Mr Ashwini K Trehan MBBS, DRCOG, FRCOG, FRCS (Edin)

Consultant Minimal Access Gynaecologist

(with special interest in Endometriosis and Keyhole Surgery)

Recognised Endometriosis Centre for the management of advanced Endometriosis

by the BSGE (British Society of Gynaecological Endoscopy)

ENDOMETRIOSIS

Mr. Trehan is well known for the surgical excision treatment of endometriosis.  His unit is one of the few which is accredited and recognized by the BSGE (British Society of Gynecological Endoscopy) for the surgical management of advanced endometriosis.  He offers one of the most advanced endometriosis surgical services in the country.

Mr Trehan has undertaken over seven hundred operations involving the removal of Stage I-IV endometriosis. He routinely undertakes operations on patients with complicated stage IV endometriosis, which may include extensive bowel adhesions, frozen pelvises and endometriotic nodular growths on the bowel, ureter and bladder.  These patients may have also had several previous unsucessful surgeries in other parts of the country. Inspite of complicated nature of the operation which lasts anything between 3- 8 hours (depending upon the stage of the disease), over 90% of the patients following endometriosis surgical treatment by Mr Trehan are fit to leave hospital after only one night’s stay and Mr Trehan's complication rates for this, one of the most complicate and demanding gynecological surgery are amongst the lowest reported in the literature.

• Endometriosis is a common gynecological condition resulting in pelvic pain and infertility.

• Although medicine is extensively used for managing endometriosis, it is mainly suppressive. The most effective treatment is surgical.

• Mr. Trehan recommends a diagnostic laparoscopy in order to determine the extent and location of the endometriosis. If the endometriosis is stage I and medical treatment has failed or there is history of infertility, surgery should be considered. If the disease is stage II, III or IV, surgery should again be strongly considered if the patient is infertile or has bad symptoms.

• For surgery, Mr Trehan recommends keyhole excision treatment rather than laser treatment. Excision is most modern treatment and offers several advantages over laser. For more information on these advantages, see below). In excision surgery, the endometriosis covering the lining of the pelvis is removed by peeling it off.

• Remember at open surgery (laparotomy), endometriosis cannot be removed from the pelvis due to poor access and magnification, and thus the patient almost always has endometriosis remaining in the pelvis at the end of open surgery. Surgery for endometriosis is thus best undertaken using a keyhole (laparoscopic) approach, not via open (laparotomy) surgery.

• If surgery is required, Mr Trehan always offers surgical excisional treatment for endometriosis (which may include surgery for endometriosis involving the bowel,bladder,ureter and severe adhesions) by keyhole means. Excisional treatment is one of the most demanding gynecological operations requiring special training.

• Conventionally, the reproductive organs are often removed as endometriosis is usually not removed, in a hope that this will help to cure the symptoms; however in spite of this drastic action, as endometriosis often still remains in the pelvis, and thus patients may continue to suffer from the symptoms of endometriosis. Mr Trehan thus removes endometriosis and preserves the reproductive organs, unless the uterus itself is also diseased and preservation of fertility is not important.

• On occasions, if a hysterectomy is necessary (when the uterus itself is diseased and fertility is complete), Mr. Trehan always combines a hysterectomy with excisional treatment as it is well documented that the pain may persist if the endometriosis is not removed via excision at the time of hysterectomy. Therefore, a hysterectomy for endometriosis should never be done without also removing the endometriosis (via excision). By definition endometriosis is disease of lining of the pelvis, not the uterus itself.

• Traditionally, the ovaries are removed to treat endometriosis with the view to remove oestrogen milieu (produced by the ovaries). This is done due to the fact that the oestrogen helps endometriosis grow. If the endometriosis itself is completely removed by excision surgery, there is no need for the ovaries to be removed as there are harmful consequences (for more information on these, please click here).  Mr Trehan has been able to save the ovaries in all patients he has treated in last several years by using his innovative excision technique for endometriosis which Mr Trehan undertakes. In addition, endometriosis involving the ovaries with large cysts can be treated by the removal the cyst only (cystectomy) and not of the ovaries, and you should therefore request your ovaries to be preserved; even if large cysts are present. Mr Trehan feels and research proves that ovaries are very important organs even after menopause and should be/can be saved even if they have cysts due to the reasons explained above.

