration (excessive production of splenic tissue). Hematomas may be quite large and are indistinguishable from hemangiosarcomas at surgery.
Coagulopathies. Rodenticide poisoning with products containing anticoagulants is a common cause of bleeding disorders in animals. The bleeding may be exclusively within the abdomen or may involve other sites (e.g. under the skin). Products containing the following active ingredients may cause a hemoperitoneum: warfarin, fumarin, chlorophacinone, diphacinone, pindone, bromadiolone, or brodaficoum.