Objectives:
To assess relationships between preoperative and postoperative dating of second trimester surgical abortion.
Study Design:
We used a de-identified institutional database to extract demographic, dating and pathology data for surgical abortions performed at 14 to 23-6/7 weeks gestational age (GA) from 9/2015- 5/2017. We excluded women with multiple gestations, fetal anomalies, and missing fetal biometric measurements. We assigned preoperative GA by ultrasonography for unknown last menstrual period (LMP) or when discrepancy between sonographic and LMP dating exceeded 7 days (<15-6/7 weeks) 10 days (16 to 21-6/7 weeks) or 14 days (22 to 23-6/7 weeks). We determined postoperative GA using fetal foot length pathology standards published by Streeter in 1920 and Drey et al., in 2005. We performed regression analysis to estimate the relationship between pre- and post-operative estimates of GA and to assess demographic effects on these estimates, and chi-square tests to assess whether fetal foot lengths were concordant with, larger than, or smaller than the expected range for the preoperative GA
Results:
The 469 patients analyzed had a median preoperative GA of 19 4/7 weeks (range 14-0/7 to 23- 6/7 weeks). Preoperative dating highly correlated with postoperative dating using both pathology standards (r2 =0.95, p<0.001), without any clinically relevant effect by BMI (Streeter and Drey, p=0.79), parity (Streeter p=0.89; Drey p=0.71), race (Streeter p=0.06; Drey p=0.07), or GA. Fetal foot lengths were larger than expected in 134 (28.6%) women using Streeter and 17 (3.6%) women using Drey standards (p><0.001). ><0.001), without any clinically relevant effect by BMI (Streeter and Drey, p=0.79), parity (Streeter p=0.89; Drey p=0.71), race (Streeter p=0.06; Drey p=0.07), or GA. Fetal foot lengths were larger than expected in 134 (28.6%) women using Streeter and 17 (3.6%) women using Drey standards (p<0.001).
Conclusion:
Preoperative and postoperative dating for second trimester surgical abortion highly correlate. Use of Streeter standards results in more women with a postoperative GA greater than expected compared to Drey standards.