High-grade serous carcinoma of the ovary is believed to originate in the fallopian tubes (FTs). A submillimeter diameter endoscope with advanced imaging capabilities may take advantage of the natural pathway of the female reproductive tract to image the FTs in a minimally invasive procedure for early detection of cancer. Our lab previously built a prototype benchtop FT endoscope with pseudowhite light imaging, multispectral fluorescence imaging and optical coherence tomography. This endoscope was approximately 0.9 mm in diameter, flexible and steerable in one direction. Several modifications have been made to create a falloposcope imaging system which is ready for clinical use. This new design includes a multilumen extrusion, a revised handle design, simplified lens design and redesigned subsystems resulting in improved mechanical characteristics, biocompatibility and portability while maintaining image quality. Additionally, these clinical endoscopes are single use, considerably less expensive and faster to build as compared to the prototype.

Microendoscopes are commonly used in small lumens in the body for which a focus near to the distal tip and ability to operate in an aqueous environment are paramount for navigation and disease detection. Commercially available distal optic systems below 1 mm in diameter are severely limited, and custom micro lenses are generally very expensive. Gradient index of refraction (GRIN) singlets are available in small diameters but have limited optical performance adjustability. Three-dimensional (3D)-printed monolithic optical systems are an emerging option that may be suitable for enabling high performance, close-focus imaging. In this manuscript, we compared the optical performance of three custom distal optic systems; a custom-pitch GRIN singlet, 3D-printed monolithic doublet, and 3D-printed monolithic triplet, with a nominal working distance (WD) of 1.5, 0.5, and 0.4 mm in 0.9% saline. These short WDs are ideal for microendoscopy in collapsed or flushed lumens such as pancreatic duct or fallopian tube. The GRIN singlet had performance limited only by the fiber bundle relay over 0.9-to 1.6-mm depth of field (DOF). The 3D-printed doublet was able to achieve a comparable DOF of 0.71 mm, whereas the 3D-printed triplet suffered the most limited DOF of 0.55 mm. 3D printing enables flexible design of monolithic multielement systems with aspheric surfaces of very short WDs and relative ease of integration.

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