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Table 2 The basic clinical and technical requirements for assessment of the AFC in clinical practice (reproduced with permission from Broekmans et al.

From: Hormonal, functional and genetic biomarkers in controlled ovarian stimulation: tools for matching patients and protocols

Considerations for the assessment of the AFC in clinical practice
Clinical considerations Technical considerations
   Select patients with regular menstrual cycles with no co-existing pathological condition that could technically affect the counting of follicles, such as ovarian endometriosis or previous ovarian surgery A limited number of personnel, appropriately trained in transvaginal sonography should perform AFCs in each unit
Real-time, two-dimensional imaging is adequate
Count follicles between days 2 and 4 of a spontaneous menstrual or oral contraceptive cycle to avoid the effect of intra-cycle variation
Include all antral follicles of 2-10 mm in diameter
Use a transvaginal transducer
Use a probe with a minimum frequency of 7 MHz, which is maintained in an adequate condition and able to resolve a structure of 2 mm in diameter
     Use a systematic process for counting antral follicles:
  1. Identify the ovary
2. Explore the dimensions in two planes (perform a scout sweep)Decide on the direction of the sweep to measure and count follicles
3. Measure the largest follicle in two dimensions
  A. If the largest follicle is ≤10 mm in diameter:
  i. Start to count from outer ovarian margin of the sweep to the opposite margin
ii. Consider every round or oval transonic structure within the ovarian margins to be a follicle
iii. Repeat the procedure with the contralateral ovary
iv. Combine the number of follicles in each ovary to obtain the AFC
  B. If the largest follicle is > 10 mm in diameter:
  i. Further ascertain the size range of the follicles by measuring each sequentially smaller follicle, in turn, until a follicle with a diameter of ≤10 mm is found
ii. Perform a total count (as described) regardless of follicle diameter
iii. Subtract the number of follicles of > 10 mm from the total follicle count
  1. 2010 [13])
  2. AFC = antral follicle count.