Laparoscopic diagnosis of endometriosis - query bank

Question: Is there is any evidence to suggest biopsy of laparoscopically diagnosed endometriosis can be negative?

Please note: the search for this response was carried out over 1 year ago. Eligible users may request an update of the evidence by submitting a new Clinical Query here.

Answer: The RCOG green-top guideline on the investigation and management of endometriosis (1) notes that “Laparoscopy is the gold standard diagnostic test in clinical practice. A meta-analysis of its value against a histological diagnosis showed (assuming a 10% pre-test probability of endometriosis) that a positive laparoscopic examination increases the likelihood of detecting the disease to 32% (95% CI 21–46%) and a negative laparoscopy decreases the likelihood to 0.7% (95% CI 0.1–5.0%).” This is based on a systematic review of the accuracy of laparoscopy in the diagnosis of endometriosis (2)
(Evidence level 1a)

The guideline also makes the following good practice point: “Positive histology confirms the diagnosis of endometriosis; negative histology does not exclude it.”
(Evidence level IV)

Negative biopsy in laparoscopically-diagnosed endometriosis has also been reported in more recent trials (3-4)


  1. The Investigation and Management of Endometriosis (Green-top 24) RCOG 2006
  2. Wykes CB. Clark TJ. Khan KS. Accuracy of laparoscopy in the diagnosis of endometriosis: a systematic quantitative review. BJOG: An International Journal of Obstetrics & Gynaecology. 111(11):1204-12, 2004 Nov. Full text available to Fellows, Members and Trainees.
  3. de Almeida Filho DP. de Oliveira LJ. do Amaral VF. Accuracy of laparoscopy for assessing patients with endometriosis. Sao Paulo Medical Journal = Revista Paulista de Medicina. 126(6):305-8, 2008 Nov. Full text
  4. El Bishry G. Tselos V. Pathi A. Correlation between laparoscopic and histological diagnosis in patients with endometriosis. Journal of Obstetrics & Gynaecology. 28(5):511-5, 2008 Jul. Abstract

Search date: April 2009

Classification of evidence levels

Ia Evidence obtained from meta-analysis of randomised controlled trials.

Ib Evidence obtained from at least one randomised controlled trial.

IIa Evidence obtained from at least one well-designed controlled study without randomisation.

IIb Evidence obtained from at least one other type of well-designed quasi-experimental study.

III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.

IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities.

This clinical query answer was produced following the clinical query protocol as described here.

The RCOG will not be liable for any special or consequential damages arising from the use or reliance on information contained within the Query Bank.

Date published: 15/04/2009


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