The operating room setup varies to some extent. Each OR and each surgeon has their own "routine" which they are comfortable with. I will present my routine for comparison sake.

The positioning of the patient is important so as to avoid musculoskeletal and neurologic complications. I position a woman for pelvic evaluation (hysteroscopy and laparoscopy) with the buttocks slightly (few centimeters) extending beyond the end of the table (after the foot of the table is lowered or removed). The back of the woman is viewed to assure that it is flat on the table once her legs have been placed in Allen's universal stirrups at this position. If the back is acutely flexed, the woman is repositioned to avoid postoperative lower back discomfort. I routinely tuck the patient's left arm at her side since I always stand on the left and if the arm is extended and placed on an arm board then (brachial) nerve damage is possible if the arm board becomes dislodged or I inadvertently lean on the arm board during the case. I also tape the left hand's fingers into a fist to avoid injury when the foot of the bed is raised at the end of the case. No joint in the leg is flexed over 60 degrees to avoid (femoral) nerve compression (associated with extreme flexion, abduction, and lateral rotation at the hip). I also am very careful to avoid excessive pressure on the lateral aspect of the lower legs within the Allen's stirrups (which helps avoid peroneal nerve damage and "foot drop"). I generally like the thigh of the leg to be roughly parallel to the floor when the table is flat to allow for greater range of motion of instruments entered into the lower laparoscopic ports. The patient is then prepped (including placement of a foley catheter) and draped in the usual sterile fashion.

I begin my pelvic evaluation for infertility with a hysteroscopy. The visibility with these systems is often far superior to other systems (partially because the cavity can be flushed of endometrial debris if present) and I have not had difficulty with the additional dilatation of the cervix that is required for the entry of a continuous flow hysteroscopic system. Therefore, I routinely use a continuous flow hysteroscope. I dilate the cervix and place the hysteroscope into the cavity (using a safe routine that I have established) once the equipment has been assembled (and checked).

The selection of the uterine distending medium for continuous flow hysteroscopy is very important.

• I use 5% Dextrose in Water (D5W) as my standard solution since it is an accepted intravenous (IV) solution, it is nonionic (can not carry an electrical charge), there is extensive clinical experience with it as an IV solution (although there are no reports in the world literature of serious morbidity or mortality attributed to the use of D5W when used for hysteroscopy), and the osmolarity of the solution (about 250 mOsm/L) is relatively close to that of blood serum (about 290 mOsm/L).
• Additional acceptable hysteroscopic solutions include other non-ionic hypo-osmolar low viscosity fluids (1.5% Glycine or Sorbitol), electrolyte containing ionic iso-osmolar solutions (Normal Saline (NSS) or Ringer's Lactate (RL)) and non-ionic hyper-osmolar solutions (32% Dextran 70 = Hyskon). Sterile Water was a fluid used early on by Urologists for transurethral resections of the prostate ("TURPs") but its use has been severely limited due to its complete absence of osmolarity and strong hemolytic effect upon intravasation. If hemolysis occurs, the resulting electrolyte changes (especially hyperkalemia) may cause changes in cardiac (heart) function (seen on the EKG = cardiac monitor). If the hemolysis is abundant the electrolyte changes can result in a complete electrical disruption of the cardiac function, cardiac arrest and sudden death in an otherwise totally healthy appearing patient. I do not believe that sterile water has a place in modern continuous flow hysteroscopy.
• Ionic solutions such as NSS and RL can carry an electrical charge and therefore can not be effectively used when a resectoscope (the electrical operative hysteroscopy instrument that I use) is used for electrical operative hysteroscopy.
• 1.5% Glycine is a commonly used standard hysteroscopic distending medium. 1.5% Glycine is a nonionic solution with an osmolarity (200 mOsm/L) that is less than D5W or serum. Glycine has an intravascular half life of about 85 minutes after which it is absorbed intracellularly. Hyperammonemia due to oxidative deamination in the liver and kidneys is associated with the use of glycine, which can cause encephalopathy. Additionally, an occasional patient may have a decrease in visual acuity (or temporary blindness) possibly due to the effect of glycine as an inhibitory neurotransmitter in the retina. These complications appear to be proportional to the absorption or intravasation of Glycine into the circulation and limit the volume of use of this distending medium.
• Sorbitol (2.7%) and mannitol (0.54%) are 6 carbon alditol isomers that are commercially available together in solution ("Cytal"). This solution has a lower osmolarity (178 mOsm/L) than 1.5% Glycine or D5W. The Sorbitol is metabolized in the liver to fructose and glucose while the mannitol is mainly filtered through the kidney and excreted unchanged in the urine. One disadvantage for the use of Cytal is caramelization of the sugars during electrocautery.
• 32% Dextran 70 is a syrup like slick solution with a high osmolarity. This solution draws free water into it (able to draw in greater than 4-6 times its own volume) so the volume used must be highly restricted to avoid volume overload. Typically, one will restrict the total volume used to 250-500cc. Uncommon but very serious potential complications of Dextran include ARDS, DIC, anaphylactic shock and renal failure. This solution is not often used for operative hysteroscopy today.

Whenever one of the hypotonic distending media (D5W, 1.5% Glycine, Sorbitol) is used for continuous flow hysteroscopy there must be an accurate and continuous tabulation of the amount of solution going into the hysteroscope and the amount of solution returning from the hysteroscope. The hypo-osmolar low viscosity fluids all have the potential for causing excess "free water" (proportional to their degree of hypo-osmolarity) and water intoxication if intravasated (or absorbed) in volumes that exceed the body's ability to excrete the excess water load. Water intoxication results in hyponatriemia (low extracellular sodium concentration in the circulation) and the movement of water across the blood brain barrier to cause cerebral edema. As the brain swells, injury to the brain by the bony confines of the skull or brain herniation may occur. The massive amount of cerebral edema that may be secondary to water intoxication is therefore associated with serious morbidity or mortality.

A protocol for monitoring and responding to excessive fluid absorption should be in place in every operating room in which operative hysteroscopy is performed. One such protocol is presented here as a "functional example." However, please note that there are other less restrictive protocols (particularly with respect to D5W) in many operating rooms. Generally, for every liter (1000 cc) of D5W infused IV the expansion of the extracellular volume in the circulation is only about 83 cc (due to distribution of the volume into the various body spaces) which decreases the plasma osmolarity by about 2%. The body's reaction to even this small decrease in osmolarity is to completely suppress the antidiuretic hormone (ADH) release from the brain's pituitary gland and cause a maximal water diuresis (usually greater than 750 cc of urine per hour).