• Bowel Endometriosis - 10% cases of endometriosis have bowel involvement; these cases are advanced cases of endometriosis. It can only be treated appropriately by an endometriosis specialist and requires an advanced form of surgery. Although many treat this form of endometriosis by bowel resection (removing part of bowel), Mr Trehan always undertakes shaving of the bowel (stripping the endometriosis of the bowel) for treatment of this condition. The reason he undertakes shaving as opposed to resection is that in a resection, the removal of a portion of the bowel is associated with a 10-15 % risk of severe complications such as faecal leakage, peritonitis, rectovaginal fistula, colostomy, anterior resection syndrome and effects on future fertility. Moreover, the improvement in quality of life and pain symptoms are similar following both forms of treatment.

Mr Trehan's Innovative Technique for Treating Endometriosis

Whist pelvic peritoneal excision surgery is an effective surgical option for treating endometriosis and is available in some hospitals, it has a recurrence rate of 21.5% at 2 years 40-50% at 5 years (ref: Guo, Hum Reprod Update 2009); this may often result in the need for repeated excision operations or in the removal of the ovaries and uterus.

The technique, ‘Total Pelvic Peritoneal Excision’ (radical excision), which Mr Trehan innovated is an extension of the above excision technique where the entire skin (peritoneum) of the pelvis is removed removing both clinical and subclinical (abnormal vascular changes) endometriosis rather only clinical endometriosis. Mr Trehan believes and his results suggest that endometriosis is not a localized disease, but is a generalized disease of the pelvic peritoneum and a radical approach like total pelvic peritoneal excision is the answer. The theory of Total Peritoneal Excision (whereby the total removal of pelvic peritoneum (skin) removes all the present and future potential pelvic sites of endometriosis) is supported by the commonly believed theories for the causation of endometriosis (Retrograde menstruation, Coelomic metaplastic, and Migratory dislocation theory.) Also, this technique helps to preserve the ovaries, which are commonly removed by other endometriosis treatments. This innovative technique not only provides good outcome results, minimizes recurrence, prevent loss of reproductive organs but is also safer technique both immediate and long term.

For more information on Total Pelvic Peritoneal Excision, see below:

• Click here to view the presentation (with minor changes) which Mr Trehan presented at the International Conferences (Lisbon 2001, San Diego 2002, Glasgow 2003, San Francisco 2004, London 2005, Kuala Lumpur 2006). This presentation shows Mr Trehan's technique and safety results of Total Peritoneal Excision of Endometriosis.

• Click here to read the peer review paper presented in 2007 to demonstrate that the internal healing following this technique too is excellent with virtually no adhesions.

• To view a presentation and poster demonstrating the outcome results of total peritoneal excision in terms of pain, patient satisfaction, safety and hospital stay, click here (presentation) and click here (poster). This was presented at the 9th International Scientific Meeting RCOG (Athens 2011),  ESGE 19 Annual congress (Barcelona 2010)  BSGE annual Scientific conference (London 2010) and Clinical audit Regional conference (Yorkshire 2009). It is an independent retrospective study, carried out by the Dewsbury District Hospital audit team in conjunction with Mr Trehan’s registrar. It revealed that the technique had good outcome results in terms of pain, patient satisfaction with all ovaries saved, a miniscule recurrence rate of endometriosis, had no major complications and 90% of patients were discharged after an overnight stay with no readmission for complication. The study looked at 207 consecutive cases who underwent total peritoneal excision in Dewsbury District Hospital (patient survey and review of case notes) from 1999 to 2006.

• Click here to view the video of the technique of TOTAL PERITONEAL EXCISION which Mr Trehan presented at various international conferences (Chicago - 2001, Lisbon - 2001, San Diego - 2002, Glasgow - 2003, San Francisco - 2004, London - 2005, Kuala Lumpur - 2006, Melbourne - 2008).

• Click here to view Presentation which suggests that the Total Pelvic Peritoneal Excision technique allows preservation of ovaries.  This was presented at the ESGE 20th Annual congress in London, 2011.

• Videos of the surgical techniques have been kept in the library of the American Society of Reproductive Medicine for training purposes-2001 .

Following this long term audit and reflection of his practice Mr Trehan has implemented some further modifications to his surgical practice such as liberal use of his innovative “Temporary Ovarian Suspension technique” and also increasing experience and understanding of the condition his recent outcome results are even better than those of the above. He will present the more recent outcome results in the future.

Video - Surgical Treatment, click here >

Mr Trehan appeared on the BBC's Politics Show on 23rd November 2003 to give his opinion on modern surgical treatment of endometriosis.

