Urea (Intravenous)

Urea is a compound that naturally occurs in mammals that, when used synthetically, is administered via injection by a physician intra-amniotically to terminate a pregnancy, causing abortion of a second trimester pregnancy past the 16th week of gestation.


What is Urea?

Urea is also known as carbamide and is an organic compound commonly found in the urine of mammals. It is also found in sweat, milk and blood as well, but urine is the most concentrated form. It is odorless, colorless and non-toxic. Urea is used by the body to excrete nitrogen, a by-product formed by the liver. Urea has uses as a raw material in the chemical industry as well as a source of nitrogen for fertilizer use. Urea is also an ingredient in many dermatological products as it promotes hydration of the skin. As far back as the 1970s, urea has been used for inducing therapeutic abortions.

Urea is injected intra-amniotically in a clinical setting and is proven to terminate pregnancy. This is a medical method to induce abortion, which today is used rarely in comparison to surgical evacuation procedures, which are more effective. Nevertheless, there are situations that require this method and urea is one of the drugs that can be used to facilitate the procedure. Other drugs are hypertonic saline, prostaglandins, mannitol, formalin and others. Urea has less of a risk of issues with coagulopathy (blood clotting ability) and is favored over saline.

Urea is manufactured synthetically as a chemical compound made up of carbon, nitrogen and oxygen. Though it is a naturally occurring substance produced by the body, it is a substance that the body recognizes as waste and therefore wants to get rid of.

How does it work?

Though urea is formed in the body, it is considered by the body to be a waste product and therefore it works to get rid of it. Applying this principle to using urea in an abortion procedure means that the fetus' body and the mother's body will work to expel or get rid of the tissues that have been injected with urea.

This procedure is known as an instillation abortion and is performed by injecting urea through the abdomen and into the amniotic sac. Before the injection is given, the cervix is dilated so that when the solution is injected, the uterine contractions will expel the fetus. The dosage amount is removed from the fluid in the amniotic sac prior to administering the dose of urea. This ensures an adequate concentration of urea so that the procedure is effective, as well as preventing sudden increase of pressure. If the first injection does not take effect, a second injection may be required within 48 hours.

The drug oxytocin is typically administered intravenously shortly after the urea instillation procedure, which shortens the time it takes from induction to abortion, thus reducing the failure rate. Antibiotics are typically prescribed to prevent infection after the procedure to prevent endometritis, an infection of the uterus.

A dilation and curettage procedure may be necessary to remove any remaining tissue. Abortion by instillation procedure has fallen out of favor due to the severe side effects reported.

Conditions treated

  • Pregnancy

Type of medicine

  • Abortifacient

Side Effects

Though urea is naturally occurring in the body, some people may experience an allergic reaction to the drug form. Any allergies that the patient has experienced to different foods, dyes, animals or preservatives should be disclosed to the medical professional prior to the procedure to determine if allergen testing is required.

Injection of urea into the uterus may cause muscle spasm and contractions that could lacerate or perforate the cervix, rupture the uterus and/or lead to hemorrhage. Blood clots may also form, blocking blood flow through the vessels, damaging the body's organs after administration of urea.

Patients may also experience the following side effects:

  • Pain in the lower abdomen
  • Confusion
  • Irregular heartbeat
  • Cramps
  • Numbness
  • Tingling pain
  • Weakness in hands or feet
  • Fatigue
  • Nausea
  • Vomiting
  • Headache
  • Diarrhea
  • Chills
  • Shivering
  • Fever
  • Vaginal discharge
  • Uterine bleeding

After the procedure, there may still be some side effects that require the attention of medical professionals. Follow up with your healthcare provider and keep a diary of any symptoms including frequency and how severe they are.

Developing a condition known as endometritis, which exhibits symptoms such as chills, fever, vaginal discharge and lower abdominal pain, is of particular concern to those patients who have undergone an instillation abortion procedure. Particular attention should be paid to patients experiencing these symptoms as they will need immediate treatment with antibiotics. If left untreated, this condition could cause major complications, including infertility and other health issues.

