Re: Spackman R, Wrigley B, Roberts A, Quinn M. 2007. The inferior hypogastric plexus: a different view. Journal of Obstetrics and Gynaecology 27:130 – 133

Dear Sir,

We read with interest the recent paper by Spackman et al. (2007) on the inferior hypogastric plexus and make the following comments.

From the perspective of radical surgery for pelvic cancer preservation of the autonomic nerves and plexi is assuming increasing clinical importance. We have shown conclusively that the uterine supporting ligaments (uterosacral ligaments, cardinal ligaments) contain autonomic nerve fibres and ganglia (Butler-Manuel et al. 2000, 2002) The vesicouterine ligaments are also reported to contain these structures (Katahira et al. 2007). The traditional surgical approach at a radical hysterectomy for cervical cancer has been to divide and ligate these ‘ligaments’, which as we have demonstrated, divides many of the pelvic autonomic nerves. Nerve-preserving or nerve-sparing procedures for gynaecological cancers have been well described (Ercoli et al. 2003; Ito and Saito 2004).

In the ‘Materials and methods’ section, the authors have presumed that the cadavers were nulliparous and the age of the cadavers they investigated is not given. Both of these factors could have affected their observations. In their fixation method they describe the use of ethanol and methanol; this combination appears to be equivalent to industrial methylated spirits? They also describe the use of a low concentration of the fixative formaldehyde (1.4%) but they do not mention an antiseptic, such as phenol. For some time, we have been preparing ‘soft-fixed’ cadavers without the use of formalin (details available on request). Experience of dissecting both formalin-fixed and ‘soft-fixed’ cadavers has revealed a very substantial difference in the dissection and identification of structures. The autonomic pelvic nerves, for example, are much more readily discernible in the ‘soft-fixed’ cadavers where their texture more closely approaches in-vivo conditions.

With regard to gynaecological surgery, there is a major difference in terms of pelvic autonomic nerve dysfunction, between a hysterectomy performed for benign reasons and a radical hysterectomy performed for pelvic malignancy (Butler-Manuel et al. 1999). Radical hysterectomy is associated with increased pelvic morbidity, and the most likely aetiological factor is pelvic autonomic nerve damage or loss. In oncological practice, resection of pelvic tumours strives to both eradicate the cancer and preserve or restore function. Increasing attention has been paid to the pelvic autonomic nerves and in recent years there have been a number of publications attesting to the feasibility of these procedures (often described as nerve-preserving or nerve-sparing) performed either open or laparoscopically. There is now clear evidence in the surgical literature that identification and preservation of the pelvic autonomic nerve plexi is feasible and safe for urological, colorectal and gynaecological cancers (Ercoli et al. 2003; Ito and Saito 2004; Barabouti et al. 2005; Rassweiler et al. 2006).

Despite these important surgical developments, Spackman et al. (2007) only briefly mention the inferior hypogastric plexus in relation to gynaecological cancer surgery including radical hysterectomy. Surgically, the superior hypogastric plexus lies adjacent to the aortic bifurcation and the right and left hypogastric nerves, which are often plexiform, become evident when the pararectal and paravesical spaces are developed surgically. The spaces are not typically defined in anatomical texts, emphasising the difference in approach of anatomists and surgeons to pelvic anatomy.

The authors do refer to the middle hypogastric plexus; however, the middle hypogastric plexus is not standard anatomical nomenclature and it does not appear either in standard anatomy or surgery texts. Therefore, it is unclear what Spackman et al. (2007) meant by the middle hypogastric plexus.

Finally, the authors refer to the potential for autonomic nerve damage at vaginal delivery and they refer to two rather old publications (Allen and Masters 1955; Allen 1971). They also suggest that convergence of nerve trunks on the vaginal vault may lead to autonomic nerve damage through ‘sustained attempts at defaecation’ (Quinn and Armstrong 2005). However, the evidence for this is weak and inconclusive. There is no doubt that vaginal delivery can compromise end organ function, in particular the anal sphincter and vaginal supports; however, it is not clear that the anatomical defect relates in full or in part to autonomic nerve dysfunction. With regard to constipation, the question of cause and effect is relevant, as autonomic nerve dysfunction, for whatever reason, may lead to constipation rather than the reverse mechanisms as proposed by the authors. In fact, altered bowel and bladder function not infrequently result from a radical hysterectomy, the result of autonomic nerve dysfunction.