CHAPTER 44 Benign tumours of the ovary
Introduction
Ovarian cysts are common, frequently asymptomatic and often resolve spontaneously. They are the fourth most prevalent gynaecological cause of hospital admission. By 65 years of age, 4% of all women in England and Wales will have been admitted to hospital for this reason. Ovarian cysts are found either during the course of investigation of abdominal pain or as a result of imaging for other reasons. It is important to distinguish between ovarian cysts that will require assessment and management and those that will resolve spontaneously. In addition, reliable prediction of their benign or malignant nature would be beneficial in order to arrange appropriate referral and management, as per Improving Outcome Guidance (NHS Executive 1999).
Physiological Ovarian Cysts
As pelvic ultrasound, particularly transvaginal scanning, is now used more frequently, physiological cysts are detected more often. The corpus luteum may persist and continue to secrete progesterone beyond its natural lifespan, and thus cause some menstrual irregularity, or haemorrhage may occur into the cyst at or just after ovulation. Most good radiologists will recognize the features of a follicle, corpus luteum or haemorrhagic cyst and will report these as such. Most simple cysts will resolve spontaneously over a period of 6 months (Zanetta et al 1996, Saasaki et al 1999). Occasionally, they can persist for longer or grow in size to become a clinical problem. Physiological cysts should simply be regarded as large versions of the cysts which form in the ovary during the normal cycle.
Failure of development of the lead follicle results in anovulation and is a classical finding in polycystic ovary syndrome (PCOS). PCOS is predominantly an endocrine abnormality, and polycystic ovaries do not cause abdominal pain (see Chapter 18, Polycystic ovary syndrome, for more information).
Clinical Presentation of Symptomatic Ovarian Cysts
Benign ovarian cysts present as follows:
Abdominal swelling, bloating and pressure effects
An attempt to assess symptoms qualitatively and quantitatively in order to distinguish women who may have an ovarian cyst from those unlikely to have a cyst suggests that recent-onset, severe and persistent symptoms should warrant further investigation (Bankhead et al 2008).
Investigation
Ultrasound
The techniques of transabdominal and transvaginal ultrasound are discussed in detail in Chapter 6. Ultrasound is the single most important investigation and can demonstrate the presence of an ovarian mass with 81% sensitivity and 75% specificity. Most ovarian masses are cystic, whilst the presence of solid areas makes a malignancy more likely. Reporting of an ultrasound finding of an ovarian cyst has been standardized in order to allow for the allocation of a scoring system to assist in the preoperative assessment of the risk of any ovarian cyst being malignant. The ultrasound is awarded a U score of 0 if no cyst is present, 1 if only one characteristic is found, and 3 if two or more characteristics are found:
Ultrasound-guided diagnostic ovarian cyst aspiration
This investigation has been introduced gradually into gynaecological practice without the benefit of appropriate trials to indicate its potential efficacy. Unfortunately, this technique has a false-negative rate of up to 71% and a false-positive rate of 2% for the cytological diagnosis of malignancy (Diernaes et al 1987