The expulsion of stomach contents after death is a real event, though it is often misunderstood and can be unsettling for those who witness it. While the sight of fluid or semi-digested material leaving the mouth or nose may resemble the action of the living, the underlying causes are entirely different. This phenomenon is a passive consequence of changes that occur within the body after all biological systems have ceased functioning.
Not True Vomiting: Postmortem Purging
The expulsion of material from the stomach after death is more accurately described as postmortem purging, which is distinct from true vomiting. Vomiting in a living person is an active, reflexive process requiring coordinated muscular contractions and neurological signaling from the brain, which are impossible after death. The act of vomiting involves forceful and synchronized movements of the diaphragm, abdominal muscles, and the stomach itself.
In contrast, postmortem purging is a passive process that occurs without any coordinated muscular effort. The contents of the stomach are simply forced out through the path of least resistance. This expulsion is often a mixture of stomach acids, partially digested food, and fluids, sometimes appearing dark or brown due to the breakdown of blood. The lack of the body’s active defense mechanisms allows internal pressures to overcome the relaxed muscles that normally keep the contents contained.
Internal Pressure from Decomposition Gases
The primary driving force behind postmortem purging is the dramatic increase in internal pressure caused by the biological process of decomposition. Once circulation stops, the immune system is no longer active, allowing the vast population of anaerobic bacteria naturally residing in the gastrointestinal tract to proliferate. These microbes begin to consume the body’s tissues, a process called putrefaction.
This microbial activity ferments the organic matter, generating large volumes of gaseous byproducts, including hydrogen sulfide, methane, and carbon dioxide. As these gases accumulate in the intestines and stomach, the abdomen begins to swell significantly in a stage of decomposition known as “bloat.” This buildup of gas creates pressure within the abdominal cavity.
The diaphragm, a large muscle separating the chest cavity from the abdomen, is pushed upward by this rising pressure. This upward force compresses the stomach and the lungs. When the pressure becomes too great, it physically squeezes the contents of the stomach toward the esophagus. The expulsion is the result of this mechanical force pushing material up and out of the body through the mouth and nose.
The Role of Muscle Relaxation and Gravity
While internal pressure provides the necessary force, the relaxation of certain muscles facilitates the expulsion of contents. Immediately after death, all muscles, including those that control the openings of the digestive tract, undergo a state of primary flaccidity, a temporary and complete relaxation. This relaxation includes the lower esophageal sphincter, the ring of muscle that normally acts as a one-way valve to keep stomach contents from moving back up into the esophagus.
The loss of muscle tone in this sphincter eliminates the barrier that would prevent regurgitation in a living person. With the sphincter relaxed and internal pressure high, the stomach contents easily pass into the esophagus and pharynx.
This process is further influenced by the position of the body and gravity. If the body is lying on its back or is moved during transport, gravity can assist the passive flow of fluids. Any change in the body’s position can shift the pressure dynamics inside the abdomen, potentially triggering the escape of stomach contents.