By Rebecca H. Allen, MD, MPH
Associate Professor, Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Providence, RI
Dr. Allen reports she is a Nexplanon trainer for Merck.
In this retrospective cohort study, manual vacuum aspiration in a hospital setting was equivalent to electric suction for uterine evacuation of molar pregnancy in terms of the risks of incomplete abortion and development of postmolar gestational trophoblastic disease.
Padron L, Rezende Filho J, Amim Junior J, et al. Manual compared with electric vacuum aspiration for treatment of molar pregnancy. Obstet Gynecol 2018;131:652-659.
Padron et al conducted this retrospective cohort study from January 2007 to December 2016 in Brazil to evaluate manual compared to electric vacuum aspiration for the treatment of molar pregnancy. Molar pregnancy (partial or complete) was confirmed on histology postoperatively. Standard preoperative evaluation at the study sites included complete metabolic profile, complete blood count, chest X-ray, and serum quantitative hCG, as well as pelvic ultrasound. All procedures were performed in an operating room setting and two units of packed red blood cells were reserved preoperatively for all subjects. Choice of vacuum source depended on the study site, as electric suction machines were not always available. All subjects received sharp curettage and total intravenous anesthesia. Oxytocin was not given routinely intraoperatively, but 10 units were administered intravenously in the recovery room over six hours as part of hospital protocol. All patients were observed for at least 24 hours and followed with serial hCG levels. Remission was defined as three consecutive weekly hCG values less than assay, followed by monthly hCG for six months in case of spontaneous remission and 12 months after completion of chemotherapy in cases of gestational trophoblastic neoplasia (GTN). Primary study outcomes were incomplete abortion (defined by clinical, hormonal, and ultrasound evaluation), uterine perforation, development of Asherman’s syndrome (amenorrhea plus intrauterine synechia on hysteroscopy), and development of postmolar GTN.
A total of 1,727 women were included in the study with 1,206 undergoing electric vacuum aspiration (EVA) and 521 manual vacuum aspiration (MVA). There were no differences between the two groups in terms of age, parity, and gestational age at diagnosis. Approximately 80% in each group had complete molar pregnancies while 20% had partial molar pregnancies. Half of each group had ultrasound guidance during the procedure, which was determined by physician discretion or uterine size greater than dates (51.5% EVA vs. 49.8% MVA, P = 0.174), and almost 60% received oxytocin intraoperatively (58% EVA vs. 55.7% MVA, P = 0.187). Approximately 13% of subjects had an incomplete abortion in each group (P = 0.949). Operative times were shorter for the EVA group (25.3 vs. 34.2 minutes; P < 0.001), but there was a slightly higher rate of uterine perforation (0.7% vs. 0.0%; P = 0.051). There was no statistically significant difference between the two groups in the development of postmolar GTN (14.2% EVA vs. 17.3% MVA; P = 0.074) or blood transfusion (6.3% EVA vs. 8.6% MVA; P = 0.714). There was a higher risk of Asherman’s syndrome in the EVA group compared to the MVA group (5.2% vs. 1.3%; P < 0.001).
COMMENTARY
The treatment of molar pregnancy is uterine evacuation with a suction dilation and curettage (D&C).1 In the United States, electric suction has been used because that is standard practice in American hospitals. Furthermore, for molar pregnancies that are diagnosed preoperatively, most OB/GYNs perform the procedure in a hospital operating room because of the risk of bleeding so they have access to a blood bank, intensive care unit, and anesthesia services. The manual vacuum aspirator was invented in the 1970s and currently is used worldwide to perform uterine evacuation whether for incomplete, spontaneous, or induced abortion.2 Often, it is used in the United States for uterine evacuation in office settings in which an electric suction machine is not available. Padron et al undertook this study to determine the safety of MVA in the treatment of molar pregnancy. They reported that one of the study sites (Antonio Pedro University Hospital of Fluminense Federal University) did not have an electric suction machine, allowing them to perform a natural experiment.
The findings of this study are reassuring in that there were no differences between MVA and EVA in terms of incomplete abortion, blood transfusion, and development of postmolar GTN. I do find an incomplete abortion rate of 13% quite high, but the authors did not describe specifically how this was diagnosed. It may be that this complication occurs more frequently after molar pregnancy evacuation compared to normal pregnancy evacuation where incomplete abortion rates are low. It is not surprising that operative times are faster for electric suction, as it provides a constant suction source compared to the MVA syringe, which must be emptied after it is full and recharged. Although initially I thought this article was going to describe the use of MVA in the office for molar pregnancy, both groups had procedures done in a hospital operating room under anesthesia with 24 hours of observation postoperatively and an oxytocin drip. Therefore, this study cannot be used to comment on the safety of uterine evacuation of known molar pregnancies in a non-hospital setting. This study has several strengths, including large numbers of subjects, histologic confirmation of molar pregnancy, and choice of suction source based on equipment available rather than physician discretion, avoiding bias.
The surprising finding was the decreased risk of Asherman’s syndrome (intrauterine synechia) with MVA compared to electric suction. It is interesting to me because both groups routinely received sharp curettage, which has been associated more with the development of Asherman’s than suction source.3 The authors speculated that this may have occurred because the MVA applies less vacuum pressure to the uterus compared with electric suction and, therefore, disrupts the endometrium less. This is an interesting theory and deserves further study. Unfortunately, as a retrospective study, we cannot know whether women in the EVA group also developed Asherman’s at a similar rate but did not present for care. In sum, although I don’t see this study necessarily changing practice in the United States, it is reassuring that both suction techniques are similar in case MVA is all that is available.
REFERENCES
- ACOG Practice Bulletin No. 53. Diagnosis and Treatment of Gestational Trophoblastic Disease. June 2004. Reaffirmed 2016.
- Yonke N, Leeman LM. First-trimester surgical abortion technique. Obstet Gynecol Clin North Am 2013;40:647-670.
- Gilman Barber AR, Rhone SA, Fluker MR. Curettage and Asherman’s syndrome-lessons to (re-) learn? J Obstet Gynaecol Can 2014;36:997-1001.
