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A hypogastric nerve-focused approach to nerve-sparing endometriosis surgery
Radical resection of deep infiltrating endometriosis (DIE) or pelvic malignancies can lead to inadvertent damage to the pelvic autonomic nerve bundles, causing urinary dysfunction in up to 41% of cases, as well as anorectal and sexual dysfunction.1 Each of these sequelae can significantly affect the patient’s quality of life.
Nerve-sparing techniques have therefore been a trending topic in gynecologic surgery in the 21st century, starting with papers by Marc Possover, MD, of Switzerland, on the laparoscopic neuronavigation (LANN) technique. In an important 2005 publication, he described how the LANN technique can significantly reduce postoperative functional morbidity in laparoscopic radical pelvic surgery.2
The LANN method utilizes intraoperative neurostimulation to identify and dissect the intrapelvic nerve bundles away from surrounding tissue prior to dissection of the DIE or pelvic malignancies. The nerves are exposed and preserved under direct visualization in a fashion similar to that used to expose and preserve the ureters. Pelvic dissection using the LANN technique is extensive and occurs down to the level of the sacral nerve roots.
Dr. Possover’s 2005 paper and others like it spurred increased awareness of the intrapelvic part of the autonomic nervous system – in particular, the hypogastric nerves, the pelvic splanchnic nerves, and the inferior hypogastric plexus. Across additional published studies, nerve-sparing techniques were shown to be effective in preserving neurologic pelvic functions, with significantly less urinary retention and rectal/sexual dysfunction than seen with traditional laparoscopy techniques.
For example, in a single-center prospective clinical trial reported in 2012, 56 of 65 (86.2%) patients treated with a classical laparoscopic technique for excision of DIE reported neurologic pelvic dysfunctions, compared with 1 of 61 (1.6%) patients treated with a nerve-sparing approach.3
While research has confirmed the importance of nerve-sparing techniques, it also shone light on the reality that the LANN technique is extremely technically challenging and requires a high level of surgical expertise and advanced training. In my teaching of the technique, I also saw that few gynecologic surgeons were able to incorporate the advanced nerve-sparing technique into their practices.
A group consisting of myself and collaborators at the University of Bologna, Italy, and the University of Cambridge, England, recently developed an alternative to the LANN approach that uses the hypogastric nerves as landmarks. The technique requires less dissection and should be technically achievable when the pelvic neuroanatomy and anatomy of the presacral fascia are well understood. The hypogastric nerve is identified and used as a landmark to preserve the deeper autonomic nerve bundles in the pelvis without exposure and without more extensive dissection to the level of the sacral nerve roots.4,5
This hypogastric nerve-based technique will cover the vast majority of radical surgeries for DIE. When more advanced nerve sparing and more extensive dissection is needed for the very deepest levels of disease infiltration, patients can be referred to surgeons with advanced training, comfort, and experience with the LANN technique.
The pelvic neuroanatomy
As described in our video articles published in 2015 in Fertility and Sterility6 and 2019 in the Journal of Minimally Invasive Gynecology,5 the left and right hypogastric nerves are the main sympathetic nerves of the autonomic nervous system in the pelvis. They originate from the superior hypogastric plexus and, at the level of the middle rectal vessels, they join the pelvic sacral splanchnic nerves to form the inferior hypogastric plexus. They are easily identifiable at their origin and are the most superficial and readily identifiable component of the inferior hypogastric plexus.
The sympathetic input from the hypogastric nerves causes the internal urethral and anal sphincters to contract, as well as detrusor relaxation and a reduction of peristalsis of the descending colon, sigmoid, and rectum; thus, hypogastric nerve input promotes continence.
The hypogastric nerves also carry afferent signals for pelvic visceral proprioception. Lesion to the hypogastric nerves will usually be subclinical and will put the patient at risk for unnoticeable bladder distension, which usually becomes symptomatic about 7 years after the procedure.7
The thin pelvic splanchnic nerves – which merge with the hypogastric nerves into the pararectal fossae to form the inferior hypogastric plexus – arise from nerve roots S2 and S4 and carry all parasympathetic signals to the bladder, rectum, and the sigmoid and left colons. Lesions to these bundles are the main cause of neurogenic urinary retention.
