The History of Hysteroscopy

The curiosity to explore the non-visible parts of the body is as old as civilization itself - ancient clinicians demonstrated ingenuity in achieving their goal. From the Hippocratic school (4th century BC) there are descriptions of tubular instruments, similar to current specula, that were used to study cavities such as the rectum and vaginal canal using ambient light (1). In the 2nd century AD, the Roman, Galen of Pergamon, now part of Turkey, a fervent student of anatomy, described the use of rectal and vaginal dilators to provide access to body cavities - but he was no early endoscopist. Seminal work was generally lacking in the middle ages although Albukasim (980–1037) in the Western Muslim Caliphate in medieval Cordoba in Spain and then the Italian Giulio Cesare Aranzi (1530–1589) described the use of a type of speculum with a set of light reflectors setting the stage for the combination of access to a body cavity and illumination of the interior (1-3).

 The roots of modern endoscopy probably rest in the hands and mind of Phillipe Bozzini, a young obstetrician from Frankfurt who was perhaps the first to conceptualize the notion that the interior of body cavities could be explored with the combination of a hollow tubular probe and illumination from an external source. In 1805 he developed and subsequently published a description of an open ended tubular endoscopic instrument designed along these principles - "As it is impossible to obtain from chemistry a substance capable of illuminating the interior of the body cavities, and thus render these accessible to our eye, by means of a straight tube inserted therein, we have to conduct light from outside through the inserted tube"(4). 

The lichtleiter, or light conductor, was a hollow tube divided by a vertical septum containing a set of concave mirrors that transmitted the light from a wax candle and allowed the visualization of body cavities such as the mouth, nose, ears, vagina, cervix, urethra, urinary bladder and rectum(2) (5). 

Decades passed but on July 12, 1853, at the Paris Académie de Médicine, the French urologist Antoine Jean Désormeaux provided the first satisfactory description of an endoscope illuminated by a kerosene lamp that was designed for the diagnosis and treatment of visible urethral and bladder conditions(6, 7).  The lamp, situated at the base of the device, was lighted by “gasogene” a compination of turpentine and alcohol. The light had to be deflected down the tube using a concave mirror set at a 45ᴼ angle.  A lens system designed to conduct the light  was superior to that designed by Bozzini, allowing for improved illumination and visualization (See Figures). In addition to the imaging channel, there was an integrated conduit designed to allow the insertion of instruments. He designed the instrument  for procedures on the urethra and urinary bladder and became the first to demonstrate performance of an endoscopic operative procedure on a living patient. For this, Désormeaux is often called one of the fathers of endoscopy and, in a way, directly influenced hysteroscopy as it was, and is, a close cousin to cystoscopy as we will soon see. We will also see that much of the development that led to contemporary hysteroscopic technique through to the end of the 20th century was actually led by those seeking to endoscopically evaluate the lower urinary tract. 

Illumination was an issue that challenged endoscopic designers and clinicians as one can imagine given the available technology of the time. Indeed, there were real risks to both patient and surgeon from the flame-based methodology used to illuminate the cavity being inspected. Sir Francis Richard Cruise (1834-1912), from Dublin, also a urologist, demonstrated the ability to perform endoscopically assisted urethrotomies using a modification of the Désormeaux device which placed the lantern on the side, not the bottom, and replaced alcohol with a petroleum camphor solution that improved illumination. Cruise also improved the visualization system by separating the illumination and imaging aspects of the device and encased the lantern supplying the light in a mahogany box so that it could be handled without burning the surgeon, or the patient (5, 8). remember, these endoscopes had no optical lenses - they were hollow tubes, and the illumination was provided by flame-producing devices making visualization difficult and the procedure somewhat risky - to both patient and surgeon.

It is at about this time that the work of Désormeaux was directed to the endometrial cavity. Credit for the first published and successful hysteroscopic procedure goes to Diomede Pantaleoni, from Macerata Italy, who had shared some time with Cruise in Dublin. The 1869 publication describes the changes made to the 12 mm diameter Desormeaux and Cruise instrument (8-10). With what was essentially an “office” procedure, Pantaleoni diagnosed a small endometrial polyp "about the size of a small blackberry" in a 60-year-old with postmenopausal bleeding. He then performed silver nitrate cauterization of the endometrial polyp and repeated the process multiple times, all under endoscopic direction. In the paper Pantaleoni offered that this was a technique that was superior to the digital or blind techniques of the time, in large part because it was unnecessary to dilate the cervix to a degree that was adequate to accept a finger. 

