Operative Hysteroscopy

The medium decides the catastrophe - A monopolar resectoscope needs electrolyte-free hypotonic fluid, and absorbed through open myometrial sinuses it drops serum sodium into cerebral edema and seizures. A bipolar system runs in saline, sparing the sodium and delivering the same volume as pulmonary edema.

The fluid deficit and its threshold - Inflow minus outflow is the only real-time index of how much medium has entered her, so ask for it at fixed intervals and agree a stop point with the surgeon before incision. That limit comes from institutional policy and current guidance, not memory.

Your own crystalloid counts - What you hang adds to the same circulating volume the surgeon is pushing in through the uterus, so run maintenance lean through a long resection and include it in the accounting.

A silent syndrome under anesthesia - Awake, she reports nausea, headache, visual disturbance and confusion as the sodium falls; asleep she tells you nothing until bradycardia with a rising pressure, or a seizure. Send a sodium as the deficit climbs toward your stop point.

Correction by protocol - Manage confirmed symptomatic hyponatremia through your institution's pathway with critical care involved, because the rate of correction is what causes the second injury.

Supraglottic airway or awake technique - No abdominal entry, no peritoneal stimulation and no relaxation needed, so an LMA with volatile or TIVA fits. Spinal to T10 or a paracervical block with sedation stay on the table because a patient who can report confusion is herself an absorption monitor; use a pencil-point needle if you go spinal.

The vagal moment at dilation - Stretching the cervix drives a reflex that produces sudden bradycardia and occasionally asystole in a young patient with high resting vagal tone. Be deep before the dilators go in, and have glycopyrrolate or atropine drawn up rather than in the drawer.

Fingers in the table break - The foot of the bed is dropped so the surgeon can sit between the legs, and a hand left at her side is crushed as it moves. Get her arms onto armboards or her hands wrapped and confirmed clear first, shoulder abduction under 90 degrees.

Perforation with an active loop - The loop cuts millimetres from the serosa, so a hot electrode through it burns bowel or lacerates vessels, and the cavity drains into the peritoneum: the view goes and the deficit jumps. Say both out loud the moment you see them.

The short case that opened up - Escalation is laparoscopy or laparotomy, so secure the airway with a tracheal tube, get a second large-bore cannula and send a group and save rather than carrying on with the anesthetic you planned.

Venous gas embolism - Air entrained down the sheath at instrument exchanges is driven into open sinuses by the pressurized cavity, showing as an abrupt fall in end-tidal carbon dioxide with hypotension. Give 100% oxygen, have the surgeon flood the field, go head-down left lateral, and call for help.

Baseline hemoglobin and pregnancy status - These women are on the list because they bleed, so anemia is the rule and there is no reserve when a resection bed opens; the baseline also separates dilution from surgical loss. Confirm pregnancy status, since this is not done on a wanted pregnancy.

Recovery after a large deficit - Pain that escalates rather than settles is perforation, not a reason for more opioid. A significant deficit earns a repeat sodium, observation and a documented handover about fluid balance, not a fast track to the door.

The uterine cavity is a potential space, so it has to be forced open with fluid before anything can be seen or cut, and that pressure is the whole problem. Resecting a submucous fibroid, a septum, or the endometrium down to its basal layer opens myometrial venous sinuses, and once intrauterine pressure exceeds venous pressure the distension medium does not seep across a membrane, it is pumped directly into the circulation through cut veins. The deeper and larger the resection, the more sinuses are open and the faster it goes. Hypotonic electrolyte-free media used with monopolar resectoscopes produce dilutional hyponatremia and cerebral edema, with seizures and death at the end of that road. Isotonic saline used with bipolar systems spares the sodium but delivers the same volume, giving circulatory overload and pulmonary edema instead.

Positioning and examination under anesthesia - The patient is placed in dorsal lithotomy in Allen stirrups, the bladder is emptied, and a bimanual examination establishes uterine size, axis and degree of anteversion or retroversion. A sharply flexed uterus is the one that gets perforated on entry.

Cervical dilation - A speculum is inserted and a tenaculum applied to the anterior lip of the cervix to straighten the uterine axis. The cervical canal is then dilated with graduated dilators to admit the resectoscope sheath, typically 8 to 10 mm, which is substantially larger than the 3 to 5 mm diagnostic scope and is why operative cases need dilation that diagnostic ones often do not.

Distension of the cavity - The medium is delivered either by a gravity column, where maximum intrauterine pressure is capped by the height of the bag above the uterus, or by an automated pressure-controlled pump. The lowest intrauterine pressure that gives an adequate view is used, because pressure buys visibility and is paid for in absorption.

Choice of medium follows the energy source - A monopolar resectoscope needs a non-conductive electrolyte-free fluid such as sorbitol or mannitol, historically glycine, so that current is not dispersed through the irrigant. A bipolar resectoscope carries both electrodes on the instrument and works in normal saline. This single decision is what determines whether an absorbed liter drops the sodium or simply fills the circulation.

Resection - A wire loop electrode shaves tissue in strips under direct vision. A submucous fibroid is shaved back flush to the cavity line, a polyp is taken at its base, intrauterine adhesions in Asherman's syndrome are divided to restore the cavity, a uterine septum is incised, or the endometrium is resected down to the basal layer for menorrhagia. Chips are removed intermittently as they obscure the view.

Continuous fluid accounting - Inflow and outflow are measured throughout and the running deficit is announced to the room. Automated pumps compute it directly; gravity systems require the scrub team to weigh drapes and measure canister volumes, which is less reliable and tends to under-read.

Concomitant laparoscopy in selected cases - For a deep intramural fibroid, dense adhesions, or a septum being cut close to the fundus, a laparoscope may be placed to watch the serosal surface, transilluminate the thinning myometrium, and warn of imminent perforation before it happens.

Hemostasis and finish - Bleeding vessels are coagulated with the loop or rollerball. Persistent bleeding from a large resection bed can be tamponaded with a Foley balloon inflated in the cavity and left for a few hours.

The three hysteroscopies on your list are not one anesthetic, and the instrument on the trolley tells you which one you have - Diagnostic hysteroscopy uses a thin scope in saline at low pressure with no cut surface, so absorption is trivial and the case is often done in the office with little more than local anesthesia. Global endometrial ablation devices such as radiofrequency systems are essentially closed: they deliver energy against the endometrium without a pressurized open resection bed, so they also sidestep the deficit problem, and their hazards are thermal injury and the short intense stimulus of the treatment cycle. It is specifically the resectoscope, with a large sheath, a cavity held open under pressure, and a cut myometrial bed full of open veins, that generates everything described above. Match your vigilance to the hardware rather than to the word hysteroscopy on the operating list.

Size the risk before the case rather than discovering it at the deficit alarm - Risk scales with the operation, and the surgeon can tell you in one sentence how bad this is likely to get. A 1 cm polyp taken at its base opens almost nothing. A 5 cm type II submucous fibroid with significant intramural extension requires deep resection into vascularized myometrium, opens a great many sinuses, and is the case that runs long, absorbs liters and gets staged into two operations for exactly that reason. Dense Asherman's adhesions are similar: poor visibility, prolonged operating time and a thin cavity wall. Ask which of these it is when you see the patient, because it determines whether you plan a routine forty-minute supraglottic anesthetic or set up for a case that may need an arterial blood gas, serial sodiums and a definite stopping point.