Reprinted from Eating Disorders Review
January/February 2010 Volume 21, Number 1
©2010 Gürze Books
According to a group of British researchers, target weights are an arbitrary means of determining a return to health for patients with anorexia nervosa. Instead, the group recommends that target weights be based on baseline pelvic ultrasound grading and follow-up scans (Eur Eat Disorders Rev 18:43, 2010).
The researchers noted that target weights are not consistently reliable for predicting the onset of menstruation and that individual weights may vary by up to 1 kg over any 24-hour period. Thus, weighing patients has poor test-retest reliability. Even dealing with a “target weight” can induce anxiety in many young people with AN, and opens up the probability of increased weight preoccupation, resistance to treatment and fabrication of weight gain. An alternative, relying upon onset or resumption for menstruation as an indication of successful treatment outcome, without reference to weight, is also problematic, since patient self-reports are often unreliable.
A study in 72 women
Dr. Rosemary Allan and colleagues at St. George’s Hospital, London, recently used pelvic ultrasound studies performed at intake and after treatment of 72 girls between the ages of 11 and 17 who were admitted to the adolescent eating disorder service at their hospital.
Pelvic ultrasound studies were performed when the patients reached 85% and 95% of their expected weights. All ultrasound studies were done transabdominally, with full bladders, and all scans were performed by one experienced pediatric radiologist using either a 2-4 MHz or 5-9 curvilinear array probe. (Transvaginal scanning was not performed because it was not considered appropriate in these young patients.) The scans documented uterine length and morphology, endometrial thickness ovarian volume, and the number, size and distribution of any cysts noted.
After evaluating 155 scans from the 72 patients, 36 scans were omitted due to difficulties in visualization, borderline grades, or presence of polycystic ovaries (8 patients). Identifying the presence of polycystic ovaries is important because they may be one more reason why the onset of menstruation is delayed, especially in patients who have reached seemingly satisfactory body mass index (BMI) percentiles.
The authors’ results recommend that patients with AN undergo pelvic ultrasound grading at the outset of treatment, and that they receive advice about the average weight gain needed to reach pelvic organ maturity based on their current BMI percentile. They also suggest that patients undergo scans again once they have gained that amount. The authors’ results suggest that about one in five patients is unlikely to progress to reproductive maturity if target weight is arbitrarily set at a 90% weight-for-height ratio. In contrast, using pelvic ultrasound allows for more objective estimates of weight gain that are reliably linked to increasing reproductive maturity. Based on their results, the use of pelvic ultrasound allows for objective evidence of the degree of reproductive organ maturity and, therefore, the likelihood of imminent start or resumption of menses, according to Dr. Allan and colleagues.