Understand that there was no distending medium designed to create the image that we use today, a circumstance that severely limited the field of view. Indeed, the contemporary approach used to evaluate the endometrial cavity was indeed the single digit exploration through a dilated cervix alluded to by Pantaleoni. The rather compromised hysteroscopic image of the time led Paul Fortunatus Mundé of Dartmouth College in New Hampshire, and the editor of the American Journal of Obstetrics and Gynecology, to state in his 1880 textbook on minor gynecological surgery: “…it will be found vastly more useful to pass the finger into the uterine cavity and touch its whole surface than to see one small disk one half to one inch in diameter” (11). Indeed, there was much left to do to make hysteroscopy a viable and useful tool.

The next major step in the evolution of endoscopy was from the partnership of a urologist from Berlin, and an instrument maker from Vienna Austria. In the late 1870s, Maximilian Carl-Friedriche Nitze, the Berlin urologist, partnered with Joseph Leiter, the Viennese instrument maker, to further develop his 7 mm diameter system and describe the first “modern” cystoscope for the Royal Saxon Medical College in Dresden Germany. One year later the device was presented to the Royal and Imperial Doctor’s Association in Vienna Austria and demonstrated on a live patient. The instrument included, for the first time, a series of optical lenses to magnify the image and an integrated, water-cooled (by circulation of ice-water in the bladder) incandescent light based on a platinum wire (1, 5, 8, 13, 14). For the first time, creative surgeons had a system that, on the surface at least, looks remarkably like the ones we use today.

A French contemporary of Gauss and Schroeder, Robert Segond, published additional modifications in 1934 that further improved imaging by increasing the diameter of the outflow component of the hysteroscopic system. This allowed more rapid “clearance” of the visual field of blood and other debris. Also included were two designs – one an 8 mm outside diameter (OD) system for diagnosis only while the other was 11 mm OD with an instrument channel (30, 31).  For all intents and purposes, this design is very similar to contemporary devices, differing in the diameters needed for the combined purposes of illumination, visualization and intrauterine instrumentation.   

In the United States, one of the great contributors to mid 20th century hysteroscopic development was William Norment (1899-1980) from Greensboro North Carolina, who published several manuscripts between 1941 and 1975. Perhaps his greatest contribution was description of a simplified technique and recognition of the poor correlation between clinical findings, radiological methods and the hysteroscopic findings where carcinomas could comingle with benign endometrial polyps and submucous leiomyomas, evading diagnosis by D&C(32, 33). 

The decades of the 1950s and 1960s saw relatively little development and adoption of hysteroscopic technique. Nevertheless, there were some incremental steps. The potential for hysteroscopic evaluation in pregnancy was explored by Aguero et al Aure, who used flexible hysteroscopes to evaluate pregnant patients in all three trimesters for a spectrum of indications from first trimester bleeding to premature rupture of the membranes (34).

Blood remained an issue with low viscosity fluids the two would comingle obscuring the image. Consequently, Edström and Fernström from Stockholm, Sweden, described the use of 32% Dextran 70 for endometrial cavity distension, a viscous solution that does not mix with blood and therefore can preserve visualization even when slight bleeding is present (35). This solution found relatively widespread adoption but it presented difficulties since it was prone to dry and “carmelize” on instruments making them unusable if not cleaned properly. It is little used today.

But let’s get back to Hopkin’s rod lenses for visualization and the fibers originally conceived by Baird for the transmission of light. An innovative entrepreneur named Karl Storz, the son of a German medical instrument maker, followed in his father’s footsteps and in 1945, at the age of 34 started a medical instrument manufacturing company in Tuttlingen Germany, that originally focused on devices for ear, nose and throat surgeons(41). Inevitably he became involved in the design of endoscopes and acquired and then merged the intellectual property for a number of technologies to design the rigid endoscopic systems still dominant today. The cold – meaning remote from the operative field - light source was released for endoscopy in 1960. 

The light from the remote (“cold”) source is transmitted via a flexible cable typically containing thousands of those tiny fibers as conceived by Baird, and implemented by Hirschowitz, to its attachment with the endoscope, that itself has bundles of similar fibers that conduct the light to the end of the device for illumination of the body cavity. The rod lenses patented by Hopkins then deliver this image to the optic or eyepiece for viewing. This system became available to the surgical community in the mid 1960s.

