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Operative Hysteroscopy Intravascular Absorption (OHIA) syndrome is a significant complication of operative hysteroscopy, arising from excessive fluid absorption during the procedure []. Although rare, severe fluid overload can result in critical conditions requiring intensive care, such as dilutional hyponatremia, hypoosmolality, cerebral edema, hypokinetic circulation, and cardiovascular collapse []. During surgical resection, hydrostatic pressure typically exceeds intravascular pressures, particularly within the venous system, facilitating the intravasation of irrigation fluid from the surgical field into the intravascular space []. The greater the disparity between these pressures, the higher the flow rate into the bloodstream and the greater the risk of fluid overload. Furthermore, despite efforts to minimize surgical time and maintain low distension pressures, fluid overload can still occur unexpectedly and before the anticipated timeframe []. Preventive measures, such as low-pressure irrigation, can help reduce fluid absorption but do not completely eliminate the risk of this complication. Monitoring fluid absorption during surgery is essential for maintaining fluid balance in individual patients.

Reports examining the clinical relationship between irrigation fluid temperature and intravasation rates or the risk of fluid overload are scarce and primarily based on theoretical models []. Studies on transurethral prostatic resection (TUR) have reported benefits of cold irrigation fluids, including shorter procedure duration, improved surgical visualization, reduced fluid use, and decreased blood loss [, ]. However, the evidence regarding increased complication rates due to hypothermia from locally applied cold irrigation solutions is mixed, and such findings have not been specifically demonstrated in hysteroscopic procedures [, ]. The use of warm distension fluid in office hysteroscopy has recently been introduced to reduce pain severity []. A recent meta-analysis of five randomized controlled trials reported that warm saline was associated with a significant reduction in the visual analog scale (VAS) pain score during the procedure and higher patient satisfaction []. However, warm irrigation solutions may be limiting for longer procedures, as the expected expansion of the vascular system can lead to a higher fluid deficit in a shorter time.

This study aims to evaluate the impact of irrigation fluid temperature on fluid deficit during hysteroscopic procedures, comparing two temperature setups: 24 °C (room temperature) and 37 °C (body temperature). Based on previous studies, we hypothesize that the use of warmed fluid will result in a larger fluid deficit, while potentially reducing postoperative pain perception.

A total of 91 women met inclusion criteria, of them 44(48%) in the room temperature group and 47(52%) in the body temperature group (Fig. ). Patients' demographic and clinical characteristics are summarized in Table . The median age and BMI were comparable between the groups. The study included participants from all ethnicities, with the largest being Afro-American, comprising one-quarter of the study population. The most common procedure performed was diagnostic hysteroscopy (Fig. ). Table outlines the hysteroscopic characteristics. The Mini TruClear™ hysteroscope was used in 93% of procedures in the room temperature group and 91% in the body temperature group ( p = 0.76). The tissue shaver was used in more than half of the procedures, with similar rates between the groups [25 (57%) vs. 31 (66%), respectively; p = 0.53]. Interestingly, the time required to reach fluid deficits of 100, 150, and 200 ml was shorter in the room temperature group compared to the body temperature group, although the differences did not reach statistical significance ( p = 0.31, 0.21, 0.25, respectively). The total fluid deficit was higher, and the total time to complete the procedure was shorter in the body temperature group, as expected; however, these differences were not statistically significant (Table ).

As hysteroscopic myomectomies are expected to expose more uterine vessels, potentially influenced by vasodilatation from the warmed solution, leading to increased intravascular absorption, an additional sub-analysis was performed based on the indication for surgery (Table ). All deficits measured were comparable between the groups for both fibroid and non-fibroid procedures. The use of warm solution did not significantly influence the fluid deficit. Postoperative pain evaluation using the VAS score in the recovery room revealed lower scores in the body temperature group compared to the room temperature group [4 (0–6) vs. 1 (0–6); p = 0.38]. This trend is consistent with previous reports associating warm temperature with reduced post-procedural pain, although it did not reach statistical significance. A multiple regression analysis was conducted to identify independent factors associated with the total fluid deficit, including age, BMI, fluid temperature, indication for surgery, and use of the tissue shaver. The use of the tissue shaver was found to be the only statistically significant independent factor associated with the fluid deficit [B = 396.19, 95% CI: 155.93–636.45, p = 0.002] (Supplement Table ).

