Endometriosis is a common, benign gynecological disorder and a leading cause of disability in women of reproductive age, responsible for dysmenorrhea, pelvic pain and subfertility.  It is a debilitating and costly disease. Surgery is the treatment of choice for its management since the efficacy of medical treatment alone is often inadequate or of limited efficacy.  Surgical excision of lesions (conservative surgery) has been shown to both improve pain and enhance fertility. This is preferred over radical surgery because most women with endometriosis are of reproductive age.

The recurrence rate

Recent reviews had estimated the recurrence rate of endometriosis to be 21.5% at 2 years and 40-50% at 5 years (Guo SW 2009), which is more frequent than previously believed.  It seems that the recurrence rate for pain or dysmenorrhea is higher than that for the clinical recurrence as defined by presence of ovarian endometrioma on pelvic ultrasound scan.  These recurrences, which lead to repeat surgeries can further reduce fertility, exacerbate pain and complications of operation, which in turn affects quality of life, and increases social costs.

How recurrences happen?

There are two main explanations leading to the recurrence of endometriosis, namely re-growth of residue lesion and de novo lesion formation.

Vignali et al. observed that during a repeat surgery, most endometriosis recurrence occurred at the same area.  Similar observation was found in cases of ovarian endometrioma, where majority (88.7%) of the recurrences was from the previously treated ovary (Guo SW 2009). Conservative surgery is sometimes insufficient to remove these lesions completely, allowing it to re-develop after operation.  The de novo endometriosis lesion occurs via the monthly retrograde menstrual blood flow into the abdominal cavity, allowing the endometrial tissue to implant.

Prevention of Recurrence

Pain symptoms

The pain symptoms of endometriosis include non-cyclical pelvic pain (chronic pelvic pain), painful menses and intercourse. The use of oral contraceptives (OC) for a period of six month or more is found to be effective in reducing endometriosis associated pain symptom recurrence.   The continuous OC regime has an advantage over the cyclical OCs, with lower recurrence and earlier benefits (Seracchioli 2010; Vlahos 2013).  Medication should be given for at least 18-24 months as the recurrence occur rapidly when medication is stopped.


Ovarian endometriosis (endometrioma)

Postoperative OC conveys a protective effect against recurrence.  Again, the continuous regime has an edge over the cyclical OC regime.  This benefit is conferred as long as the woman is on OC treatment but vanished rapidly upon discontinuation (Kaori K 2015).


All women with endometriosis, following a conservative surgery (for pain symptoms or endometrioma), should be on medication (continuous OC) as long as possible until she is ready to conceive (Dunselman GA 2014). This will effectively reduce endometriosis recurrence and need for repeat surgery, which carries its own complications.


  1. Dunselman GA et al., Hum Reprod 2014
  2. Guo SW. Hum Reprod Update 2009
  3. Kaori K et al., Fert Steril 2015
  4. Seracchioli R et al., Fert Steril 2010
  5. Vlahos N et al., Fert Steril 2013
  6. Vignali M et al., J Minimal Invasive Gynecol 2005

Author: Dr Ng Soon Pheng

Dr. Ng Soon Pheng MD(USM), M.Med (O&G), Fellow Reprod Medicine (Singapore), AM (Mal) Dr. Ng Soon Pheng qualified from University Kebangsaan Malaysia (UKM), Malaysia. After obtaining his post graduate degree, Dr. Ng Soon Pheng continued his clinical fellowship training in the field of IVF in Singapore. He was also the recipient of Yayasan Sultan Iskandar (Johor) Scholarship for the fellowship stint. Dr. Ng Soon Pheng has more than 10 years of working experience in the field of Obstetrics and Gynaecology in the public and university hospital, with special interests in infertility. He was an Associate Professor with the Department of O&G in Universiti Kebangsaan Malaysia (UKM) specialising in infertility. Dr. Ng Soon Pheng is currently Consultant Obstetrician and Gynaecologist with special interests in infertility at Columbia Asia Hospital - Puchong.