The inferior hypogastric plexi split into the vesical, uterine, and rectal branches, which carry the sympathetic, parasympathetic, and sensory fibers from both the splanchnic and hypogastric nerves. Damage to the inferior hypogastric plexi and/or its branches may induce severe dysfunction to the target organs of the injured fibers.
A focus on the hypogastric nerve
Our approach was developed after we studied the anatomic reliability of the hypogastric nerves through a prospective observational study consisting of measurements during five cadaveric dissections and 10 in-vivo laparoscopic surgeries for rectosigmoid endometriosis.4 We took an interfascial approach to dissection.
Our goal was to clarify the distances between the hypogastric nerves and the ureters, the midsagittal plane, the midcervical plane, and the uterosacral ligaments in each hemipelvis, and in doing so, enable identification of the hypogastric nerves and establish recognizable limits for dissection.
We found quite a bit of variance in the anatomic position and appearance of the hypogastric nerves, but the variances were not very broad. Most notably, the right hypogastric nerve was significantly farther toward the ureter (mean, 14.5 mm; range, 10-25 mm) than the left one (mean, 8.6 mm; range, 7-12 mm).
The ureters were a good landmark for identification of the hypogastric nerves because the nerves were consistently found medially and posteriorly to the ureter at a mean distance of 11.6 mm. Overall, we demonstrated reproducibility in the identification and dissection of the hypogastric nerves using recognizable interfascial planes and anatomic landmarks.4
With good anatomic understanding, a stepwise approach can be taken to identify and preserve the hypogastric nerve and the deeper inferior hypogastric plexus without the need for more extensive dissection.
As shown in our 2019 video, the right hypogastric nerves can be identified transperitoneally in most cases.5 For confirmation, a gentle anterior pulling on the hypogastric nerve causes a caudal movement of the peritoneum overlying the superior hypogastric plexus. (Intermittent pulling on the nerve can also be helpful in localizing the left hypogastric nerve.)
To dissect a hypogastric nerve, the retroperitoneum is opened at the level of the pelvic brim, just inferomedially to the external iliac vessels, and the incision is extended anteriorly, with gentle dissection of the underlying tissue until the ureter is identified.
Once the ureter is identified and lateralized, dissection along the peritoneum is carried deeper and medially into the pelvis until the hypogastric nerve is identified. Lateral to this area are the internal iliac artery, the branching uterine artery, and the obliterated umbilical ligament. In the left hemipelvis, the hypogastric nerve can reliably be found at a mean distance of 8.6 mm from the ureter, while the right one will be found on average 14.5 mm away.
The hypogastric nerves form the posteromedial limit for a safe and simple nerve-sparing dissection. Any dissection posteriorly and laterally to these landmarks should start with the identification of sacral nerve roots and hypogastric nerves.
Dr. Lemos reported that he has no relevant disclosures.
Dr. Lemos is associate professor in the department of obstetrics and gynecology at the University of Toronto.
References
1. Imboden S et al. J Minim Invasive Gynecol. 2021 Aug;28(8):1544-51. doi: 10.1016/j.jmig.2021.01.009.
2. Possover M et al. J Am Coll Surg. 2005;201(6):913-7. doi: 10.1016/j.jamcollsurg.2005.07.006.
3. Ceccaroni M et al. Surg Endosc. 2012;26(7):2029-45. doi: 10.1007/s00464-012-2153-3.
4. Seracchioli R et al. J Minim Invasive Gynecol. 2019;26(7):1340-5. doi: 10.1016/j.jmig.2019.01.010.
5. Zakhari A et al. J Minim Invasive Gynecol. 2020;27(4):813-4. doi: 10.1016/j.jmig.2019.08.001
6. Lemos N et al. Fertil Steril. 2015 Nov;104(5):e11-2. doi: 10.1016/j.fertnstert.2015.07.1138.
7. Possover M. Fertil Steril. 2014 Mar;101(3):754-8. doi: 10.1016/j.fertnstert.2013.12.019.
Radical resection of deep infiltrating endometriosis (DIE) or pelvic malignancies can lead to inadvertent damage to the pelvic autonomic nerve bundles, causing urinary dysfunction in up to 41% of cases, as well as anorectal and sexual dysfunction.1 Each of these sequelae can significantly affect the patient’s quality of life.