The main findings of the study are: 1- Fluid temperature did not significantly influence the fluid deficit during hysteroscopy; 2- Similar findings were observed in both fibroid- and non-fibroid–indicated hysteroscopies, though subgroup analyses were limited by small sample sizes in the fibroid cohort.; and 3- A trend toward lower VAS scores was observed with body-temperature fluid.

The adoption of in-office hysteroscopy is influenced by both appropriate patient selection and the availability of necessary equipment and resources. Vaginoscopy is the preferred entry technique, as it has been shown to reduce intra-procedural and post-procedural pain [].

Hysteroscopy is a minimally invasive procedure that can be performed either in an office setting or an operating room, depending on the underlying pathology []. Recently, an increasing number of clinics have started offering in-office hysteroscopic interventions, such as endometrial sampling, polypectomy, and submucosal myomectomy. Advances in technology have facilitated the use of smaller hysteroscopic equipment, eliminating the need for cervical dilatation, which is often associated with significant patient discomfort [, ]. Additionally, the adoption of vaginoscopy as a preparatory step has further minimized the potential for painful vaginal and cervical interventions, enhancing patient comfort during the procedure []. n this study, we included patients who underwent the procedure in the operating room to utilize the TruClear™ hysteroscope, which features a fluid collection system essential for the precise evaluation of fluid deficit. This equipment is exclusively available in the operating room at our institution. To enhance patient comfort, all procedures were initiated with vaginoscopy, minimizing the potential for pain or bleeding associated with the intervention.

The primary benefits of performing interventional hysteroscopy in an ambulatory setting include avoiding general anesthesia, reducing operating room costs, and saving time for the patient []. However, one of the main challenges is managing patient pain, which is often a limiting factor in completing the procedure [, ]. To address this issue, surgeons have introduced the use of warmed solutions, which have been shown to significantly reduce Visual Analog Scale (VAS) pain scores []. The pain-reducing effect of warmed solutions has been demonstrated previously in other procedures, including warmed humidified insufflation (WHI) in laparoscopic abdominal surgeries, hysterocontrast sonography, and hysterosalpingography [–]

The use of warm solution as a distension medium during hysteroscopy for pain alleviation remains controversial [, –]. Isaat et al. [] conducted a prospective randomized placebo-controlled study involving 100 women undergoing office hysteroscopy. Visual Analog Scale (VAS) scores were compared between women treated with 0.9% normal saline fluid warmed to 36 °C and those treated with saline at room temperature (25°C). The study found no significant differences in VAS scores during the procedure ( p = 0.554) or 5 min afterward ( p = 0.12). In contrast, Gulucu et al. [] assessed six VAS measurements during office hysteroscopy in 100 women randomly assigned to receive distension fluid at 37 °C or 25°C. They reported significantly lower VAS scores in the warm fluid group during specific phases of the procedure, including the cervical ostium transition, intra-cavity phase, and at the end of the procedure ( P < 0.05). A recent meta-analysis of five randomized controlled trials involving 441 patients concluded that using warm saline in office hysteroscopy effectively reduces pain during and after the procedure and improves patient satisfaction []. In our study, no statistically significant difference in VAS pain scores was observed between the two fluid temperature groups. However, there was a trend toward lower pain scores with the warm solution (4 vs. 1; p = 0.38).

Concerns regarding the use of warm solutions during hysteroscopy are primarily related to the potential for vascular expansion, which may increase intravascular absorption. This could elevate the fluid deficit during the procedure, limiting its duration and increasing the risk of hysteroscopy intravascular absorption (OHIA) syndrome []. Although rare, OHIA syndrome can cause significant morbidity and even mortality following what is generally considered a minor and safe procedure expected to conclude uneventfully. Studies evaluating fluid deficit as a function of irrigation solution temperature during hysteroscopy are limited and largely conducted on simulation models. Fonseca et al. [] investigated the role of solution temperature on absorption rates during endoscopic surgery. They assessed the time to reach fluid overload at various temperatures—17°C, 27 °C, and 37°C—using both electrolyte and non-electrolyte irrigation solutions. Their findings indicated that increasing the solution temperature from 17 °C to 37 °C resulted in a predicted 54% increase in the mean absorption rate and a 65% reduction in the theoretical "safe" duration of surgery for both solution types.

