A hypothesis for the pathogenesis and natural history of proximal tubal blockage.

This paper reviews the literature on the proximal Fallopian tube and attempts to synthesize the available information into an hypothesis to elucidate the pathogenesis and natural history of proximal tubal blockage (PTB). There is evidence that the unique anatomy and physiology of the proximal Fallopian tube may predispose this tubal segment to a 'physiological' blockage, by tubal secretions and/or material back flowing from the uterine cavity, during the estrogen-dominant phase of the menstrual cycle. This would normally be reversed during the subsequent progesterone-dominant phase. However, if this reversal process is defective, organization of this material can occur, which can lead to initially incomplete and then complete tubal obstruction. Tubal wall damage does not normally exist in these cases. This sequence of events is supported by our experience in transcervical tubal cannulation. Flushing and/or guide-wiring the tubes can re-establish tubal patency and fertility. The tubal perfusion pressure, assessed during transcervical tubal cannulation procedures, can serve as a marker of the severity of PTB and the success of recanalization.