Click here to view a BBC News article about one of Mr Trehan's patients published in 2010.

Click here to view a Daily Mail article about one of Mr Trehan's patients published in 2011.

The following pictures of Endometriosis have been taken by Mr Trehan during the course of his procedures:

Laparoscopic Appearance of Endometriosis

Laparoscopic Excision (Peeling off) & Coagulation of Endometriosis

Conservative Treatment of Endometriosis in Patients Wanting Pregnancy

Keyhole Hysterectomy and Excision of Endometriosis

Keyhole Hysterectomy, Removing Ovaries (Oophorectomy) and Excision Endometriosis

Summary, Advice and Questions You Can Ask Your Doctor/Gynaecologist

·       Endometriosis is a chronic gynaecological condition producing pelvic pain and infertility.

o   Ask your doctor to refer you to a consultant with a special interest in endometriosis.

IN DEPTH

Endometriosis is a common condition affecting 10-15% of women of reproductive age (1,2).  The disease is encountered in some form in 25% of infertile women and 60% of those with endometriosis suffer from infertility (3).  Approximately 1.25 million women in the UK are affected with endometriosis.

In this condition patches of tissue similar to the lining of the womb appear on the lining of the pelvis, ovaries, bowel and occasionally other organs and respond to hormones from the ovaries in the similar way as lining of the womb resulting in menstrual bleeding at endometriotic sites.  The amount of loss of blood in these endometriotic implants depends on the size of the implant.  This bleeding result in bruising and by the time this bruising starts to heal there is further onslaught of bleeding during the following menstruation.  This repeated bleeding, bruising and healing results in scarring of the lining of the pelvis.  These scars result in organs like tubes, ovaries, uterus and bowel to stick to each other (adhesions) distorting anatomy and may also involve nerves.  Bleeding can also result in cyst formation (called chocolate cysts).

Symptoms

Endometriosis is a common cause of chronic pelvic pain, painful sex, painful periods, backache, bowel symptoms and infertility. The pain & infertility caused by endometriosis can place strain on a woman's relationship, family, career and even psychological well being.

What Causes Endometriosis

Following are the two most common theories. 

• Lining of the womb (endometrium) in the menstrual blood comes out through the vagina during menstruation but small amount passes through fallopian tube into the pelvic cavity and settle on the skin (peritoneum) lining the pelvis and grows forming endometriosis.

• The lining of the pelvis (peritoneum) develops from the same tissue as the lining of the womb (endometrium) and so has potential to change in to endometrium under certain influence like genetic, hormonal, immunological etc; and forms endometriosis.

Is Endometriosis a Progressive Disease?

Endometriosis is generally considered as a progressive disease but the data to substantiate this are scanty.  Repeat laparoscopy over 12 months,  endometriotic deposits resolved spontaneously in a quarter, deteriorated in nearly half and were unchanged in the remainder (4).

Diagnosis of Condition

Although the history may suggest the diagnosis at present the only way to confirm it is by Laparoscopy (5-7) under a short general anaesthetic.  A specialist looks in to the tummy with a special camera through one or two small cuts in the abdominal wall. It is usually done on a day stay basis.

Laparoscopy is the gold standard test for Endometriosis.

Click here for the corresponding presentation (may take a few minutes).

Management of Endometriosis

Endometriosis is an extremely complex medical condition and treatment is similarly complicated.  Treatment needs to be based on each patient’s individual circumstances and objectives.

A careful diagnosis by a specialist with a special interest in this condition is needed before a realistic prognosis can be achieved. 

The treatment options are medical and surgical.

Medical Treatment

The aim of medical treatment is to prevent cyclical bleeding in the endometriotic implants.  This is achieved by stopping menstruation for approximately 6 months.  Women do not menstruate during pregnancy, menopause or if they have a high level of male hormones in the body so one of the above situations is mimicked by giving drugs.  It is hoped that these drugs will dry up and inactivate (atrophy) the endometriosis. 

Except for combined contraceptive pills and Mirena (hormone coil) most of the drugs for example GnRH analogues, Danazole and Progestogens are used for a short period of 6 months to avoid side effects.

Whilst easy to prescribe, drug therapy has number of problem:

• All these hormones may produce unpleasant side effects reducing quality of life (8) resulting in discontinuation of treatment. 

• During treatment 70-90% of patients have a significant and substantial improvement of pain score (9) and a short term improvement of quality of life (8,10) but up to 75% may experience symptoms after discontinuation of treatment for 6 months (11).