Nerve-sparing techniques have therefore been a trending topic in gynecologic surgery in the 21st century, starting with papers by Marc Possover, MD, of Switzerland, on the laparoscopic neuronavigation (LANN) technique. In an important 2005 publication, he described how the LANN technique can significantly reduce postoperative functional morbidity in laparoscopic radical pelvic surgery.2
The LANN method utilizes intraoperative neurostimulation to identify and dissect the intrapelvic nerve bundles away from surrounding tissue prior to dissection of the DIE or pelvic malignancies. The nerves are exposed and preserved under direct visualization in a fashion similar to that used to expose and preserve the ureters. Pelvic dissection using the LANN technique is extensive and occurs down to the level of the sacral nerve roots.
Dr. Possover’s 2005 paper and others like it spurred increased awareness of the intrapelvic part of the autonomic nervous system – in particular, the hypogastric nerves, the pelvic splanchnic nerves, and the inferior hypogastric plexus. Across additional published studies, nerve-sparing techniques were shown to be effective in preserving neurologic pelvic functions, with significantly less urinary retention and rectal/sexual dysfunction than seen with traditional laparoscopy techniques.
For example, in a single-center prospective clinical trial reported in 2012, 56 of 65 (86.2%) patients treated with a classical laparoscopic technique for excision of DIE reported neurologic pelvic dysfunctions, compared with 1 of 61 (1.6%) patients treated with a nerve-sparing approach.3
While research has confirmed the importance of nerve-sparing techniques, it also shone light on the reality that the LANN technique is extremely technically challenging and requires a high level of surgical expertise and advanced training. In my teaching of the technique, I also saw that few gynecologic surgeons were able to incorporate the advanced nerve-sparing technique into their practices.
A group consisting of myself and collaborators at the University of Bologna, Italy, and the University of Cambridge, England, recently developed an alternative to the LANN approach that uses the hypogastric nerves as landmarks. The technique requires less dissection and should be technically achievable when the pelvic neuroanatomy and anatomy of the presacral fascia are well understood. The hypogastric nerve is identified and used as a landmark to preserve the deeper autonomic nerve bundles in the pelvis without exposure and without more extensive dissection to the level of the sacral nerve roots.4,5
This hypogastric nerve-based technique will cover the vast majority of radical surgeries for DIE. When more advanced nerve sparing and more extensive dissection is needed for the very deepest levels of disease infiltration, patients can be referred to surgeons with advanced training, comfort, and experience with the LANN technique.
The pelvic neuroanatomy
As described in our video articles published in 2015 in Fertility and Sterility6 and 2019 in the Journal of Minimally Invasive Gynecology,5 the left and right hypogastric nerves are the main sympathetic nerves of the autonomic nervous system in the pelvis. They originate from the superior hypogastric plexus and, at the level of the middle rectal vessels, they join the pelvic sacral splanchnic nerves to form the inferior hypogastric plexus. They are easily identifiable at their origin and are the most superficial and readily identifiable component of the inferior hypogastric plexus.
The sympathetic input from the hypogastric nerves causes the internal urethral and anal sphincters to contract, as well as detrusor relaxation and a reduction of peristalsis of the descending colon, sigmoid, and rectum; thus, hypogastric nerve input promotes continence.
The hypogastric nerves also carry afferent signals for pelvic visceral proprioception. Lesion to the hypogastric nerves will usually be subclinical and will put the patient at risk for unnoticeable bladder distension, which usually becomes symptomatic about 7 years after the procedure.7
The thin pelvic splanchnic nerves – which merge with the hypogastric nerves into the pararectal fossae to form the inferior hypogastric plexus – arise from nerve roots S2 and S4 and carry all parasympathetic signals to the bladder, rectum, and the sigmoid and left colons. Lesions to these bundles are the main cause of neurogenic urinary retention.
