By John C. Hobbins, MD, Professor, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora. Dr. Hobbins reports no financial relationships relevant to this field of study.
Synopsis: A recent study comparing patients having had loop electrosurgical excision procedures with those who had punch biopsies alone or Pap smears only has shown no differences in cesarean rates between groups.
Source: Frey HA, et al. Risk of cesarean delivery after loop electrosurgical excision procedure. Obstet Gynecol 2013;121:39-45.
Loop Electrosurgical Excision Procedure (LEEP) has played an important role in the diagnosis and treatment of cervical cancer. However, since the cervix is so intimately involved in the conduct of labor, obvious questions emerge regarding whether removing tissue from the cervix will have an adverse effect on subsequent pregnancies.
In an effort to see if LEEP affected the cesarean section rate (CSR), researchers from St. Louis reviewed their records over a 10-year period (1996-2006).1 Five hundred ninety-eight women were identified who had LEEPs prior to their next pregnancies. Data also were collected on another 522 matched controls, all of whom had had cervical biopsies, as well as another 588 patients who had had Pap smears alone prior to pregnancy. The investigators then focused on decisions and events occurring during these patients’ next pregnancies, such as CSR, reasons for the cesarean sections, and indications for induction of labor. They also tried to correlate these delivery variables with the size of the LEEP specimens obtained and the time interval between the procedures and the deliveries.
After adjusting for age, parity, prior cesarean delivery, body mass index, and birth weight, there were no differences in the CSRs in those with LEEPs compared with the Pap smear group if delivery occurred at term (28.5% vs 26.3%; relative risk [RR], 1.08; 95% confidence interval [CI], 0.88-1.33) or if preterm (45% vs 46%; RR, 0.98; CI, 0.72-1.33). Also, there were no differences in CSR in term patients with LEEPs compared with punch biopsy patients at term (26.1% vs 26.5%; RR, 1.08; CI, 0.88-1.33) or preterm (45.4% vs 41.8%; RR, 0.98; CI 0.72-1.33).
Importantly, when “failure to progress” or “arrest of labor” were used as a reason for cesarean delivery, there were no differences between groups, nor were there differences in the percentages of inductions. Last, the length of time between the LEEP and delivery and the amount of cervical tissue removed at the time of the LEEP had no bearing on the route of delivery. Specifically, the average LEEP tissue sample measured 1.8 cm3 for those having a cesarean section vs 1.7 cm3 for those having a vaginal delivery (P = 0.71).
The concept that cervical scarring post-LEEP may affect the dynamics of labor and, therefore, the route of delivery is worth studying, and this paper certainly seems to put that concern to rest. LEEPs did not increase the rate of cesarean delivery, in general, nor increase the rate of arrested of labor, in particular. Neither was there a greater need for induction of labor in these patients. The size of the tissue sample did not have an effect on the ability of the cervix to dilate.
What about the opposite effect of LEEP on cervical tissue integrity? Is it possible that removal of cervical tissue weakens the cervix to the point of causing preterm labor? This answer is not so clear. For example, a study from Finland involving 624 patients suggested that LEEP is associated with a doubling of preterm birth (PTB) when compared with controls (12% vs 6.5%).2 Furthermore, a repeat LEEP increased the rate of PTB five-fold.
Counterpoint information has emerged from Parkland Hospital in Dallas where investigators studied 511 patients who had LEEPs and found no increase in the rate of PTB over controls (no LEEPs).3
If there really is a risk of PTB with LEEPs, then there are two possible reasons: 1) The stability of the cervix is simply weakened by the removal of tissue or 2) The distance between the ectocervix and the amniotic cavity is shortened, thus providing bacteria with a shorter pathway to the membranes.
First, little stability is provided by the last few millimeters of the cervix, and prior to preterm labor the cervix shortens from the inside, not the outside. Second, although not yet borne out by solid data, our anecdotal impression is that patients who are many months post-LEEP do not have shorter cervices in the second trimester.
So ... until further data have emerged to further confuse or clarify the issue, we can tell our LEEP patients that their risk of delivering by cesarean section is no greater than anyone not having the procedure. However, it still is unclear if LEEP predisposes them to preterm labor. Although I have been inclined to be very optimistic about their chances for a term delivery, I have been suggesting that an ultrasound cervical length (CL) assessment be accomplished at 18 to 24 weeks. If the measurement is > 3 cm and they do not have a history of PTB, the risk of preterm labor is very low. If the CL is 2.5-3.0, then they should return in 10 days for a repeat examination. If there is no change, then they can be reassured, and no further testing is necessary. If the CL is < 2.5 cm, then they should be considered at some risk for PTB and managed according to the provider’s protocol du jour.
1. Frey HA, et al. Risk of cesarean delivery after loop electrosurgical excision procedure. Obstet Gynecol 2013;121:39-45.
2. Jakobsson M, et al. Loop electrosurgical excision procedures and the risk for preterm birth. Obstet Gynecol 2009;114:504-510.
3. Werner CL, et al. Loop electrosurgical excision procedure and risk of preterm birth. Obstet Gynecol 2010;115:605-608.