MORISON'S SPACE: LOCATION, ANATOMY, FUNCTIONS - ANATOMY AND PHYSIOLOGY - 2025

The space Morison is an intra - abdominal area that is bounded by the liver on top and the right kidney at the bottom. Due to its location it is also known as the subhepatic space or hepatorenal recess.

It is called Morison's space because it was described by the eminent English surgeon James Rutherford Morison (1853-1939). It is said that it is a virtual space since under normal conditions it has no content and is collapsed by the layers of intra-abdominal tissue. The amount of fluid normally found in the peritoneum is 50 mL.

Public Domain, However, in the case of abdominal trauma, it is one of the first sites where abdominal fluids are deposited and that is when it becomes important. Its evaluation is essential when a rupture of the stomach, esophagus, or organs neighboring the liver, such as the gallbladder, is suspected.

Rutherford Morison. By Unknown -, CC BY 4.0, Any of these contents in the Morison space represents a reason for the patient to undergo emergency surgery.

Anatomy

The abdominal cavity is covered by a membrane of connective tissue called the peritoneum. This covers or supports the intra-abdominal organs. The areas that form between two organs covered by peritoneum are called peritoneal recesses. They are folds that create bag-shaped spaces, that is, they are open on one side and closed on the other side.

Throughout the abdominal cavity there are several spaces formed by the peritoneum, and Morison's is one of the most important.

Location

Morison's space is located within the abdominal cavity. Specifically, it is the area that is located below the right hepatic lobe and above the right kidney.

This space, under normal conditions, is collapsed. That is, there is no space as such. It has no fluid or organ content.

Features

The peritoneal spaces have no other function than to separate two organs. In healthy people, abdominal examinations, such as an ecosonogram or computerized axial tomography, cannot distinguish these spaces.

In the case of Morison's space, it is used to identify lesions in the intra-abdominal organs. For example: if the abdominal ecosonogram shows fluid under the liver, which is the area that corresponds to Morison's space, it can be assured that there is some injury that is causing the accumulation of fluid in that space.

Therefore, when the space becomes visible on an imaging test, it helps diagnose conditions that cause fluid to accumulate within the abdomen.

By I, Drahreg01, CC BY-SA 3.0, Amounts as small as 40 mL of fluid can be seen in Morison's space on abdominal computed tomography (CT).

Once the presence of fluid is diagnosed and its origin is evidenced, the therapeutic modality is decided. The patient may have a conservative treatment for some conditions, but must be taken to the operating room for others of more urgent resolution.

Related diseases

The conditions associated with Morison's space are those that allow the accumulation of fluid within the abdominal cavity.

There are different diseases and injuries that manage to accumulate enough fluid in the abdomen causing it to fill up, as well as other peritoneal spaces.

Ascites

The accumulation of fluid within the abdominal cavity is known as ascites. The most common cause is cirrhosis of the liver, but it can also occur from malignant diseases such as ovarian cancer.

When there is enough fluid within the abdomen, the peritoneal spaces begin to fill. Through a computerized axial tomography (CT) scan of the abdomen, the fluid-filled space of Morison becomes visible.

When a significant amount of fluid accumulates, starting at 1.5 liters, the pressure begins to become very uncomfortable for patients, so a decompression procedure called paracentesis is performed.

Paracentesis is an invasive procedure in which a needle is inserted into one of the declining areas of the trunk. It can be done guided by an ecosonogram and, in this case, aspiration of the space where the liquid can be seen more clearly will be carried out.

Decompression helps improve the patient's symptoms, but the root cause of the problem must be treated to prevent the abdomen from filling up with fluid again.

Blunt abdominal trauma

Blunt abdominal trauma occurs when there is a serious injury to the abdomen from a blunt blow.

This type of condition represents a challenge in the diagnosis since many organs can be injured and even be bleeding inside the abdomen, without the doctor being able to know it with the naked eye. Undetected internal bleeding is the leading cause of preventable death in trauma patients.

The physical examination may provide some clues, but it is ultimately the radiological evaluations that offer the final diagnosis.

Morison's space is the first peritoneal space that is reviewed through the focused ecosonogram in the abdomen in case of trauma or FAST echo, for its acronym in English.

When liquid content is found in Morison's space, an echo-guided puncture is performed to assess the nature of the content. It can be blood, bile, or gastric contents. In any case, this is a criterion for the patient to be taken to emergency surgery.

Intra-abdominal abscess

An abdominal abscess is an accumulation of contaminated fluid within a membrane, located in an intra-abdominal area or organ.

Subhepatic or adrenal abscesses usually fill Morison's space and can be seen on plain radiography studies such as a standing plain abdominal radiograph.

Diagnosis is made according to the patient's medical history, laboratory findings, and evidence from radiological procedures, mainly computerized axial tomography (CT).

Once the diagnosis of intra-abdominal abscess is reached, treatment can be performed by placing a catheter from the abscess cavity to the outside to drain it, without the need for surgery.

If the abscess is very large or the patient is very symptomatic, a surgical drainage is performed with abdominal surgery.

In both procedures, the administration of intravenous antibiotics should be indicated to complete the patient's treatment.

References

1. Kalra A, Tuma F. Anatomy, Abdomen and Pelvis, Peritoneum. (2018). Taken from: ncbi.nlm.nih.gov
2. Rubenstein, WA; Uh, YH; Zirinsky, K; Kneeland, JB; Whalen, JP; Kazam E. (1985) Posterior peritoneal recesses: assessment using CT. Radiology. Taken from: ncbi.nlm.nih.gov
3. Bloom BA, Gibbons RC. Focused Assessment with Sonography for Trauma (FAST). (2019). Taken from: ncbi.nlm.nih.gov
4. Closed abdominal trauma. (1966). Closed abdominal trauma. British medical journal. Taken from: ncbi.nlm.nih.gov
5. Chiejina, M; Samant, H. Ascites. (2018) Taken from: ncbi.nlm.nih.gov