The inferior hypogastric plexi split into the vesical, uterine, and rectal branches, which carry the sympathetic, parasympathetic, and sensory fibers from both the splanchnic and hypogastric nerves. Damage to the inferior hypogastric plexi and/or its branches may induce severe dysfunction to the target organs of the injured fibers.
A focus on the hypogastric nerve
Our approach was developed after we studied the anatomic reliability of the hypogastric nerves through a prospective observational study consisting of measurements during five cadaveric dissections and 10 in-vivo laparoscopic surgeries for rectosigmoid endometriosis.4 We took an interfascial approach to dissection.
Our goal was to clarify the distances between the hypogastric nerves and the ureters, the midsagittal plane, the midcervical plane, and the uterosacral ligaments in each hemipelvis, and in doing so, enable identification of the hypogastric nerves and establish recognizable limits for dissection.
We found quite a bit of variance in the anatomic position and appearance of the hypogastric nerves, but the variances were not very broad. Most notably, the right hypogastric nerve was significantly farther toward the ureter (mean, 14.5 mm; range, 10-25 mm) than the left one (mean, 8.6 mm; range, 7-12 mm).
The ureters were a good landmark for identification of the hypogastric nerves because the nerves were consistently found medially and posteriorly to the ureter at a mean distance of 11.6 mm. Overall, we demonstrated reproducibility in the identification and dissection of the hypogastric nerves using recognizable interfascial planes and anatomic landmarks.4
With good anatomic understanding, a stepwise approach can be taken to identify and preserve the hypogastric nerve and the deeper inferior hypogastric plexus without the need for more extensive dissection.
As shown in our 2019 video, the right hypogastric nerves can be identified transperitoneally in most cases.5 For confirmation, a gentle anterior pulling on the hypogastric nerve causes a caudal movement of the peritoneum overlying the superior hypogastric plexus. (Intermittent pulling on the nerve can also be helpful in localizing the left hypogastric nerve.)
To dissect a hypogastric nerve, the retroperitoneum is opened at the level of the pelvic brim, just inferomedially to the external iliac vessels, and the incision is extended anteriorly, with gentle dissection of the underlying tissue until the ureter is identified.
Once the ureter is identified and lateralized, dissection along the peritoneum is carried deeper and medially into the pelvis until the hypogastric nerve is identified. Lateral to this area are the internal iliac artery, the branching uterine artery, and the obliterated umbilical ligament. In the left hemipelvis, the hypogastric nerve can reliably be found at a mean distance of 8.6 mm from the ureter, while the right one will be found on average 14.5 mm away.
The hypogastric nerves form the posteromedial limit for a safe and simple nerve-sparing dissection. Any dissection posteriorly and laterally to these landmarks should start with the identification of sacral nerve roots and hypogastric nerves.
Dr. Lemos reported that he has no relevant disclosures.
Dr. Lemos is associate professor in the department of obstetrics and gynecology at the University of Toronto.
References
1. Imboden S et al. J Minim Invasive Gynecol. 2021 Aug;28(8):1544-51. doi: 10.1016/j.jmig.2021.01.009.
2. Possover M et al. J Am Coll Surg. 2005;201(6):913-7. doi: 10.1016/j.jamcollsurg.2005.07.006.
3. Ceccaroni M et al. Surg Endosc. 2012;26(7):2029-45. doi: 10.1007/s00464-012-2153-3.
4. Seracchioli R et al. J Minim Invasive Gynecol. 2019;26(7):1340-5. doi: 10.1016/j.jmig.2019.01.010.
5. Zakhari A et al. J Minim Invasive Gynecol. 2020;27(4):813-4. doi: 10.1016/j.jmig.2019.08.001
6. Lemos N et al. Fertil Steril. 2015 Nov;104(5):e11-2. doi: 10.1016/j.fertnstert.2015.07.1138.
7. Possover M. Fertil Steril. 2014 Mar;101(3):754-8. doi: 10.1016/j.fertnstert.2013.12.019.
Radical resection of deep infiltrating endometriosis (DIE) or pelvic malignancies can lead to inadvertent damage to the pelvic autonomic nerve bundles, causing urinary dysfunction in up to 41% of cases, as well as anorectal and sexual dysfunction.1 Each of these sequelae can significantly affect the patient’s quality of life.