• Medical treatment mainly suppresses, not eradicates (12) with annual recurrence rate of 5-20% and 5 yearly recurrence rate of 37% for minimal disease and 75% for severe disease.  (13-16).

Short-term medical treatment has a place in the management of pain produced by very early (stage 1) disease; advanced disease 2-3 months before operation to make the operation safe and after the operation (17-19) to treat remaining invisible endometriosis and larger endometriotic areas close to the bladder, ureter (tube carrying the urine), bowel and blood vessels not removed at surgery to avoid complications.  Long-term medical treatment in the form of combined contraceptive pills (6,20) and Mirena (hormone coil) can also be used to control symptoms of endometriosis. 

Medical treatment should not be used to treat infertility (21) as it delays fertility and there is no evidence that it increases fertility.

Surgical Therapy

The surgery offers long term and effective treatment for endometriosis without producing unpleasant side effects of medicines but there are risks of surgical complications as with any major procedure.  Several studies have shown that surgery helps return the anatomy of the pelvis to normal, significantly reduces pain (22) and improve chances of pregnancy (23-25).  The operation is usually undertaken by the laparoscopic (keyhole) method.  Laparoscopy permits better access, better magnification and more complete excision than laparotomy (large cut on the tummy).  In very extensive disease involving bowel a traditional open operation may be necessary.

Excision/Laser

The operation is usually undertaken by the laparoscopic (keyhole) method. Using the Laparoscope the endometriosis is either burned with laser or electric cautery or "peeled" off (excision). Although laser had been and still being used in the surgical management of the endometriosis, but the excisional (peeling off) treatment of endometriosis is the most effective, successful (26-33)and modern surgical treatment of endometriosis with five-year cure rate of  81% (22, 34-35). In excision (peeling) off method the skin covering the pelvis (peritoneum) containing endometriosis is peeled off from the organs of the pelvis.

In very advanced disease involving the bladder, bowel, ureter (tube carrying urine) or pelvic blood vessels it may not be possible to remove (laser or excise)every patch of the disease without risking damage to vital organs and thus some endometriotic patches on these vital organs maybe left behind to avoid complications

There are several drawback of laser ablation (burning) in comparison to excision (peeling off) of the endometriosis.

In laser surgery:

• Incomplete removal of lesion occurs - anatomy and pathology distorted by heat and thus lesion especially deep patches of endometriosis is less easily seen.   Laser burns the surface of endometriosis leaving deep patches(5mm or more lesion) behind which continue to grow resulting in an early return of symptoms.

• As the tissue is burned it does not allow removed tissue (endometriosis) to be analysed (histology) under the microscope. 

• There is an increased risk of thermal damage to internal organs.

• There is an increased risk of adhesion formation (sticking to organs) - as ablation leaves ischaemic raw area.

• Carbon particles left behind by the laser may cause a reaction in the tissue which can be its own cause of pain.

Click here to view corresponding presentation (may take several minutes).

Endometriosis & Place of Hysterectomy

There is a misconception among women that hysterectomy is the answer for endometriosis. The disease is usually on the lining of the pelvis and not on the uterus and therefore removing the uterus does not eradicate the disease or cure all the symptoms (36-38).  In most cases of endometriosis, the uterus is entirely normal.

• Hysterectomy may be necessary in a few special circumstances such as the presence of a fibroid, enlarged uterus due to endometriosis in the womb (adenomyosis) and associate pelvic infections etc. 

• If hysterectomy is necessary it should be combined with excision (peeling off) endometriosis from the pelvis, as endometriosis will continue to grow under the influence of hormones from ovaries. 

• A keyhole hysterectomy is advantageous as endometriosis can also be effectively peeled off (excised) under the magnification of Laparoscope at the time of hysterectomy. Endometriosis involving the pelvis can not be removed at open operation thus women having open hysterectomy by large cut are left with endometriosis in the pelvis at the end of the operation.

Click here to view corresponding presentation (may take several minutes).

Endometriosis & Place of Removing Ovaries

As the ovarian hormones feeds endometriosis it is expected that if the ovaries are removed at the time of hysterectomy all of the endometriosis may die off resulting in cure of all the symptoms:  

o   However, this does not always happen and symptoms may continue (36, 38-40) if the endometriosis itself not removed.

o   Hormone replacement treatment may stimulate endometriosis and the pain may return if endometriosis not removed

Thus it is likely to give a better cure rate if endometriosis is excised (peeled off) even if the ovaries are removed at the time of hysterectomy.