Robert Neuwirth of New York, also known for his early adoption of laparoscopy, can be considered to be one of the first to have used this technology to influence the next stage in the worldwide development of hysteroscopic surgery, starting in the late 1960s and extending for more than 30 years, into the next century. He is particularly known for his role in leveraging the utility of the urologic resectoscope for intrauterine procedures using radiofrequency electrical energy (8). He was behind the concepts that included tubal sterilization in 1971 (42), adhesiolysis (1973)(43) and, submucous myomectomy using a loop electrode for electrosurgical morcellation and extraction(44). He also participated in the development of the thermal balloon endometrial ablation device, one of the newer non-resectoscopic techniques for endometrial ablation(45). 

Two gynecologic surgeons from Los Angeles and the University of Southern California began to publish series on operative hysteroscopic techniques. In 1976 March and Israel reported hysteroscopically directed tubal cannulation(46) and reported a series of hysteroscopic adhesiolysis on 10 patients, all performed in an outpatient setting and all resulting in normal menses (47). This report was followed by others and dramatically changed the approach to Asherman Syndrome from blind and blunt destruction of adhesions to the directed approach now accepted today as the prevailing standard of care. 

In 1981, Milton Goldrath from Detroit, Michigan, USA, reported on the use of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for endometrial ablation. The FDA approved the Nd:YAG laser for that purpose in 1986 and the resectoscope for gynecologic procedures in 1989 (8, 50). Soon after, a number of other creative surgeons demonstrated that endometrial ablation could be performed using the monopolar RF resectoscope with a loop electrode (De Cherney)(51) or coagulation, typically with a rolling ball electrode (Vancaillie)(52) and some years later a vaporizing electrode (Vercellini)(53). These techniques were hysteroscopically directed methods for performing a procedure first reported without endoscopic control in the late 19th century and rediscovered towards the end of the 20th century, when they have often been misnamed as "second generation" endometrial ablation devices. Indeed, Goldrath invented one of these systems, and the only one that has hysteroscopic control - the Hydrothermablator, that uses heated saline to perform the procedure(54, 55). 

One solution to this problem would be the use of physiologic solutions for RF electrosurgery. However, for more than a century, RF electrosurgery in the bladder, and more recently the uterus, had been based on the notion that electrolyte free media must be used and the two poles of the circuit had to be separated – one directed to the target tissue, the other formerly placed on the patient remote from the operative field. However, in the last 20 years of the 20th century, it became apparent that by placing both electrodes on the resectoscope in close proximity to each other, it was possible to achieve a tissue effect while operating in a physiological solution, a design that dramatically changed the landscape for RF electricity in the uterus. Several designs were introduced almost contemporaneously, including a dispersive sheath for a standard monopolar resectoscope reported by Isaacson in 1997(64), and a purpose built resectoscope built by a California company called FemRx initially published in 1998(65). This concept has now been adopted by all manufacturers of resectoscopes although monopolar systems are still in use even today. Five French diameter bipolar instruments – needle, vaporizing and coagulating - for use with standard operating hysteroscopic systems were introduced by George Vilos, from London Ontario Canada in 1999(66, 67).

The addition of the video camera to hysteroscopy was transformational. While hysteroscopic surgery can be performed with one hand holding the endoscope to the eye, while the other hand controls an instrument, it can be clumsy, and procedures that require detailed coordination of hand, foot and the endoscope are virtually impossible. Furthermore, such an approach doesn’t allow for simultaneous viewing by a trainee, for supervision of a trainee, or for presenting surgical cases in a way that fosters education and collective development of technique.  

Video cameras only date back to the 1940s but these were large devices comprising hundreds of pounds of tubes, cases and connectors, that had no real utility in surgery.  The clear video images used to guide contemporary endoscopic surgery really are based on technology conceptualized by Einstein in the 1920, but ultimately introduced in 1969s – the charged coupled device, or CCD – the original small grid of tiny sensors that capture photons of light and convert them to energy which can be stored and into images that. This CCD was developed at AT&Ts Bell Laboratories by George Smith and Willard Boyle who received the 2009 Nobel Prize in physics(78), and the invention was translated in 1972 to color video imaging by Michael F. Tompsett, also from Bell Labs(79).