The findings of this study did not demonstrate a significant difference in fluid absorption based on the temperature of the fluid. Although a trend was observed in the warm solution group, where shorter durations were noted to reach specific fluid volumes (100, 150, 250 mL), the differences were not statistically significant. This trend was also apparent in cases where hysteroscopic myomectomies were performed, as more vessels are typically exposed, potentially increasing fluid absorption. However, this difference did not reach statistical significance in this subgroup either. A possible explanation for this lack of significance could be the relatively short duration of the procedures, which were influenced by the nature of the pathology. The procedures conducted in this study reflect the variety typically performed in an outpatient clinic (Fig. ), making these findings relevant. They may provide reassurance to surgeons regarding the use of warm solutions without the concern of potentially limiting procedure duration or increasing patient risk.

Another possible explanation is the smaller temperature differential between the groups in this study, which may not have been large enough to produce a significant difference in fluid deficit, as demonstrated by Fonseca et al. []. The chosen temperature ranges (body temperature and room temperature) were based on previous studies and clinical practices [, ]. Since no procedures were terminated due to significant fluid deficit, the selected temperature difference was likely sufficient for the evaluation and provides scientific support for the clinical use of both. However, further studies might investigate the impact of cooling distention fluids in procedures that require longer durations, such as larger myomectomies (FIGO 2–3), which are often performed in two stages due to fluid deficit limitations.

To the best of our knowledge, this is the first randomized controlled trial comparing hysteroscopic fluid deficit at room temperature versus body temperature in humans. All procedures were conducted in a single surgery center by a specialized and consistent surgical team, which minimized potential confounders that could have influenced the study results. Additionally, the external validity of the study is high, as it included a diverse population with various gynecological pathologies.

However, several limitations of this study should be acknowledged. First, the study sample was relatively small, with a limited number of participants treated for fibroids. Since fibroids are more likely to be associated with increased fluid absorption and may lead to early termination of the procedure, a larger cohort would have provided more robust and generalizable data. Second, fluid loss during the vaginoscopy portion of the procedure was not measured separately, potentially leading to an overestimation of the total fluid loss associated with the procedure. Third, all procedures were performed under general anesthesia, which prevented assessment of intraoperative pain related to fluid temperature and limits the applicability of the findings to office-based hysteroscopy, where patient comfort and tolerance are key considerations. Lastly, both soft and dense tissue shavers were included in the study. Although these devices share a similar mechanism of action, they differ in their application and efficiency—particularly in treating larger or more fibrotic lesions—which may have introduced variability in fluid absorption outcomes.

The aim of this study was to evaluate the association between irrigation fluid temperature and fluid deficit during hysteroscopic procedures. The study findings suggest that irrigation fluid at body temperature, as compared to room temperature, does not significantly impact fluid deficit during hysteroscopy, regardless of the procedure’s indication. To the best of our knowledge, this is the only randomized controlled trial comparing the effects of room-temperature versus body-temperature irrigation fluid on fluid deficit during hysteroscopy in humans.

Despite concerns regarding the potential for higher fluid deficits with warm fluids, the findings support the use of body-temperature irrigation fluid, which may help reduce patient discomfort during ambulatory hysteroscopic procedures. This information is valuable for both physicians and patients when selecting optimal procedural conditions. However, these findings should be interpreted with caution given the relatively small sample size, the exploratory nature of subgroup analyses, and the fact that all procedures were performed under general anesthesia, which may limit applicability to office-based hysteroscopy settings. Larger studies are needed to validate these results and assess their generalizability across broader clinical scenarios. Future investigations should consider comparing multiple irrigation fluid temperatures—including cooled solutions—to more comprehensively evaluate their impact on fluid absorption, procedural efficiency, and patient-reported outcomes, particularly in longer procedures or those involving larger fibroids where fluid deficit may be clinically limiting.