Is perforation of the appendix a risk factor for tubal, infertility and ectopic pregnancy? An appraisal of the evidence

OBJECTIVE: To critically assess the evidence that appendiceal perforation i s a risk factor for subsequent tubal infertility or ectopic pregnancy. DATA SOURCES: Epidemiologic studies investigating the relationship between appendectomy and infertility or ectopic pregnancy were identified by search ing the MEDLINE database from 1966 to 1997. Appropriate citations were also extracted from a manual search of the bibliographies of selected papers. STUDY SELECTION: Twenty-three articles were retrieved. Only 4 presented ori ginal data including comparisons to a nonexposed control group and they for m the basis for this study. DATA EXTRACTION: Because the raw data or specific techniques of data analys is were not always explicitly described, indices of risk for exposure were extracted from the data as presented and were analysed without attempting t o convert them to a common measure. DATA SYNTHESIS: Articles were assessed according to the criteria of the Evi dence Based Medicine Working Group for evaluating articles on harm. Review of the literature yielded estimates of the risk of adverse fertility outcom es ranging from 1.6 (95% confidence interval [CI] 1.1 to 2.5) for ectopic p regnancy after an appendectomy to 4.8 (95% CI 1.5 to 14.9) for tubal infert ility from perforation of the appendix. Recall bias, and poor adjustment fo r confounding variables in some reports, weakened the validity of the studi es. CONCLUSIONS: The methodologic weaknesses of the studies do not permit accep tance of increased risk of tubal pregnancy or infertility as a consequence of perforation of the appendix, so a causal relationship cannot be supporte d by the data currently available. Only a well-designed case-control study with unbiased ascertainment of exposure and adjustment for confounding vari ables will provide a definitive answer.