The CREST Study

Here’s the RoshReview Question of the Week!

Which of the following methods of sterilization has the highest relative risk for ectopic pregnancy?

Check your answer and get a special deal on RoshReview at the link above!


Background: 

  • Who did the study? 

    • Study was done by the US Collaborative Review of Sterilization Working Group 

    • CREST was part of the CDC and conducted with the NICHD 

    • Conducted with 10 year follow up and was done at multiple medical centers (Baltimore, MD, Buffalo, NY, Chapel Hill, NC, Honolulu, HI, Houston, TX, Memphis, TN, Sacramento CA, St. Louis, MO, San Francisco, CA) 

  • Where was the study published? 

    • AJOG in 1996 

    • Presented at the Annual Meeting of the American Gynecological and Obstetrical Society in Napa, CA in 1995 

  • Why was the study done?

    • Tubal sterilization is the most prevalent form of contraception among married women and formerly married women in the US 

    • While sterilization was common, there was not widespread data about their efficacy, especially over time 

  • Objective: To assess the effectiveness of various methods of tubal occlusion 

Methods: 

  • Who was included? 

    • Prospective study of women undergoing tubal sterilization at the above mentioned medical centers from 1978 -1986 

    • Ages 15-44 years 

    • Patients were approached before their sterilization procedure 

  • How was it done? 

    • If the patient agreed, information about her history was obtained 

      • Characteristics of the surgical procedure, including complications during the surgery and afterward, were recorded 

      • Contacted at 1 month for brief follow-up 

      • Annual follow-up planned for 5 years for all patients 

      • If they were enrolled early enough, patients also had annual followup for 8-14 years after sterilization 

      • If the patient could not be contacted for the follow up then the last completed interview was used in the analysis 

    • At the follow up, all patients were asked: “Since your tubal sterilization, have you had a positive pregnancy test or been told by a physician that you were pregnant?” 

      • If yes, the interviewer then had a separate form with additional info about the pregnancy 

      • Excluded from further follow up if they became pregnant, had a repeat sterilization, a tubal anastomosis, or hysterectomy 

    • Type of tubal occlusion included: (don’t need to say all of these) 

      • Laparoscopic unipolar coagulation - don’t do these anymore! 

      • Laparoscopic bipolar coagulation - I have never seen this 

      • Laparoscopic silicone rubber band application - I think I did a few of these 

      • Laparoscopic spring clip application - Filshie clips? 

      • Partial salpingectomy (including Pomeroy, other types of partial, and total salpingectomy) 

    • If a pregnancy was identified, they were classified into: 

      • True failure (pregnancy conceived after sterilization) 

      • Luteal phase pregnancy (pregnancies conceived before sterilization but ID’ed after) 

      • Pregnancy resulting from tubal anastomosis or IVF 

      • Or pregnancy of unknown status (didn’t get the information) 

Results 

  • Who: 

    • 10,863 women enrolled → 178 were excluded from analysis

      • Some were due to loss to follow up, refusal to be interviewed at 1 month follow up, or refusal for prolonged follow up 

      • Others excluded because of hysterectomy, repeat tubal ligation, or death  

    • Demographics 

      • Median age: 30 (so pretty young!) 

      • Most women were non-Hispanic White (52.7%) and had had at least 2 pregnancies 

      • Most common procedure: silicone band (31.2%), followed by bipolar coagulation (21.2%), postpartum partial salpingectomy (15.3%)

        • For us, that is super different! Since I think what i have done the most is postpartum or interval total salpingectomies 

        • Though for a bit, we also did Pomeroys and Parklands  

  • Follow-up 

    • 89.2% were interviewed at 1 year after sterilization, 81% at 3 years, 73% at 5 years, and 57.7% 8-14 years (so some drop off, but that’s expected) 

    • At each follow up interval, younger women (age 18-27) had lower percentage of follow-up than older women 