Nerve-sparing techniques have therefore been a trending topic in gynecologic surgery in the 21st century, starting with papers by Marc Possover, MD, of Switzerland, on the laparoscopic neuronavigation (LANN) technique. In an important 2005 publication, he described how the LANN technique can significantly reduce postoperative functional morbidity in laparoscopic radical pelvic surgery.2
The LANN method utilizes intraoperative neurostimulation to identify and dissect the intrapelvic nerve bundles away from surrounding tissue prior to dissection of the DIE or pelvic malignancies. The nerves are exposed and preserved under direct visualization in a fashion similar to that used to expose and preserve the ureters. Pelvic dissection using the LANN technique is extensive and occurs down to the level of the sacral nerve roots.
Dr. Possover’s 2005 paper and others like it spurred increased awareness of the intrapelvic part of the autonomic nervous system – in particular, the hypogastric nerves, the pelvic splanchnic nerves, and the inferior hypogastric plexus. Across additional published studies, nerve-sparing techniques were shown to be effective in preserving neurologic pelvic functions, with significantly less urinary retention and rectal/sexual dysfunction than seen with traditional laparoscopy techniques.
For example, in a single-center prospective clinical trial reported in 2012, 56 of 65 (86.2%) patients treated with a classical laparoscopic technique for excision of DIE reported neurologic pelvic dysfunctions, compared with 1 of 61 (1.6%) patients treated with a nerve-sparing approach.3
While research has confirmed the importance of nerve-sparing techniques, it also shone light on the reality that the LANN technique is extremely technically challenging and requires a high level of surgical expertise and advanced training. In my teaching of the technique, I also saw that few gynecologic surgeons were able to incorporate the advanced nerve-sparing technique into their practices.
A group consisting of myself and collaborators at the University of Bologna, Italy, and the University of Cambridge, England, recently developed an alternative to the LANN approach that uses the hypogastric nerves as landmarks. The technique requires less dissection and should be technically achievable when the pelvic neuroanatomy and anatomy of the presacral fascia are well understood. The hypogastric nerve is identified and used as a landmark to preserve the deeper autonomic nerve bundles in the pelvis without exposure and without more extensive dissection to the level of the sacral nerve roots.4,5
This hypogastric nerve-based technique will cover the vast majority of radical surgeries for DIE. When more advanced nerve sparing and more extensive dissection is needed for the very deepest levels of disease infiltration, patients can be referred to surgeons with advanced training, comfort, and experience with the LANN technique.
The pelvic neuroanatomy
As described in our video articles published in 2015 in Fertility and Sterility6 and 2019 in the Journal of Minimally Invasive Gynecology,5 the left and right hypogastric nerves are the main sympathetic nerves of the autonomic nervous system in the pelvis. They originate from the superior hypogastric plexus and, at the level of the middle rectal vessels, they join the pelvic sacral splanchnic nerves to form the inferior hypogastric plexus. They are easily identifiable at their origin and are the most superficial and readily identifiable component of the inferior hypogastric plexus.
The sympathetic input from the hypogastric nerves causes the internal urethral and anal sphincters to contract, as well as detrusor relaxation and a reduction of peristalsis of the descending colon, sigmoid, and rectum; thus, hypogastric nerve input promotes continence.
The hypogastric nerves also carry afferent signals for pelvic visceral proprioception. Lesion to the hypogastric nerves will usually be subclinical and will put the patient at risk for unnoticeable bladder distension, which usually becomes symptomatic about 7 years after the procedure.7
The thin pelvic splanchnic nerves – which merge with the hypogastric nerves into the pararectal fossae to form the inferior hypogastric plexus – arise from nerve roots S2 and S4 and carry all parasympathetic signals to the bladder, rectum, and the sigmoid and left colons. Lesions to these bundles are the main cause of neurogenic urinary retention.