In women under the age of 50 years, an attempt should be  made to conserve at least one ovary if not both, because removal may result in menopause and all its long-term unpleasant after-effects.  However with preservation of ovaries there is a possibility of recurrence of endometriosis but it is still worth considering this approach rather than losing the ovaries before menopause (The special technique of excision which Mr Trehan uses the likelihood of recurrence of endometriosis is very small).  For more information on why the ovaries should be preserved, please click here.

Finally both medical/surgical  treatment has a place and it should be based on each patients individual circumstances and objectives.

All the information provided above reflects the modern view for the management of endometriosis.  The information is based on various medical publications.

Click here to view corresponding presentation, may take several minutes).

References

1.         Schmidt LC, Endometriosis: a reappraisal of pathogenesis and treatment.  Fertility Sterility 1985; 44:157

2.         Hasson HM, Incidence of endometriosis in diagnostic laparoscopy. J Reprod Med 1976; 16:135-8.

3.         Olive DL, Haney AF.  Endometriosis associated infertility: a critical review of therapeutic approaches, Obst Gynaecol Surv 1986; 41:538

4.         Cooke ID, Thomas EJ.  The medical treatment of  mild endometriosis. Acta Obstet Gyneacol Scand Suppl 1989; 150: 27-30.

5.         Brosen I.  Diagnosis of Endometriosis.  Seminar in Reproductive Endocrinology; 1997 15, 229-233.

6.         Moore J, Kennedy S, and Prentice A.  Modern combined oral contraceptives for pain associated with endometriosis.  Cochrane Database of Systematic Reviews.  8-8-1997.  Update software.

7.         Bergqvist A Current drug therapy recommendations for the treatment of endometriosis.  1999; Drugs 58, 39-50.

8.         Scottish clinical Research Audit Group.  Measuring health-related quality of life outcomes in women with endometriosis: results of the gynaecology audit project in Scotland.  Health Bull 1997: 55: 109-117.

9.         Damario MA Roack JA, Pain recurrence: a quality of life issue in endometriosis.  (Review) (99refs).  International Journal of Obstetrics & Gynaecology.  50 suppl 1: S27-42, 1995 Sep.

10.        Burry KA.  Nafarelin in the management of endometriosis: quality of life assessment.  Am J Obstet Gynaecol 1992: 166: 735-739.

11.        Miller JD.  Shaw RW.  Casper RF.  Rock JA.  Thomas EJ.  Dmowski WP.  Surrey E.  Malinak LR.  Moghissi K: Historical prospective cohort study of the recurrence of pain after discontinuation of treatment with Danazol or a Gonadotropin-releasing hormone agonist.  Fertility & Sterility.  70(2): 293-6, 1998 Aug.

12.        Brosen IA – Endometriosis current issue in diagnosis and medical management (Reviews 28 refs) Journal of Reproductive Medicine 43 (3 suppl): 281-6, 1998 March)

13.        Redwine DB.  Laparoscopic excision of endometriosis (LAPEX) by sharp dissection In: Martin DC, Redwine DB, Reich H, Kresch AJ, editors.  Laparoscopic Appearances of Endometriosis, Vol 1.  Memphis, Tennessee: Resurge Press, 1990: 9-19.

14.        Barbieri RL.  The use of danazol as a treatment of endometriosis.  In: Thomas E, Rock J, editors.  Modern approaches to Endometriosis.  London: Kluwert Academic Publishers, 1991: 239-256

15.        Walker KG, Shaw RW.  Gonadotropin-releasing hormone analogues for the treatment of endometriosis: long-term follow-up.  Fertil Steril 1993: 59: 511-515.

16.        Moore J, Kennedy S, Prentice A.  Modern combined oral contraceptives for the treatment of painful symptoms associated with endometriosis (Cochrane review).  In: The Cochrane library 1999, Issue 3.  Oxford: Update software.

17.        Hornstein MD, Hemmings R, Yuzpe AA, Heinrichs W.LeRoy.  Use of nafarelin versus placebo after reductive laparoscopic surgery for endometriosis.  Fertil Steril 1997; 68:860-4.

18.        Vercillini P, Crosignani PG, Fadini R, Radici E, Belloni C, Sismondi P.  A gonadotrophin-releasing hormone agonist compared with expectant management after conservative surgery for symptomatic endometriosis.  Br J Obstet Gynaecol 1999; 106:672-7.

