What Is Rectus Sheath Hematoma

Introduction

A Rectus Sheath Hematoma (RSH) is a bleeding that fills a connective tissue space in the abdomen called the ‘rectus sheath’. A ‘hematoma’ is a bleed or clot forming within the body’.² It is often very easy to treat, needing very little intervention by the doctors, but it can cause serious complications if left without medical supervision. It is important to understand the causes and treatment methods but first we will explore the anatomy of the rectus sheath and how a hematoma may form within it.¹

Anatomy of the rectus sheath

The rectus sheath is formed by a series of connective tissue that connect to the different abdominal muscles. There are 4 major muscles that make up the abdomen. These are the rectus abdominis, external oblique, internal oblique and transverse abdominal. The rectus abdominis are the first muscles more commonly known as ‘abs’. Flanking the sides is the external oblique and deeper to that is the internal oblique. These muscles are connected across both sides by a type of connective tissue known as an ‘aponeurosis’. The layer of connective tissue connecting the external oblique muscles lies above the rectus abdominis. The layer of connective tissue connecting the internal oblique splits into two where one goes above and another goes below the rectus abdominis. The transverse abdominis connective tissue lays below the rectus abdominis and is the final layer. All of these layers together form the rectus sheath. The rectus sheath’s function is to provide protection for the muscles and blood vessels that it encloses. This allows the muscles and vessels to be well supported and contract with maximal strength without damaging organs behind the rectus sheath.³ 

Causes of rectus sheath hematoma

The main causes of a rectus sheath hematoma are due to bleeding from two main arteries. These are the superior epigastric artery and the inferior epigastric artery, which sit above and below the abdomen. Damage to these arteries can cause blood to collect within the rectus sheath. Most often this damage can come from trauma to the abdominal area but it may also become damaged from forceful contraction of the abdominal muscles. 

One of the biggest risk factors for rectus sheath hematoma is being on anticoagulant medication. In over 70% of cases, the individual is found to be using anticoagulant drugs for other conditions. These drugs increase the risk of bleeding and so if the artery is damaged it can lead to greater bleeding than compared to someone not on these drugs. Rectus Sheath Hematoma is more common in women. This is because women have less abdominal muscle mass so they are at greater risk of damage to arteries. It has also been found that chronic kidney disease is related to an increased risk of rectus sheath hematoma along with many other things such as:⁴ 

• Immunosuppression
• Abdominal wall injections
• Steroid therapies
• Antiplatelet therapy
• Severe cough

Symptoms of rectus sheath hematoma⁵

• Abdominal pain
• Abdominal wall mass
• Nausea
• Vomiting
• Tender abdomen
• Fever
• Abdominal distension
• Abdominal cramping

Diagnosis of rectus sheath hematoma

First a physical examination is performed to determine if the individual has something called ‘Carnett’s sign’. The doctor tells the individual to lie down flat on a bed so that they can feel the tenderness in the abdomen. They will then instruct the individual to sit halfway upright and feel for the tenderness again in the same place. If there is greater pain in the same area it shows that the blood remains in the same place and it is most likely within the rectus sheath. 

In order to confirm a diagnosis the best option is to have a CT scan of the abdomen as well as blood testing. This allows the doctors to determine the size of the hematoma and the volume of blood that has been collected within the rectus sheath. ‘Ultrasonography’ may also be used but it is not preferred as a CT scan is much more specific.⁶

Treatment options

In most cases doctors will use ‘Conservative management’. This means that they will do little to interfere with a rectus sheath hematoma and let it resolve on its own. In the majority of cases the rectus sheath hematoma, due to being self-restricted, is able to drain by itself and symptoms will improve typically within a week. 

If there is no improvement with conservative management then certain surgical options are explored. The most common method used is known as ‘microcoil embolisation’.⁸ This method involves inserting an ‘embolisation coil’ into the affected blood vessel. This coil triggers the formation of a blood clot in the blood vessel by slowing blood flow and stimulating certain clotting factors in the blood. The bleeding will stop and any blood within the rectus sheath will then be able to drain by itself. The microcoil method is usually the most successful however it is a difficult, time-consuming and expensive procedure. If the microcoil does not work then direct surgical intervention is done where the blood is drained directly from the rectus sheath to reduce pressure and relieve pain. There is a risk, however, that surgery can increase the bleeding. This is because as the blood is drained the pressure within the rectus sheath decreases which may lead to more blood leaking out of the blood vessel if it has not been properly sealed. Fortunately the risk of this occurring is very low and the chance of needing surgery in the first place is very low as well therefore the outlook on recovery is generally very positive.⁷ 

Complications

If a rectus sheath hematoma remains untreated the main complication is pain in the abdomen and damage from serious bleeding. There is also the risk that it may become infected which can pose a serious health risk and will require much more intensive treatment. Therefore it is important to visit a health professional and follow guidance and treatment.  As we mentioned before, surgery may lead to increased bleeding which will need further surgical correction.  After treatment, there is a small risk that it may reoccur in the future but the chance of this happening can be reduced with suitable management.⁹ 

Recovery and prognosis

In general there is a positive outlook for individuals with rectus sheath hematoma as there is usually very minimal intervention. It may pose a greater risk in elderly and pregnant individuals but quick diagnosis and treatment can greatly reduce the time needed for recovery and any risks of negative complications. 

After treatment, the individual will need to have a follow-up appointment to assess recovery. The doctor will also inform the patient about how to adjust physical activities to prevent any bleeds from occurring again. A physiotherapist may also recommend certain low-intensity conditioning exercises to strengthen the abdominal muscles which can prevent further bleeding in the future. It is important to avoid heavy exercise as this can do more harm than good. If the individual was taking any blood thinning medication before the rectus sheath hematoma then the doctor would advise stopping these medications for some time and reviewing the situation in the future before resuming them when it is safe. 

Summary

Rectus Sheath Hematoma is the collection of blood within the rectus sheath after damage to blood vessels in the abdomen causing pain and swelling of the abdomen. It can happen due to trauma or strong contraction of muscles leading to rupture of the blood vessels. Diagnosis involves a physical examination followed by a CT scan to see the location, size and volume of the hematoma and how serious the bleeding is. Treatment is conservative and often resolves on its own but surgical options are available if there is no improvement. Recovery can take a few weeks and there is a small risk of complications such as recurrence and infection. If you are experiencing any of the symptoms mentioned then seek advice from a healthcare professional.