    • Black, non Hispanic women also had lower rates of follow up compared to white non-Hispanic women 

  • Sterilization failures

    • Out of 10,685 women in the analysis, only 143 were true sterilization failures = 1.3% failure rate  

      • 21 (14.7%) ended in SAB 

      • 26 (18.2%) were TABs 

      • 41 (28.7%) ended in delivery 

      • 47 (32.9%!!!) ended in ectopic pregnancies 

    • Another 34 women not included in analysis had luteal phase pregnancies  

    • 16 were from tubal anastomosis and IVF, and 5 were “unknown” classification

  • Above table: lifetime accumulation of sterilization failure by method from 1-10 years per 1000 procedures and 95% CI (only showing years 1-4 because all the years made the table huge) 

    • We can see that for clip and interval partial salpingectomy, there seems to be a higher rate of lifetime pregnancies 

    • Lowest risk was postpartum partial salpingectomy 

  • Also looked at 10-year cumulative probability of failure is affected by age at tubal sterilization 

    • Probability for failure in women <28 is greater than for women sterilized at ages >34 (makes sense … if you’re younger, you likely have more “fertile” years ahead of you) 

  • After adjustment for age, race, and study site, interval partial salpingectomy, spring-clip application, and bipolar coagulation were more likely than postpartum partial salpingectomy to result in sterilization failure 

  • After adjustment, black women were at higher risk than white women for sterilization failure 

  • There were also interestingly differences between sites! 

So what did this all mean? 

  • Sterilization failure rates 

    • Higher than previously thought! For all comers it was a little over 1% 

    • HIgher failure rates occurred after longer times (ie. more than 1-2 years, which was what other studies had looked at)

      • Failure rates between 5-10 years after procedure ranged from 1.2-8.3/1000 procedures depending on method 

    • Method failure rate also is affected by age, race, and also institution! (meaning how well or properly you do the procedure could affect effectiveness) 

    • Also, risk of ectopic increases with tubal ligation 

  • What was the follow-up or impact of the CREST study? 

    • There was way more data collected than just this, and way more than just this study that was published from the CREST dataset 

    • Some other studies that were interesting: 

      • Risk of regret after tubal sterilization (1985) - 2% regretted after 1 year, 2.7% did so after 2 years 

        • Characteristics of those that had more regret: age <30 (regardless of parity), concurrent C/S

          • After 5 year follow up, risk of regret in those 20-24 was 4.3%, rate for those 30-34 was 2.4% 

          • Where do we get this 20% risk of regret from??? - different study from 1999 - in women <30 years of age 

            • In that same study for women >30, risk of regret was 5.9% 

            • Also, for women <30 the cumulative probability of regret decreased as time since birth of the youngest child increased

            • Risk of regret was actually lowest for women with no previous births!!

      • Unintended laparotomy associated with laparoscopic tubal sterilization: rate was: 51/5021, so about 1%

        • Increased risk: prior abdominal or pelvic surgeries  

      • Characteristics of those that sought tubal reanastomosis

        • 6.2% sought information for reanastomosis 

        • Women who were <30 were more likely to seek out this information 

        • Of those that actually had anastomosis, they were more likely to be white, have lower gravidity, and be younger, and to have experienced changes in marital status

  • How does this change our practice? 

    • We are performing different procedures from the ones that were studied in the CREST procedure

      • Nevertheless, I still quote the findings from this study for patients when they want them: 

        • Risk of failure depends on method

        • Risk overall of failure is low, but can be as high as 1% overall, and even higher depending on age and type of procedure 

        • Risk of conversion to laparotomy from laparoscopy is overall low but increases with more surgeries in the belly 

        • Risk of regret is as high as 20% – I think I may now qualify this only for certain populations! 

      • We shouldn’t NOT perform sterilization procedures, however, just because of risk of regret 

        • Even if someone is nulliparous, young, and not married, if they are well counseled and still desire sterilization, we can perform it