Clinical Review
2014 Update on abnormal uterine bleeding
Randomized data shed light on AUB associated with fibroids, adenomyosis, and the use of progestins
Details of the study
The purpose of the study was to evaluate the prevalence of CSD formation in the cesarean scar at 6 to 12 weeks after cesarean delivery with TVUS and gel infusion study (GIS) in 197 women. The uterus was closed in two layers for four women and in one layer for all others.
The cohort was followed with menstruation questionnaires at 6 to 12 weeks, 6 months, and 12 months after surgery. The questionnaire response rate at 12 months for those women who had both TVUS and GIS evaluation of the scar was 73%. Data analysis accounted for confounding factors such as breastfeeding and amenorrhea, use of hormonal contraception, use of a levonorgestrel intrauterine system (LNG-IUS) as well as a body mass index (BMI) of at least 25 kg/m 2.
Consistent with previous studies showing the superiority of saline-infused studies over TVUS for CSD identification, 4 van der Voet and colleagues found that GIS was more sensitive than TVUS in diagnosing CSD (64.5% vs 49.6%, respectively). The percentage of women with CSD who had undergone two cesarean deliveries was 68.2%, while the percentage with CSD who had undergone three cesarean deliveries was 77.8%.
Data analysis correlated postmenstrual bleeding with the following CSD characteristics:
- depth and width of the defect
- residual myometrial thickness to the serosal surface of the uterus
- ratio of residual myometrium divided by the adjacent normal myometrial thickness.
Those women who had a ratio of residual myometrium to adjacent normal myometrium of less than 0.5 were more likely to report postmenstrual bleeding than those with a ratio greater than 0.5 (odds ratio, 6.1; 95% confidence interval, 1.74–21.63). The investigators stated that 1 out of 3 women with CSD identified by GIS reported postmenstrual bleeding, compared with 1 out of 10 women without identifiable CSD.
Study takeaways have merit
In summary, despite the small cohort of 197 women and the relatively short observation period of 1 year, these data collected by van der Voet and colleagues enable the gynecologist to begin to more fully understand the potential impact of cesarean section and the probability of AUB following an abdominal delivery. Applying these study statistics to the number of cesarean sections performed annually in the United States translates to nearly 280,000 women yearly who may experience postmenstrual bleeding related to a defect in the cesarean section scar.
Prospective cohort studies with longer follow-up periods are needed to assess the longer-term risks of CSD-related bleeding. As the authors suggest, perhaps the possibility of post–cesarean section AUB should be considered as part of the informed consent process for cesarean delivery.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
• Contrast infusion sonography has better sensitivity than TVUS at identification of the scar defect.
• About 64.5% of women are predicted to have scar defects after one cesarean delivery.
• The incidence of scar defects increases with increasing number of cesarean deliveries.
• One of three women with CSD is predicted to experience postmenstrual bleeding.
• Women with deeper and wider defects are more likely to experience postmenstrual bleeding.
• Post–cesarean section AUB is a probable occurrence in approximately 20% of all cesarean deliveries. Perhaps this information should be considered part of the informed consent process for cesarean delivery.
