Polarization-sensitive OCT as an early predictor of spontaneous pre-term birth.

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Spontaneous pre-term birth costs the UK NHS over £1billion annually and is a major cause of disability in the young. Babies that are born before the normal 38 weeks of gestation must spend the first weeks or months of their lives being kept alive artificially in incubators. Modern incubators represent a huge advance in medical care for premature babies and means that babies born as early as 28 weeks gestation now have an 80-90% chance of surviving to adulthood. Nonetheless, premature babies have an increased risk of growing up with disabilities such as cerebral palsy, retarded mental development, visual and hearing defects, breathing difficulties etc. Obstetricians and gynaecologists around the world are thus urgently trying to develop tools that can predict when a particular woman might be at risk of delivering her baby prematurely, so that preventative measures can be taken to try to delay the delivery and/or to try to speed up the development of the baby's lungs before he or she is born. A great deal of research is being undertaken currently to develop such a predictive tool, especially at Sheffield where we are pioneering methods that physically examine the cervical tissues themselves, as well as analyzing samples of the mother's blood or vaginal fluid. Despite these efforts however, the search is still ongoing to find a test that is sufficiently reliable to be useful to doctors, The human foetus develops in the womb and is contained within the protective, fluid-filled sack called the placenta. The placenta is held in position by the cervix, which is the narrow opening that separates the womb from the vagina. The mechanical strength of the cervix is what holds the developing baby inside the mothers body until it is ready to be delivered. Normal birth requires a softening (technically called "ripening") of the cervix, so that the baby can squeeze its way out. The strength of most body tissues, including the cervix, comes from a protein called collagen. As we age, the collagen content of our skin falls and so our skin becomes looser and more stretchy. Collagen can be degraded by a hormone called relaxin; this hormone is produced by the female body during pregnancy and is believed to contribute to a reduction in collagen content within the cervix. Might the risk of spontaneous preterm birth increase if the rate of collagen degradation is too high? Might it be possible to measure an "index" of collagen content of the cervix non-invasively, at various stages of a pregnancy? If so, might this index be able to identify women with an elevated risk of delivering prematurely sufficiently early that treatments can be applied in time to avoid the premature delivery? We will answer these questions by building a novel new type of camera that can measure the collagen content of the cervix, via a small imaging probe (similar to those used in keyhole surgery) that is inserted into the vagina and placed a few millimeters from the surface of the cervix. The procedure will be similar to an examination called "colposcopy" (which aims to detect cervical cancer) but will focus on the abundance of the collagen protein, not the health of the cells. Our technique is called "polarization sensitive optical coherence tomography" and we have already shown that it can measure the collagen content of cervical tissue samples that have been generously donated by women undergoing hysterectomies. The next stage is to use this measurement technique in the clinic, to image the cervix in its natural state. to this we will build a novel imaging probe and associated data collection system and then make trial measurements in volunteers. We will this learn what is the potential benefits of this technology for predicting pre-term birth.