The role of childbirth in the aetiology of rectocele
I thank Drs Spencer and Pakarian for their kind comments. From own experience, I feel that there are major differences between anatomy on dissection and what we see intraoperatively, which is why I have reservations regarding cadaver anatomical studies as they have been conducted in the past, i.e. in formalin-fixated cadavers. The rectovaginal septum, or, if you want, a fibrous extension of the perineal body extending and fusing with the vagina cranially, can invariably be demonstrated on surgical dissection of the posterior vaginal wall, although its thickness and cranial extent varies a lot. When we see a defect on imaging, the cranial margin on dissection is generally well defined and easily located. The ‘true rectocele’ is a special case in pelvic reconstructive surgery: for the first time we are not just treating a ‘bulge’ but a defect that can be defined and quantified on imaging.
However, the issue of obesity as an aetiological factor is an interesting one, which we have not looked into before. It may not have anything to do with accumulation of fat in the area of the defect, which should be obvious on imaging due to the high echogenicity of adipose tissue. There does not seem to be much fat in the midline, it is all lateral in the pararectal spaces.
In an ongoing four-dimensional ultrasound study involving a total of 1000 women, we should be able to look into the issue of aetiology in much more detail. In the meantime, I can only offer the intriguing finding that there was indeed a significant relationship between body mass index (BMI) and rectocele at the postpartum visit: BMI 28.6 kg/m2 (SD 4.45) in intact versus BMI 32.4 kg/m2 (SD 2.97) (P= 0.005 on Mann–Whitney U test) in women with a true rectocele. We will have to have a close look at pre-pregnancy BMI/weight gain/BMI at delivery versus symptoms and versus prevalence and size of defects, both antepartum and postpartum.
Many thanks for this interesting and helpful communication.