Abstract
We hypothesized that patients at our hospital who received general anesthesia as the initial anesthetic technique for dilation and curettage for loss of pregnancy during the first or second trimesters would have a higher estimated blood loss compared to patients who had sedation. We searched our electronic medical record system for patients who had a dilation and curettage for the indication of loss of pregnancy during the first or second trimesters from July 1, 2018, to June 30, 2021. A total of 165 (72%) and 64 (28%) patients had general anesthesia and sedation, respectively, as the initial anesthetic technique. Patients who had general anesthesia and sedation had estimated blood loss interquartile ranges of 50 to 500 mL and 30 to 100 mL, respectively (P < 0.01). A multivariate model that controlled for gestational age and location of procedure found that the odds ratio of patients receiving sedation for dilation and curettage in the labor and delivery suite was 7.24 (95% confidence interval 2.92, 17.94; P < 0.01) compared to the main operating room. Dilation and curettage that used sedation was associated with a lower estimated blood loss and was more likely to be performed in the labor and delivery suite.
Keywords: Abortion, spontaneous, anesthesia, general, deep sedation, dilatation and curettage
Miscarriage is the loss of pregnancy before viability, and it is estimated that 23 million miscarriages occur each year throughout the world.1 The management of loss of pregnancy is broadly divided between expectant, medical, and surgical treatment options, and dilation and curettage is one surgical treatment option for pregnancy loss.2 The choice of anesthetic technique for dilation and curettage depends on operative indication, patient comorbidities, and the preferences of the patient, anesthesia provider, and obstetrician. Patients at our hospital who have dilation and curettage for miscarriage have either general anesthesia or deep sedation. Our primary aim was to determine the difference in estimated blood loss between dilation and curettage performed under general anesthesia and deep sedation, and our secondary aim was to identify which patients at our hospital received general anesthesia for dilation and curettage. We hypothesized that patients at our hospital who received general anesthesia as the initial anesthetic technique for dilation and curettage for loss of pregnancy during the first or second trimesters would have a higher estimated blood loss, a higher body mass index, and a later gestational age compared to patients who received sedation for the same procedure.
METHODS
The Baylor Scott & White Research Institute institutional review board waived informed consent for this study. This was a retrospective observational study, and we determined a priori that we would examine 3 years of data at Baylor Scott & White Medical Center – Temple. Patients who had dilation and curettage for the indication of miscarriage in the first and second trimesters from July 1, 2018, through June 30, 2021, were included in the study. A study investigator entered demographic and clinical data from the electronic medical record (Epic, Verona, WI) into Research Electronic Data Capture hosted at our institution. Extracted data were analyzed using SAS version 9.4 (Cary, NC).
We used a chi-square test to evaluate categorical variables in bivariate associations when the expected cell count was ≥5 and used a Fisher’s exact test when expected cell counts were ≤4. We used an unpaired t test to evaluate continuous variables in bivariate associations that had a normal distribution and used a Mann-Whitney U test to evaluate continuous variables in bivariate associations that did not have a normal distribution. We used the Kolmogorov-Smirnoff test to determine if a sample deviated from the normal distribution. Statistical significance was determined a priori to have a P value ≤ 0.05. We performed a multivariate ordinal logistic regression that included the variables of location of procedure and gestational age to predict which anesthetic technique the patients received.
RESULTS
A total of 165 (72%) and 64 (28%) patients received general anesthesia and deep sedation for dilation and curettage during the study period, respectively. Patients who received general anesthesia had a higher estimated blood loss and were more likely to have had their procedure performed in the main operating room suite compared to patients who received deep sedation. There was no difference in body mass index or gestational age between patients who received general anesthesia and deep sedation. Demographic and clinical data for the two cohorts are presented in Table 1. Of the patients who had general anesthesia, 81 (49%) had a supraglottic airway and 84 (51%) had endotracheal intubation for airway management. A multivariate ordinal logistic regression that controlled for gestational age and location of procedure found that the odds ratio of patients receiving sedation for dilation and curettage in the labor and delivery suite was 7.24 (95% confidence interval 2.92–17.94; P < 0.01) compared to the main operating room (Table 2).
Table 1.
