Regarding Uterine Bleeding

Which of the following is a true statement regarding uterine bleeding?
A. Normal menstrual bleeding occurs every 21 to 35 days with an average blood loss of 120 cc.
B. The degree of endometrial shedding is not related to estrogen exposure while the endometrium is proliferating.

C. Greater than three-fourths of dysfunctional uterine bleeding is attributable to anovulation.
D. Carcinoma is the most common cause of uterine bleeding in postmenopausal women.
E. Uterine bleeding in a premenarchal girl is pathognomonic for neoplasm.

Answer  C. (Greater than three-fourths of dysfunctional uterine bleeding is attributable to anovulation.)

Discussion: 

Typically, menses occur every 21 to 35 days and volume is usually less than 60 cc. Repeated blood loss of greater than 80 cc can lead to anemia. The normal bleeding duration is 4 to 6 days. 

Abnormal uterine bleeding can be either anatomic or, more likely, dysfunctional (DUB). 

Anatomic causes include :

• trauma, 
• infection such as cervicitis and salpingitis, 
• carcinomas, 
• polyps, 
• uterine fibroids, and 
• adenomyosis. 

More than 75% of DUB is due to anovulation. 

Causes of anovulation include:

•  hyroid abnormalities, both hypothyroidism and hyperthyroidism, 
• adrenal disease, 
• polycystic ovarian syndrome, 
• endometriosis, 
• premature menopause, 
• medication, 
• stress, and 
• nutritional abnormalities such as morbid obesity, malabsorption, or anorexia nervosa. 

The degree of endometrial growth and thus shedding is related to the degree of estrogen exposure. Moreover, long-term exposure to unopposed estrogen can lead to endometrial hyperplasia and abnormal uterine bleeding. 

In females older than 40 years of age with abnormal bleeding, carcinoma is the most important consideration, but it is not the most common cause. The most common cause of uterine bleeding in postmenopausal women is atrophy of the vaginal mucosa or endometrium. During the course of a workup for DUB, an endometrial biopsy must be done. If hyperplasia is discovered, the patient must have further evaluation including dilation and curettage. 

Uterine bleeding in a premenarchal girl is only rarely due to neoplasm; more common causes are foreign body, vulvovaginitis, and urologic factors.