The peritoneum is the membrane that lines the inside of the major body cavity holding the lower organs like the intestine. An intraperitoneal injection, therefore, is an injection that introduces liquid into the cavity surrounded by the membrane. Although this technique is most commonly used to inject animals like laboratory mice with medications, certain groups of people can also receive this form of injection. Generally these are people with cancer of the peritoneal area, which includes women with ovarian cancer.
A doctor can administer an injection in a variety of ways, but some techniques are more appropriate than others for different conditions. For example, an intramuscular injection, such as one given in the upper arm, is often used for administering vaccine injections. Injections directly into a vein can be useful for administering fluids, and injections under the skin also form a part of a doctor's injecting skills. Generally, however, intraperitoneal injections are not a route often used for administering these types of substances.
Inside the trunk of the human body is the peritoneal cavity. This is a space where various organs float around and are supported and protected by other parts of the trunk. Any medical procedure that involves placing a tool or a substance into this area can be described as intraperitoneal; therefore, an injection into the area is an intraperitoneal injection.
Typically, when a doctor wishes to administer a substance, whether it is a medicine or a vaccine, the aim is to get the substance to the target area as soon as possible, in as efficient a manner as possible. Intravenous injections are the most effective way of delivering a substance into the blood, and consequently around the body, but they can be painful and require some skill. Injections through the skin, or into the muscle, are quick and simple techniques. An intraperitoneal injection, on the other hand, sends the substance into the peritoneal cavity. This, however, is only effective for treating problems in the peritoneal cavity itself.
Cancers of the organs inside the peritoneal cavity may spread to other nearby organs. In addition, the tumors may be inaccessible for chemotherapy drugs administered to other parts of the body such as through the veins. For these reasons, cancer treatment is the major use of an intraperitoneal injection technique. Ovarian cancer is one such cancer that may benefit from this type of drug delivery; other examples include cancers of the liver, pancreas or colon.