Demographic and clinical data
| Variable |
General anesthesia
(N = 165) |
Sedation
(N = 64) |
P
value |
|---|---|---|---|
| Age (years): mean ± SD | 30 ± 6 | 28 ± 6 | 0.15 |
| Body mass index (kg/m2): median (IQR)a | 28.2 (23.5–34.7) | 27.4 (22.4–33.5) | 0.16 |
| Gravidity: median (IQR) | 3 (2–4) | 3 (2–4) | 0.72 |
| Parity: median (IQR) | 1 (0–2) | 1 (0–2) | 0.25 |
| Gestation (weeks): mean ± SD | 9.4 ± 2.6 | 9.0 ± 2.3 | 0.33 |
| Indication for dilation and curettage | 0.64 | ||
| Missed abortion | 112 (68%) | 41 (64%) | |
| Incomplete abortion | 37 (22%) | 18 (28%) | |
| Otherb | 16 (10%) | 5 (8%) | |
| Location of procedure | <0.01* | ||
| Main operating room | 157 (95%) | 47 (73%) | |
| Labor and delivery suite | 8 (5%) | 17 (27%) | |
| Time of day of procedure start | 0.94 | ||
| 0700–1559 | 120 (73%) | 47 (73%) | |
| 1600–2359 | 41 (25%) | 15 (23%) | |
| 0000–0659 | 4 (2%) | 2 (3%) | |
| Operative time (min): mean ± SD | 29.5 ± 16.7 | 27.0 ± 13.5 | 0.29 |
| Estimated blood loss (mL): median (IQR) | 200 (50–500) | 55 (30–100) | <0.01* |
| Units of transfused PRBC, perioperative: median (IQR) | 0 (0–0) | 0 (0–0) | 0.84 |
| Postoperative disposition | 0.38 | ||
| Home | 146 (88%) | 61 (95%) | |
| Admitted to medical/surgical bed | 16 (10%) | 3 (5%) | |
| Admitted to intensive care unit | 3 (2%) | 0 |
aN = 161 for general anesthesia and N = 56 for sedation.
bGeneral anesthesia group: 5 anembryonic pregnancy, 5 suspected molar pregnancy, 6 pregnancy of unknown location. Sedation group: 2 anembryonic pregnancy, 3 pregnancy of unknown origin.
IQR indicates interquartile range; PRBC packed red blood cells; SD, standard deviation.
Table 2.
Multivariate logistic regression
| Variable | Odds ratio | 95% CI | P value |
|---|---|---|---|
| L&D suite vs main OR | 7.24 | 2.92–17.94 | <0.01 |
| Gestational age: 1-week increase | 0.93 | 0.82–1.06 | 0.29 |
CI indicates confidence interval; L&D, labor and delivery; OR, operating room.
DISCUSSION
We found that patients who had dilation and curettage performed under general anesthesia had a clinically and statistically significant larger estimated blood loss compared to patients who had the same procedure performed under deep sedation. When we controlled for gestational age and location of procedure, we determined that patients had an odds ratio of approximately 7 of receiving sedation for dilation and curettage performed in the labor and delivery suite compared to the same procedure performed in the main operating room suite.
Other investigators have determined that estimated blood loss for dilation and curettage is greater with general endotracheal anesthesia. Conn et al found that patients who had general endotracheal anesthesia for dilation and curettage had a mean estimated blood loss of 290.1 mL compared to 87.5 mL for subjects who had total intravenous anesthesia with propofol.3 Similarly, Clare et al found a mean estimated blood loss of 113.6 mL for inhalational agents and 40.2 for noninhalational agents.4 The estimated blood loss for our cohorts did not have a normal distribution, and we had interquartile ranges of 50 to 500 mL for patients who had general anesthesia and 30 to 100 mL for patients who had deep sedation. The increased estimated blood loss in patients who have dilation and curettage performed with volatile anesthetics can likely be attributed to the relaxation of myometrium caused by these agents.5 Our findings of decreased estimated blood loss with sedation without adverse anesthetic complications suggest that this is a safer anesthetic technique for dilation and curettage compared to general anesthesia.
There is a paucity of publications that examines the impact of anesthetic technique on dilation and curettage. A large retrospective review of surgical abortions performed under deep sedation during the first and second trimesters of pregnancy found that only one patient out of approximately 62,000 required endotracheal intubation.6 A recent randomized controlled trial compared subjects who had dilation and curettage performed with ketamine and propofol, dexmedetomidine, and isoflurane and propofol and found that subjects in the dexmedetomidine group had less hypoventilation and apnea but more bradycardia compared to subjects in the other groups.7 Another randomized controlled trial found that subjects who received tramadol during propofol sedation for dilation and curettage had similar analgesia but fewer respiratory complications compared to subjects who received fentanyl.8 A randomized controlled trial in subjects who underwent dilation and curettage with a propofol induction followed by 50% nitrous oxide found that those who received alfentanil during induction of anesthesia required less propofol and had a faster orientation time after the procedure compared to those who received ketamine during induction of anesthesia.9
In our study, we found that patients who had dilation and curettage performed in our labor and delivery suite were more likely to receive sedation compared to patients who had the same procedure performed in our main operating room suite. The most common surgical procedure performed in our labor and delivery suite is cesarean delivery, and general anesthesia is typically avoided.10 Our surgical and anesthesia care teams appear to have chosen the anesthetic technique for dilation and curettage based predominantly on where in the hospital the procedure was performed rather than individual patient characteristics, and we attribute this decision making to loss of situational awareness. In the 1990s, crisis resource management training for anesthesiologists was created that focused on nontechnical skills to improve patient safety.11 Similarly, a review article examined acquisition of situational awareness skills using simulated environments in the operating room environment and concluded that more training is needed in this area.12
Our study had several limitations. One limitation was that we had missing data for body mass index and were unable to include this variable in our ordinal logistic regression model. Another limitation of our study was that we did not use a quantitative method to estimate blood loss. A final limitation of our study was that we did not have adequate statistical power to detect rare anesthetic complications such as failed airway or aspiration.
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