No specific data exists that compares age groups and any side-effects experienced during instillation abortion via intra-uterine injection of urea.


Patients differ and so will the dosing requirements, which will ultimately be determined by your healthcare professional. In adults and teenagers, up to 250 milliliters is typically injected through the abdomen into the uterus. Prior to this, the same amount of fluid is removed from the amniotic sac in order to ensure the effectiveness of the concentration of urea and to avoid a sudden increase in pressure. If the first dose is not effective, the injection may be repeated 48 hours later, if required.


Inform your doctor if you have any allergies prior to receiving urea. This includes allergies to other drugs, foods, dyes, animals and so on.

Specific drugs that have known interaction with urea include:

  • Arsenic Trioxide
  • Droperidol
  • Levomethadyl

Food interactions

Certain foods should be avoided when receiving treatment of certain drugs. In the case of urea, there is a reaction to licorice and, for this reason, this food should be avoided in any form.

Other interactions

Medical issues such as those listed below should be disclosed to your doctor:

It is recommended that patients undergoing instillation abortion procedures via urea injection prevent dehydration by taking fluids orally. Intravenous fluids may be administered during the procedure as well.


This procedure has fallen out of favor due to the association it has with serious adverse health effects. The effectiveness of the procedure is in the 30 to 40 percentile range, leaving it on the low side of effectiveness. There are also the following risks:

  • Accidental injection of urea into the mother's bloodstream
  • Possible uterine damage
  • Infection
  • Hemorrhage
  • Pain from excessive contractions
  • Rupture due to previous uterine scars

There is also a risk of depression after a terminated pregnancy. Counseling by a licensed mental health professional or grief counselor should be sought out by those going through this procedure. Symptoms of depression include more than two week of:

  • Fatigue
  • Sleep deprivation
  • Loss of appetite
  • Feeling of sadness, emptiness or anxiety

Between 1 and 2 percent of patients that had the urea instillation technique must be hospitalized for endometritis, which is an infection that occurs in the lining of the uterus. If left untreated, this infection can lead to damaged reproductive organs, fertility issues and other problems that are associated with health in general. Symptoms include:

  • Swelling of the abdomen
  • Vaginal bleeding or discharge
  • Constipation
  • Discomfort during bowel movements
  • Fever
  • Nausea
  • Pain in the lower abdominal, pelvis or rectal area


Storage temperature as specified by the manufacturer should be between 59 and 86 degrees Fahrenheit (15 and 30 degrees Celsius) in an area that is protected from light exposure.


Intra-amniotic urea, when injected into the uterus, causes abortion in late trimester pregnancies. This method uses the properties found in the drug urea to terminate the pregnancy by causing spontaneous abortion due to evacuation of a terminated fetus. Other drugs are used in combination to remove any remaining tissues and assist in expulsion. With this method, the procedure may require up to 48 hours to complete.

Side effects including blood clots, ruptured uterus, pelvic infection, heavy bleeding and infertility have been reported in women who have had this procedure. The abortion procedure itself has a high risk of causing depression, so counseling by a trained professional is highly recommended.

Complications can also arise in patients who have pre-existing conditions such as diabetes, uterine fibroids, kidney or liver disease or sickle cell anemia. All medical conditions and medical treatments should be discussed with your doctor prior to undergoing this or any other medical procedure.

Patients undergoing this procedure should report any nausea, vomiting, diarrhea, headaches, bleeding, cramping or unusual fatigue and weakness to their doctor immediately.

Doses vary, but an injection of 250 milliliters is recommended via injection into the uterus in adults and teenagers. The drug is administered only in a clinical setting by a trained medical professional. Storage of the drug is under manufacturer's direction in a room temperature setting without exposure to heat, light or moisture.

Last Reviewed:
December 22, 2017
Last Updated:
April 23, 2018
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