The inferior hypogastric plexi split into the vesical, uterine, and rectal branches, which carry the sympathetic, parasympathetic, and sensory fibers from both the splanchnic and hypogastric nerves. Damage to the inferior hypogastric plexi and/or its branches may induce severe dysfunction to the target organs of the injured fibers.
A focus on the hypogastric nerve
Our approach was developed after we studied the anatomic reliability of the hypogastric nerves through a prospective observational study consisting of measurements during five cadaveric dissections and 10 in-vivo laparoscopic surgeries for rectosigmoid endometriosis.4 We took an interfascial approach to dissection.
Our goal was to clarify the distances between the hypogastric nerves and the ureters, the midsagittal plane, the midcervical plane, and the uterosacral ligaments in each hemipelvis, and in doing so, enable identification of the hypogastric nerves and establish recognizable limits for dissection.
We found quite a bit of variance in the anatomic position and appearance of the hypogastric nerves, but the variances were not very broad. Most notably, the right hypogastric nerve was significantly farther toward the ureter (mean, 14.5 mm; range, 10-25 mm) than the left one (mean, 8.6 mm; range, 7-12 mm).
The ureters were a good landmark for identification of the hypogastric nerves because the nerves were consistently found medially and posteriorly to the ureter at a mean distance of 11.6 mm. Overall, we demonstrated reproducibility in the identification and dissection of the hypogastric nerves using recognizable interfascial planes and anatomic landmarks.4
With good anatomic understanding, a stepwise approach can be taken to identify and preserve the hypogastric nerve and the deeper inferior hypogastric plexus without the need for more extensive dissection.
As shown in our 2019 video, the right hypogastric nerves can be identified transperitoneally in most cases.5 For confirmation, a gentle anterior pulling on the hypogastric nerve causes a caudal movement of the peritoneum overlying the superior hypogastric plexus. (Intermittent pulling on the nerve can also be helpful in localizing the left hypogastric nerve.)
To dissect a hypogastric nerve, the retroperitoneum is opened at the level of the pelvic brim, just inferomedially to the external iliac vessels, and the incision is extended anteriorly, with gentle dissection of the underlying tissue until the ureter is identified.
Once the ureter is identified and lateralized, dissection along the peritoneum is carried deeper and medially into the pelvis until the hypogastric nerve is identified. Lateral to this area are the internal iliac artery, the branching uterine artery, and the obliterated umbilical ligament. In the left hemipelvis, the hypogastric nerve can reliably be found at a mean distance of 8.6 mm from the ureter, while the right one will be found on average 14.5 mm away.
The hypogastric nerves form the posteromedial limit for a safe and simple nerve-sparing dissection. Any dissection posteriorly and laterally to these landmarks should start with the identification of sacral nerve roots and hypogastric nerves.
Dr. Lemos reported that he has no relevant disclosures.
Dr. Lemos is associate professor in the department of obstetrics and gynecology at the University of Toronto.
References
1. Imboden S et al. J Minim Invasive Gynecol. 2021 Aug;28(8):1544-51. doi: 10.1016/j.jmig.2021.01.009.
2. Possover M et al. J Am Coll Surg. 2005;201(6):913-7. doi: 10.1016/j.jamcollsurg.2005.07.006.
3. Ceccaroni M et al. Surg Endosc. 2012;26(7):2029-45. doi: 10.1007/s00464-012-2153-3.
4. Seracchioli R et al. J Minim Invasive Gynecol. 2019;26(7):1340-5. doi: 10.1016/j.jmig.2019.01.010.
5. Zakhari A et al. J Minim Invasive Gynecol. 2020;27(4):813-4. doi: 10.1016/j.jmig.2019.08.001
6. Lemos N et al. Fertil Steril. 2015 Nov;104(5):e11-2. doi: 10.1016/j.fertnstert.2015.07.1138.
7. Possover M. Fertil Steril. 2014 Mar;101(3):754-8. doi: 10.1016/j.fertnstert.2013.12.019.