The Fertile and Infertile Phases of the Menstrual Cycle are Signaled by Cervical-Vaginal Fluid Die Swell FunctionsWang, Jian PhD*; Usala, Stephen J. MD, PhD†; O'Brien-Usala, Faye DC‡; Biggs, William C. MD, FACE†; Vaughn, Mark W. PhD§; McKenna, Gregory B. PhD¶Author Information *Graduate Student, Department of Chemical Engineering, Texas Tech University, Lubbock, TX; †Clinical Associate Professor, Department of Internal Medicine, Texas Tech University, Health Sciences Center, Amarillo, TX; ‡Clinical Coordinator, Amarillo Medical Specialists, Amarillo, TX; §Associate Professor, Department of Chemical Engineering, Texas Tech University, Lubbock, TX; and ¶Horn Professor, Department of Chemical Engineering, Texas Tech University, Lubbock, TX. Drs Wang, Usala, and McKenna have disclosed that they are inventors of the die swell device and method, for which a patent is pending. Drs Usala, Biggs, Vaughn, and McKenna have disclosed that they have a current and previous relationship/financial interest as stock shareholders of AMS Rheology and Reproduction, Inc. Dr O’Brien-Usala has no significant relationships with or financial interests in any commercial organizations pertaining to this educational activity. All staff in a position to control the content of this CME activity have disclosed that they have no financial relationships with, or financial interests in, any commercial companies pertaining to this educational activity. Lippincott CME Institute has identified and resolved all faculty and staff conflicts of interest regarding this educational activity. Reprints: Gregory B. McKenna, PhD, Department of Chemical Engineering, Texas Tech University, 6th and Canton, Mail Stop 3121, Lubbock, TX 79409-3121. E-mail: [email protected] Chief Editor's Note: This article is the 16th of 18 that will be published in 2009 for which a total of up to 18 AMA PRA Category 1 Credits™can be earned. Instructions for how credits can be earned precede the CME Examination at the back of this issue. The Endocrinologist: November/December 2009 - Volume 19 - Issue 6 - pp 291-297 doi: 10.1097/TEN.0b013e3181bed4a2 Buy Take the CME Test Metrics Abstract Natural family planning is a method of fertility awareness based in part on detection of the fertile and infertile phases of the menstrual cycle through self-observation of cervical-vaginal secretions. Cervical-vaginal fluid (CVF) contains cervical mucus, a hydrogel that undergoes cyclic changes in viscoelasticity. We constructed a die swell device to study the viscoelastic properties and establish material functions of CVF samples that women obtain by self-aspiration. Two women for a total of 8 cycles provided day-specific CVF, urine and blood samples. Day-specific CVF samples were indexed to the day of ovulation (day 0) defined as the day of the luteinizing hormone peak. These samples were analyzed by extrusion through the die swell device and measurement of the subsequent flowgrams. Die swell ratio (B) was measured as the ratio, (maximum diameter of fluid swell after extrusion)/(inner die diameter), and die swell position (DisMax) was measured as the start position of maximum swell from the die orifice. These 2 rheological material functions, B and DisMax, were found to reliably correlate with the fertile and infertile phases of the cycle. This novel die swell device and methodology enables detection of viscoelasticity and therefore the presence of cervical mucus in CVF. Furthermore, it provides rheological measurements of cervical-vaginal secretions that correlate with the fertile and infertile phases of the menstrual cycle. The die swell device and methodology may serve as an aid for natural family planning. © 2009 Lippincott Williams & Wilkins, Inc.