19.        American College of Obstetricians and Gynaecologists.  Endometriosis.  Int J Gynaecol Obstet 1993;43:221-7.

20.        Farquhar C and Sutton C The evidence for the management of endometriosis.  Current Opinion in Obstetrics and Gynaecology 1998; 10, 321-262.

21.        Hughes E, Fedorkow DM, Collins J, Vandekerckhove P.  Ovulation suppression versus placebo in the treatment of endometriosis in: The Cochrane Library, issue 2: 1998: Oxford: Update software.

22.        Redwine DB.  Conservative laparoscopic excision of endometriosis by sharp dissection: life table analysis of reoperation and persistent or recurrent disease.  Fertil Steril 1991;56:628-34.

23.        Hughes EG, Fedorkow DM, Collins JA: A quantitative overview of controlled trials in endometriosis-associated fertility.  Fertil Steril 1993: 59(5): 963-970.

24.        Adamson DJ, Pasta DJ.  Surgical treatment of endometriosis-associated infertility: Meta-analysis compared with survival analysis.  AM J Obstet Gynaecol 171: 1488-1505, 1994.

25.        Marcoux S, Maheux R, Berube S laparoscopic surgery in infertile women with minimal or mild endometriosis.  Canadian Collaborative Group on Endometriosis.  N Engl J Med 1997 337, 217-2.

26.        Martin DC.  Laparoscopic and vaginal colpotomy for excision of infiltrating cul de sac endometriosis.  J Reprod Med 1988: 33: 806-808.

27.        Konincz PR, Meuleman C, Demeyere S, Lesaffre E, Cornillie FJ.  Suggestive evidences that pelvic endometriosis is a progressive disease, whereas deeply infiltrating endometriosis is associated with pain.  Fertil Steril 1991: 55: 759-765.

28.        Reich H, McGlynn F, Salvat J.  Laparoscopic treatment of cul de sac obliteration secondary to rectocervical deep fibrotic endometriosis.  J Reprod Med 1991: 36: 516-522.

29.        Nezhat C, Nezhat F, Pennington E.  Laparoscopic treatment of infiltrative rectosigmoid colon and rectovaginal septum endometriosis by the technique of video laparoscopy and the CO2 laser.  Br J Obstet Gynaecol 1992: 99: 664-667.

30.        Reich H.  Endometriosis.  In: Hulka JF, Reich H.  Textbook of Laparoscopy.  Philadelphia: WB Saunders, 1994: 211-217.

31.        Redwine BD.  Laparoscopic en bloc resection for the treatment of the obliterated cul de sac in endometriosis.  J Reprod Med 1995: 37: 695-698.

32.        Wood C, Maher P.  Peritoneal surgery in the treatment of endometriosis-excision or thermal ablation? Aust NZ J Obstet Gynaecol 1996: 36: 190-197.

33.        Garry R.  Laparoscopic excision of endometriosis: the treatment of choice? Br J Obstet Gynaecol 1997: 104: 513-515.

34.        Redwine D.  Non laser reduction of endometriosis.  In Sutton C and Diamond M (eds) Endoscopic Surgery for Gynaecologist.  Saunders, London.  1993; 220-228.

35.        Wheeler JM, Malinak LR.  Recurrent endometriosis.  Contrib Gynecol Obstet 1987;16:13-21.

36.        Redwine DB: Endometriosis persisting after castration: clinical characteristics and results of surgical management.  Obstet Gynaecol 83: 405-413, 1994.

37.        Namnoum AB, Hickman TN. Goodman SB, Gehlback DL, Rock JA.  Incidence of symptom recurrence after hysterectomy for endometriosis.  Fertil Steril 1995: 64: 898-902.

38.        Metzger DA, Lessey BA, Soper JT, McCarrty KSJ, Haney AF: Hormone resistant endometriosis following total abdominal hysterectomy and bilateral salpingo-oophorectomy: correlation with histology and steroid receptor content.  Obstet Gynaecol 78: 946-950, 1991.

39.        O’Connor DT: Endometriosis.  Melbourne, Churchill Livingstone, 1987.

40.        Clayton RD, Hawe JA, Love JCC, Wilkinson N, Garry R.  Recurrent pain after hysterectomy and bilateral salpingo-oophorectomy for endometriosis: evaluation of laparoscopic excision of residual endometriosis.  Br J Obstet Gynaecol 1999: 106: 740-744.