A rectus sheath hematoma is an accumulation of blood in the sheath of the rectus abdominis muscle

Rectus abdominis muscle

The rectus abdominis muscle, also known as the "six pack", is a paired muscle running vertically on each side of the anterior wall of the human abdomen . There are two parallel muscles, separated by a midline band of connective tissue called the linea alba...

. It causes abdominal pain

Abdominal pain

Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...

 with or without a mass.

The hematoma

Hematoma

A hematoma, or haematoma, is a localized collection of blood outside the blood vessels, usually in liquid form within the tissue. This distinguishes it from an ecchymosis, which is the spread of blood under the skin in a thin layer, commonly called a bruise...

 may be caused by either rupture of one of the epigastric arteries

Epigastric arteries

Epigastric arteries can refer to:* Superficial epigastric artery* Superior epigastric artery* Inferior epigastric artery...

 or by a muscular tear. Causes of this include anticoagulation, coughing, pregnancy

Pregnancy

Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

, abdominal surgery

Abdominal surgery

The term abdominal surgery broadly covers surgical procedures that involve opening the abdomen. Surgery of each abdominal organ is dealt with separately in connection with the description of that organ Diseases affecting the abdominal cavity are dealt with generally under their own names The term...

 and trauma

Physical trauma

Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...

. With the advent of an ageing population and the widespread use of anticoagulant medications, there is evidence that this traditionally benign condition is becoming more common and more serious .

On abdominal examination

Abdominal examination

The abdominal exam, in medicine, is performed as part of a physical examination, or when a patient presents with abdominal pain or a history that suggests an abdominal pathology.The exam includes several parts:* Setting and preparation...

, these patients may have a positive Carnett's sign

Carnett's sign

In medicine, Carnett's sign is an eponymous finding on clinical examination in which abdominal pain remains unchanged or increases when the muscles of the abdominal wall are tensed. For this part of the abdominal examination, the patient can be asked to lift the head and shoulders from the...

.

Most hematomas resolve without treatment, but they may take several months to resolve.