A saline abortion is a second-trimester abortion method in which a concentrated salt solution is injected into the amniotic sac to end a pregnancy. It was once a common approach for terminations between roughly 16 and 24 weeks of gestation, but it has been almost entirely replaced by safer, faster alternatives. CDC surveillance data from 2022 show that intrauterine instillation methods, including saline abortion, account for less than 0.1% of all abortions performed in the United States.
How the Procedure Works
During a saline abortion, a long spinal needle is passed through the abdominal wall and into the amniotic cavity, the fluid-filled space surrounding the fetus. A portion of the amniotic fluid is withdrawn and replaced with 150 to 250 milliliters of a 20% saline (sodium chloride) solution. That highly concentrated salt solution triggers a chain of events inside the uterus that ultimately leads to labor and delivery of the fetus.
The saline causes cells in the uterine lining to die, which releases natural hormones called prostaglandins. These prostaglandins stimulate the uterine muscle to begin contracting. At the same time, the disruption reduces the delivery of progesterone, a hormone that normally keeps the uterus relaxed during pregnancy. With less progesterone and rising prostaglandin levels, contractions become self-sustaining and intensify until the fetus and placenta are expelled.
What the Patient Experiences
After the injection, there is a significant waiting period before labor begins. One large clinical review found the average time from injection to delivery was about 40 hours, with a range of 11 to 98 hours. That means some patients waited four days or longer. During this time, contractions gradually build in intensity, similar to labor contractions. The process typically completes with a spontaneous delivery of the fetus, often without additional medical intervention, though in some cases supplemental medications were given to speed things along.
The experience was physically demanding. Patients went through what amounted to induced labor in the second trimester, with progressive cramping, pain, and eventually the passage of the fetus and placental tissue. Hospital stays of one to several days were common given the unpredictable timeline.
Risks and Complications
Saline abortion carried a higher rate of serious complications compared to alternative instillation methods. One large comparative study found that hypertonic saline had roughly twice the rate of serious complications: about 2.2 per 100 procedures, compared to 1.0 per 100 for the combination of urea and prostaglandin that eventually replaced it.
The most dangerous complication was acute hypernatremia, a sudden and severe rise in sodium levels in the bloodstream. This occurred when the concentrated saline solution entered the maternal circulation too quickly. One documented case involved a 15-year-old patient at 18 weeks of pregnancy who developed cerebral edema (brain swelling), pulmonary edema (fluid in the lungs), and kidney failure after the hypertonic saline reached her bloodstream. She ultimately recovered with intensive supportive care, but the case illustrated why clinicians grew cautious about the method.
Other recognized risks included infection, retained placental tissue requiring further intervention, heavy bleeding, and disseminated intravascular coagulation, a condition in which the blood’s clotting system becomes dangerously disrupted.
Why It Was Replaced
By the 1980s, evidence was mounting that alternatives were both safer and faster. A direct comparison between hypertonic saline and a urea-prostaglandin combination showed the newer method cut the average time from injection to completion nearly in half: 14.2 hours versus 25.6 hours. The complication rate was also significantly lower. Researchers concluded that urea-prostaglandin was the superior option, and medical practice shifted accordingly.
Today, second-trimester abortions are performed almost exclusively using one of two approaches. Surgical dilation and evacuation (D&E) accounts for the large majority, with about 6.9% of all U.S. abortions in 2022 being surgical procedures after 13 weeks. Medication-based protocols using modern prostaglandin drugs handle most of the remainder. These methods are faster, more predictable, and carry fewer serious risks than saline instillation ever did.
Recovery After Second-Trimester Abortion
While saline-specific recovery data is limited given how rare the procedure is today, recovery from any second-trimester abortion follows a general pattern. Bleeding can last up to a week continuously, or come and go for up to four weeks. Small blood clots are normal. Cramping typically persists for a few days, and some people experience a temporary episode of heavier bleeding and cramps around four to six days afterward.
Pregnancy-related nausea and fatigue generally resolve within three days. Breast tenderness and firmness, sometimes with fluid leaking, can take seven to ten days to subside fully, with the initial swelling improving after three to four days. A normal menstrual period typically returns within four to seven weeks.
Because saline abortion involved a longer and more physically taxing process than modern methods, recovery could be more uncomfortable, particularly given the extended labor-like experience and the potential for more significant uterine cramping afterward.