Vacuum Aspiration: Clinical Procedure, History, and Methodology
Vacuum or suction aspiration is a gynaecological procedure that uses a vacuum source to remove an embryo or fetus through the cervix. It is generally safe, and serious complications rarely occur. It is now known to be one of the safest obstetric procedures, and has saved countless women's lives. Vacuum aspiration is the surgical procedure used for almost all first-trimester abortions in many countries, if medication abortion is not a viable option.
Clinical Uses and Indications
The procedure is performed to induce abortion, as a treatment for incomplete spontaneous abortion (otherwise commonly known as miscarriage) or retained fetal and placental tissue, or to obtain a sample of uterine lining (endometrial biopsy). It is also used to terminate molar pregnancy. Some sources may use the terms dilation and evacuation or "suction" dilation and curettage to refer to vacuum aspiration, although those terms are normally used to refer to distinctly different procedures.
When used as a spontaneous abortion management or as a therapeutic abortion method, vacuum aspiration may be used alone or with cervical dilation anytime in the first trimester (up to 12 weeks gestational age). For more advanced pregnancies, vacuum aspiration may be used as one step in a dilation and evacuation procedure. Additionally, the procedure can also aid in regulation of the menstrual cycle and to obtain a sample for endometrial biopsy. A study found use of Karman vacuum aspiration to be a safer option for endometrial biopsy when compared to the alternatives such as conventional endometrial curettage.
Historical Development
Vacuuming as a means of removing the uterine contents, rather than the previous use of a hard metal curette, was pioneered in 1958 by Drs Wu Yuantai and Wu Xianzhen in China. Dorothea Kerslake introduced the method into the United Kingdom in 1967 and published a study in the United States that further spread the technique. In Canada, the method was pioneered and improved on by Henry Morgentaler, achieving a complication rate of 0.48% and no deaths in over 5,000 cases. He was the first doctor in North America to use the technique, which he then trained other doctors to use.
Harvey Karman in the United States refined the technique in the early 1970s with the development of the Karman cannula, a soft, flexible cannula that avoided the need for initial cervical dilatation and so reduced the risks of puncturing the uterus.
The Procedure and Methodology
Vacuum aspiration is an outpatient procedure that generally involves a clinic visit of several hours. The procedure itself typically takes less than 15 minutes. There are two options for the source of suction in the use of these procedures:
- Electric vacuum aspiration (EVA): Suction is created with an electric pump.
- Manual vacuum aspiration (MVA): Suction is created with a manual pump, such as a hand-held 25cc or 50cc syringe.
Both of these methods can create the same level of suction, and therefore are considered equivalent in terms of efficacy of treatment and safety. The difference in use primarily comes down to provider preference.
Step-by-Step Clinical Process
The clinician places a speculum into the vagina in order to visualize the cervix. The cervix is cleansed, then a local anesthetic (usually lidocaine) is injected in the form of a para-cervical block or intra-cervical injection into the cervix. The clinician may use instruments called "dilators" in incrementally larger sizes to gently open the cervix, or medically induce cervical dilation with drugs or osmotic dilators administered before the procedure. Finally, a sterile cannula is inserted into the uterus.
Global Usage Statistics
The following data represents the combined usage of MVA and EVA in various countries for relevant gestations (typically 3-13+6 weeks):
- Sweden (2005): 42.7%
- United Kingdom (England & Wales, 2006): 64%
- United States (2016): 59.9%