Minor obstetric and gynecologic procedure linked to increased risk of preterm delivery

Although D&C is generally considered safe and easy to perform, it is associated with some serious (if rare) side effects, including perforations to the cervix and uterus, infection, and bleeding. Now, an analysis 21 cohort studies which included almost 2 million women has found that a D&C performed in cases of miscarriage or induced abortion increases the chance of preterm birth (under 37 weeks) in a subsequent pregnancy by 29%, and of very preterm birth (under 32 weeks) by 69%.

With a background population risk of preterm delivery of about 6% in women without a D&C, these results suggest that an earlier D&C would increase the risk to 7.6%. This increase of 1.6% corresponds to 16 extra preterm births per 1000 women treated by D&C.

Results of the study are presented today at the Annual Meeting of ESHRE in Lisbon by gynaecologist Dr Pim Ankum of the Academic Medical Centre of the University of Amsterdam, the Netherlands.

These statistically significant increases in incidence were measured against control groups of similar women without a D&C prior to pregnancy, but the risk remained similarly increased (+28%) for D&C even when the control groups were limited to women with a medically managed miscarriage or termination. And the risks were even higher in women with a history of multiple D&Cs.

The results, says Dr Ankum, "warrant caution in the use of D&C after miscarriage and induced abortion," and add further weight to the case for less invasive procedures in such circumstances.

In proposing an explanation for the increased risk from D&C, he suggested that dilatation of the cervix may cause permanent damage which affects cervical tightness, with premature opening of the cervix and subsequent premature birth a consequence. Other intra-cervical procedures, such as cervical biopsy or cauterization, may also cause an increased risk of subsequent preterm birth. Cervical damage might also impair the anti-microbial defence mechanism in the cervix, which could lead to ascending genital tract infection, a known cause of preterm birth.

In the light of this study, whose results were described as "robust," and with the availability of less invasive medical treatments (such as misporostol), Dr Ankum called for a more "restrained use" of D&C. Indeed, this decline in use appears already to have begun, reflected in the increased popularity of misoprostol either as an alternative to D&C or for cervical priming prior to curettage. Nevertheless, gynaeoclogists in the Netherlands still treat 50% of all miscarriages with D&C (around 10,000 surgical procedures a year) -- and this, said Dr Ankum, is probably reflects usage in other countries.

Dr Ankum described preterm birth as "the biggest challenge in western obstetrics," with severe neonatal morbidity (and a need for intensive care treatment for infant respiratory distress syndrome, feeding problems, neonatal jaundice and cerebral palsy) and infant mortality. Adoption of alternatives to D&C for termination and miscarriage would in theory reduce this risk to the basic background level.

Abstract title: Does dilatation and curettage (D&C) increase the risk of preterm birth in the subsequent pregnancy? A systematic review and meta-analysis

Notes

1. Dilatation refers to widening the cervix, and curettage to the removal of tissue from within the uterus.

2. Among the less invasive alternatives suggested by Dr Ankum are the prostaglandin misoprostol, widely used to induce labour during pregnancy and treat postpartum bleeding as a result of inadequate uterine contraction during labour.