Butterfly Resection of Advanced Endometriosis "SOSURE" Technique

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  • SOSURE is a mnemonic created by the author that provides a framework of operative steps that maximise access and optimise endometriosis surgery.
  • Source offers surgeon and assistant a structured method for dissection ensures the lead surgeon is exclusively occupied with operating/dissection, whilst the assistant, rather than holding intrusive structures out of the way, can aid in tissue dissection and maintaining a clear surgical field. As a result, surgery is safer & quicker.
  • Not all the steps are necessary for all cases and the order by which they need to be performed will vary.


SOSURE Technique

Survey/Sigmoid Mobilisation (S)


  • Mobilisation of the sigmoid colon frees the bowel from the sidewall, allowing it to be manipulated more readily facilitate left ureterolysis.
  • Gentle traction towards the midline is applied to the sigmoid colon, often by lying an open atraumatic grasper over the bowel.
  • The fusion line that is subsequently revealed between the peritoneum of the sigmoid and the peritoneum (also known as “the white line of Toldt”) can be cut just medial to the peritoneum.

Ovarian Mobilisation (O)

  • In advanced endometriosis, the ovaries may be adherent to the uterus, pelvic sidewall, bowel or to each other (often with associated endometriomas).
  • A combination of traction and blunt/sharp dissection can be used to mobilise the ovaries. The intention here is to free the ovaries from associated adhesions so they can be mobilised for suspension and to ensure any disease hidden under the ovaries can be accessed and excised.

Suspension of Ovaries/Uterus (S)

Ovarian Suspension

  • We use a non-braided suture on a straight needle (Prolene 2-0) for ovarian suspension.
  • The straight needle is introduced just lateral to the inferior epigastric vessels and 4-5 cm below the lateral operating ports. The needle is positioned using graspers/needle holders and passed through the ovary prior to being extruded from the abdomen adjacent to the insertion.
  • It is important to avoid vessels in the abdominal wall and also visualise the full length of the needle at all times, as both ends can be traumatic to surrounding structures.
  • We usually leave the ovarian suspension sutures in place for 5-7 days in an attempt to reduce the risk of adhesions between the ovaries and pelvic sidewalls. Removal is performed in the community typically by the patients GP surgery.

Uterine Suspension

  • Uterine suspension can deliver strong and stable traction and anteversion of the uterus that is arguably superior to that produced by a uterine manipulator. It also removes the need for a second assistant for uterine manipulation.
  • We use two techniques to perform uterine suspension, depending on the severity of disease and the amount of upward traction required:
    • Using a straight 2-0 prolene, the suture is introduced perpendicular to the abdomen close to pubic symphysis, taking care to avoid the bladder.
    • Whilst one grasper retracts the uterus, the other passes the needle through the fundus perpendicular to the axis of the uterus, going through myometrium only, before being removed from the same position it entered the abdomen.

Ureterolysis (U)

  • Ureterolysis frees and lateralises the ureters in order to prevent potential injury during surgery. It also facilitates the ureters being under direct vision when dissecting close by.
  • We always begin our ureteric dissection in an area of normal tissue to allow dissection of the correct surgical plane.
  • The ureters are identified over the pelvic brim and the overlying peritoneum is grasped so that it can be retracted away from the underlying ureter. A small incision can be made in the tented peritoneum using either cold scissors or an ultrasonic energy device. Gentle traction is applied at the edges of the peritoneum and the ureter can be exposed using a combination of blunt dissection, cold scissors and ultrasonic/bipolar energies.
  • Care should be taken to not compromise the ureteric blood supply by avoiding the use of energy close to the ureter and by keeping the adventitia intact.
  • Our usual practise is to reserve the use of ureteric stents for patients known to have hydroureter or where there is an intraoperative concern for either the integrity of the ureter or its blood supply.

Rectovaginal/Pararectal Space Entry (R)

  • Access to the rectovaginal space, where necessary, can be obtained using blunt and sharp dissection with caution advised in the use of electrosurgical instruments in close proximity to the bowel to minimise the risk of thermal injury.
  • In cases where a nodule involves the rectum but is not full thickness and therefore does not require either a disc or segmental resection and is also adherent to the uterus/uterosacral ligaments, it is our preference to completely dissect the disease away from the bowel first and then excise the nodule off the back of the uterus. We have found this facilitates a cleaner shave and more complete excision, allowing the surgeon to get beyond the nodule to healthy tissue.
  • Using a rectal probe to provide countertraction and a grasper pulling gently on the uterosacral ligament, the pararectal space can be entered by dissecting the avascular space adjacent to the rectum.
  • It is during this step where suspension has another benefit – since there is no
  • uterine manipulator in situ, the rectal probe is not impeded when introduced and positioned within the pelvis. Gentle movements of the rectum using the probe can also help to demonstrate the margins of the bowel reducing the risk of inadvertent injury.
  • If both pararectal spaces are opened, then both sides can be extended to meet with the rectovaginal space, ensuring complete excision of the affected area.

Excision of Disease (E)

  • At this point the important structures are safely separated from the disease, all visible endometriosis can be excised.
  • If both pelvic sidewalls and both uterosacral ligaments are involved, the ‘Butterfly Area’ (bilateral pelvic sidewalls, uterosacral ligaments and torus uterinus) will often need to be excised.
  • Care should be taken to not compromise the nerve plexuses within the pelvic sidewall during excision, especially the hypogastric nerves and the inferior hypogastric plexuses. If the hypogastric nerve is severed during resection because it is involved in disease, trying to preserve at least one side is of great importance.

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